How to Protect Transplanted Islets

The immune system of a person with Type 1 diabetes is obnoxiously good at killing off insulin-producing islet cells. First, it knocks off as many islets as it can find, and then it waits to see if any more show up. Any islets transplanted into the T1 body must run a gauntlet of killer T cells to survive long enough to integrate into the body. Most don’t live that long; some 90% of islets die either during transplant or shortly thereafter, making islet therapy often an expensive T1 therapy of last resort.

One of the ways to change that calculus is to create better shelter for transplanted islets. The Diabetes Research Institute (DRI) has been working on biologically engineering something called a BioHub, which would create a kind of safe house for transplanted islets to get established before having to face off against the body’s immune system. It would have to be a smart shelter that allows insulin to go out and nutrients and blood to come in, but somehow bars T cells from wreaking havoc. The goal is to make things more hospitable for these pioneering islets, says Dr. Cherie Stabler, director of tissue engineering at the institute.

“We’re not going to take the islets and put them in a desert,” says Dr. Stabler. “We’re going to to put them in a house that has electricity, that has plumbing, that has all the things we need to give them.”

DRI researchers are studying various ways to create this kinder, gentler environment for islets. One option that’s being seriously explored is a sponge-like silicone wafer, slightly larger than a quarter, that allows transplanted islets to safely reside in the body of a Type 1 diabetic. This would be like creating a new mini-organ that would take up some of the work of the pancreas. An advantage to this strategy is that it keeps islets organized, says Dr. Norma Kenyon, a senior scientist at the institute.

“If you put single cells in the body, they are all just going to migrate and just go where they want to go,” Dr. Kenyon says.

Another advantage of a BioHub device is that it can give scientists a focal point for islet treatment. In the future, endocrinologists may be able to directly inject transplanted islets into the BioHub device. And immunosuppressive drugs could also be injected directly into the islet shelter, rather than given systemically, as they are now. That would remove a huge barrier to islet therapy for younger children with Type 1.

“We can’t give immunosuppressive drugs to a 13-year-old. That’s not a cure for everyone,” says Dr. Stabler. “We need to develop more novel, innovative, less burdensome immunosuppressive therapy.”

Researchers at the institute believe they will know within the next couple of years whether they can successfully develop a BioHub islet safe house. Human trials are ongoing.

Bob Benchley contributed additional reporting for this story.

To learn more about the Diabetes Research Institute’s BioHub research, watch this video.

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Craig Idlebrook is a past editor for Insulin Nation, Type 2 Nation, and Información Sobre Diabetes. He is now the community engagement and content manager for T1D Exchange.

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