Stem cells derived from reprogramming adult cells may have limited usefulness as an alternative to embryonic stem cells, leading researchers said this week.

The study found that induced pluripotent stem cells, which have been the darling of stem cell scientists for the past couple of years, retain a “memory” of their original adult tissue. This may make it difficult to convert them to other cell types for medical treatment, say researchers from Harvard and Johns Hopkins. The findings were published online in Nature. Similar results from other Harvard researchers were published in Nature Biotechnology.

This could be a setback for regenerative medicine because iPS cells are a promising and ethical uncontroversial alternative for embryonic stem cells. However, researchers have already begun finding ways around the limits that the study has identified, so that the iPS cells could still be used for treating illnesses such as diabetes and Parkinson’s disease.

“It’s a challenge to be understood and overcome,” George Daley, a researcher at the Harvard Stem Cell Institute and Children’s Hospital in Boston and lead author of the Nature study, told Bloomberg Businessweek. “We already have strategies for overcoming this.” ~Bloomberg Businessweek, Jul 19