Research targets adult stem cells

LOS ANGELES – Several recent studies suggest adult stem cells can produce a range of tissues, reviving prospects that benefits of embryonic stem cells could be realized without accom- panying moral and regulatory concerns.

The studies are preliminary and have not been validated by other labs.

Unlike embryonic stem cells, which can grow into every tissue type in the body, adult stem cells are focused narrowly on regenerating a single type of tissue.

Scientists have theorized it might be possible to turn back their developmental clocks and retrain them to behave more like embryonic cells.

At a hospital affiliated with Tufts University School of Medicine, stem cells extracted from human bone marrow helped rebuild heart muscle and blood vessels in rats. At a biotech company in San Diego, researchers induced stem cells from mouse hair follicles to become neurons. At the University of Indiana, scientists transformed stem cells from mouse bone marrow into nerve cells that facilitate hearing.

But some proponents of embryonic stem cells say they are unconvinced that their colleagues have unlocked any new abilities of adult stem cells, partly because past experiments have failed to stand the test of time.