In Parkinson disease, and to a lesser extent, Huntington disease, clinical trials of fetal tissue transplantation have provided a proof of principle that cell replacement can work. But by and large the promise of using human stem cells for replacement tissues and organs has fallen short of hopes.
New research reported in Nature offers renewed hope. Researchers in Japan have used human stem cells to create tiny human livers like those that arise early in fetal life. When the scientists transplanted the rudimentary livers into mice, the little organs grew, made human liver proteins, and metabolized drugs as human livers do.
Ideological opponents have dismiss the medical potential of stem cell therapy, claiming embryonic stem cells have negligible promise compared to adult stem cells.
Stem cells are the cells from which all other cells originate. In a human embryo, a large portion of the embryo’s cells are stem cells. Even though most of these cells become differentiated, all humans retain some stem cells in various parts of their bodies. These cells, with the correct chemical cue, can develop into specialized cells which an ailing body might need.
Although human studies are years away, it’s believed this is the first time anyone has used human stem cells, created from human skin cells, to make a functioning solid organ, like a liver, as opposed to bone marrow, a jellylike organ.
“This is a major breakthrough of monumental significance,” said Dr. Hillel Tobias, director of transplantation at the New York University School of Medicine and chairman of the American Liver Foundation’s national medical advisory committee., to the New York Times.
“Very impressive,” said Eric Lagasse of the University of Pittsburgh, who studies cell transplantation and liver disease. “It’s novel and very exciting.”
Researchers estimate it could take a decade or more before this practice could be fully exploited.
- “Scientists Fabricate Rudimentary Human Livers,” New York Times
- Video: Stem cells used to grow human liver on mouse, Telegraph (UK)
- Video of process over 72 hours