Why are beta cells transplanted?
Insulin-producing beta cells in the pancreas are critical for helping to keep blood sugar levels in a healthy range. Type I diabetes develops when these cells, found in cell clusters called islets, are attacked and destroyed by a person’s own immune system. Clinical trials have shown that it is possible to restore healthy blood sugar regulation (normoglycemia) by transplanting functional islets into people living with type I diabetes. However, 50-70% of the transplant can be lost within the first week, with much of the loss happening mere minutes after transplantation.
What’s happening to new transplants?
Once in their new environment, transplanted islets face lethal challenges. The inevitable contact with blood during the transplantation process immediately triggers an immune cascade which results in an army of immune cells congregating at the site of the transplant to destroy it. Another hurdle for new transplants is that they don’t have access to an established network of blood vessels (this takes time to establish), which islets rely on to receive oxygen and nutrients. Finally, demand for insulin and other hormones puts the islets under stress, and high concentrations of sugars and fats further stresses them out and can lead to death. This overwhelming combination of factors makes it difficult for newly transplanted islets to stand a chance at survival.
What can we do?
Scientists are working hard all around the world to neutralize the threats transplanted islets face. Different approaches being researched include: a) trying a variety of transplant sites; b) surrounding transplanted islets in a substance called hydrogels, which contain factors that promote blood vessel formation (vascularization); and c) adding other cell types or chemical coatings around islets before transplanting them to protect them from the immune response or help speed up blood vessel formation to supply oxygen. Finally, transplanting islets derived from stem cells represents another approach as these cells can be engineered to help improve their survival and function.
With continued research, medical science is moving towards identifying a combination of approaches that may one day establish islet transplantation as a realistic treatment option for type I diabetes.
About the author
Masha Beletsky
Masha Beletsky is pursuing a PhD at the University of British Columbia studying how to improve islet survival after transplantation by genetically engineering stem cell-derived islets. Masha is also the co-founder and Vice President of the BC Biotech Network, a non-profit that seeks to build community within Vancouver's biotech bubble and empower and support early stage career scientists.
