Protecting insulin-producing cells from immune system gives benefits of transplant to resolve diabetes without drawbacks of anti-rejection drugs
Type I diabetes is often diagnosed in childhood and can be devastating. Unable to produce insulin in their own bodies to metabolise glucose, children must depend on regular injections of insulin, with doses determined by blood tests several times a day, to avoid falling into a coma as blood sugar levels drop; moreover, the long-term damage caused by abnormal sugar levels can be severe.
“The absence of this natural ability – minute-to-minute regulation of glucose levels – can result in long-term complications, such as blindness, amputation and kidney failure,” explained Dr Klearchos Papas of the Departments of Surgery and Medical Imaging at the University of Arizona College of Medicine – Tucson. “Even with automated insulin delivery devices and continuous glucose monitoring – the best way possible to control your blood sugar – you still can end up with these consequences.”
One method of controlling type I diabetes that has been a investigated in depth is transplanting insulin-producing cells, known as islets, into the liver. If accepted, these sense glucose levels and secrete insulin into the bloodstream to break it down. But in common with all transplants, donors must take drugs to suppress their immune systems to prevent rejection. The side effects of these drugs are unpleasant and can be dangerous, so this technique is not recommended for children.
Papas and his team have been researching this problem for the past two decades, and in collaboration with chemicals company Novo Nordisk and other researchers in the US, Canada and Australia, has found a solution which blends engineering with cell science. The key to the technique is to place the islet cells inside an implantable, porous container. In the journal Endocrine Connections, the researchers explain how they keep the cells alive inside the container made of a silicone-based organic polymer, polydimethylsiloxane. “It’s like a tea bag,” Papas said. “The tea leaves stay inside but tea, or insulin, comes out. And the tea bag keeps out the immune cells that would normally attack the islets.”