All previously identified stem cells in adult tissues could only go on to form the cell types found in that tissue. Stem cells lodged in the brain form cell types found in the brain, and blood-forming stem cells form all the cell types of the blood. The cells discovered by Tlsty could form anything. Hughes describes the work like this:
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.
After putting these cells onto a plastic plate and letting them stew in nutrients and growth factors known to nurture the development of heart muscle cells, Tlsty’s junior colleague Somdutta Roy created heart cells that actually beat in the lab dish. “When she first saw the beating cardiomyocytes, she did a little dance,” Tlsty says. “Then she called everybody in the lab over to look at them.” With other nutrient blends, the team brought neurons, bone, fat and blood vessels to life.The story goes on to quote two other CIRM grantees. Deepak Srivastava of the Gladsone Institutes says he thinks the cells could have a therapeutic role. Srivastava has been central to a new field of direct reprogramming, in which one type of adult cell is converted directly into a different type of cell. Paul Knoepfler of UC Davis says in the story that it's still unclear why tissues would contain such cells.
After this Tlsty's study was published in March, CIRM President Alan Trouson wrote about the work in his monthly science picks:
Like much of science, these results will gain strength when they are replicated by other teams. But Tlsty and her team have already begun looking for similar cells in other tissues in the body.Amy Adams