In the Proceedings of the National Academy of Sciences, researchers from UC San Diego reported that they have identified a signaling pathway necessary for stem cells to replicate. Small molecule compounds that inhibited this pathway dramatically reduced the tumor-forming potential of these human embryonic stem cells.
The researchers experimented on immune-deficient mice that received grafts of human embryonic stem cells. The research focused on a protein called Nanog essential to the unlimited replication of embryonic stem cells. Nanog also suppresses cell differentiation signals. Interfering with Nanog’s function inhibits the replication, and assists in differentiation. The differentiated cells are not vulnerable to making teratomas like the undifferentiated embryonic stem cells are. The paper, “Phosphorylation stabilizes Nanog by promoting its interaction with Pin1,” is available at PNAS’ Website.
“But this differentiation is never complete, meaning that the final product is a mixture of cells inevitably containing undifferentiated embryonic stem cells. So by transplanting these cells into a patient, there’s clearly a risk of producing teratomas,” said Yang Xu, a professor of biology who headed the team that published the report, in a UCSD press release on the study. Last month, Xu received a $1.2M grant from the California Institute for Regenerative Medicine for another research project, to make induce immune tolerance to transplants of cells grown from human embryonic stem cells. (HWM and B Fikes)