Stem cell therapy gives diabetics new hope
A new method of producing insulin from stem cells and protecting it from body's immune system could pave way for improved experimental treatments for diabetes.
In type 1 diabetes, body turns on its own "system" to attack so-called beta cells called "islets" in pancreas. These beta cells are responsible for measuring blood sugar and producing insulin to keep it stable. When "they" are depleted, person is at risk for high or low blood sugar and must rely on insulin injections. One of treatments designed to end this addiction is transplantation of donor islets in diabetic patients, but this process is complicated by a number of obstacles. Donors are in short supply, especially since transplants usually require several to provide enough islets. The islets also often fail to connect to blood supply, and although they are similar to other transplants, they run risk of being attacked by recipient's immune system, which will regard this as an invasion. As a result, patients are forced to take drugs that suppress their immune systems, protecting their transplants but exposing rest of body to other diseases. To overcome some of these problems, one research group sought to find another source of islets by coaxing induced pluripotent stem (IPs) cells into producing so-called Hilos, or human islet-like organelles. These heroes, grown in a 3D environment that mimics pancreas and then enhanced with a "gene switch" that successfully produces insulin and can regulate blood sugar function, were transplanted into diabetic mice.
-Resistance to immune attacks-
Having found a potential solution to problem of supply chain, scientists decided to address problem of immune rejection. They focused on a protein called PD-L1, a protein known to suppress body's immune response. When team coaxed Hiros into producing PD-L1, they were able to effectively "hide" transplant from attack by body's immune system. They transplanted Hilos with and without PD-L1 into diabetic mice to test their function. Initially, both transplants were intended to restore blood sugar control, but gradually unprotected Xiros ceased to function. But Pd-L1 Hiros helped diabetic mice regulate their blood sugar levels for more than 50 days. "This is first study showing that you can protect heroes from genetic manipulation of immune system," said Michael Downes, a senior scientist at Salk Institute for Biological Research and author of study, published Wednesday in journal Nature. -Authors of a study in a journal. He added in a statement released by Salk: "If we can use this as a treatment, patients won't need to take immunosuppressants." including type 1 diabetes and type 2 diabetes. Islet transplantation is often considered a treatment option for type 1 diabetic patients whose disease is result of an autoimmune response. But while prospect of islet isolation from stem cells may seem like an attractive solution, study warns that it could be "prohibitively expensive." The authors write that a more likely application of this study may be to use PD-L1 protection approaches to ensure successful transplantation without need for immunosuppressants.
Stem cell therapy gives diabetics new hope
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