Adult stem cells may not deliver on their promise.

Since researchers isolated and cultured embryonic stem cells in 1998, they have fueled hopes of stem cell cures for everything from Parkinson’s disease to diabetes.

But faced with opposition to embryonic stem cell research and treatments, they have increasingly looked elsewhere for their cell source.

Until recently, adult stem cells seemed a good candidate. Study after study has shown that certain cells in the adult body, such as blood stem cells, could be coaxed to form various tissues in the same way as embryonic stem cells.

But some researchers are now questioning such findings, and have begun to investigate whether the results of previous studies were merely laboratory artifacts.

One study, for example, involved culturing adult stem cells for weeks before showing that they were multipotent when transplanted in mice. Cells cultured that long can behave oddly and have a greater risk of becoming cancerous.

Some researchers are now calling for more rigorous experimental standards and less hype. “We need to step back and do definitive experiments rather than flashy ones,” says Stuart Orkin, a blood stem cell researcher at Harvard Medical School, in a recent Nature article.


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