PITTSBURGH, -- U. S. medical researchers say they've developed a vaccine that might be able to prevent and even reverse development of type 1 diabetes. The scientists at the University of Pittsburgh Medical Center and the Baxter Healthcare Corp. said microspheres carrying targeted nucleic acid molecules fabricated in laboratories have been shown to prevent and even reverse new-onset cases of type 1 diabetes in animal models. In research conducted at the Children's Hospital of Pittsburgh, the scientists injected the micro- spheres under the skin near the pancreas of mice with auto- immune diabetes. The microspheres were then captured by white blood cells known as dendritic cells that released the nucleic acid molecules within the dendritic cells, the re- searchers said. The released molecules reprogrammed the cells, and then migrated to the pancreas. There, they turned off the immune system attack on insulin-producing beta cells. Within weeks, the scientists said, diabetic mice were producing insulin again with reduced blood glucose levels. The study is reported in the June issue of the journal Diabetes.