Islet cell transplantation is being touted as a future option for treating type 2 diabetes, even though it’s an experimental procedure that has only been tried on type 1 diabetics.
“I’m a big proponent of islet cell transplantation for type 2 diabetics,” says Dr. Gordon Weir, who is one of the world’s foremost experts on islet cell transplantation as Co-Head of the Section on Islet Cell and Regenerative Biology, the Diabetes Research and Wellness Foundation Chair at the Joslin Diabetes Center, and Professor of Medicine at Harvard Medical School. “I tell people this and they look at me like I’m a little nuts. But, I believe there is no reason it couldn’t work effectively. I’m actually more optimistic about islet cell transplant for type 2 than for type 1.”
Several significant hurdles need to be overcome, however, before either type 1 or type 2 diabetics benefit from islet cell transplantation. Chief among them is perfecting a method for producing islet cells beyond having to rely on those provided by deceased organ donors, and making the procedure cost effective enough for widespread use.
Islet cell transplantation is a strictly experimental procedure in which insulin-producing islet (pronounced eye-let) cells from cadaver pancreases are transplanted into the liver of a type 1 diabetic. The procedure replaces the islet cells killed off as a result of an autoimmune response, which typically causes type 1 diabetes.
Type 2 diabetes, meanwhile, is not considered an autoimmune disease that kills off islet cells. Instead, type 2 is characterized by the body’s inability to respond to insulin (insulin resistance) or by a decrease in insulin production. But, according to Weir, just because type 2 has a different root cause than type 1 doesn’t mean transplanting islet cells into type 2 diabetics would not be effective.
“Pancreas transplants have been shown to work well in treating type 2 diabetes,” Weir says. “If the type 2 diabetes is caused by a resistance to the action of insulin, then we can give them more cells. If their cells are making too little insulin, then we can give them more cells. Either way, it would work. It’s similar to administering a shot of insulin.”
Weir is not alone is considering the theoretical possibility of an islet cell transplant for treating type 2 diabetes. Orgenesis is a company that is perfecting a process of turning a diabetic’s own liver cells into pancreatic cells that can then be transplanted back into the person to cure their diabetes. In their marketing materials Orgenesis says their technology could be used to treat type 2 diabetes, even though it’s not yet been tested or tried in a clinical setting.
“Just because it’s never been done,” says Orgenesis President and CEO Vered Caplan, “doesn’t mean it can’t be done or that it wouldn’t work. It makes perfect sense that it would.”
Weir cautions that replacing the beta cells (which is the specific part of the islet cell that produces insulin) through a transplant would only treat type 2 diabetes. It would not “cure” it in the classic sense of eradicating the cause. That, however, is beside the point.
“Type 2 itself can be viewed as two separate diseases,” Weir says. “In one, insulin resistance is caused by obesity and lifestyle. In the other, beta cells fail and produce less insulin. Either way we can improve blood sugar control by transplanting beta cells. That means the patient will be a heck of a lot healthier and we can cut their chances of developing diabetic complications. The transplant, however, can’t improve obesity or other lifestyle factors, but we can at least protect them from the effects of diabetes.”
Another factor that indicates islet cell transplantation might be an effective treatment for type 2 is the fact that type 2 diabetics are not suffering from an autoimmune response. Type 2 diabetes is not caused by the body targeting and killing islet cells in the first place, like in type 1 diabetes. That means, Weir says, that type 2 diabetics might not need post-transplant immunosuppression, like type 1 subjects now require, in order to not reject the newly transplanted cells.
“Also,” Weir says, “islet these cells die very slowly in type 2 diabetics. A transplant then might last a decade, or even more. And, when those cells become resistant or die, we can simply transplant more.”
Given all these potential benefits, why aren’t researchers transplanting islet cells into type 2 diabetics to test the effectiveness of the procedure? The primary reason is that islet cells are extremely scarce and expensive to harvest and transplant. The only source is donated cells from cadaver pancreases. Additionally, each person who receives a transplant would require two or more transplants to have a chance for making it effective.
That problem, however, is being addressed. There are many companies, such as Orgenesis, working on ways to produce islet cells without relying on donor cells. These include generating them from embryonic stem cells, as well as growing islet cells from an adult’s own existing cells. In April researchers at the New York Stem Cell Foundation announced they had grown a stem cell line of insulin-producing beta cells from the skin cells of an adult diabetic.
“If there was a new source of beta cells it would mean that islet cell transplantation has real potential to become a viable treatment for type 2 diabetes,” says Weir—a man whose personalized license plate says ISLETS. “And I can tell you, the science is moving very quickly toward making it a reality.”