These cells, called stem cells, are recruited to the liver from the bone marrow and function as liver cells, according to a new study by New York University School of Medicine and Yale University School of Medicine scientists that proves for the first time that this process occurs in humans. Stem cells were long thought to be limited to organs that supply fresh sources of new cells throughout life, such as blood cells from the bone marrow and skin cells from skin. And cells from bone marrow, for example, couldn't become anything but blood cells. Some suspected there might be hepatic stem cells, but they lacked proof of their existence - until now. Each day a giant eagle eats the liver of Prometheus, who is bound by chains to a rock.
Bone marrow is supposed to turn out blood cells.
The goal is now to harness the potential of this finding into new avenues for therapeutics. The liver is the body's workhorse for many metabolic functions, and it also supplies blood-clotting factors. It is at least theoretically possible that healthy genes could be inserted into hepatic stem cells from the bone marrow, and these new cells would correct metabolic and blood-clotting abnormalities. In the new study, two women with leukemia, a blood-cell cancer, received bone marrow transplants from male donors as part of their therapy, and four men with severe liver disease received liver transplants from female donors. The researchers used the Y chromosome, which is found only in males, as a clever way to keep track of stem cells.