Protecting Beta Cells from the Immune System

By Josh Baxt

Type 1 diabetes is caused by an overactive immune response that kills off insulin-producing beta cells. While beta cells can be transplanted to replace the ones that have been lost, the immune system will eventually kill those off as well.

For transplantation to be a viable treatment, the immune system must be controlled. Current transplant recipients take immunosuppressive drugs to prevent their T cells from attacking replacement beta cells, presenting patients with a stark choice between diabetes and a suppressed immune system.

Sanford-Burnham adjunct assistant professor Dr. Pamela Itkin-Ansari is taking a different approach. Her laboratory has placed human pancreatic precursor cells in an immuno-protective device and transplanted them into mice. She was testing whether precursor cells will mature into productive beta cells in the body and whether the encapsulation device, made from a material akin to Gore-Tex, could prevent the immune system from attacking transplanted cells.

“We wanted to see if we could protect the cells from the immune system rather than suppressing the immune system,” says Dr. Itkin-Ansari.

Early studies were very positive, as the transplanted cells responded to glucose and produced insulin and the protective device kept the immune system at bay.

“We were excited to see how well they did,” says Dr Itkin-Ansari. “We could see evidence of new beta cells forming and replicating. That meant the environment in the device was conducive to beta cell maturation and function. We wondered whether  T cells, although unable to penetrate the device, would cluster around it. Interestingly, we found no evidence of an active immune response, suggesting that the cells in the device were invisible to the immune system.”

More recently, the protective device was studied in preclinical trials and continues to show great promise. In addition, Dr. Itkin-Ansari and Viacyte,  a San Diego biotechnology company, have received funding from the California Institute for Regenerative Medicine to marry this immune-protective technology with efforts to use stem cells to generate a virtually unlimited supply of beta cells. We’ll keep you updated on their progress.

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Josh Baxt

Josh was a Sanford-Burnham Communications staff member.