Scientists at the University of California San Diego (UC San Diego) School of Medicine and Burnham Institute for Medical Research (Burnham) have found that transplanted pancreatic precursor cells encased in polytetrafluorethylene (PTFE, a material akin to Gore-Tex) are protected from the immune system, are glucose-responsive and can control an animal's blood sugar. The study, which suggests a new approach to treating Type 1 diabetes, was published in the April 8 issue of the journal Transplantation.

"This approach may give us the option of hiding cells from the patient's immune system rather than eliminating the immune system entirely," said Pamela Itkin-Ansari, PhD, assistant adjunct professor at the UC San Diego School of Medicine and Burnham.

Type 1 diabetes results from an autoimmune response -- when the body attacks and kills insulin producing beta cells. A limitation to cell transplantation therapy to treat diabetes is the need for long term immunosuppression, which carries health risks. Transplanting them in a protective device would alleviate the need to use immunosuppressive drugs.

The study answered two key questions about beta cell transplantation: Can the device protect transplanted cells from the immune response and can the transplanted cells thrive within the device? In both cases, the answer was yes.

"The results exceeded our expectations," said Itkin-Ansari. "We had thought that T-cells, although unable to penetrate the device, would cluster around it. But we found no evidence of an active immune response, suggesting that the cells in the device were invisible to the immune system."

To determine whether the cells would be immunoprotected, the team transplanted mouse islets into other mice. To study the cells' survivability inside the device, they used human cells in immunosuppressed mice. In addition to showing that the transplanted cells could thrive inside the PTFE device, the study demonstrated that using precursor cells, instead of more committed beta cells, enhanced the transplant's chances of success.

"In performing the transplant, we damage the vasculature and many of the cells die in the first week," said Itkin-Ansari. "But we found that by using young tissue, before it had completely differentiated, the transplanted cells could regenerate into fully functional beta cells, compensating for those losses. This has important implications for how stem cell derived tissue should be transplanted in the future."

This study was funded by grants from the Juvenile Diabetes Research Foundation, the National Institute of Diabetes and Digestive and Kidney Diseases, and the JW Kieckhefer Foundation.