Category Archives: Genetic Engineering

Introduction

Cancer has been one of the main cause of deaths worldwide and poses a serious challenge and threat to human health. The current clinical therapies used for the treatment of different cancers include surgery, radiotherapy, immunotherapy, hormonal therapy, and chemotherapy. The choice can be monotherapy or combination therapy and depends on several factors like cancer origin, stage, location, and grade.1 Even though these anticancer therapies can be effective, they have certain disadvantages, like: (a) they can cause pharmacological adverse effects at normal tissues; (b) they lack the ability of center-point targeting deep within tumor mass; (c) they mostly acquire drug resistance and are unable to eradicate the entire cancer cell population in the tumor.2 Hence, there is an utmost need to develop some innovative therapeutics that should be simple, cost-effective, and could serve as a substitute to conventional treatments to fight cancer. In this regard, recent advancements in the utilization of tumor-targeting bacteria engineered with different therapeutic payloads have been found to be quite unique and effective strategies of cancer therapy.3

Recently, some microbes, cells, bacteria, and viruses have been found to possess unique characteristics of movement towards tumor microenvironment (TME). Thus, these candidates have been utilized as carriers of antitumor payloads including drug-loaded nanoformulations to target the cancer much more efficiently. These properties are not possessed by conventional antitumor nanoparticles (NPs) alone.

Natural cancer-targeting bacteria have the ability to selectively penetrate, colonize, and degenerate tumors.4 These bacteria can be engineered to perform controlled delivery of specific and diverse therapeutic payloads/drug-loaded nanoformulations into TME at the desired dosage. These therapeutic payloads include cytotoxic proteins, angiogenesis modulators, immunomodulators, prodrug-converting enzymes, small interference RNAs (siRNAs), and drug-loaded nanoformulations, as shown in Figure 1.3,5

Figure 1 Diagrammatic representation of different molecules expressed by engineered-tumor targeting-bacteria, used as therapeutic agents against different cancers.

The toxicity issues on nearby normal tissue are a main concern for systemic injection of therapeutic agents at the tumor site. These complications have led to improve the center-point target delivery of anticancer drugs and drug nanoformulations to enhance the therapeutic potential and minimize the toxic effects. Rapid advancement in the drug-loaded nanomaterials in the past decade has been a powerful thrust for the innovation of cancer treatment. Some nanomaterials like liposomes, micelles, polymers, metal nanoparticles (NPs), etc., have been widely used as drug-loaded targeted delivery vehicles and play a significant role in cancer treatment. These nanocarriers have been loaded with different antitumor drugs, which include doxorubicin, paclitaxel, cisplatin, tamoxifen, etc.68

In comparison to normal tissues, solid tumors are more permeable to therapeutic agents including NPs due to enhanced permeability and retention effect (EPR).9 The EPR-effect is now a well-acknowledged phenomena, validated in different cancer models as well as in cancer patients.10 Cancer tissues with rich blood vessels exhibit a good EPR effect and concomitantly respond to treatments, whereas tumors with reduced blood flow demonstrate poor drug delivery and treatment strategies.11 It has been reported that nitric oxide (NO) is one of the most important factors to enhance the EPR effect through vasodilation, opening of cell junction gaps of endothelial cells, and increasing the blood flow within the hypovascular cancerous mass.

Only a few drug-loaded nanoformulations have shown remarkable success in cancer management, as many challenges still persist in the clinical application of these nanomaterials. The TME is characterized by hypoxia, acidity, immunosuppression, and high interstitial fluid pressure (IFP).12 Therefore, the pinpoint targeted application of nanoformulations at the tumor site is still a challenge which needs to be achieved to effectively eradicate the cancer menace.

Incorporation of specific therapeutic payloads within or on the surface of a particular bacteria as a tool of tumor therapy is now considered as an innovative approach for cancer management. The TME displays a unique environment for an ideal breeding site for some obligate and facultative anaerobic bacteria.13 Bacteria like Bifidobacterium, Clostridium, Escherichia coli (E. coli), and Salmonella typhimurium (S. typhimurium) can preferentially proliferate in immunosuppressive, eutrophic, and hypoxic environments found around tumor tissues. By the use of synthetic biological technology and genetic engineering, these engineered bacteria can achieve center-point targeted delivery of anticancer drugs, specific proteins, antibodies, enzymes, antigens, and cytokines.14

This article reviews the latest developments in engineering some specific tumor-targeting bacteria to enhance further their anticancer potential with immunotherapeutic agents, tumoricidal vectors and enzymes, cytotoxic agents, and drug-loaded NPs. In addition, some bacteria derived therapeutic agents like spores and membrane vesicles to carry different therapeutic payloads to deep sites of diverse tumors are also discussed. Furthermore, the prospects of the future developments and clinical trials for cancer prevention and treatment are also discussed.

Some bacteria love to accumulate at tumor sites as the TME provides a suitable milieu and such microorganisms can reach this area through flagellar motion.15 The obligate and facultative anaerobic bacteria find a suitable habitat within the TME as it is a nutrient-rich territory.9 S. typhimurium and E. coli, as facultative anaerobes, can sense the nutrient-rich and favorable environment through their chemoreceptors and get accumulated in the periphery as well as the core of tumor region.13 Bacteria preferably colonize in these regions as it displays an immunosuppressive environment, so is not usually cleared by neutrophils and macrophages. In contrast, the immune system quickly clears the bacteria present in the circulatory system and other major organs. In comparison to the normal tissue, the cancerous tissue displays a chaotic vasculature and large capillary spacing that impedes the delivery of therapeutic agents. The powerful motor properties of bacteria help it to pass through the blood vessels to reach the tumor area.

Since, no oxygen is needed to survive for obligate anaerobic bacteria, they preferably migrate towards the hypoxic areas of the tumor. The flagellar motility enables some bacteria to overcome the diffusion resistance as Bifidobacterium and Clostridium have been located at hypoxic areas around the tumor. Due to the poor lymphoid fluid drainage and blood vessel leaking, the tumor tissues possess higher IFP.16 The increased IFP hinders the conventional therapeutic agents to reach the deeper tumor mass, thus impacts its uptake by the cancer cells. The engineered bacteria with therapeutic payloads can bypass this predicament by their flagellar motion to reach deep inside the necrotic core.4

Some bacteria like Clostridium spp., Listeria, and Salmonella have innate properties of tumor-targeting, which enables them to target, pierce, proliferate, and reduce solid tumors by different mechanisms.3,4 Clostridium genus bacteria like C. butyricum and C. novyi-NT can survive in hypoxic conditions present around the tumor mass.17 These bacteria can destroy the cancer tissue by exotoxins, which damage the cancer cell membranes and enter these cells and disrupt their essential functions.18 These bacteria can also recruit CD8+ T-cells, macrophages, and granulocytes to the cancerous area and neutrophils mediate the release of TNF-related apoptosis-inducing ligand (TRAIL) (Figure 2).19

Figure 2 Diagrammatic representation of different mechanisms followed by engineered-tumor-targeting-bacteria for cancer therapy.

Listeria spp. bacteria can target the cancer tissue through tumor-infiltrating myeloid-derived suppressor cells (MDSCs), which wander to the immunosuppressive TME. A unique cellcell spread mechanism is involved in the transport of Listeria from MDSCs to cancer cells.20 Listeria spp. bacteria and cytotoxic T-cells in combination directly target the cancer cells and lead to shrinkage of the tumor mass.21 These bacteria can activate NADP(+) oxidase within cancer cells and increase the intracellular Ca2+ level, thus triggering the production of reactive oxygen species (ROS). These biochemical changes lead to direct killing of cancer cells.21 In addition, Listeria spp. can transform some infected MDSCs into immune-stimulating phenotypes that can produce interleukin-12 (IL-12), involved in natural killer (NK) and T-cell response (Figure 2).20

Within the TME, some metabolites produced by quiescent cancer cells act as chemo-attractants for S. typhimurium.22 In the presence of tumor environment, these bacteria proliferate and trigger necrosis, apoptosis, and cell rupture, thus kill the surrounding cancer cells.14 The cancer cells are forced to produce gap junction protein (connexin 43) by Salmonella spp. This protein reduces the immunosuppressive expression of indoleamine 2,3-dioxygenase (IDO) and enhances the transfer and cross-presentation of processed tumor antigenic peptides between cancer cells and dendritic cells (DCs).23 In addition, S. typhimurium flagellin reduces the frequency of regulatory T-cells (Tregs) and enhances the antitumor response of NK and CD8+ T-cells (Figure 2).3

Wild-type probiotics have been used to study bladder cancer, cervical cancer, breast cancer, liver cancer, in addition to colorectal cancer.24 These probiotics can be directly delivered at the TME to reduce non-specific pharmacological effects on normal tissues. The tumor-targeting bacteria and probiotics have some limitations in their use as anticancer agents, as it is challenging to balance the bacterial dosage for therapeutic purpose and the measure of toxicity.14,25 In addition, tumor-targeting and probiotics have limitations in eradicating completely the tumor mass and further probiotics lack the intrinsic therapeutic potential of tumor targeting.17 There is still a problem of high risk infection and toxicity by using these bacteria.26 The intratumoral injection of therapeutic bacteria at tumor sites is a good option to reduce the toxicity and infection rate, but it cannot be used during the metastatic tumor phase.27

Coley used bacilli (Streptococcus pyogenes) for the first time in 1891 for the treatment of osteosarcoma.28 Several mechanisms are involved in bacteria-mediated cancer suppression like the activation of immune system. The concentration of oxygen in the tumor tissue is only 728 mm Hg (14%), while it is 4060 mm Hg (58%) within the normal tissue.29 Bacteria can also recruit inflammatory cells like NK cells and granulocytes for TME, important for anti-tumor response.30 In addition, bacteria can induce CD4+ T-cells in the TME to produce interferon- (IFN-) and can also activate CD8+ T-cells to inhibit tumor growth.31

The toxicity of bacteria can be minimized with the aid of genetic modifications in addition to enhanced selective targeting.13 It involves the chromosomal deletion of purI and msbB genes of S. typhimurium (VNP20009) to reduce their septic shock and virulence.32 In addition, the leu-arg-deficient genetically modified S. typhimurium A139 strain possesses exceptional tumor-targeting ability.33

The therapeutic role of bacteria can be classified into three groups as: (a) antitumor immune activation, (b) secretion of bacterial toxins, and (c) swelling and apoptosis of tumor cells by invaded bacteria. Bacteria demonstrate wonderful immune activation capability. For example, dendritic cells and macrophages get colonized in the presence of Salmonella and are induced to produce interleukin-1 (IL-1). These bacteria also lead to connexin 43 (Cx43) upregulation and the gap junctions formation between tumor and the dendritic cells,34 that leads to significant anticancer immune response. Further, the inflammatory response is also activated through pathogen-associated molecular patterns (PAMPs), which facilitates cytokine release that contributes to cancer immunotherapy.35 For example, toll-like receptor 4 (TLR4) signal transduction is induced by lipopolysaccharides (LPS) that promotes IL-1 production from the macrophages.36 In addition, the NK cells are stimulated by the flagellin that induces the production of IFN- (Figure 2).37

The toxins produced from bacteria can activate apoptotic pathways. For example, cytolysin A (ClyA) mediates caspase induced cell death and also forms gaps within the cell membranes.38 ClyA, produced from E. coli K-12, inhibits the cancer growth. In addition, the tumor progression is correlated with nitric oxide (NO) level. The higher level of NO mediates apoptosis of cancer cells, resulting in tumor regression.39

As microscopic robots, bacteria can be reprogrammed following simple genetic rules or sophisticated synthetic bioengineering principles to produce and deliver antitumor agents based on the clinical needs. The engineering of bacteria to combat cancer is performed at different levels as virulence attenuation, enhancement of tumor targeting, targeting the tumor stroma, drug expression strategies, and the expression of cytotoxic agents. In addition, the engineering of tumor-targeting bacteria is also achieved through the biosynthesis of metal NPs and delivery of drug-loaded nanoformulations. Furthermore, the bacterial spores and bacterial membrane vesicles are also utilized as an anticancer strategy. All these strategies of antitumor approaches are briefly discussed here:

While using specific bacteria against a cancer, it is very important to minimize their virulence against the host immune system, keeping in view that the intrinsic antitumor activity of some bacteria are due to their virulence factors.30,40 Therefore, the antitumor activity of a bacteria should not be lost while attenuating them. Some highly toxic bacterial strains have been attenuated to safer strains through the deletion of major virulence genes. Deletion of purI and msbB genes in S. typhimurium led to the formation of VNP20009 strain, which is extensively used in cancer-bearing mice for different antitumor studies.41 This strain has been accordingly tested in Phase I trials in human cancers, but the outcome has been disappointing.42 The failure is expected to be due to penta-acylated lipid A, a toll-like receptor 4 (TLR4) antagonist.43 New mutant Salmonella strains have been engineered by the deletion of pagL, pagP, and 1pxR genes to produce hexa-acylated lipid A with high affinity for TLR.44

The lipopolysaccharide (LPS)-driven septic shock has also been reduced dramatically by the deletion of msbB gene in Salmonella genus.45 The integration of LPS gene within chromosome in araBAD locus resulted in production of strains with attenuated virulence and enhanced therapeutic effects.46 The downregulation of endotoxin-associated genes led to the formation of another nontoxic Salmonella strain. Salmonella spoT and relA-mutant strains exhibited negligible toxicity as these strains are defective in ppGpp, signaling molecules involved in toxin gene expression. These strains exhibited excellent antitumor activity through the activation of inflammasome (IPAF, NLRP3), which can induce the expression of numerous proinflammatory cytokines.

The cytotoxicity of L. monocytogenes is achieved by the deletion of genes, involved in cell invasion and defects in phagolysosome release, achieved by HIy deletion.47 Mutant strains of L. monocytogenes lacking inIA and inIB are invasion defective and the strains lacking ActA or actA PESTf-like sequences also lack intracellular diffusion ability.48 The additional approach to attenuate virulence with enhanced tumor-specific proliferation is achieved by the introduction of specific nutrient-dependent mutations in bacteria. The examples of some attenuated strains of several tumor-targeting bacteria and their description is listed in Table 1.

Table 1 Description of Some Genetically Modified Bacterial Strains Used for Tumor Therapy

The approaches to enhance the bacterial tumor targeting can also improve both antitumor efficacy as well as safety aspects. Regarding this approach, the ppGpp-deficient strain SHJ2037 has been genetically engineered to exhibit cancer-specific ligands on its cell surface. An v3 integrin binding with Arg-Gly-Asp peptide has been fused to protein A on the outer membrane to drive its expression.57 The resulted strains possessed enhanced cancer-specific activity and significantly augmented antitumor activity in mDA-MB-435 melanoma xenografts overexpressing v3 integrin and mDA-MB-231 breast cancer cells. The bacteria have also been engineered to target tumor-associated genes like lymphoma-associated antigen CD20 and carcinoembryonic antigen (CEA). These strains possess reduced non-specific accumulation in the spleen and liver and effective antitumor activity.58 The bacteria L. monocytogenes were coated with plasmid-loaded NPs expressing bioluminescence genes to exploit biotin-streptavidin binding. This strain, known as microrobot, could be traced by the bioluminescence imaging as it delivers the functional nucleic acid molecules within the solid tumors.59

A fascinating alternative to enhance the tumor selectivity is achieved by displaying synthetic adhesins (SAs) on the E. coli surface. These adhesins have a modular structure with stable -domain needed for outer membrane anchoring and surface exposed antibody domains with high specificity and affinity which can be selected from large libraries.60 Some probiotic strains have been designed with enhanced tumor specificity and increased injection capacity of bacteria.61

The cancer growth and metastasis is equally supported by angiogenesis, and targeting this tumor neovascularization offers a favorable trend for cancer therapy. Endostatin (20 kDa C-terminal fragment from type XVIII collagen) has been found to possess inhibitory potential on tumor vessel formation with least side-effects or drug resistance.62 The attenuated strain of S. typhimurium was cloned with endostatin and siRNA against transducer and activator of Stat3 and the therapeutic efficacy was investigated on HCC. It showed satisfactory reduction in cancer proliferation and metastasis and reduced the tumor vasculature as well. This strategy led to the downregulation of VEGF expression, regulatory T-cells and TGF- expression. In addition, there was an enhancement in inflammatory cytokines including TNF- and IFN- and increased CD4+/CD8+ T-cell population.63

VEGF and its receptor (VEGFR) are well known tumor angiogenesis proteins. S. typhimurium (SL3261) expresses the extracellular VEGFR2 domain and the oral administration of this strain led to reduced pulmonary metastasis, neovascularization, and tumor growth. In addition, the administration of this strain led to an increased population of CD4+ and CD8+ T-cells near tumor regions.64

Endoglin (CD105) is a member of the TGF- receptor family and its gene promoter is overexpressed in tumoral endothelial cells. Hypoxia and TGF-1 are known to upregulate the endoglin gene promoter. Therefore, targeting the endoglin is considered as a novel strategy of cancer therapy.65 In mouse breast cancer models, Listeria based vaccines have been used against CD105, Lm-LLO-CD105A, and Lm-LLO-CD105B as a treatment strategy. Such vaccines inhibited primary and metastatic tumors by the reduction of angiogenesis and elevated antitumor immune response.66

A strict control over the production and targeting of most payloads by tumor-targeting bacteria is of utmost importance as these are toxic to both normal and tumor cells. A precise trigger for the payload expression can minimize its systemic toxicity while maximizing its therapeutic effect. By the insertion of a specific promoter sequence upstream of a drug-encoding gene, a controllable gene expression can be maintained, convening transcriptional control through external signals. The triggering for gene regulation is mainly classified into three categories as (a) internal triggering, (b) self-triggering (quorum sensing-QS), and (c) external triggering.67 The special properties of TME like acidosis, hypoxia, and necrosis are sensed by tumor-targeting bacteria, which are utilized to improve their cancer specificity. It includes hypoxia inducible promoters (HIP-1) and pepT, activated by nitrate and fumarate reduction present in the hypoxic environment of cancerous tissue.68 This hypoxia-inducible expression method was proposed to function during anaerobic conditions only to express essential genes like asd. Furthermore, a glucose sensor has also been engineered in E. coli to sense the glucose level in TME leading to its therapeutic effect.69

The expression of cytotoxic agents can be firmly regulated to check their toxic potential on normal tissues. Bacteria like E. coli, Paratyphi A, and S. typhimurium produce a 34 kDa pore-forming hemolytic protein known as cytolysin A (ClyA), secreted without any post-translational modifications. Several bacterial strains have been engineered to express ClyA from a constitutive promoter.70 In addition, ClyA is programmed to express from inducible promoters activated by doxycycline and arabinose, and excellent tumor inhibition has been reported.

The induction of apoptosis in cancer cells is a novel alternative of tumor management. In this regard, apoptin, a virus-derived protein in chicken, has been selectively used to induce apoptosis in different human cancer cell types through the p53-independent, Bcl-2-insensitive pathway.71 A significant cancer reduction with minimal systemic toxicity has been observed in human laryngeal cancer-bearing mice by the transformation of apoptin-encoding eukaryotic expression plasmid (pCDNA3.1) into the attenuated S. typhimurium strain.

Some other cytotoxic agents for the induction of apoptosis, like Fas ligands, TNF-, and TRAIL, have limited use due to their hepatotoxicity and short half-life.72 Some bacterial strains have been used to deliver these proteins directly within the cancerous tissues to overcome these limitations.

Yersinia express invasin on its surface which can selectively bind to 1 integrin and triggers bacterial entry into host cells. In mice, the introduction of E. coli strain co-expressing invasin, ovalbumin, as well as LLO has been shown to invade 1-integrin, expressing tumor cells to show strong therapeutic effects.73 Furthermore, azurin is a low-molecular weight redox protein which initiates cancer cell apoptosis through its internalization. This protein helps to release cytochrome c from mitochondria by raising the intracellular level of p53 and Bax. The E. coli based azurin delivery has been reported to suppress 4T1 mouse breast cancer and B16 mouse melanoma, and this approach stimulates inflammatory response and prevents pulmonary metastasis.74

Some specifically engineered bacteria have played a significant role in transporting different types of payloads up to extracellular TME and intracellular locations of tumor cells. Employment of some novel nanocarriers for conventional drugs and therapeutic agents helps to improve their bioavailability and pharmacodynamic and pharmacokinetic parameters. Different types of nanomaterials are used to improve the solubility of anticancer drugs, prolong circulation time, and enhance their accumulation within the TME. Native drug-loaded nanoformulations encounter diffusion limitations in the extracellular matrix and get accumulated in the periphery of the tumor rather than in the hypoxic core of the tumor.

Non-pathogenic strains of S. typhimurium have been engineered under the control of prokaryotic radiation-inducible RecA promoter to secrete TRAIL protein. The TRAIL protein induces its toxicity through caspase-3 activation. On irradiation, S. typhimurium secreted TRAIL can lead to caspase-3-mediated apoptosis and death in 4T1 breast cancer cells in culture. In mice, the systemic injection of these engineered bacteria led to TRAIL expression by 2Gy -irradiation with delayed breast cancer growth.75

In E. coli, invasin genes have been cloned to express the invasin proteins.76 These proteins are normally exploited by Y. pseudotuberculosis as an entry pass into the host cells during their invasion. The invasins bind with 1-integrin proteins expressed by cancerous and epithelial cells. The invasins enter the host cells through receptor-mediated endocytosis and exploit their anticancerous activity.

In the host cells, E. coli are armed with listeriolysin O (LLO), which forms pores in the lysosomes.76 The expression of invasins in the cytosol results in cancer cell death. In addition, E. coli also helps to boost the immune system at the infection site and systematically with PAMPs expressed, recognized by Pattern Recognition Receptors (PRRs) on immune cells. The interaction of immune cells with PAMPs leads to reactive nitrogen and ROS release. This interaction also leads to the activation of T lymphocytes like CD4+ T-cells and CD8+ T-cells, which are capable of halting further proliferation of tumor cells (Figure 2).

The E. coli derived enzyme asparaginase (L-ASNase) has been utilized for the treatment of acute lymphocytic leukemia.77 This enzyme catalyzes the formation of aspartate from asparagine and to some extent forms glutamate from glutamine and both the reactions are important for cancer treatment.78 A treatment strategy was devised for acute lymphoblastic leukemia by using Salmonella bacteria expressing L-ASNase. The araBAD E. coli inducible promoter was used to design Salmonella cells to deliver L-ASNase to cancer cells.79

A promising approach to cancer therapy has been achieved by silencing specific target genes by using small interference RNAs (siRNAs). The greatest challenge to RNA interference therapy is the requirement of a specific delivery system for siRNAs to the tumor region. Mouse models have been investigated to check the activity of siRNA through bacteria-based delivery systems against indoleamine 2,3-dioxygenase (IDO),80 Stat,63 Sox,81 survivin,82 and the cell cycle-associated polo-like kinase 1 (PLK1).

Recombinant Salmonella has been orally administered in tumor-bearing nude mice, leads to decreased cancer growth, and displayed more sensitivity towards cis-diamine-dichloroplatinum (II) (DDP). Transforming growth factor- (TGF-) is a naturally occurring ligand for EGFR, which is overexpressed in tumor cells. A recombinant immunotoxin like PE38 has been constructed by conjugating TGF- and laboratory-engineered Pseudomonas exotoxin A. Tumors in the mouse model as well as in vitro, PE38 exhibit a toxic effect on cancer cells which express EGFR.83 However, dose-dependent hepatotoxicity has been reported by systemic injection of TGF--PE38.84

In one study, DppGpp Salmonella mutant expressing recombinant TGF-PE38 were investigated, which showed neither attack nor proliferation within mammalian cells,85 but exerted their anticancer effects by the expression of proinflammatory cytokines from neutrophils and macrophages, such as TNF and IL-1.79 The study included the construction of a plasmid with DNA encoding TGF-PE38, inserted into Salmonella cells. Breast and colon tumors with enhanced levels of EGFR expression in mouse models were employed for this study. An inducible system based on PBAD promoter from E. coli was used.86 For the export of TGF-PE38 recombinant protein from Salmonella, an engineered phage lysis system was employed as a bacterial membrane transport signal, fused to the proteins.87 Both these approaches were found to be effective. It was observed that TGF-PE38 produced from bacteria reduced cancer progression as compared to non-engineered Salmonella alone.87 Increased expression of EGFR was observed by the treatment with TGF-PE38 in cancer cells which induced the apoptosis consequently. Therefore, bacteria can be an innovative strategy for enhancing the effectiveness of immunotoxins for cancer treatment.88

A study was performed to investigate the cytotoxic activity of Salmonella strain equipped with salicylate-inducible expression apparatus, that modulates the expression of cytosine deaminase (CD).89 5-FU resistant Salmonella strains were produced for the increased production of bacterial CD. In addition, purD mutation was developed to regulate the intracellular proliferation in the presence of adenine as well as to prevent intracellular Salmonella death. This approach led to the production of Salmonella strains CD to kill cancer cells in the presence of 5-FU.89 As compared to other cancer-targeting bacteria, engineered Salmonella strains have attained a special momentum in the delivery of antitumor payloads within the TME. Table 2 describes some examples of anticancer agents delivered by different Salmonella strains.

Table 2 Some Examples of Anticancer Agents Delivered or Targeted by Different Salmonella Strains

Cytokines are well-known to have antitumor potential by inducing apoptosis in tumor cells. These molecules can activate, proliferate, and differentiate immune cells via anti-angiogenesis effects on tumor vasculature. Different cytokines like IL-12, IL-18, and GM-CSF have been checked for clinical trials for tumor therapy.104 Several cytokines have been delivered in the TME by tumor-targeting bacteria, where it augments the antitumor immune response. The primary tumor growth in mice was potentially inhibited by the intravenous administration of attenuated S. typhimurium strain expressing IL-18. This led to increased number of CD4+ T and NK cells and massive leukocyte infiltration (especially granulocyte) at TME. This approach also led to enhanced cytokine production at TME including IFN-, IL-1, TNF-, and GM-CSF.105

The delivery of tumor associated antigens led by engineered bacteria can sensitize TME and overcome the self-tolerance provoked by the regulatory T-cells, thus elicit effector and memory T-cell response towards the antigen-producing cancer cells.106 Different prostate cancer-associated antigens like prostate-specific antigen (PSA) have been worked out by bacteria-based vaccines tested on several mouse models.107 The gene delivery of endogenous PSA has been performed by using attenuated S. typhimurium (SL7207), which led to alleviated immune response in murine prostate cell antigens and considerably reduced the tumor growth.92

Some promising cancer inhibition effects have also been observed by using a gene therapy approach by using antigens against HER-2/neu,108 Mage-b, NY-ESO,109 and Survivin.110 All these findings led to deep interest in the field of immune checkpoint blockade (ICB) cancer therapy. The success of ICB therapy during clinical trials has been limited to only a few patients, some reasons include host resistance like immunosuppressive TME.111 The bacterial tumor colonization can induce proinflammatory reactions involving enhanced expression of IFN-, IL-1, and TNF-, as well as NK and T-cell activation, thus a combination of bacterial therapies and ICB can overcome the host resistance.112

The conversion of prodrugs into cytotoxic agents by the expression of prodrug-converting enzymes is a smart strategy of tumor eradication. This method reduces the side-effects associated with systemic administration and improves the cancer treatment efficacy. Bacteria have been used to deliver prodrug-converting enzymes.112 These enzymes include cytosine deaminase (CD), which converts nontoxic 5-fluorocytosine (5-FC) into a chemotherapeutic agent, 5-fluorouracil (5-FU) (Figure 2). This drug is highly toxic as it is metabolized to a product which interferes with the DNA and RNA synthesis.113 Another prodrug-converting enzyme/prodrug combination includes the herpes simplex virus type I thymidine kinase/ganciclovir (HSV1-TK/GCV) system, widely studied for tumor therapy. The expression of cancer-specific HSV1-TK can convert nontoxic precursor ganciclovir into a toxic form, ganciclovir-3-phosphate, that kills the cancer cells. The in vivo efficacy of Bifidobacterium infantis strain expressing HSV1-TK and GCV was examined in a rat bladder cancer model. This led to an efficient and targeted approach inhibiting the cancer effectively via apoptosis through the enhanced expression of caspase 3.112

E. coli DH5 is a good example of a prodrug-converting enzyme strain which expresses -glucuronidase that hydrolyzes glucuronide prodrug 9ACG into 9-aminocamptothecin (9AC), a topoisomerase I inhibitor which efficiently inhibits tumors.114 Furthermore, the attenuated S. typhimurium (VNP20009) has been used as a vector to deliver carboxypeptidase G2 that exhibits enhanced anticancer activity in conjunction with prodrug administration.115

Liposomes have gained a special importance as active vehicles for the delivery of diverse therapeutic compounds. The surface modifications of conventional liposomes with different ligands have led to the formation of second generation liposomes, with higher drug loading capacity, targeted drug-delivery, and enhanced anticancer activity.116 A novel anticancer therapeutic strategy was designed by using anticancer drug, paclitaxel (PTX) containing liposomes within S. typhimurium. This procedure was initiated by binding biotin molecules on the outer membrane proteins of bacteria and consequently streptavidin molecules were coated on the PTX-loaded liposomes. The motility analysis of bacteria-loaded liposomes exhibited higher average velocity as compared to free bacteria. The cytotoxicity tests were performed on breast cancer cell line (4T1) to figure out the anticancer therapeutic efficacy of the PTX-containing liposome loaded bacteria. In addition, tumor targeting bacteria displayed robust cancer-targeting ability. These findings reveal that engineered bacteria could be an efficient alternative for anticancer therapy.117

Salmonella were loaded with low-temperature sensitive anticancer drug doxorubicin (DOX) loaded within liposomes targeting colon cancer cells to deliver this drug and simultaneously macrophages polarized to M1 phenotype with high intensity focused ultrasound heating (4042C). The studies showed that the liposomal loading was highly efficient without affecting the bacterial viability. These drug-loaded liposome-containing bacteria demonstrated efficient intracellular trafficking, excellent nuclear localization of DOX, and induced in vitro pro-inflammatory cytokine expression of colon cancer. By using murine colon tumor models, these engineered bacteria significantly enhanced the therapeutic efficacy and macrophage polarization to M1 phenotypes as compared to control samples. Further, these bacteria focused ultrasound treatments, which have the potential to improve the colon cancer therapy.118

Bacterial membrane-based nanoformulations include bacteria-derived nanovesicles (BDNVs) and bacterial membrane-coated NPs. BDNVs range in size from 20400 nm, composed of double lipid layer. BDNVs are mainly classified into four groups based on their source and structure as: outer membrane vesicles (OMVs), outer-inner membrane vesicles (OIMVs), double-layered membrane vesicles (DMBs), and cytoplasmic membrane vesicles (CMVs).119 The BDNVs have been used against cancer, due to their cancer penetration ability, surface modification, and drug loading capacity.

Several genetically modified bacteria including E. coli derived 400 nm nanovesicles have been loaded with chemotherapeutic agents like DOX.120 The feasibility of using BDNVs to transport/deliver siRNA for drug-resistant cancer treatment has also been reported.121 Table 3 lists examples of some cargo items delivered by bacterial membrane vesicles derived from different bacteria for the strategy of cancer management.

Table 3 Efficacy of Different Therapeutic Agents Loaded in Bacterial Membrane and Targeted Against Different Cancers

In addition to gene and drug carrying potential, BDNVs also hold the capability of activating the immune response against cancer. Diverse immunostimulatory molecules loaded in OMVs have been investigated recently for vaccine and delivery system usage. The anticancer command of genetically modified E. coli derived OMVs exhibited excellent tumor-targeting ability due to their enhanced EPR effect.130 Some immunomodulatory agents induce the production of anticancer agents like CXCL10 and IFN-, which can successfully eradicate the established tumors.

The OMVs derived from E. coli BL21 cells have been chemically modified with Calcium phosphate (CaP) shells. These pH-sensitive shells neutralize the acidic TME to polarize the cancer-associated macrophages and avoid the severe systemic inflammation potentially induced by CaP free OMVs. The anti-inflammatory M2 macrophage phenotypes synergized with the intrinsic immunostimulatory effect of OMVs, have eventually led to a 60% survival rate at day 80 compared with day 0 in the group applying naked OMVs.

BDNVs have also been loaded with NPs to provide additional functions like photosensitivity. Bacteria-cancer cell hybrid membrane-coated photosensitizing hollow polydopamine NPs have been synthesized recently for the approach of cancer eradication (Figure 3).131 The anticancer cytokines were potentially produced by bacterial membranes through different immunostimulatory membrane components.

Figure 3 Diagrammatic representation of hollow polydopamine-NPs synthesis from the membranes of tumor-targeting-bacteria and cancer cells and its injection and immunotherapy/photothermal therapy in animal cancer models.

Cancer cell membrane proteins serve as excellent tumor antigens, which synergize with anticancer cytokines and induce a substantial immune response. The combination of photothermal treatment and anticancer immune therapy has been reported to eradicate melanoma. Further, the uploading of NPs within bacterial membranes adds the functionality in photothermal response and also helps to enhance the immune response to fight against cancer (Figure 3).

Bifidobacterium longum (B. longum) have been engineered to conjugate poly(lactic-co-glycolic acid) (PLGA) NPs (PLGA-NPs) targeting the tumor specifically to achieve precision treatment and imaging. B. longum selectively colonizes in hypoxic regions of the animal body, successfully targeting into solid tumors. Further, perfluorohexane (PFH) has been used to wrap the core of PLGA-NPs to improve its specificity and efficacy for cancer therapy. PFH/PLGA-NPs kills the cancer cells by the deposition of energy by affecting the acoustic environment during High Intensity Focused Ultrasound (HIFU) irradiation. This strategy has been effective in treatment and diagnosis, providing stronger imaging, a longer retention period, and much better tumor therapy.132

A combination of bacteriolytic therapy (COBALT) strategy was applied by using C. novyi devoid of its lethal toxin (C. novyi-NT) spores loaded with conventional chemotherapeutic drugs. It led to extensive antitumor capability against hemorrhagic cancer.133 Bacteria-facilitated NPs delivery into the cancer cells takes the advantage of the invasive property of these microorganisms. The drug-loaded cargos are not carried inside the bacteria, rather these payloads remain attached on the microorganism surface.

S. typhimurium bacteria have been precisely engineered to transport drug-loaded nanoformulations and penetrate prostate cancer cells to deliver their antitumor cargos. Some methods established for the cargo loading and delivery include the attachment of NPs to the Salmonella membrane. The example includes the sucrose-conjugated AuNPs attached to the surface of Salmonella bacteria. The other method includes the attachment of streptavidin-conjugated fluorophores on biotinylated Salmonella membrane, that enhances the transport of and drug delivery.134

Bacteria have been significantly employed for the biosynthesis of metal NPs. The bacterial synthesis of NPs involves spontaneous and simple biochemical and biophysical processes leading to the formation of monodisperse and stable formulations. The exact mechanism of its biosynthesis at molecular level is not yet well understood.135 The bacteria exploit different mechanisms like biosorption, solubility changes, extracellular precipitation, bioaccumulation, chelation, and metal complexation for the synthesis of metal NPs involving reducing NAD(P)H-dependent enzymes like cysteine desulfhydrase, glutathione, nitrate reductase, and sulphite reductase.136

Diversified bacteria growing in extreme environmental condition like archaea,137 Deinococcus radiodurans,138 and marine139 ecosystem have been associated with metal NPs biosynthesis. Metal NPs, especially belonging to heavy and toxic group namely Au, Ag, Cd, Ni, Pd, Pt, Se, Ti and some metal oxides like CeO2, Fe3O4, TiO2, Zirconia, and ZnO along with their functional derivatives, have been reported to be synthesized by bacteria.140

The anticancer activity of S. rochei HMM13 synthesized silver NPs (AgNPs) has been checked on different tumor cell lines like breast carcinoma cells (MCF-7), hepatocellular carcinoma cells (HepG-2), prostate carcinoma cells (PC-3), colon carcinoma cells (HCT-116), intestinal carcinoma cells (CACO), lung carcinoma cells (A-549), cervical carcinoma cells (HELA), and larynx carcinoma cells (HEP-2). The percentage of all these different cancer cell lines demonstrated a dose-dependent decrease in their viability percentage by the exposure of these NPs.

The uptake of AgNPs by different tumor cells are catabolized to form amino acids and Ag ions.141 The released Ag+ cations interact with cellular macromolecules like DNA and proteins. These ions lead to protein modifications, DNA damage, and enhanced mitochondrial permeability of cancer cells resulting in enhanced oxidative stress. All these changes in cancer cells push them to apoptosis.142

Magnetically controlled biosensors, contrast agents in MRI diagnosis, and drug delivery system popularly consist of superparamagnetic iron oxide (FeO) nanoparticles (FeONPs).143 Magnetotactic bacteria exclusively contain magnetosomes, unique lipid bound organelles, and provide some special characteristics to these bacteria for cancer management. These magnetosomes possess narrow size distribution, regular morphology, resistance to agglomeration, and low toxicity profile, which makes them excellent for drug and gene delivery applications. The magnetosomes are nanometer-sized crystals, naturally synthesized through cytoplasmic membrane invaginations, followed by influx of iron and certain proteins, leading to magnetite crystal biomineralization.144 These bacteria belong to the -Proteobacteria group and are mostly Gram-negative, having a micro-aerobic or anaerobic type of metabolism.145 These bacteria are capable to produce naturally iron sulfide (greigite) and iron oxide (magnetite) NPs covered by a lipid bilayer.

The magnetosomes help in aligning the bacteria for external magnetic fields and optimal nutrient and oxygen conditions. The magnetosomes have been isolated from bacteria and have been useful in medical applications like peptide screening in drug development.146 Further, these magnetosomes have been utilized for anticancer gene therapy and drug delivery.147 These specialized bacteria have gained a distinct position as a smart drug delivery system in cancer patients.148

The chain alignment of magnetosomes in Magnetospirillum gryphiswaldense is aligned to enhance the hyperthermia outcome during cancer therapeutics.149 In comparison to FeONPs, magnetosomes have been reported with enhanced efficacy as MRI-contrast agents.150 As a heat sensitive system, bacterial magnetosomes have been used as a smart chemotherapeutic approach.

The magneto-aerotactic behavior of Magnetococcus marinus strain MC-1 has been exploited to transport up to 70 drug-loaded nanoliposomes till extremely low oxygen regions of the cancerous tissue. It has been reported that up to 55% of drug-loaded bacterial cells can penetrate the colorectal xenograft in severe combined immunodeficiency (SCID)-mice.151 Bacterial magnetic nanoparticles (BMN) have been coated with polyethyleneimine (PEI), resulting in a size range of 4555 nm, used to transfect DNA in mammalian cell lines.152

In comparison with the older methods, the bacterial magnetosomes have been complexed with anticancer antibodies (BM-Ab) to achieve greater antitumor efficacy under the magnetic therapy.153 For the application in drug delivery and imaging protocols, these magnetic and AuNPs have been used as efficient theranostic agents.154 Magnetotactic bacteria derived magnetosomes have been conjugated with Au nanorods and folic acid to form nanohybrids. These nanohybrids serve as effective theranostic agents for the detection and photomechanical killing of cancer cells.155 These NPs have been applied as high contrast probes to seek out even single-cell diagnostics as well as photothermal agents for single-cell therapy (Figure 2). The application, efficacy, and theranostic mechanisms of different types of metal nanoformulations, delivered by diverse tumor targeting strains of bacteria, are summarized further in Table 4.

Table 4 Summary of Different Metal Based Drug-Nanoformulations Loaded in Various Tumor-Targeting Bacteria for Cancer Therapy

The majority of anaerobic bacteria produce highly resistant spores which can survive even in an oxygen-rich environment. Once the favorable conditions like that of TME are met, these spores germinate and the bacteria thrive accordingly, targeting the nearby cancer cells. C. novyi-NT bacteria are genetically modified to be devoid of lethal toxins which target cancer cells without involving side-effects.173 An intratumoral injection of C. histolyticum spores in mice resulted in marked lysis of cancerous tissue. A similar phenomenon has been observed by intravenous injection of C. sporogenes spores in mice.156 The spores of C. novyi-NT are rapidly cleared by the reticuloendothelial system from circulation as observed by toxicological and pharmacological evaluation. Injection of these spores in healthy rabbits or mice even with large doses showed no clinical toxicity. However, the toxicity was related to spores dosage and tumor size in diseased mice.174 In addition, bacterial spores have also been used as carriers of anticancer drug delivery agents, therapeutic proteins, gene therapy vectors, and cytotoxic peptides.175

A brief description of some important anticancer agents delivered by tumor-targeting bacteria near or within cancer cells and their concise mechanism of action has been described in various articles and is illustrated in Figure 4.

Figure 4 Some examples of anticancer agents delivered by different tumor-targeting bacteria and their brief mechanism of action.

It has been reported that only a few bacteria reach TME on their own, so active research is going on in engineering other bacteria to carry or produce and deliver anticancer compounds within the tumor regions. The clinicians need to effectively navigate bacterial therapies near cancer sites, as most tumors are inaccessible by direct injection of antitumor agents. Further, the engineered bacteria should controllably and reliably release their anticancer drugs they carry or encode.176 The incorporation of synthetic compounds within the live bacteria can allow remote control guidance of certain actions or functionality. The light has a limited ability to penetrate the cancerous tissues which hampers its approach, even though optically triggered navigation and control have enormous potential. The use of ultrasound has filled some gaps, as it has a broad range of applications in medical diagnostics and monitoring.177

Recently, to augment the ultrasound images of tissues, gas-filled microbubbles have been used due to their distinct and strong acoustic response. In addition, some special forms of super-powered and focused ultrasound have been used to boost the transport of drug-loaded nanobubbles by the use of acoustic pressure waves as an external energy source to push it to deeper regions of TME. This tactic has achieved some promising results in glioblastoma, as the bloodbrain barrier (BBB) is a challenge to overcome for drug transport.178

In the recent past, ultrasound has been used to track the bacteria for therapeutic purposes in vivo. Bacteria have been genetically engineered to express the acoustic reporter gene (ARG), which encodes the compounds of gas vesicles that scatter ultrasound waves, thus generating an echo to enable the bacterial location deep inside living mice.179 The application of magnetic fields is another source of external energy which can be remotely and safely used in the human body.

The advantage that anaerobic bacteria tend to shift to low oxygen environment, coupled with anticancer drugs and the natural homing mechanism of an externally directing magnetic field, has demonstrated enhanced penetration and accumulation for therapy in mouse tumors. The magnetotactic bacteria act like little propellers on a rotating magnetic field with tissue models on a chip, creating a flow that pushes nanomedicine out of the blood vessels and deeper in tissues.

Attaching magnetic materials to non-magnetic bacteria is an alternative to control such bacteria by the external magnetic field.180 Tiny magnetic NPs have been attached to E. coli in addition with DOX and upon treatment with cancer cells, it has been reported that such bacteria are remotely controlled by the magnetic field to improve their tumor targeting.181 The science of external energy source and controllable genetically engineered bacteria are a fascinating new direction in the field of cancer management. The convergence of mechanical engineering, synthetic biology, and robotics has opened up a new approach of using tiny robots to destroy different cancer types.182

For the management of cancer in human subjects, different bacterial strains have been selected since the use of live bacteria by Dr. Coley in 1891.183 Among different bacterial species, Listeria vaccine strains have shown promising results, and some strains are tested in Phase II and Phase III clinical trials.184 The attenuated strain of S. typhimurium (VNP20009) was the first strain to enter a phase I human clinical trial in 1999, tested on 24 patients with metastatic melanoma and metastatic renal carcinoma. Although different proinflammatory cytokines like IL-1, IL-6, IL-12, and TNF- were reported to be raised in some patients, no objective tumor regression was reported.185 S. typhimurium (VNP20009) was used in another clinical trial involving metastatic melanoma patients, but no remarkable tumor response was reported.186 To enhance the therapeutic potential, S. typhimurium (VNP20009) was engineered to express E. coli CD, that converts 5-FC to toxic 5-FU. An intratumoral injection of these bacteria was used in three patients suffering from esophageal adenocarcinoma and head and neck squamous carcinoma. Even after the six treatment cycles, no significant adverse response was observed in these patients.

Recently, some other phase I clinical trials have been reported by using S. typhimurium (VNP20009) and S. typhimurium (4550) expressing IL-2, as summarized in Table 5. The conclusion of these trials disclosed that the differences between human patients and preclinical animal models might be due to dissimilarities in tumor structure and growth rates that might alter bacterial TME behavior. The clinical trials by Salmonella spp. have demonstrated that TLR4-mediated signaling is important for tumor colonization and antitumor activity, as a VNP20009 strain missing lipid A function was unsuccessful to colonize tumor sufficiently to suppress tumor growth. Although limited, these clinical trials have revealed some significant hurdles and some challenges that must be overcome for successful human application in the future. Some examples of clinical trials using several bacteria are listed in Table 5.

Table 5 Previous and Ongoing Clinical Trials Involving Tumor-Targeting Bacteria and Cancer Bearing Human Subjects

The complete treatment of cancer is considered a challenging task as hypovascular areas provide inadequate access to drug-loaded nanoformulations. Even though some tumor-targeting bacteria have been genetically engineered to combat various cancers, several future studies are needed to address and expediate the further advancement of nanobiohybrid systems in tumor therapy.

These prospective studies need to know the shape of the nanoformulations as it is a significant parameter for nanobiohybrid systems, which impacts on bacterial transport efficiency. The loading quantity and volume of nanomaterials also affect the bacterial movement. In addition, the performance of nanobiohybrid interaction between nanomaterials and bacteria is of utmost importance to adopt varied loading strategies based on different nanomaterials to augment the performance. The attachment of NPs on the bacterial surface can affect bacterial chemoreceptors in response to TME. Therefore, abiotic/biological interfaces need to be carefully designed to conserve the chemotaxis and bacterial mobility.

The role of exogenous and endogenous stimuli is very important for the release of nanomaterials from the bacteria at tumor regions. It is very significant to known the spatiotemporal control of drug action at the heterogeneous environment of tumors. Furthermore, the limitations of metal toxicity in living systems need an act of balancing between the positive therapeutic effects of metal oxide NPs and their toxic side-effects.190 Any delayed elimination or absence of dissolution/biodegradation can be followed by generation of intracellular ROS, DNA damage that triggers apoptotic cell death.191

The possession of bacterial immunogenicity and toxicity is very important to ensure the safety aspects. Even though a variety of bacteria are non-pathogenic, the possible toxicity may threaten immunocompromised patients with advanced stage cancer. Engineering bacteria to knock out virulence genes is of utmost importance. In addition, the complexity of the biological environment makes it necessary to develop feasible methods to control the noncatalytic therapy process to inhibit adverse catalytic reactions and prevent any damage to normal tissue. The lack of information on diverse mechanisms and side-effects of bacterial cancer therapy with development of smart microorganisms to treat specific cancers remains a significant challenge.

The therapeutic potential of different bacteria for the cancer management has been taken into significant consideration in the recent decade. Numerous bacteria possess great potential as anticancer strategies, however, this novel therapeutic approach has both advantages as well as disadvantages. The tumor-targeting bacteria possess several unique features like tumor selectivity and genetic modification capabilities. The center-point targeting of anticancer therapeutic payloads through specific bacteria is still a challenging task which can be resolved by a proper understanding about drug-nanoformulation design and its loading within bacteria, bacterial genetic setup, modifications, etc. Recent advancement in microbiology, drug-nanoformulations, and genetic engineering on the same desk have guided some anticancer bacteria to deliver different anticancer payloads at tumor sites with high precision. The bacterial anticancer therapy is still at its basic stage and more future research needs to be conducted to bypass the limitations and side-effects of this therapy by using genetic engineering and precise modifications of some antitumor agents. Despite the promising in vivo and in vitro results of anticancer bacteriotherapy, a few studies have led to clinical trials. In spite of some remarkable achievements, several critical issues like inflammation and toxicity must be resolved before the possible translation of this anticancer strategy into clinical use.

The researcher would like to thank the Deanship of Scientific Research, Qassim University for funding the publication of this project.

The author reports no conflicts of interest for this work.

1. Liang P, Ballou B, Lv X, et al. Monotherapy and combination therapy using antiangiogenic nanoagents to fight cancer. Adv Mater. 2021;33(15):2005155. doi:10.1002/adma.202005155

2. Mansoori B, Mohammadi A, Davudian S, Shirjang S, Baradaran B. The different mechanisms of cancer drug resistance: a brief review. Adv Pharma Bull. 2017;7(3):339. doi:10.15171/apb.2017.041

3. Liu S, Xu X, Zeng X, Li L, Chen Q, Li J. Tumor-targeting bacterial therapy: a potential treatment for oral cancer. Oncol Lett. 2014;8(6):23592366. doi:10.3892/ol.2014.2525

4. Duong MT, Qin Y, You S-H, et al. Bacteria-cancer interactions: bacteria-based cancer therapy. Exp Mol Med. 2019;51:115. doi:10.1038/s12276-019-0297-0

5. Sarotra P, Medhi B. Use of bacteria in cancer therapy. Recent Results Cancer Res. 2016;209:111121.

6. Khan AA, Allemailem KS, Almatroudi A, Almatroodi SA, Alsahli MA, Rahmani AH. Novel strategies of third level (organelle-specific) drug targeting: an innovative approach of modern therapeutics. J Drug Deliv Sci Technol. 2020;61:102315.

7. Allemailem KS, Almatroudi A, Alrumaihi F, et al. Novel approaches of dysregulating lysosome functions in cancer cells by specific drugs and its nanoformulations: a smart approach of modern therapeutics. Int J Nanomedicine. 2021;16:5065. doi:10.2147/IJN.S321343

8. Allemailem KS, Almatroudi A, Alsahli MA, et al. Novel strategies for disrupting cancer-cell functions with mitochondria-targeted antitumor drugloaded nanoformulations. Int J Nanomed. 2021;16:3907. doi:10.2147/IJN.S303832

Originally posted here:
Engineering Tumor-targeting Bacteria with Different Payloads | IJN - Dove Medical Press

Spatial computing stocks have been in the limelight in recent weeks. These companies are at the forefront of disruptive innovations that converge the physical world with the digital world. In turn, spatial computing stocks have been on the mind of investors.

The technology can be described as the digitization of activities of machines, people, objects, and the environments in which they take place to enable and optimize actions and interactions. In other words, spatial computing uses the three-dimensional (3D) space around an object so that it can interact with the rest of the world regardless of its location. It incorporates numerous technologies, including global positioning systems (GPS), artificial intelligence (AI), machine learning (ML) and the Internet of things (IoT).

The growing need to enhance human-machine and machine-to-machine interaction continues to fuel rapid advances in the spatial computing market. In fact, analysts indicate that investing in a small spatial computing stocks now could represent as significant an opportunity as buying an Apple(NASDAQ:AAPL) stock in its early days.

Moreover, spatial computing offers applications in almost all aspects of life, including gaming, shopping, transportation, engineering and agriculture. Zion Market Researchs report indicates that The global Spatial Computing Market, which was estimated at 22.22 (USD Billion) in 2019 and is anticipated to accrue earnings worth 196.21 (USD Billion) by 2026, is set to record a CAGR of nearly 41% over 2020-2026.

With that said, here are three spatial computing stocks that should constitute great additions to any portfolio in 2022 and beyond.

Now, lets dive in and take a closer look at each one.

52-Week Range: $261.54 $400.34

Dividend Yield: 1.22%

Moline, Illinois-based Deere is a leading manufacturer of heavy agricultural equipment worldwide. It has been hailed as one of the most prominent names in the fourth industrial revolution, a fusion of advances in artificial intelligence (AI), robotics, the Internet of Things (IoT), genetic engineering, quantum computing, and more.

In fact, Deere uses machine learning, AI and computer vision applications to boost yields, reduce costs and enhance overall sustainability in agriculture. For example, the company recently announced an allied distribution agreement with Smart Guided Systems to sell its Smart-Apply Intelligent Spray Control System. In turn, tractors use it in high-value crop applications.

This system relies on LiDAR, which stands for Light Detection and Ranging, is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. The technology offered by Deere helps farmers decrease the number of chemicals they use on crops.

Furthermore, Deere announced fourth-quarter results in late November that beat estimates. Revenue increased 16% year-over-year (YOY) to $11.33 billion. Net income came in at $1.28 billion or $4.12 per diluted share, up 70% YOY from $757 million, or $2.39 per diluted share, in the prior-year quarter. Cash and equivalents ended the period at $8.13 billion.

Our results reflect strong endmarket demand and our ability to continue serving customers while managing supply-chain issues and conducting contract negotiations with our largest union, CEO John May said.

For most manufacturers, inflation and supply-chain bottlenecks have been roadblocks in 2021 and Deere is no exception. However, management anticipates demand for farm and construction equipment to continue benefiting from economic growth and infrastructure investments.

DE stock currently sells for roughly $348 and has soared 29% so far in 2021. Shares are currently trading at 2.6 times trailing sales, and the 12-month median price forecast for Deere stock stands at $415.

52-Week Range: $10.45 $37.60

Sunnyvale, California-based Matterport is a spatial data company focused on digitizing and indexing physical spaces such as real estate, factories or travel and leisure locations. On its 3D data platform, individuals can turn physical spaces into accurate as well as immersive digital twins.

Matterport announcedQ3 results in early November. Total revenue increased 10% YOY to $27.7 million. The company generated non-GAAP net loss of $14 million, or 6 cents loss per share, compared with non-GAAP net income of $1.5 million in the previous year. Cash and equivalents ended the period at just under $149 million.

If you have recently looked at real estate listings online, you might have noticed digital twins of homes made on Matterport. Millions of users have also downloaded its free app, Matterport for Mobile.

In Q3, over 6 million digital twins were uploaded to the platform. And the number of subscribers went up by 116% YOY. Regular InvestorPlace.com readers are likely to remember that Matterport has strategic partnerships with Meta Platforms(NASDAQ:FB) and Amazon (NASDAQ:AMZN).

MTTR stock is currently at $22.30 per share, up over 50% over the past six months. Additionally, shares are trading at 66 times trailing sales, and the 12-month median price forecast for Matterport stock is $28. Thus, interested investors should consider buying the dips.

52-Week Range: $539.49 $1,243.49

Palo Alto, California-based Tesla has become a global leader in electric vehicles (EVs). It is also en route to launching a fully autonomous driving service in the coming years.

The self-proclaimed spatial computing evangelist Robert Scoble suggests Tesla is the only automaker to have a neural networkbased system on the road. He also believes Tesla could disrupt or even replace Apple Maps and Alphabets (NASDAQ:GOOG), (NASDAQ:GOOGL) GoogleMaps within the next two years as Tesla robotaxi will be available widely.

Moreover, Tesla released Q3 results in late October. Total revenue increased 57% YOY to $13.76 billion. Non-GAAP net income went up by 139% YOY to $2.09 billion, or $1.86 per non-GAAP diluted share, up from $874 million, or 76 cents per non-GAAP diluted share, a year ago. Also, the company generated free cash flow of $1.3 billion, and cash and equivalents ended the period at $16.1 billion.

On the results, the firm cited that the third quarter of 2021 was a record quarter in many respects. We achieved our best-ever net income, operating profit and gross profit.

As of now, TSLA stock hovers around $930, up 32% year-to-date (YTD). Additionally, shares are trading at 24.7 times trailing sales, and the 12-month median price forecast for TSLA stock sits at $924.50. Nonetheless, potential investors could consider buying around $900 or even below.

On the date of publication, Tezcan Gecgil did not have (either directly or indirectly) any positions in the securities mentioned in this article. The opinions expressed in this article are those of the writer, subject to theInvestorPlace.comPublishing Guidelines.

Tezcan Gecgil, Ph.D., has worked in investment management for over two decades in the U.S. and U.K. In addition to formal higher education in the field, she has also completed all three levels of the Chartered Market Technician (CMT) examination. Her passion is for options trading based on technical analysis of fundamentally strong companies. She especially enjoys setting up weekly covered calls for income generation.

Originally posted here:
3 Spatial Computing Stocks to Buy to Get in on the Next Hot Tech Trend - InvestorPlace

While only 28% of the workforce in STEM in the US is made up of women and in Australia, among the university-qualified STEM workforce women only take up 29%. So, you may be surprised to learn, Lithuania is a hub for womens empowerment and technological advancement, with women making up more than 58% of all scientists, far outpacing the trend in all of Europe, the US and Australia.

Gender parity in the Lithuanian STEM fielddidntjust happen. It developed overtime andby means ofintentionalinvestment, leadingto a culture where women not onlychooseSTEMbut excelin the field.Lithuanias biotech sector has women to thank foritsgrowth rate of 87% over the past decade, a major boom by any standard and the fastest in Europe.

Agn Vaitkeviien is one of these women, who has risen to be a leading expert in the biotech field. She is now the COO at Cureline Baltic a company at the forefront of global lab diagnostic services.

Agne holds a BS in molecular biology from the Vilnius University in Lithuania and a MS in organ, tissue and cell donation from the University of Barcelona in Spain. Since 2006 she has been working in the field of cell therapy as a quality assurance specialist. In 2013, Agne co-founded a life science startup company and managed its activities in the field of advanced therapy medicinal product research and manufacturing as CEO until 2019.

Since 2019 she has been actively involved as an expert in EU programs, such as IMI2, EIT Health Innostarts and consults biotechnology companies in life science product development management. For the last three years, Agne has been actively involved in life science expert groups within governmental organisations such as Enterprise Lithuania, Science, Innovation and Technology Agency, Invest Lithuania and others.

The Lithuanian biotechnology association elected Agne as a vice-president in 2019 and delegated responsibilities of coordinating foreign affairs and startup support activities within the association to her and in 2020 she became an executive director of Lithuanian biotechnology association.

Here at Women Love Tech, we talked with Agne and asked her what fueled her interest in biotech?

I always was creative, participating in various activities when I was a pupil in school, in music, in dances and so on. I never thought tech would involve much creativity until I met a very inspiring scientist, just by accident, who described to me a lot of technical projects she was working on in creating various innovations to solve todays healthcare problem. I was so amazed and so inspired that I wanted to pursue and learn as much as I could about biotech and how it can empower and solve global issues.

On my career path, I found theres even more than just the health sector within biotech and found the ability to use this skill to generate ideas and solutions for various issues. The environmental or climate change sector is also very open to innovations and new technology developments, and so a lot of the activities that I do today are related to all creation and acceleration of new ideas and innovations in that application. Im very happy that I accidentally met someone whose story inspired me to enter the biotechnology sector.

Lithuania is ahead of the game when it comes to gender parity in STEM. What is the reason for this and how was it pertinent to you?

Yes, Lithuania, is one of the few leaders of women balance exceeding 50% compared to men in STEM, and this is probably related to historical progress. For instance, in the tech industry, Lithuania was always ahead, always a centre of technologies, whether its lasers or biotechnology under the Soviet Union. This created an environment for generations of scientists and technologists to enter this sector. Women were always involved in the general workforce, even in the 1950s. I think this is what has been passed down through time that women are active in the work environment through learning and participating in the technology sector both as technicians and as creators.

Only within the last decade, when I launched a startup company together with my partners and became a leader in biotech, did I find out there are challenges in this area for women to move forward. I try to be active in encouraging women to pursue their careers in STEM, in tech science. Im also working with the education system to emphasise examples of women in STEM that might motivate other women to take this career path.

Some of the most prominent female scientists in the field of life sciences in Lithuania who I look up to are: Prof Dr Aurelija virblien, Prof Dr Sonata Jarmalait, Prof Dr Vaiva Lesauskait, Prof Edita Suiedelien, Dr Urt Nenikyt, Dr Inga Matijoyt, Dr Jurgita Skieceviien and Dr Ieva Plikusien to name a few of them.

What would you say to women wanting to pursue a career in STEM?

Just recently I had this conversation with schoolteachers on how to show young girls more diverse options so they can learn more about whats available. To show them the amazing colors, creativeness, and possibilities in the area of STEM.

I see the importance of this in my own life as a mum. I myself have a daughter, who loves to do science experiments and play while exploring technology. I think thats something that must be emphasised more in education and in parenting.

For women seeking jobs, the job market in STEM is growing every day, and we need highly-skilled, qualified people working in this area, whether its men or women. I think this adds value to a person to pursue a career in this field, to see rapid changes and growth. And there are some stereotypes which show it might be a complicated and very difficult field, but its not if youre eager and motivated to learn. So, I think its important to use motivational tools and educational points to show the STEM career is reachable and very available today.

What are you currently working on?

Besides my career, I also actively participate in activities organised by Lithuanian Biotechnology Association. One of them is Women in Biotech which inspires women to become leaders in this field by introducing different stories of various career types available in the biotech industry.

The Lithuanian Biotechnology Association is currently working on creating an accelerator mentorship program for women in collaboration with our Irish partners to have a more international approach. As said, during the progress of women in biotech, we see how these inspirational stories impact women, women scientists and young students on choosing their path. We also get a better understanding of key steps and how goals you set up can be achieved. The accelerator programs are really, really important, to help with the first steps and Im looking forward to setting goals for this program too.

What can the rest of the world learn from the way Lithuania empowers women?

In my opinion, Lithuania has a lot of strong scientists who carry out research that is important to Lithuania and the world. And in recent years, we have seen a very active involvement of women in the promotion of science, which is extremely crucial.

Lithuania is one of the fastest-growing centres of life science in Europe. During the last decade, Lithuanias biotechnology sector grew by an average of 16.4% per year, and in 2020 alone by 87%. This growth is linked to several factors. The most important ingredient is active, curious and smart scientists.

Older generation scientists with the highest level of competencies and young ambitious students, doctoral students, and researchers are excellent synergy in developing scientific ideas in an academic and business environment. State support and investment in this sector, which enables motivated developers to develop their ideas, are essential. This paired with decades of experience in genetic engineering and proteomics, means Lithuania has a lot of potentials to create and develop global innovations in the field of medicine and the environment.

In Lithuania, we have some other very strong other fields of science and technology, such as lasers, information technologies, which perfectly merge into the interdisciplinary directions of biotechnology and life sciences development. We still must try much harder in all these areas, but the gained competencies and openness to co-creation are some of the reasons why other countries are trying to work together, create the latest technologies and implement innovative solutions in the fields of human health, industrial biotechnology and the environment.

Whats your favorite apps and podcasts and why?

I follow a lot of IT, laser technologies and space technology news. And interesting specific influencers that share their stories, successes, startup stories on how they progress over time. LinkedIn, also, is one of the main tools for me to connect and be updated on whats happening in the world. My newsfeed has a lot of scientific publications and magazines, and the newest publications in science as well.

I am working on organising Virtual Biotech Cafe podcasts which are available online in the Lithuanian language. Every last Thursday of the month we meet with scientists and the startups and businessmen which are working in the area of biotech and share the innovations with users. So, we have a one-on-one discussion with the participants and discuss various topics, whether its drug development or food industry innovations or genetic engineering topics, startup stories and similar. So, these are my favorite podcasts for now.

In my personal time, I love to listen to books read by actors. And we have this National Lithuanian radio which has these podcasts on reading these classical books and modern books by good actors. So, I enjoy listening to them in the evenings before I go to bed.

Tell us how you came across Women Love Tech, wed love to hear your favorite stories so we can do more of them?

My LinkedIn news feed caught one of the articles about how to encourage women in STEM. I was engaged in more content on Women Love Tech and became a follower.

For more information about how Lithuania leads Europe with the number of women working in STEM, visit here.

For more information from Women Love Tech about women in STEM, visit here.

Dr Cathy Foley On Encouraging Women In STEM

Read the rest here:
Lithuania Breaks Through With 58% Of All Scientists Female - Women Love Tech

image:Journal publishes original scientific papers, reviews, and case studies on a broad spectrum of topics in lactation medicine. It presents evidence-based research advances and explores the immediate and long-term outcomes of breastfeeding, including the epidemiologic, physiologic, and psychological benefits of breastfeeding view more

Credit: Mary Ann Liebert, Inc., publishers

The percentage of infants fully breastfed at 1,3, and 6 months significantly decreased during the COVID-19 pandemic among participants of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) in Southern California. The percentage of infants who received any breastfeeding also decreased during these time periods, as reported in a study published in the peer-reviewed journal Breastfeeding Medicine. Click here to read the article now.

Breastfeeding education is one of the pillars of the WIC program. It provides staff with the proper lactation training. During the COVID-19 pandemic, WIC services began to be offered remotely instead of face-to-face.

Investigators Maria Koleilat, DrPH, MPH, from California State University, and coauthors, compared fully breastfeeding rates pre-COVID-19 to during COVID-19 among WIC participants and found that rates dropped significantly from 41.79% to 28.09% at 1 month, 28.51% to 18.06% at 3 months, and 15.66% to 10.38% at 6 months.

The investigators offer several possible explanations for the decrease in breastfeeding rates. Breastfeeding support is a priority in the WIC program, they state. However, the shift to remote services delivery and the corresponding reduction in live support of WIC services due to the pandemic may explain the decline in breastfeeding rates and the increase in early weaning in 2020. Another possible explanation is the mixed messages that new parents received regarding the safety of COVID-19 and breastfeeding.

These data document the disruptive and negative impact of the COVID-19 pandemic on infant well-being and the challenges to our health and social system to reestablish basic public health practices, says Arthur I. Eidelman, MD, Editor-in-Chief ofBreastfeeding Medicine.

About the JournalBreastfeeding Medicine, the official journal of theAcademy of Breastfeeding Medicine, is an authoritative, peer-reviewed, multidisciplinary journal published 10 times per year in print and online. The Journal publishes original scientific papers, reviews, and case studies on a broad spectrum of topics in lactation medicine. It presents evidence-based research advances and explores the immediate and long-term outcomes of breastfeeding, including the epidemiologic, physiologic, and psychological benefits of breastfeeding. Tables of content and a sample issue may be viewed on theBreastfeeding Medicine website.

About the Academy of Breastfeeding MedicineThe Academy of Breastfeeding Medicine (ABM) is a worldwide organization of medical doctors dedicated to the promotion, protection, and support of breastfeeding. Our mission is to unite members of the various medical specialties with this common purpose. For more than 20 years, ABM has been bringing doctors together to provide evidence-based solutions to the challenges facing breastfeeding across the globe. A vast body of research has demonstrated significant nutritional, physiological, and psychological benefits for both mothers and children that last well beyond infancy. But while breastfeeding is the foundation of a lifetime of health and well-being, clinical practice lags behind scientific evidence. By building on our legacy of research into this field and sharing it with the broader medical community, we can overcome barriers, influence health policies, and change behaviors.

About the PublisherMary Ann Liebert, Inc., publishersis known for establishing authoritative peer-reviewed journals in many promising areas of science and biomedical research. A complete list of the firm's more than 100 journals, books, and newsmagazines is available on theMary Ann Liebert, Inc., publishers website.

Breastfeeding Medicine

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The Impact of COVID-19 on Breastfeeding Rates in a Low-Income Population

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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Impact of COVID-19 on breastfeeding - EurekAlert

How about making a list of great movies? Here are the most anticipated movies of 2022 to be legendary. You will surely find something interesting.

Movies and TV series are all about helping people cope with stress and have a great time. So surely you love going to cinemas or watching your favorite movie masterpieces on your TV screen. But which films are worth your attention? Should you visit the cinema every time you see a new poster? Well, check the most anticipated movies of 2022.

Youve probably heard of this franchise at least once. The original Scream film was considered the benchmark for horror films in the mid-90s. But its time for a new scenario and a soft reboot. So get ready to watch a group of teenagers and a dark story that will lead to unexpected consequences. A movie like this is perfect for a student party. But first, you should read pen.camp reviews and delegate your papers to someone else. Surely you dont want to be distracted by trifles and watch a new horror movie with your friends.

Imagine that the Moon has changed its orbit, and now the Earth is in danger. A group of astronauts from NASA will find out the secrets of the Earth satellite and decide on a dangerous expedition. Even though this is not an AAA movie, you will surely be delighted to see Halle Berry and Patrick Wilson as the main protagonists. In addition, the film has an interesting plot and good visuals. You will surely have a great time at the cinema.

Millions of DC fans eagerly await the new movie about the Knight of Gotham. This time you have to see Batman, who is disillusioned with justice and tormented by his ghosts of the past. Plus, noir is a new feature of the franchise. The Batman will appear as a detective who uses erudition and fights only if necessary. At the same time, the director assured the audience that there would be plenty of action scenes, so this action movie should appeal to all comic book fans.

But you should remember that the film is long enough. What if youre a student and dont have time? Surely you are ready to ask a question like, is ultius legit? Dont worry. There are many companies where you can delegate your assignments. You will surely be able to free up time for watching movies.

The universe of Harry Potter is as amazing as every honest bookwormlab.com review. Want to know what the main similarities are? The fact is that you will always be on your toes because of the secrets you have to learn. The point is that Dumbledore must find a way to defeat Gellert Grindelwald as quickly as possible. This time, the role of the antagonist will be played by the charismatic Dane Mads Mikkelsen, so a whirlpool of emotions and unexpected plot twists await you.

And here is the most anticipated melodrama (and comedy), which will become a new part of the famous franchise. Reese Witherspoon has to prove that a girl can be a great lawyer this time. According to the pre-release trailers, fans of the franchise will have more humor, interesting stories, and a new love story. So this is why you should visit the cinema on the day of the premiere.

Tom Cruise is so cool that he will star in this legendary franchise to his last breath. This time, the protagonist will have to face insidious enemies, betrayal, and a global conspiracy. Only Pete Maverick Mitchell can handle the situation and defeat all enemies. So if you love spring and summer blockbusters, you will surely like this movie.

Can you imagine how rapidly the John Wick franchise is growing? Many fans love the visuals, stunts, and good gunfights. The fourth part will be devoted to the new confrontation between the legendary hitman and a new criminal group. Who will win this battle? Most likely, you will find out the answer to this question at the end of May 2022.

And here is one new movie that aims to expand the original franchise. According to the plot, genetic engineering has reached a new stage of development, and now scientists can create improved dinosaurs. Unfortunately, however, a brilliant idea turns out to be a complete failure because people did not consider all the risks. But, if you love watching giant reptiles fight each other and destroy everything around you, then you should buy a ticket to the cinema in June.

All of the above films are worth your attention. The fact is that each plot and cast is quite interesting and you will surely enjoy watching movies. All you need is to buy a ticket on time or wait for the premiere in online cinemas. Anyway, now you have enough options for the final choice.

Read more:
The Most Anticipated Movies of 2022 - Film Threat

Life goes on as gene-edited foods begin to hit the market. Japanese consumers have recently started buying tomatoes that fight high blood pressure, and Americanshave been consuming soyengineered to produce high amounts of heart-healthy oils for a little over two years. Few people noticed these developments because, as scientists have said for a long time, the safety profile of a crop is not dictated by the breeding method that produced it. For all intents and purposes, it seems that food-safety regulators have done a reasonablejob of safeguarding public health against whatever hypothetical risks gene editing may pose.Credit: Karuchibe

But this has not stopped critics of genetic engineering from advocating for more federal oversight of CRISPR and othertechniquesused to make discrete changes to the genomes of plants, animals and other organisms we use for food or medicine. Over at The Conversation, a team of scientists recently made the case for tighter rules inCalling the latest gene technologies natural is a semantic distraction they must still be regulated.

Many scientists have defended gene editing, in part, by arguing that it simply mimics nature. A mutation that boosts the nutrient content of rice, for example, is the same whether it was induced by a plant breeder or some natural phenomenon. Indeed, the DNA of plants and animals we eatcontains untold numbersof harmless, naturally occurringmutations. But The Conversation authors will havenone of this:

Unfortunately, the risks from technology dont disappear by calling it natural Proponents of deregulation of gene technology use the naturalness argument to make their case. But we argue this is not a good basis for deciding whether a technology should be regulated.

They have written a very longpeer-reviewed articleoutlining a regulatory framework based on scale of use.The ideais that the more widely a technology is implemented, the greater risk it may pose to human health and the environment, which necessitates regulatory control points to ensure its safe use. Its an interesting proposal, but its plagued by several serious flaws.

The most significant issue with a scale-based regulatory approachis that its a reaction to risks that have never materialized. This isnt to say that a potentially harmful genetically engineered organism will never be commercialized. But if were going to upend our biotechnology regulatory framework, we need to do so based on real-world evidence. Some experts have actually argued, based on decades of safety data, that the US over-regulates biotech products. As biologist and ACSHadvisorDr. Henry Miller and legal scholar John Cohrssen wroterecently in Nature:

After 35 years of real-world experience with genetically engineered plants and microorganisms, and countless risk-assessment experiments, it is past time to reevaluate the rationale for, and the costs and benefits of, the case-by-case reviews of genetically engineered products now required by the US Environmental Protection Agency (EPA), US Department of Agriculture (USDA) and US Food and Drug Administration (FDA).

Real-world data aside for the moment, there are some theoretical problems with the scalabilitymodel as well. Theargument assumes thatrisks associated with gene editing proliferate as use of the technology expands, because each gene edit carries a certain level of risk. This is a false assumption, as plant geneticist Kevin Folta pointed out on a recentepisode of the podcastwe co-host (21 minute mark).

Scientists have a variety of tools with which to monitor and limit the effects of specific gene edits. For example,proteins known asanti-CRISPRs can be utilized to halt the gene-editing machinery so it makes only the changes we want it to. University of Toronto biochemist Karen Maxwell has explained how this couldwork in practice:

In genome editing applications, anti-CRISPRs may provide a valuable off switch for Cas9 activity for therapeutic uses and gene drives. One concern of CRISPR-Cas gene editing technology is the limited ability to control its activity after it has been delivered to the cell . which can lead to off-target mutations. Anti-CRISPRs can potentially be exploited to target Cas9 activity to particular tissues or organs, to particular points of the cell cycle, or to limit the amount of time it is active

Suffice it to say that these and other safeguards significantly alter the risk equation and weaken concerns about a gene-edits-gone-wild scenario. Parenthetically, scientists design these sorts of preventative measures as they developmoregenetic engineering applications for widespread use. This is why the wide variety of cars in production todayhave safety featuresthat would have been unheard of in years past.

To bolster their argument, The Conversation authors made the following analogy:

Imagine if other technologies with the capacity to harm were governed by resemblance to nature. Should we deregulate nuclear bombs because the natural decay chain of uranium-238 also produces heat, gamma radiation and alpha and beta particles? We inherently recognize the fallacy of this logic. The technology risk equation is more complicated than a supercilious its just like nature argument

If someone has to resort to this kind of rhetoric, the chances are excellent that their argument is weak. Fat Man and Little Boy,the bombs droppedon Japan in 1945, didnt destroy two cities because a nuclear physicist in New Mexico made a technical mistake. These weapons are designed to wreak havoc. Tomatoes bred to produce more of an amino acid, in contrast, are not.

The point of arguing that gene-editing techniques mimic natural processes isnt to assert that natural stuff is good; therefore, gene editing is also good. Instead, the point is to illustrate that inducing mutations in the genomes of plants and animals is not novel or uniquely risky. Even the overpriced products marketed as all-naturalhave been improvedby mutations resulting from many years of plant breeding.

Nonetheless, some scientistshave arguedthat reframing the gene-editing conversation in terms of risk vs benefit would be a smarter approach than making comparisons to nature. I agree with them, so lets start now. The benefits of employing gene editing to improve our food supply and treat disease far outweigh the potential risks, which we can mitigate. Very little about modern life is naturaland its time we all got over it.

Cameron J. English is the director of bio-sciences at theAmerican Council on Science and Health. Visithis websiteand follow ACSH on Twitter@ACSHorg

A version of this article was originally posted at theAmerican Council on Science and Healthand is reposted here with permission. The American Council on Science and Health can be found on Twitter@ACSHorg

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Viewpoint: An argument for CRISPR crops 'Very little about modern life is natural and it's time we all got over it' - Genetic Literacy Project

Gene therapy is a powerful developing technology that has the potential to address myriad diseases. For example, Huntington's disease, a neurodegenerative disorder, is caused by a mutation in a single gene, and if researchers could go into specific cells and correct that defect, theoretically those cells could regain normal function.

A major challenge, however, has been creating the right "delivery vehicles" that can carry genes and molecules into the cells that need treatment, while avoiding the cells that do not.

Now, a team led by Caltech researchers has developed a gene-delivery system that can specifically target brain cells while avoiding the liver. This is important because a gene therapy intended to treat a disorder in the brain, for example, could also have the side effect of creating a toxic immune response in the liver, hence the desire to find delivery vehicles that only go to their intended target. The findings were shown in both mouse and marmoset models, an important step towards translating the technology into humans.

A paper describing the new findings appears in the journal Nature Neuroscience on December 9. The research was led by Viviana Gradinaru (BS '05), professor of neuroscience and biological engineering, and director of the Center for Molecular and Cellular Neuroscience.

The key to this technology is the use of adeno-associated viruses, or AAVs, which have long been considered promising candidates for use as delivery vehicles. Over millions of years of evolution, viruses have evolved efficient ways to gain access into human cells, and for decades researchers have been developing methods to harness viruses' Trojan-Horse-like abilities for human benefit.

AAVs are made up of two major components: an outer shell, called a capsid, that is built from proteins; and the genetic material encased inside the capsid. To use recombinant AAVs for gene therapy, researchers remove the virus's genetic material from the capsid and replace it with the desired cargo, such as a particular gene or coding information for small therapeutic molecules.

"Recombinant AAVs are stripped of the ability to replicate, which leaves a powerful tool that is biologically designed to gain entrance into cells," says graduate student David Goertsen, a co-first author on the paper. "We can harness that natural biology to derive specialized tools for neuroscience research and gene therapy."

The shape and composition of the capsid is a critical part of how the AAV enters into a cell. Researchers in the Gradinaru lab have been working for almost a decade on engineering AAV capsids that cross the blood-brain barrier (BBB) and to develop methods to select for and against certain traits, resulting in viral vectors more specific to certain cell types within the brain.

In the new study, the team developed BBB-crossing capsids, with one in particular AAV.CAP-B10that is efficient at getting into brain cells, specifically neurons, while avoiding many systemic targets, including liver cells. Importantly, both neuronal specificity and decreased liver targeting was shown to occur not just in mice, a common research animal, but also in laboratory marmosets.

"With these new capsids, the research community can now test multiple gene therapy strategies in rodents and marmosets and build up evidence necessary to take such strategies to the clinic," says Gradinaru. "The neuronal tropism and decreased liver targeting we were able to engineer AAV capsids for are important features that could lead to safer and more effective treatment options for brain disorders."

The development of an AAV capsid variant that works well in non-human primates is a major step towards the translation of the technology for use in humans, as previous variants of AAV capsids have been unsuccessful in non-human primates. The Gradinaru lab's systematic in vivo approach, which uses a process called directed evolution to modify AAV capsids at multiple sites has been successful in producing variants that can cross the BBBs of different strains of mice and, as shown in this study, in marmosets.

"Results from this research show that introducing diversity at multiple locations on the AAV capsid surface can increase transgene expression efficiency and neuronal specificity," says Gradinaru. "The power of AAV engineering to confer novel tropisms and tissue specificity, as we show for the brain versus the liver, has broadened potential research and pre-clinical applications that could enable new therapeutic approaches for diseases of the brain."

The paper is titled "AAV capsid variants with brain-wide transgene expression and decreased liver targeting after intravenous delivery in mouse and marmoset." Goertsen; Nicholas Flytzanis (PhD '18), the former scientific director of the CLARITY, Optogenetics and Vector Engineering Research(CLOVER)Center of Caltech's Beckman Institute; and former Caltech postdoctoral scholar Nick Goeden are co-first authors. Additional coauthors are graduate student Miguel Chuapoco, and collaborators Alexander Cummins, Yijing Chen, Yingying Fan, Qiangge Zhang, Jitendra Sharma, Yangyang Duan, Liping Wang, Guoping Feng, Yu Chen, Nancy Ip, and James Pickel.

Funding was provided by the Defense Advanced Research Projects Agency, the National Institutes of Health, and the National Sciences and Engineering Research Council of Canada.

Flytzanis, Goeden, and Gradinaru are co-founders of Capsida Biotherapeutics, a Caltech-led startup company formed to develop AAV research into therapeutics.

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New Technology is One Step Closer to Targeted Gene Therapy - Caltech

One 2021 study looked at the genome of Solanum sitiens a wild tomato species which grows in the extremely harsh environment of the Atacama Desert in Chile, and can be found at altitudes as high as 3,300m (10,826ft). The study identified several genes related to drought-resistance in Solanum sitiens, including one aptly named YUCCA7 (yucca are draught-resistant shrubs and trees popular as houseplants).

They are far from the only genes that could be used to give the humble tomato a boost. In 2020 Chinese and American scientists performed a genome-wide association study of 369tomato cultivars, breeding lines and landraces, and pinpointed a gene called SlHAK20 as crucial for salt tolerance.

Once the climate-smart genes such as these are identified, they can be targeted using Crispr to delete certain unwanted genes, to tune others or insert new ones. This has recently been done with salt tolerance, resistance to various tomato pathogens, and even to create dwarf plants which could withstand strong winds (another side effect of climate change). However, scientists such as Cermak go even further and start at the roots they are using Crispr to domesticate wild plant species from scratch, "de novo" in science speak. Not only can they achieve in a single generation what previously took thousands of years, but also with a much greater precision.

De novo domestication of Solanum pimpinellifolium was how Cermak and his colleagues at the University of Minnesota arrived at their 2018 plant. They targeted five genes in the wild species to obtain a tomato that would be still resistant to various stresses, yet more adapted to modern commercial farming more compact for easier mechanical harvesting, for example. The new plant also had larger fruits than the wild original.

"The size and weight was about double," Cermak says. Yet this still wasn't the ideal tomato he strives to obtain for that more work needs to be done. "By adding additional genes, we could make the fruit even bigger and more abundant, increase the amount of sugar to improve taste, and the concentration of antioxidants, vitamin C and other nutrients," he says. And, of course, resistance to various forms of stress, from heat and pests to draught and salinity.

Read more here:
The tomatoes at the forefront of a food revolution - BBC News

In an effort to improve treatment for obsessive compulsive disorder (OCD), researchers headed by teams at Brown University, and Baylor College of Medicine, have for the first time recorded electrical signals in the human brain that are associated with ebbs and flows in OCD symptoms, over an extended period, while individuals went about daily living in their homes. The research could be an important step in making an emerging therapy called deep brain stimulation (DBS) responsive to everyday changes in OCD symptoms.

In addition to advancing DBS therapy for cases of severe and treatment resistant OCD, this study has the potential for improving our understanding of the underlying neurocircuitry of the disorder, said Wayne Goodman, PhD, at Baylor College of Medicine. This deepened understanding may allow us to identify new anatomic targets for treatment that may be amenable to novel interventions that are less invasive than DBS. Goodman is co-author of the researchers published paper in Nature Medicine, which is titled, Long-term ecological assessment of intracranial electrophysiology synchronized to behavioural markers in obsessive-compulsive disorder.

OCD causes recurring unwanted thoughts and repetitive behaviors, and is a leading cause of disability. The condition, which is often debilitating, may affect perhaps 2-3% of the worlds population, the authors noted. Up to 20-40% of cases dont respond to traditional drug or behavioral treatments. Approximately 10% of individuals fail to achieve benefit from any intervention.

Deep brain stimulation, a technique that involves delivering mild electrical pulses via small electrodes precisely placed in the brain, can be effective in treating more than 50% of patients for whom other therapies failed. Over half of patients with treatment-resistant OCD are responders to DBS targeted to the ventral capsule/ventral striatum (VC/VS) region, the researchers further noted. To date, however, the number of patients who have received DBS for OCD is still in the hundreds.

One limitation of DBS is that it is unable to adjust to moment-to-moment changes in OCD symptoms, which are impacted by the physical and social environment. But adaptive DBS which can adjust the intensity of stimulation in response to real-time signals recorded in the braincould be more effective than traditional DBS and reduce unwanted side effects.

OCD is a disorder in which symptom severity is highly variable over time and can be elicited by triggers in the environment, said David Borton, PhD, an associate professor of biomedical engineering at Brown University, a biomedical engineer at the US Department of Veterans Affairs Center for Neurorestoration and Neurotechnology and a senior author of the new research. A DBS system that can adjust stimulation intensity in response to symptoms may provide more relief and fewer side effects for patients. But in order to enable that technology, we must first identify the biomarkers in the brain associated with OCD symptoms, and that is what we are working to do in this study. As the authors noted, An electrophysiological biomarker of symptom state would enable aDBS for OCD and other psychiatric disorders, which may provide a better approach for treating fluctuations in symptom intensity.

The research, led by Nicole Provenza, a recent Brown biomedical engineering PhD graduate from Bortons laboratory, was a collaboration between Bortons research group, affiliated with Browns Carney Institute for Brain Science and School of Engineering; the research groups of Wayne Goodman PhD, and Sameer Sheth MD, PhD, at Baylor College of Medicine; and Jeff Cohn, PhD, from the University of Pittsburghs Department of Psychology and Intelligent Systems Program and Carnegie Mellon University.

For their study, Goodmans team recruited five participants with severe OCD who were eligible for DBS treatment. Sheth, lead neurosurgeon, implanted in each participant an investigational DBS device from Medtronic, which is capable of both delivering stimulation and recording native electrical brain signals. Using the sensing capabilities of the hardware, the team gathered brain-signal data from participants in both clinical settings and at home as they went about daily activities. The DBS implants used in our study allow for real-time frequency-domain analysis of electrophysiological activity recorded simultaneously during stimulation delivery from the implanted electrodes, they wrote.

Along with the brain signal data, the team also collected a suite of behavioral biomarkers. In the clinical setting, these included facial expression (automatic facial affect recognition; AFAR) and body movement. Using computer vision and machine learning, they discovered that the behavioral features were associated with changes in internal brain states. At the participants homes, the team measured self-reports of OCD symptom intensity as well as biometric dataheart rate and general activity levelsrecorded by a smart watch and paired smartphone application, provided by Rune Labs. All of those behavioral measures were then time-synched to the brain-sensing data, enabling the researchers to look for correlations between the two.

Here, we acquired electrophysiological data with behavioral readouts over both short and long timescales, the team commented. In the clinic, we examined changes in affect (AFAR) during DBS parameter changes over short timescales (seconds to minutes). At home during participant-controlled recordings, we captured behavioral changes (self-reported OCD symptoms) over longer timescales (days to weeks to months) in natural settings, collected continuous data during natural and planned exposures, and developed methods to synchronize behavioral metrics to intracranial electrophysiology.

This is the first time brain signals from participants with neuropsychiatric illness have been recorded chronically at home alongside relevant behavioral measures, Provenza said. Using these brain signals, we may be able to differentiate between when someone is experiencing OCD symptoms, and when they are not, and this technique made it possible to record this diversity of behavior and brain activity.

Provenzas analysis of the data showed that the strategy did pick out brain-signal patterns potentially linked to OCD symptom fluctuation. While more work needs to be done across a larger cohort, this initial study shows that this technique is a promising way forward in confirming candidate biomarkers of OCD. we demonstrated the utility of at-home data collection for biomarker identification by observing correlations between spectral power and self-reported OCD symptom intensity.

We were able to collect a far richer dataset than has been collected before, and we found some tantalizing trends that wed like to explore in a larger cohort of patients, Borton said. Now we know that we have the toolset to nail down control signals that could be used to adjust stimulation level according to peoples symptoms.

Once those biomarkers are positively identified, they could then be used in an adaptive DBS system. Currently, DBS systems employ a constant level of stimulation, which can be adjusted by a clinician at clinical visits. Adaptive DBS systems, in contrast, would stimulate and record brain activity and behavior continuously without the need to attend clinic. When the system detects signals associated with an increase in symptom severity, it could ramp up stimulation to potentially provide additional relief. Likewise, stimulation could be toned down when symptoms abate. Such a system could potentially improve DBS therapy while reducing side effects.

Work on this line of research is ongoing. Because OCD is a complex disorder than manifests itself in highly variable ways across patients, the team hopes to expand the number of participants to capture more of that variability. They seek to identify a fuller set of OCD biomarkers that could be used to guide adaptive DBS systems. Once those biomarkers are in place, the team hopes to work with device makers to implement their DBS devices.

Our goal is to understand what those brain recordings are telling us and to train the device to recognize certain patterns associated with specific symptoms, Sheth said. The better we understand the neural signatures of health and disease, the greater our chances of using DBS to successfully treat challenging brain disorders like OCD. As the authors concluded, This work demonstrates the feasibility and utility of capturing chronic intracranial electrophysiology during daily symptom fluctuations to enable neural biomarker identification, a prerequisite for future development of adaptive DBS for OCD and other psychiatric disorders, the author concluded. The platform presented here lays the groundwork for future transformational studies reliant on ecological neural and behavioral monitoring and assessment of neuropsychiatric illness.

Read more from the original source:
Electrical and Behavioral Signals in OCD Could Guide Adaptive Therapy - Genetic Engineering & Biotechnology News

Gene therapy is still in its infancy and has yet to achieve its full potential. First-generation gene therapies have been challenged by safety issues due to their inability to target cells and organs without also penetrating non-targeted cells and organs, especially the liver. Capsida's proprietary, targeted, non-invasive gene therapy technology allows more selective targeting of specific tissues and cells, overcoming many of the problems associated with first-generation gene therapies, specifically off-target cell and organ activity. In addition, it allows the gene therapy to be delivered non-invasively through intravenous (IV) administration. The company's already strong leadership team is poised to actualize the promise of gene therapy with the addition of Mr. Anastasiou and the promotions of Drs. Flytzanis and Goeden.

"I can't imagine a more exciting time to join this organization," said Mr. Anastasiou. "Capsida is enabling gene therapy to become what the industry, physicians, and patients have been dreaming it will be. Our patent-protected technology allows the targeting of cells and organs while limiting the negative impact on non-targeted areas, and can be applied across multiple therapeutic areas. Another important benefit of our technology is that we are able to deliver the gene therapy non-invasively through IV administration. I'm honored to lead this talented team to achieve Capsida's potential and to improve and even save patients' lives."

Mr. Anastasiou joins Capsida from Lundbeck, where he was an executive vice president and a member of the executive committee, reporting to the CEO. As the president of Lundbeck's U.S. and Canadian business operations, Mr. Anastasiou has built organizations from the ground up. He brings significant leadership experience managing diverse organizations and bringing them together to achieve common goals. He led as many as 1,200 employees and achieved net revenues of $1.5 billion. During his 12-year tenure at Lundbeck, Mr. Anastasiou held several progressive leadership positions, playing a pivotal role in developing and launching multiple products and building the company's cross-functional capabilities. Mr. Anastasiou serves on the Board of PhRMA and the global advisory board for the Healthcare Businesswomen's Association. Mr. Anastasiou begins his new role with Capsida on January 3, 2022.

"We're thrilled to welcome Peter as Capsida's new CEO," said Beth Seidenberg, M.D., founding managing director at Westlake Village BioPartners, one of the company's lead investors, and Capsida board member. "Peter has deep industry expertise, a broad network, and significant public company experience, which will be valuable as Capsida grows. In addition, his strong track record of success demonstrates he is a visionary leader who will be able to deliver on the promise of targeted non-invasive gene therapy to help underserved patients and achieve business success."

"During his tenure at Lundbeck, Peter has created significant shareholder value, creating and leading organizations and successful blockbuster product launches," said Clare Ozawa, Ph.D., managing director at Versant Ventures, one of Capsida's lead investors, and Capsida board member."Under Peter's leadership, we will continue to build Capsida as the industry's leading targeted, non-invasive gene therapy company with the ability to transform the lives of patients with life-threatening genetic disorders."

Prior to Lundbeck, Mr. Anastasiou held management roles at Neuronetics, Inc., Bristol-Meyers Squibb Company, and Eli Lilly and Company. He holds an MBA from the Kelley School of Business at Indiana University, and a B.A. in economics and management from Albion College.

Capsida co-founders Nicholas Flytzanis, Ph.D., promoted to CSO and Nick Goeden, Ph.D., promoted to CTO

In addition to Mr. Anastasiou's appointment, Capsida announced that Dr. Flytzanis has been promoted toCSO and Dr. Goeden has been promoted to CTO.

"The promotions of Drs. Flytzanis and Goeden are in recognition of the significant contributions they have made since co-foundingCapsida in 2019," said Mr. Anastasiou. "Their steadfast commitment to delivering on the promise of Capsida's differentiated, non-invasive gene therapy platform has been a key driver behind many of the company's early achievements."

"Drs. Flytzanis' and Goeden's strong scientific and technical expertise and know-how have already delivered results in the startup of Capsida based on Caltech'sbasic research on targeted non-invasive gene delivery to the brain," said Capsida co-founder Viviana Gradinaru, Ph.D. "Their promotions are timely as Capsida enters the phase of delivering from the lab and for the patients."

Prior to co-founding Capsida, Dr. Flytzanis served as scientific director of the CLOVER research center at the California Institute of Technology (Caltech), leading an interdisciplinary team to develop and disseminate emerging technologies focused on the cross-section of neurological research and gene therapy. His research spans the fields of tissue clearing and imaging, optogenetics and rodent behavior, and adeno-associated virus (AAV) engineering and gene therapy, with collaborations across multiple institutions. During his Ph.D., Dr. Flytzanis applied protein engineering and directed evolution across biological modalities, with a focus on developing AAVs as therapeutic tools for neurological disease.

Dr. Flytzanis holds a Ph.D. in biology from Caltech and a B.S. in biology from the Massachusetts Institute of Technology.

Prior to co-founding Capsida, Dr. Goeden led a team developing the novel adeno-associated virus (AAV) engineering technology underlying Capsida's biologically driven gene therapy platform. During his tenure as a postdoctoral fellow in Dr. Gradinaru's lab at Caltech, he developed high-throughput methods for screening combinatorial libraries to explore the AAV fitness landscape and engineered novel AAVs with high efficiency and specificity for the rodent and primate brain. During his Ph.D., Dr. Goeden developed a novel organ bioreactor to study real-time metabolomics in diseased states, exploring the relationship between gene expression and the pathophysiology of neurodevelopmental disorders.

Dr. Goeden holds a Ph.D. in neuroscience from The University of Southern California and a B.S. in biology from Caltech.

About Capsida Biotherapeutics

Capsida Biotherapeutics Inc. is an industry-leading gene therapy platform company creating a new class of targeted, non-invasive gene therapies for patients with debilitating and life-threatening genetic disorders. Capsida's technology allows for the targeted penetration of cells and organs, while limiting collateral impact on non-targeted cells and organs, especially the liver. This technology allows for the delivery of the gene therapy in a non-invasive way through intravenous administration. Capsida's technology is protected by a growing intellectual property portfolio which includes more than 30 patent applications and one issued U.S. patent 11,149,256. The company is exploring using the technology across a broad range of life-threatening genetic disorders. Its initial pipeline consists of multiple neurologic disease programs. The company has strategic collaborations with AbbVie and CRISPR, which provide independent validation of Capsida's technology and capabilities. Capsida is a multi-functional and fully integrated biotechnology company with proprietary adeno-associated virus (AAV) engineering, multi-modality cargo development and optimization, translational biology, process development and state-of-the-art manufacturing, and broad clinical development experience. Capsida's biologically driven, high-throughput AAV engineering and cargo optimization platform originated from groundbreaking research in the laboratory of Viviana Gradinaru, Ph.D., a neuroscience professor at the California Institute of Technology. Visit us at http://www.capsida.com to learn more.

SOURCE Capsida Biotherapeutics

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Capsida Biotherapeutics Poised to Capitalize on Industry-leading Gene Therapy Technology With New CEO, CSO, and CTO - PRNewswire