There is a flurry of activity going on in labs around the world to harness the extraordinary potential of stem cells. Those who suffer from diabetes are poised to benefit significantly from this work.
By definition, stem cells have the ability to self renew and differentiate into other cells types. In 1998 University of Wisconsin scientist James Thomson and colleagues reported the isolation of pluripotent stem cells from few day-old embryos obtained from fertility clinics. These embyronic stem (ES) cells were shown to be capable of vast expansion and differentiation into some 200 different cell types found in the body.
The promise was immediately obvious – in theory healthy cells could be produced to replace damaged or defective cells to treat human disease. Despite this potential, ethical issues associated with the source of these cells prompted governments to put severe restrictions on their use for research.
In 2006, Japanese scientists at Kyoto University led by Shinya Yamanaka made a remarkable discovery. They demonstrated that cultured mouse skin cells could be reprogrammed into stem cells with the potential of ES cells by simply introducing four genes into the cells. These cells were termed induced pluripotent stem (iPS) cells and, just one year later, both Yamanaka’s and Thomson’s teams achieved the same feat with human skin cells, thereby providing the world with a less controversial source of stem cells.
This protocol gave us the tools to envision patient specific cell therapy. A patient in need of a specific cell type could provide a tiny skin sample to be used to generate stem cells, which could then be expanded, differentiated into the desired cell type, and then transplanted to treat their disease or injury. Moreover, iPS cells provide a means to study human disease. Stem cells can be generated from patients and subsequently differentiated into the diseased cell type to study its defects and develop corrective measures to treat the disease. This year Yamanaka shared a Nobel Prize with British Scientist John Gurdon for this work.
Those who suffer from diabetes can take hope. The disease afflicts an estimated 350-million people worldwide and is caused by insufficient production of insulin from pancreatic beta-cells. Many patients rely on daily insulin injections to survive, but a few have received an expermental therapy consisting of transplant of cadaveric islets – clusters of the insulin producing beta-cells collected from organ donors. The procedure involves infusion of a few teaspoons of cells into the portal vein and frees patients from the burdens of glucose monitoring and insulin injections. With a proven effective clinical path, an unlimited source of insulin producing cells is needed to make this approach widely available. Could stem cells hold the answer?
Over the past decade, there have been considerable advances towards harnessing stem cells to tackle diabetes. Developmental biologists are elucidating how beta-cells are created, often with model systems such as fish, and this knowledge is being exploited to create recipies to convert stem cells into beta-cells. Success has already been obtained in treating diabetes in animal models. iPS cells have now been made from patients with diabetes and these have been converted to beta-cells – an important first step towards modeling diabetes to understand the root cause. With momentum gaining, I wouldn’t be surprised if stem cells can deliver us from diabetes within the next decade.