Invention Allows Transplanted Cells to Evade Immune System

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The human body's immune system is similar to having millions, if not billions, of snipers at the ready aiming and poised to shoot any foreign invader which is why transplanted tissues and organs are so vulnerable to rejection.

The technology for growing insulin-producing beta cells from human embryonic stem cells was successfully accomplished by Harvard researchers in 2014. However, the immune system, unable to distinguish between the good guys and the bad, quickly destroyed those cells that were cultivated and transplanted in mouse models.

Foreign body reactions, or FBRs, occur as a result of strong responses from the immune system that elicit an inflammatory response that can lead to scarring and necrosis of donor tissue.

The tactic to overcoming such responses, scientists realized, was using escape and evasion techniques to allow the transplanted cells to go undetected by the immune system. Researchers at the Massachusetts Institute of Technology were able to complete this mission successfully without triggering an immune response by encapsulating the insulin-producing cells with a protective armor of alginate derivatives. Alginates are naturally occurring compounds from marine brown seaweed that aid in the prevention and treatment of immune- and inflammatory-related diseases (function as an immune barrier).

According to a study published in the journal Nature Medicine, scientists implanted stem cell-derived encapsulated pancreatic beta cells into mice with chemically induced Type 1 diabetes mellitus (T1DM) without any immunosuppression. They observed correction of blood glucose levels in hyperglycemic mice, up until the removal of the beta cells 174 days later. Once removed, the implants still contained viable insulin-producing cells.

There are approximately 300 million cases of diabetes globally costing the global economy roughly $376 billion in 2010, about 11.6 percent of the total world healthcare expenditure. Economics aside, diabetes takes a tremendous toll on quality of life compounding the importance of finding a cure.

T1DM is the most common chronic disease of childhood, although one fourth of cases can occur in adulthood. The disease is characterized by the deficiency of insulin caused by the autoimmune destruction of insulin-producing pancreatic beta cells. Insulin is a hormone that helps the body to absorb and use glucose and other nutrients from food, store fat, and build up protein. Without insulin, blood glucose (sugar) levels become higher than normal.

Currently, the main form of treatment includes lifestyle adjustments, and self-care can control blood sugar levels and minimize the risk of disease-related complications, and as the authors note, much of the ill effects of the disease are due to issues of daily compliance. The process by which the beta cells of the pancreas release insulin in response to blood sugar is highly dynamic and cannot be accurately mimicked by exogenous insulin injections.

This study is the first to demonstrate the ability of transplanted, stem cell-derived, pancreatic beta cells to achieve blood glucose control long-term without inciting all-out war by the immune system. This lays the groundwork for future studies in humans using similar techniques.

The implications of the success of this trial are significant. The benefits of such a therapy for individuals suffering from T1DM with regard to quality of life and economic burden of this disease are almost priceless.