The Rise of the Multi-Talented Adult Stem Cell

Note: UCSF's Thea Tlsty, PhD, is a recipeint of a Spring 2013 Catalyst Award for “Endogenous Pluripotent Somatic Cells from Adult Human Tissue with Potential for Regenerative Medicine: Applications in Corneal Transplantation” (Therapeutics)

By Virginia Hughes via

You started out as a single cell. It divided, and so did its daughters and granddaughters, eventually producing trillions of cells with specific identities—red blood cells, neurons, heart muscle cells that beat, beat, beat. For as long as biologists have studied this maturation process, they’ve believed that cells in adult tissue can’t readily take on a whole new identity. But researchers are challenging this idea with the startling discovery of adult cells that retain their flexibility—a possible boon for treating devastating diseases.

The new work is the latest in a series of breakthroughs involving what are called pluripotent (for “many potentials”) stem cells, which give rise to any specialized cell type. In 1998, researchers first isolated human embryonic stem cells, but research on them has been hampered because it requires harvesting cells from discarded human embryos. In 2006, Shinya Yamanaka, of Kyoto University, avoided that ethical controversy when he discovered that adult skin cells can be removed from the body and genetically reprogrammed to revert to a pluripotent state. The work won him last year’s Nobel Prize.

What’s surprising about the new stem cell breakthrough is that researchers don’t have to turn back the cellular clock. Molecular pathologist Thea Tlsty and colleagues at the University of California, San Francisco, had been studying wound-healing cells in the breast, known to divide furiously in response to injury, when they hit upon a small subset carrying surface molecules similar to those on pluripotent stem cells. About 1 in every 10,000 breast cells appears to belong to a class of stem cells never seen before, now dubbed “endogenous pluripotent somatic” cells.