Thursday, September 10, 2009

Oh No! Not More Stem Cells!

I came across two articles yesterday about stem cells, so it's time for another "embryo vs. adult" article. As background, see my earlier blog The Stem Cell Debate is Over? about the difference between adult and embryonic stem cells. So, onto the latest news in stem cell research.

According to Liposuction Leftovers, fat cells, as a byproduct of liposuction can quickly and easily be converted into iPS (induced pluripotent) stem cells, which provides an easy way to to do research with iPS cells, and potentially a faster way to provide treatments derived from those cells. The research isn't "scalpel ready", of course, but the idea would be to do a liposuction-like procedure to remove fat cells form a patient, convert them to iPS cells, and use those cells to treat a variety of diseases on the patient himself. Since the cells are the patient's own tissue there is no risk of tissue rejection or other immune problems. As the article states

“Thirty to 40 percent of adults in this country are obese,” agreed cardiologist Joseph Wu, MD, PhD, the paper’s senior author. “Not only can we start with a lot of cells, we can reprogram them much more efficiently. Fibroblasts, or skin cells, must be grown in the lab for three weeks or more before they can be reprogrammed. But these stem cells from fat are ready to go right away.”

The fact that these cells don't have to be cultured is important, because existing ways to culture human skin cells to make iPS cells involves using mouse-derived "feeder cells", and scientists are concerned about cross-species contamination which could be a barrier to developing treatments using the cells.

At the same time I can across Immune Response in Mice Suggests Limits to Embryonic Stem Cell Therapy. This research was done on mice. Mice are used in a lot of research not because scientists want to kill them, but because their immune systems are very similar to a human's. They are used where the research would be dangerous to humans, or the effects are unknown. As the article states:

"We all want to know what's going to happen if you transplant these stem cells into a person," said Mark Davis, MD, PhD, the Burt and Marion Avery Family Professor and professor of microbiology and immunology. But because unmodified embryonic stem cells can cause cancer, the researchers transplanted the cells into mice rather than people.

Proponents of embryonic stem cell research claim that embryonic stem cells are "given a free pass" by the body's immune system, but that is conjecture. So the researchers studied the mouse immune system's response to embryonic stem cells, and discovered than contrary to the beliefs of embryonic stem cell researchers, the immune system does attack embryonic stem cells, since they are foreign tissue. As the article quotes

"It's getting harder and harder to believe that these cells are immunoprivileged," said Joseph Wu, MD, PhD, assistant professor of cardiovascular medicine and of radiology. "In fact, the rejection of these cells confirms our suspicions that they do cause an immune response."


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