Two new articles released in as many weeks point to further questions concerning the use of induced pluripotent stem (iPS) cells, that is, mature or adult stem cells reprogrammed to into “embryonic-like” stem cells. These cells were immediately hailed as a great breakthrough and touted as an ethical alternative to embryonic stem (ES) cell research. However, closer scrutiny is revealing a laundry list of problems with iPS cells.
The earliest research with iPS stem cells utilized viruses to insert specific genes into the adult stem cells. These viruses increased the risk of causing cancer in both the stem cells and prospective patients receiving them. Then came a method in which messenger RNA (mRNA) was used to reprogram the adult stem cells. Despite claims that no human embryos were killed in the process of creating these particular stem cells, aborted fetal cell lines as well as human embryonic stem cell lines were used in the research not only for comparison, but in the mRNA “cocktail” used to accomplish the reprogramming. Tumors and teratomas, hallmarks of embryonic stem cell research, were the result.
A study published in Nature on February 3 indicates that the iPS stem cell, which was supposed to be equivalent to an embryonic stem cell having been reprogrammed back to a “blank slate” condition does not completely become the blank slate as thought. Instead, researchers found that the “transformation from adult [stem cell] to [embryonic] stem cell was invariably incomplete or inadequate,” and “riddled with indelible marks, a consistent pattern of reprogramming errors.” Further, these “reprogramming quirks were passed on when iPSCs were then coaxed into a more specialized cell.”
In other words, there are parts of the mature adult stem cell that, although reprogrammed, are resistant to change and/or transformation. The resulting iPS stem cell may look like an embryonic stem cell on its surface, but underneath, it is not the same and it may not act the same.
Further, an article in the February 11 issue of Scientific American states that, “The act of reprogramming cells to make them as capable as ones from embryos apparently can result in aberrant cells that age and die abnormally, suggesting there is a long way to go to prove such cells are really like embryonic stem cells and can find use in therapies.”
Again, we have to ask: Why is research and funding not directed toward ethical adult and umbilical cord stem cells that are already treating and curing dozens of conditions and diseases?
For further reading:
http://www.nature.com/news/2011/110202/full/470013a.html