Improved Protection for Transplanted Stem Cell-Derived Islets

Insulin-producing beta cells are essential for effective blood sugar control. However, in individuals with type 1 diabetes, these cells are mistakenly destroyed by the immune system. That means exogenous insulin must be used instead to manage blood sugar. For years, scientists have been researching ways to replace or reproduce these islet cells. Two of the most common challenges faced, however, have been the need for long-term immunosuppression to protect transplanted cells from rejection, and limited availability of donor cells.

A recent study found that an improved source of encapsulation may protect islet cells from an immune response without decreasing their ability to secrete insulin. By using a conformal coating that is only a few tens of micrometers thick (as opposed to hundreds of micrometers thick), not only could insulin flow more freely through the encapsulation, so could oxygen, nutrients, and glucose as well. Yet larger immune cells were still unable to penetrate the barrier. In addition, the thinner coating allowed for more cells to be contained in a smaller space, and the capsule could be implanted in a wider range of locations so long as there was strong vascular function.

The encapsulated cells were implanted in NOD-scid mice and compared with non-coated stem cells as well as human islets. There were no statistically significant differences in performance of the cells and their ability to regulate glucose levels. The mice all showed a reversal in diabetes with the transplanted cells and returned to hyperglycemia once the cells were explanted.

The use of a microencapsulation method allows for more variability in placement of transplanted cells and helps protects against hypoxia-induced islet death and cell rejection. Furthermore, the thinner coating enabled islets to obtain better oxygenation because they are closer to blood vessels. It also allowed insulin to be secreted more quickly because it flowed more freely through the barrier.

One drawback that researchers noted was that encapsulated islets are unable to shed dead cells because they are contained within the capsule and have a lower absolute quantity of insulin secretion when compared to non-coated stem cell-derived islets.

Through this study, the researchers concluded that, “CC (conformal-coated) mouse islets can reverse diabetes long-term in a fully MHC-mismatched model.” While additional research is necessary to explore the effectiveness of this process in humans, it is a step in the right direction toward one day potentially curing type 1 diabetes.

Though not involved with this study, Diabetes Research Connection (DRC) stays abreast of the latest advancements in the field and provides critical funding to early career scientists pursuing novel research studies for type 1 diabetes. It is through these types of projects that researchers are able to improve quality of life for individuals living with the disease and move closer to finding a cure. To learn more about current DRC-funded projects or support these efforts, visit https://diabetesresearchconnection.org.

 

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