A New Islet Source on the Horizon?
Researchers are speculating that human bone marrow may contain stem cells that are capable of differentiating into insulin-producing islet cells.
According to research published in the March 15, 2003, issue of the Journal of Clinical Investigation, four to six weeks after receiving bone marrow transplants, mice with diabetes were showing signs of producing insulin.
Green Light Means Go
Mehboob Hussain, MD, and colleagues in the Department of Medicine and Pharmacology at New York University School of Medicine genetically engineered a group of mice whose islet cells would turn fluorescent green when insulin was being produced.
The study used this group of mice as bone marrow donors for another group of mice, whose bone marrow had been destroyed with radiation.
When the bone marrow of the donor mice was transplanted into the recipient mice, the pancreases of the recipient mice began to show the fluorescent green color.
Speaking with Diabetes Health, Hussain described bone marrow as "a newly discovered source of cells that have the potential of becoming functional [insulin-producing] cells." He is hopeful that this research eventually "could lead to an entirely new way" of treating diabetes, without insulin injections, the transplantation of cadaver organs or anti-rejection drugs.
How Is This Approach Different?
Hussain explains that his group's procedure differs from the Edmonton Protocol islet transplantation procedure in that bone marrow is easily accessible from humans who are alive.
"Removal of some bone marrow is easily tolerated," he notes.
The Edmonton Protocol involves transplanting islets from deceased donors to people with diabetes, who then must follow a multi-drug immunosuppressive regimen to prevent rejection of the transplant.
Hussain adds that the new research did not involve transplanting islets; rather, the recipients received bone marrow stem cells that then seemed to "morph into islet cells within the recipients."
At this point, the researchers do not know whether such an approach would require anti-rejection drugs.
"If the donor cells could . . .evade the host's immune system—either by nature or after ex vivo [outside the body] genetic engineering—then there might be no need for anti-rejection medication," Hussain speculates.
No Politics Involved
The good news is that harvesting adult stem cells from bone marrow does not involve the same ethical dilemmas that researchers using embryonic stem cells now encounter.
"Application of adult stem cells is not limited by current ethical or political constraints," says Hussain. "Adult stem cell transplantation could be viewed [as] similar to a blood transfusion or a living-donor organ transplant—both procedures are performed routinely."
More Studies Needed
Exciting as this research is, there are still many basic questions to be answered before it translates into a new treatment for diabetes. Researchers do not know which specific types of bone marrow stem cells are able to differentiate into islet cells, what signals them to differentiate, or what levels of new islet cells would be required.
Most important, Hussain also would not speculate on whether his research team's findings for mice will be applicable to people with diabetes.
"This . . .cannot be answered without doing the experiment in humans. However, there are results from patients who had received bone marrow transplantation for reasons other than diabetes that suggest that the findings in mice can be translated into findings in humans."Click Here To View Or Post Comments