Two independent teams of scientists have concluded that induced pluripotent stem cells (iPSCs) don't behave exactly like the stem cells found in early human embryos that are just a few days old. Investigators at the Massachusetts General Hospital Center for Regenerative Medicine have confirmed that iPSCs retain some characteristics of the cells from which they were derived--something that could both assist and impede potential clinical and research uses. In their report to be published in Nature Biotechnology, the researchers also describe finding that these cellular "memories" fade and disappear as cell lines are cultured through successive generations.
The findings may pose a challenge to previous research that suggested these reprogrammed cells may be substituted for embryonic stem cells, Bloomberg points out. However, researchers are already developing ways to get around the limits identified in the study, so the iPSCs can be used to treat certain conditions. "It's a challenge to be understood and overcome," George Daley, a researcher at the Harvard Stem Cell Institute and Children's Hospital in Boston and lead author of a separate Nature study, told Bloomberg over the phone. "We already have strategies for overcoming this."
Still, the study results are a setback for the field of regenerative medicine, in which stem cells are used to grow new body tissues aimed at repairing or replacing body parts damaged from injury or illness, Bloomberg notes. "How faithfully iPSCs can be reprogrammed into a truly embryonic state has been a longstanding question, and we have found that the cell of origin does affect the capacity of iPSCs to differentiate in vitro into particular cell types," says Konrad Hochedlinger of the MGH Center for Regenerative Medicine in a statement. "But when cultured iPSCs go through many rounds of cell division, they lose that memory."