Scientists say they've shown for the first time in a living animal that bone marrow cells can become insulin-producing cells in the pancreas. They hope this could be the first step toward developing a therapy for diabetics that doesn't require regular insulin injections.
A team led by Andreea Ianus of New York University transplanted bone marrow cells from male mice into female mice whose marrow had been destroyed by radiation. The donor cells were engineered to produce a fluorescent protein (GFP) if they started producing insulin. About 6 weeks after transplantation, the researchers found male cells (identified by their Y chromosomes) in the pancreases of the females. The cells produced insulin and other substances associated with pancreatic beta cells. They report their findings in the March Journal of Clinical Investigation.
The work is "fascinating" and "important ... if it turns out to be right," says diabetes researcher Douglas Melton of Harvard University. Other researchers, such as Markus Grompe of Oregon Health Sciences University in Portland, are maintaining a healthy skepticism. "Many labs have looked at bone marrow-derived pancreatic cells and not seen similar results," says Grompe, who wonders if the insulin signals are a sign that donor cells merely fused with resident insulin-producing beta cells instead of transforming into beta cells themselves.
Ianus and colleagues, however, believe they've ruled out that possibility. Co-author Mehboob Hussain explains that they tested for fusion by inserting male marrow cells into females whose beta cells contained an inactivated form of GFP. The male cells did not contain GFP but had an enzyme that activates the inactive form of GFP. The cells didn't glow, indicating that the male marrow cells hadn't fused to the female beta cells.
High hopes are riding on the next experiment, which is to see whether marrow cells will actually restore insulin in a mouse model of diabetes. Although the rate of new cell production was low in experiments with non-diabetic mice, Hussain predicts that the rate of new beta cell production will be much higher in damaged pancreases.