Dr. Shinya Yamanaka, a scientist who did key scientific experiments to turn adult cells into pluripotent stem cells is the subject of a New York Times story on the bright prospects for stem cell research. Yamanaka sees both embryonic and induced pluripotent stem cells as still risky for therapies. But he's optimistic about solving these problems.
As for the cells with which he now works, iPS cells, many hurdles remain before they are truly as versatile as the embryonic stem cells they mimic. “Embryonic stem cells are not safe,” he said. “But at the moment, iPS cells are more dangerous.”
For instance, many skin cells only partly complete the transition to stem cells, and there are no reliable markers yet to flag those that are incomplete. Embryonic stem cells also tend to form benign tumors made of a mix of muscle, bone and other cell types. For unknown reasons, Dr. Yamanaka’s stem cells are more prone to produce them. One of the trigger genes can cause cancer, and the viruses that ferry the transforming genes into a target skin cell may not deliver them where they are needed.
To turn stem cells into other cell types requires many changes in the regulatory state of the cells. DNA has many sites on it where proteins bind, methyl groups get placed, and other changes are made to regulate the behavior of tens of thousands of genes. Each type of cell in the body has a different pattern of regulation. To develop control over cell state is a very difficult undertaking.
The iPS (induced pluripotent stem) cells made by transforming adult cells (e.g a piece of skin tissue) hold much promise for two reasons. First, since creation of the cells avoids use of an embryo the iPS cells do not elicit big ethical objections. Second, iPS cells can be made using a person's own starter cells. So they are much more likely to be immunologically compatible. Dr. Yamanaka’s work in figuring out how to create iPS cells will eventually result in therapies that many of us will get. If you are still alive 30 years from now expect to get in line for stem cell therapies for all that ails you.
What I first want from stem cell therapy: the quality of eyesight I had as a teenager.
|Share |||Randall Parker, 2009 December 21 10:39 PM Biotech Stem Cells|