Therapies for diabetes using stem cells

The recent explosion of interest in cell replacement therapies and the use of cord blood banks for diabetes have driven primarily by the dramatic progress in allergenic islet cell transplantation. For the first time, the Edmonton group actually demonstrated that islet transplantation is a viable therapy for people who have diabetes.

This advance was dependent largely on progress in immunosuppressive drug therapy that allowed for a steroid-free regimen. Further advances in this area are likely to result in even better long term results as there is evidence that even the current improved drug regimens are toxic stem cells.

While the success of the Edmonton trial was an important proof of principle, it did not address the major problem with islet transplantation, which is actually the grossly inadequate supply of cadaveric pancreases as a source of islets. Solving this problem has been a major focus of research in stem cells biology and will surely have effects on stem cells banks.

Many different potential sources of cells for stem cells replacement, each with its own advantages and disadvantages, are being studied. Overall, three major sources of cells are being pursued. Those are embryonic stem cells, adult stem cells and cell lines.

Mainly because of the ethical concerns about cells, many studies have actually been directed towards inducing stem cell differentiation from adult stem cells, either from the pancreas or from other sources such as bone marrow. Although many investigators have claimed that stem cells from ectopic organs such as bone marrow can be induced to differentiate into a variety of cell types such as neurons, there have been no studies as yet in which cells have been generated from adult stem cells outside of the pancreas.

Questions have been raised recently about the plasticity of adult stem cells. The possibility that apparent differentiation may result from fusion of adult stem cells with differentiated cells has been raised. Elegant experiments using marked stem cells have not found evidence that bone marrow derived cells can differentiate into non hematopoietic lineage.

A great deal of effort has been made to identify stem cells within the pancreas. It has been known for some time that the pool of stem cells can be regenerated when placed under stress by a number of manipulations, including partial pancreatectomy, drugs, and immune medicated damage. A central question in cell biology concerns the identity of cells that give rise to the regenerated cells.