Fact Sheet

Do No Harm

May 7, 2004

Nature Study: No Evidence of Embryonic Stem Cell Advantage in Treating Diabetes

Media reports that a study published this week in Nature provides new evidence that embryonic stem cells (ESCs) provide the best avenue for treating diabetes are wildly off the mark. The study shows no such thing:

• The study was not about embryonic stem cells, and did nothing to show their superiority over adult stem cells or their usefulness for diabetes.
• The study did confirm that adult beta cells (which produce insulin) can regenerate in adults, without adding any foreign cells from embryos or anywhere else. While the authors did not find evidence that adult pancreatic stem cells (which would be capable of producing beta cells) exist, they also found that adult beta cells themselves are capable of regenerating. The study provides support for a particular theory as to how these adult cells regenerate - and it offers a new avenue for research and possible therapies that would not have to use ESCs. Another such avenue was recently announced by researchers at Massachusetts General Hospital, who cured diabetic mice by injecting them with donor spleen cells - it seems these cells "retrained" the mice's immune systems to stop attacking their own insulin-producing cells, allowing new cells to regenerate (possibly from their own remaining beta cells) without adding new stem cells from any outside source. The Boston Globe called this "a surprising breakthrough that could soon be tested in local patients and open a new chapter in diabetes research." (S. Kodama et al., in Science 302, 1223-1227; 14 Nov 2003; Boston Globe, Nov. 14, 2003, p. A2).
• Recent studies strongly call into question the capability of embryonic stem cells for treating juvenile diabetes.
  
  Researchers at the University of Calgary, for example, have found that the insulin-producing cells derived from ESCs are not the "beta cells" needed to reverse diabetes. While the cells produced some insulin, they failed to function as a normal beta cell and to produce the insulin when it was needed; when placed in mice they did not reverse diabetes but only formed teratomas (tumors) (S. Sipione et al., "Insulin expressing cells from differentiated embryonic stem cells are not beta cells," Diabetologia 47, 499-508, March 2004; published online 14 February 2004). And an author of the new Nature study also co-authored a recent study acknowledging that human embryonic stem cells spontaneously develop genetic "abnormalities" in culture -- a problem that may prevent any clinical use of these cells in humans for a long time to come (C. Cowan, D. Melton et al., in The New England Journal of Medicine 350, 1353-1356, March 25, 2004, published online March 3, 2004).

New advances in adult cell therapies provide scientifically well-grounded reasons for hope in their own right. They should not be twisted into yet another political weapon by those fixated on embryonic stem cell research.