If you skin your knee, your body makes new skin. If you donate a portion of your liver, whats left will grow back to near-normal size. But if you lose a billion heart cells during a heart attack, only a small fraction of those will be replaced. In the words of Ke Cheng, an associate professor of regenerative medicine at N.C. State, The hearts self-repair potency is very limited.

Cheng has designed a nanomedicine he hopes will give the heart some help. It consists of an engineered nanoparticle that gathers the bodys own self-repair cells and brings them to the injured heart tissue.

In this case, the self-repair cells are adult stem cells. A stem cell is a very rich biological factory, Cheng said. Stem cells can become heart muscle, or they can produce growth factors that are beneficial to the regrowth of heart muscle.

After a heart attack, dying and dead heart cells release chemical signals that alert stem cells circulating in the blood to move to the injured site. But there just arent very many stem cells in the bloodstream, and sometimes they are not sufficiently attracted to the injured tissue.

Matchmakers with hooks

The nanomedicine Cheng designed consists of an iron-based nanoparticle festooned with two different kinds of hooks one kind of hook grabs adult stem cells, and the other kind of hook grabs injured heart tissue. Cheng calls the nanomedicine a matchmaker, because it brings together cells that can make repairs with cells that need repairs.

The hooks are antibodies that seek and grab certain types of cells. Because the antibodies are situated on an iron nanoparticle, they and the stem cells theyve grabbed can be physically directed to the heart using an external magnet. Cheng calls the nanomedicine MagBICE, for magnetic bifunctional cell engager.

The magnet is a first pass to get the iron-based particles and antibodies near the heart. Once there, the antibodies are able to identify and stick to the injured heart tissue, bringing the stem cells right where they need to go. Using two methods of targeting the magnet and the antibodies improves the chances of being able to bring a large number of stem cells at the site of injury.

In addition to providing a way to physically move the stem cells to the heart, the iron nanoparticles are visible on MRI machines, which allows MagBICE to be visualized after its infused into the bloodstream.

Cheng doesnt foresee much toxicity from the nanomedicine unless someone is allergic or particularly sensitive to iron. In fact, the iron-based nanoparticle that forms the platform for the antibodies is an FDA-approved IV treatment for anemia.

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Can a bodys own stem cells help heal a heart?