Credit: Horst Puschmann

Diabetes mellitus is a chronic disease that affects at least 171 million people worldwide. Many people with diabetes are dependent on insulin and must take daily injections to regulate the levels of glucose in their blood. Failure to control blood glucose levels can result in various acute and long-term complications that can have severe health effects, including hypoglycemia, diabetic ketoacidosis, cardiovascular disease, chronic renal failure and retinal damage. Although insulin and other medications may help people to manage the disease, they are not a cure. The search for a cure continues, and new research shows promise.

A group of scientists led by Marc R. Hammerman (Washington University School of Medicine, St. Louis, MO) has shown that two-part transplants of pancreatic cells from embryonic and adult pigs can cure diabetes in rats. The cells engrafted successfully into the rats' tissues and produced enough insulin to control their blood sugar levels—without the need to administer immune-suppressive drugs to prevent transplant rejection (Am. J. Pathol. published online 25 June 2010; doi:10.2353/ajpath.2010.091193).

The study used Lewis rats with diabetes induced by streptozotocin. The diabetic rats were treated with pancreatic primordial cells obtained from fetal pigs (at embryonic day 28, a very early stage of organ development). Previous studies had shown that these cells were tolerated by both rats and rhesus macaques without immune-suppressive treatments. Several weeks later, the rats were given a second transplant of pig pancreatic cells: adult islet cells. Islets are the insulin-producing cells of the pancreas. Beginning 4 weeks after islet cell transplantation and continuing for several months, rats that received both cell treatments had normal blood glucose levels. In comparison, rats that had received only embryonic cells had elevated blood glucose levels. In addition, Hammerman and his colleagues observed that the adult islet cells had successfully engrafted in rats that received both cell treatments, whereas the transplanted islet cells underwent immune rejection in rats that did not receive embryonic cells beforehand.

Next, Hammerman's group plans to test the approach in rhesus macaques. “In essence, first transplanting embryonic pig pancreatic cells enables adult pig islet implants to cure diabetes in rats without immune suppression drugs,” Hammerman stated in a press release. He continued, “We are now carrying out experiments to test whether the same transplant surgery works in diabetic non-human primates without using immune suppression drugs. If it does, we hope to evaluate pig cell transplants in people with diabetes.”