Back to the Future
Scientists have known for decades that we possess stem cells that replenish our bodies’ tissues. Blood-forming (hematopoietic) stem cells, for example, can spawn red cells, white cells and all the other types of blood cells. Most intriguing of all are human embryonic stem cells, capable of developing into any of the body’s more than 100 different types of tissue—a characteristic known as pluripotency.
Researchers suspected that if human embryonic stem cells could be isolated, they could be used to renew or repair all sorts of human tissues. But even the simple act of obtaining human stem cells for scientific study proved difficult.
A breakthrough came in 1998, when James Thomson of the University of Wisconsin discovered how to isolate stem cells from early human embryos and culture them in laboratory dishes. Ideally, these human embryonic stem cells could then be made to develop into any tissue type desired. But obtaining human embryonic stem cells meant sacrificing the embryo, triggering opposition to their use. In 2001, President George W. Bush limited federal funding for such research to 60 human embryonic stem cell lines then in existence.
The field was reinvigorated by Shinya Yamanaka, M.D., a Japanese researcher. In 2006, Dr. Yamanaka found that inserting four particular genes into adult mouse skin cells caused those cells to go backward developmentally and turn into cells closely resembling embryonic stem cells. He then showed that these engineered cells, dubbed “induced pluripotent stem cells (iPSCs),” could—like embryonic stem cells—be coaxed to differentiate into many cell types. A year later, he duplicated the experiment using adult human skin cells. His discovery that mature, fully differentiated cells could be reprogrammed to become pluripotent would earn him a share of the 2012 Nobel Prize in Physiology or Medicine.
“Thanks to Dr. Yamanaka’s breakthrough, researchers finally have a source of embryonic-like human stem cells that is free of ethical constraints,” says Paul S. Frenette, M.D., professor of medicine (hematology) and of cell biology, and chair and director of the Ruth L. and David S. Gottesman Institute for Stem Cell and Regenerative Medicine Research at Einstein. “While it’s too early to assess the full impact of this technology, iPSCs have great potential in everything from disease modeling to drug testing to regenerative medicine.”
Einstein investigators are currently using iPSCs to study autism, schizophrenia, cataracts, liver disease and blood disease. To encourage further iPSC research, the Gottesman Institute has established a Pluripotent Stem Cell Unit, which creates iPSCs for the Einstein research community and provides training in maintaining and differentiating iPSCs.