A vocal proponent of embryonic stem cell research, Harvard professor Douglas Melton, claims that there is “no evidence whatsoever for the existence of an adult pancreatic stem cell”. In an experiment on mice reported in the leading journal Nature, he tracked the development of new insulin-producing beta cells as the mice recovered from surgical trauma to their pancreas. All the new beta cells came from older beta cells rather than from stem cells. In the absence of adult pancreatic stem cells, he argues, scientists will have to use stem cells derived from embryos.

Professor Melton’s paper will undoubtedly be used as ammunition in the highly-charged controversy over federal funding for therapeutic cloning in the US. Diabetes is probably the disease with the highest profile in the debate and has the most powerful lobby. However, not everyone agrees with Melton’s interpretation of his experiment. Vijay Ramiya of the University of Florida told the Washington Post that the results were unrealistic because the mice did not have diabetes. And fellow Harvard researcher Denise Faustman feels that the best way to generate beta cells may not involve stem cells but drugs which encourage beta cells to multiply.