To their surprise, UC San Francisco researchers have discovered a new type of cell in women's breast tissue that might one day be used to heal a variety of wounds and damaged organs, without having to destroy embryos to acquire stem cells.
The newly discovered cells act similarly to embryonic stem cells in that they can be placed in mice or in a Petri dish and "instructed" to produce many different cell types.
That raises hope that the cells might someday be used as a sort of personalized "patch kit," without the controversy that has surrounded stem cells taken from human embryos.
"When we saw that they could make cartilage, bone, gut, brain, pancreas cells -- even beating heart tissue -- we were excited and intrigued," said senior study author Thea Tlsty, a UCSF professor of pathology.
"We were not looking for this," she said. "This was unexpected."
The study was published Monday in the online early edition of the Proceedings of the National Academy of Sciences.
Scientists had previously believed that so-called pluripotent cells, which can transform into most cell types, did not exist in the body beyond the embryonic stage of development.
The new cells may have some advantages over a 2007 scientific breakthrough that revolutionized the field of regenerative medicine -- the discovery that adult skin cells could be reprogrammed or reverse-engineered to act like embryonic stem cells and transform into a variety of cell
Researchers dubbed these reprogrammed cells induced pluripotent stem cells, or iPS. Such cells are made without destroying embryos, and hundreds of scientists around the world are researching them, but some have wondered whether these cells might form cancerous tumors when introduced into a human body.
Tlsty noted that the newly discovered cells are more genetically stable than the iPS cells and are limited in how often they can reproduce, making them less likely to form cancers.
"They have great potential," Tlsty said. "If this develops the way we think it's going to develop, it really could be a significant step forward for regenerative medicine."
A leading California stem cell researcher who was not involved with the study called the results "really interesting and intriguing" but said more research is needed.
"Any unusual finding awaits independent replication and further exploration," said Larry Goldstein, director of the UC San Diego stem cell research program.
"Time will tell as investigators try to replicate the finding. Is it a mirage, a blind alley, or a path to a valley full of riches?" he said.
The cells were first discovered in healthy breast tissue from women who were undergoing breast reductions. Researchers have since looked at tissue from more than 60 women. All had some of the cells, although it isn't yet known whether they exist in older women and young girls.
"We anticipate that we'll be able to get them from other tissues, and that's some of the research that we're doing now," Tlsty said. She added that researchers believe the cells will be found in both men and women.
They are calling the newly identified cells endogenous pluripotent somatic cells, or ePS.
"Pretty much everything we've asked them to make, they've made," Tlsty said. "These cells have responded beautifully."
Sandy Kleffman covers health. Contact her at 510-293-2478. Follow her at Twitter.com/skleffman.