New Treatments Are Emerging For Type-1 Diabetes

"WHERE ARE the islets of Langerhans?" is a trick question that pops up from time to time in quizzes. The answer is to be found not in atlases of geography, but rather in those of anatomy, for the so-called islets are in fact clusters of cells scattered through the pancreas. There they synthesise and release a range of hormones, including insulin, which regulates glucose levels and thus metabolism.

The islets' insulin producers are called beta cells. (Cell types alpha, gamma, delta and epsilon perform other tasks.) They are the only bodily sources of that hormone. So, if their number declines, trouble looms. And decline it does, in the condition known as type-1 diabetes. This happens when, in a phenomenon called autoimmunity, the body's own immune system attacks its complement of beta cells, wiping out as many as 80%.

Without an alternative supply of insulin, someone with type-1 diabetes will die. (In type-2 diabetes, insulin continues to be produced but the body's cells acquire resistance.) Supplementary insulin can be administered by injection or via a device called an insulin pump. But a better way might be to replace the missing beta cells and somehow protect them from immune attack.

A few lucky patients do indeed have their beta cells replaced by transplantation from human donors. And Vertex Pharmaceuticals, a firm in Boston, is testing beta cells grown from stem cells for the same purpose. But neither approach includes immune protection. This means both require the administration of drugs to immunosuppressive prevent the rejection that follows any transplant, let alone one where autoimmunity is at play. One of the sessions at this year's meeting of the American Association for the Advancement of Science in Denver therefore looked into how transplanted beta cells might be made hypoimmunogenic - in other words, invisible to a patient's immune system.