ScienceDaily (June 6, 2011) — An experimental cure for Type 1 diabetes has a nearly 80 percent success rate in curing diabetic mice. The results, being presented at The Endocrine Society's 93rd Annual Meeting in Boston.The therapy attempts to counter the two defects that cause this autoimmune form of diabetes: autoimmune attack and destruction of the insulin-producing beta cells by T cells. First, the researchers genetically engineer the formation of new beta cells in the liver using neurogenin3. This gene defines the development of pancreatic islets, which are clusters of beta cells and other cells. Along with neurogenin3, they give an islet growth factor gene called betacellulin to stimulate growth of these new islets.
The second part of the therapy aims to prevent the mouse's immune system from killing the newly formed islets and beta cells. Previously the research team combined neurogenin3 with the gene for interleukin-10, which regulates the immune system. However, with that gene, they achieved only a 50 percent cure rate in diabetic mice, Yechoor said.
In the new study, the investigators added a gene called CD274 or PD-L1 (programmed cell death 1 ligand-1). It inhibits activity of the T cells only around the new islets in the liver and not in the rest of the body, he explained.
"We want the gene to inactivate T cells only when they come to the new islet cells. Otherwise, the whole body would become immunocompromised," Yechoor said.
This treatment reversed diabetes in 17 of 22 mice, or 78 percent.