How pigs might help humans with type-1 diabetes
In a first step for finding a new therapy for type-1 diabetes, researchers at Northwestern University have transplanted pancreatic cells from one species to another. The hope is to be able to transplant insulin producing cells from pigs to humans without rejection.
The study authors explain hard to control type-1 diabetes can be treated transplants from deceased donors, but there is a shortage of islet cells available. The result is that many people with the disease suffer from diabetes complications while they wait for a donor.
The researchers have developed a new method that prevented the islet cells from being rejected that study co-senior author Stephen Miller said in a press release is “…a big step forward.”
“Our ultimate goal is to be able to transplant pig islets into humans, but we have to take baby steps,” said Xunrong Luo, M.D., co-senior author of the study. “Pig islets produce insulin that controls blood sugar in humans.”
Until now, an interspecies islet transplant for controlling type-1 diabetes was impossible because of rejection.
But now researchers have found how to coax the immune system. They transplanted islet cells from rats to mice. The cells lived for up 300 days without the need for immunosuppressant drugs that have serious side effects.
Luo notes transplanting insulin producing cells from rats to mice is probably easier than from pigs to humans. However, the finding showed it can be done without the need for drugs.
Luo found out if she ‘killed off’ beta-cells at the same time the islet cells from the donors were being transplanted the mice would not produce rejection antibodies.
In an attempt to get the immune system to recognize the islet cells and not attack, Luo removed a type of white blood cells from the spleen of rats. The cells were killed with a chemical and then injected into the mice and ‘mopped up’ by scavenger cells. Fragments of the cells that remained told the immune system’s T-cells to accept and not attack the remaining transplanted rat islet cells.
But rejection was still a threat, but this time from B-cells that are also major antibody producers and one of the major hurdles for interspecies transplants. The mice started producing immune cell antibodies when the islet cells were transplanted.
Luo used B-cell depleting antibodies that are already used in human transplants to overcome the rejection. When the B-cells returned after the transplant they no longer attacked. The finding shows promise for helping humans with type-1 diabetes that could improve quality of life for those awaiting donors to control the disease.
“With this method, 100 percent of the islets survived indefinitely,” Luo said. “Now we’re trying to figure out why the B-cells are different when they come back.”