By Alice Park, Time. Wednesday, Sep. 02, 2009
This week, scientists at the Harvard Stem Cell Institute (HSCI) reported the first success in generating new populations of insulin-producing cells using skin cells of type 1 diabetes patients. The achievement involved the newer embryo-free technique for generating stem cells, and marked the first step toward building a treatment that could one day replace a patient's faulty insulin-making cells with healthy, functioning ones.
The experiment, published in the Proceedings of the National Academy of Sciences, also provided the first good model — in a petri dish — of how type 1 diabetes develops, giving scientists a peek at what goes wrong in patients affected by the disease. Such knowledge could lead to not only new stem cell-based treatments, but also novel drug therapies that might improve the symptoms of the disease.
The findings, published in the current issue of the Journal of the American Medical Association, exemplify the remarkable gains made by diabetes researchers, who are battling a continuously spreading disease that now affects nearly 8% of adults and children.
Douglas Melton, co-director of HSCI, and his team took skin cells from two type 1 diabetes patients, exposed the cells to a cocktail of three genes that reverted them back to an embryonic state — which are referred to as pluripotent stem cells — then instructed the newly reborn cells to grow into beta cells, the cells in the pancreas that secrete insulin. In type 1 diabetes, these beta cells no longer work to break down the glucose that floods the body after each meal, leading to blood sugar spikes that can damage the kidneys and heart.
To test whether their lab-made cells could function like normal beta cells, Melton's group exposed them to glucose in a dish. When sugar levels were high, the cells produced more of a protein that beta cells release when they break down sugar; when glucose levels were low, the protein levels were low as well.
Diabetes researchers believe that the disorder is caused by some type of immune reaction gone awry — immune cells are "trained" in the thymus gland to recognize the body's own cells and protect them from destruction. For some reason, this education doesn't occur properly in type 1 diabetes patients, and the immune system sees the pancreatic beta cells as foreign. Melton's team is currently working to generate thymus cells from diabetic patients in the same way they created the beta cells, in order to put all the players together in a lab dish, in a kind of biological diorama of the disease. The researchers are hoping to learn whether diabetes begins in the thymus or in the pancreas, where beta cells somehow change and are no longer recognized or protected by the immune system. "We still really don't know the mechanism of what causes this disease," says Melton. "We don't know which cell is initially responsible, and we don't know if certain people are destined to get it, or if there are things we can do to prevent it, or how to reverse it."
More...
