Another potential treatment is the combination of two growth factors called gastrin and epidermal growth factor (EGF), which has been shown to promote beta-cell regeneration in rats. Researchers at Waratah Pharmaceuticals in Woburn, Massachusetts, developed this combination for therapy, calling it Islet Neogenesis Therapy (INT). In 2004, an extended phase I clinical trial of INT in people with Type 1 diabetes, designed to test the safety of the therapy, showed no serious or unexpected side effects.
In a study reported in the Journal of Clinical Endocrinology and Metabolism in 2005, researchers from Waratah and the University of Alberta in Edmonton, Alberta, Canada, cultured human islets for four weeks in medium containing neither agent, gastrin or EGF alone, or a combination of EGF and gastrin. The islets were then cultured for another four weeks in a control medium. At the end of the second four-week period, the group receiving the gastrin-EGF combination had three times as many insulin-producing beta cells as they started with.
Next, the researchers implanted human islets into NOD-SCID mice — mice with a deficient immune system — so as to sidestep transplant rejection and autoimmunity. They then injected some of the mice with the EGF-gastrin combination. In the mice treated with EGF-gastrin, there was an increase in beta cell numbers and insulin levels within the islets. When they injected glucose into the mice, there was a brisk secretion of insulin from the human islet grafts, demonstrating that the beta cells were functional. Research into the promise of beta-cell regeneration continues.