Islet transplantation needs further research

Medical Tribune June 2008 P7

David Brill

Islet transplantation is a promising technique for treating diabetic patients but the field still faces many unresolved issues, according to an expert.

“We can clearly state that a successful islet transplant can potentially provide insulin independence and halt long-term diabetic complications,” said Dr. Paolo Fiorina of Harvard Medical School, Boston, US, and the San Raffaele Scientific Institute in Milan, Italy.

Reviewing registry data from 7 years of transplants, he said that insulin independence can be achieved in 70 to 80 percent of patients who receive an infusion of islets. He added that the procedure is relatively easy to perform, is associated with short hospital stays and, when successful, can reduce the occurrence of hypoglycemic episodes.

Fiorina also highlighted studies which demonstrated that islet transplantation can improve cardiac and endothelial function and reduce cardiovascular mortality in type 1 diabetic patients. Successful islet transplantation can also improve graft survival and function among patients
who have received a kidney transplant, he said.

He concluded, however, that further study is required before the technique can be declared superior to insulin pumps or pancreas transplantation.

The safety of islet transplantation, for example, remains to be confirmed. Transaminitis occurs in half of patients, while 10 to 15 percent experience bleeding and five percent develop thrombosis. Longer-term complications include hyperlipidemia, hypertension, mouth ulcers
and an increased risk of sensitization and infection.

More research is also needed to improve procedural success rates, according to Fiorina.

“We still don’t know why islets fail,” he said, suggesting that graft rejection, insulin resistance and poor graft quality could all be important factors.

“All together, these problems make islet transplantation hard work,” said Fiorina.

The need for lifelong immunosuppression is another concern facing islet transplantation patients. This treatment can cause nephrotoxicity, and researchers have noted a decrease in kidney function 3 years after the procedure, as measured by glomerular filtration rate.

Reducing the toxicity of immunosuppression could help to improve the success of islet transplantation, according to Fiorina. He described this area of research as “an exciting and growing field.”

Islet transplantation was first performed in 1999. By 2007, 579 procedures had been documented in the Cell Transplant Islet Registry, most of them performed in North America and Europe.