Stem Cells in the Treatment of Diabetes
Diabetes mellitus affects 18 million people in the U.S. alone (8.7% of the population) and more than 190 million worldwide. The prevalence of diabetes has increased alarmingly in the past three decades and, corresponding to global dietary and lifestyle trends, is projected to nearly double in the next ten years (1). Although diabetes can be treated, serious complications from improperly managed diabetes are common and can lead to death. Recent reports suggest that one of the most promising potential treatments may come from the use of stem cells, undifferentiated cells that can be coaxed into becoming insulin-producing islet-like cells that reduce diabetes symptoms in mice (2).
There is one ethical catch, however: stem cells can be derived from a number of sources, including adult tissues, but the purest source of stem cells with the greatest therapeutic potential is early-stage embryos. The process of deriving stem cells destroys the embryo. Does the human embryo have moral status that would proscribe its destruction, regardless of the potential good that might be achieved? If so, are there still avenues of stem cell research that are both scientifically viable as well as morally permissible?
Diabetes is a disease that results from the body's inability to maintain consistent levels of glucose (the main energy source for cells) in the blood. In a healthy individual, blood glucose levels are kept within a certain range by insulin, a hormone that aids the uptake of glucose by cells. The release of insulin in response to blood glucose levels is coordinated by clusters of cells in the pancreas called islets; residing in these islets are the beta cells, the cells that actually produce (and release) insulin. Diabetes develops when there too few functioning beta cells (2).
Diabetes can be controlled by frequent monitoring of blood glucose levels and either medication
(type II diabetes) or insulin injections (type I diabetes), but improper management of the disease results in serious complications, including heart and kidney damage, blindness and loss of extremities. One promising novel treatment for type I diabetes is pancreatic islet cell transplantation, but this therapy is limited by the number and availability of donated organs for transplant. If stem cells can be induced to differentiate into functional islet cells in the lab, they may form a renewable source for transplantation, allowing this cell-based treatment to become available on a practical scale (3, 4).
Stem cells are self-renewing, unspecialized cells that give rise to multiple specialized cell types through a process of differentiation. Theoretically, stem cells could be induced in the laboratory to become any specialized body cell type, including pancreatic islet cells, and then transplanted back into a patient to replace diseased or damaged tissue (2). Transplantation of stem cells or stem-cell derived tissue into human...