International Stem Cell Corporation Chairman Comments on UC San Diego Study That Finds Therapies Using Induced Pluripotent Stem Cells Could Encounter Immune Rejection Problems

Scientists at the University of California, San Diego, announced last week that they had discovered that the class of stem cells known as "induced pluripotent stem cells" or "iPS" cells could cause an immune rejection problem when transplanted into mice. Scientists had hoped that these cells would have two big advantages over embryonic stem cells: they would not be controversial because their creation did not entail the destruction of human embryos; and, since the stem cells could be made from a particular patient’s skin cells, they could be used to make tissues that would not be rejected by the patient’s own immune system. Although responses in humans may be different, the discovery of an immune response in mice suggests that the second of these hopes may not be so easily realized.

That is disappointing news in many ways, but it illustrates what we at International Stem Cell Corporation (ISCO) think will be one of the great benefits of the Parthenogenetic Stem Cells our scientists have created and patented.

Parthenogenetic stem cells are not only pluripotent they also do not involve any destruction or damage to a viable human embryo. Since they are never fertilized (and can't become a child) they carry the DNA of only the egg donor and not the added DNA of a father or other sperm donor. This results in the possibility of matching these cells to large groups of people without causing immune response problems.

The science is a bit complicated, but the result is illustrated by the fact that the very first stem cell line ISCO created using its newest techniques has the potential to match the immune systems of over 50 million people. With the right donors, cell lines from as few as 50 donors (one respected scientist has said as few as 10 donors) could match a very large portion of the world's population. There is a lot of work yet to be done, but if one thinks of it as comparable to a blood bank, but for stem cells instead, the concept becomes quite exciting.

Lastly, even if iPS cells are never used for transplant therapy, they still have wonderful research potential, so those who hoped for medical breakthroughs using them should not despair. They are, and will be, very important, even though there are better pathways to transplant therapy.

Kenneth C. Aldrich - Chairman

International Stem Cell Corporation

Source: Press Release from the University of California San Diego http://www.eurekalert.org/pub_releases/2011-05/uoc--sft051211.php