While the prospect of porcine islet transplants holds much promise and "is one of the best options for (type 1 diabetes) treatment," the biggest obstacle will come from the human immune system's willingness to accept the new cells, says Ewan McNay, an assistant professor of internal medicine specializing in endocrinology at Yale University's School of Medicine in New Haven, Conn. "This is the case with any transplant surgery," adds McNay, who studies the effects of transplantation more generally. "Type 1 diabetes is an autoimmune disease to begin with, so it's likely those stem cells will face the same problems that the original pancreas had."
MicroIslet is hoping to begin human xenotransplantation trials by the end of the year. Candidates for the procedure will be diabetes patients who have received kidney transplants. "These are people who are encountering the same problems that attacked their original kidney," Hoffman says.
Pig insulin is a good candidate for xenotransplantation to humans because it differs from human insulin by only a single amino acid. Although the Food and Drug Administration has approved porcine organ xenotransplants, it is still unclear how long these new islets can remain functional in a human body, Hoffman says. "If they lasted six months to a year,'' he says, "you could have treatment at those intervals."