Type 1 diabetes, in the past referred to as juvenile-onset or insulin-dependent diabetes, for the majority of people is caused when the body turns on itself and directs the immune system to attack and destroy cells in the pancreas that produce insulin. The cells, called beta-islet cells, produce insulin, a hormone that is necessary for the regulation of glucose, the primary blood sugar used by the body for energy. Because their bodies can no longer produce the insulin they need, people with type 1 diabetes must inject themselves with insulin to keep blood sugar under control.
The experimental therapy uses a specially modified virus to carry into liver cells a gene that senses glucose levels in the blood, coupled with a gene that will cause the liver cells to produce a modified form of insulin that the body can readily use.
When the gene package was injected into the livers of rats with a chemically induced type of diabetes and into mice with a hereditary form of the disease, blood glucose levels returned to normal within two weeks of treatment, and have remained normal for more than five months in mice and more than eight months in rats. The treated animals have shown no apparent side effects from the treatment, report Ji-Won Yoon, PhD, and associates at the University of Calgary in Alberta, and at Yonsei University Medical School in Seoul.
"One of the significant findings of our study is that the liver cells producing [the modified insulin] now take over the function of insulin-producing beta cells, which have been completely destroyed by the autoimmune attack in the mice," Yoon comments in a written statement. But because the new insulin-producing cells are different from beta cells, they are apparently protected from immune system attacks, Yoon says.