Magnetic resonance imaging (MRI) with an approved contrast agent may provide a practical way of monitoring the survival of transplanted pancreatic islets. In the September issue of the journal Diabetes, researchers from the Martinos Center for Biomedical Imaging at Massachusetts General Hospital (MGH) report successfully tracking over time the fate of islets transplanted into mice using a protocol currently being tested in human patients.
"Clinical trials and animal studies show that there is a significant loss of islets following transplantation due to many factors, not just rejection," says Anna Moore, PhD, of the MGH Martinos Center, who led the study. "Currently there is no direct way to follow the causes behind this loss and how it proceeds over time. Monitoring islet survival by noninvasive imaging could give us the ability to detect and measure rates of islet loss under a variety of conditions, which could help develop procedures leading to better therapeutic outcomes."
Pancreatic islet transplants are being investigated as a way to treat or cure patients with type 1 diabetes, in which the insulin-producing islets are attacked by the body's immune system. In an effort to replace destroyed islets and restore normal insulin production and glucose metabolism, several methods of islet transplantation have been developed and tested. One of the most promising called the Edmonton Protocol, since it was developed at the University of Alberta is currently the subject of a multicenter clinical trial. In a 2005 report, the Edmonton group noted that, while islet survival is improving, problems continue to exist both with immune rejection and with the initial post-transplantation engraftment of islets. Even in animal studies involving transplants from genetically identical donors, which should not produce immune rejection, as many as 60 percent of islets are lost in soon after the procedure.