Diagnostic Imaging
June 2003

OVERREAD

Islet cell infusions ease diabetes in severe cases

Experimental procedure shows promise for type 1 diabetes patients with unstable disease

Image-guided infusions of islet cells may allow some patients with diabetes to live without dependence on injected insulin. To date, the technique has been tested only in patients whose diabetes is so unstable that the risks of transplant are deemed smaller than the risks of the disease itself.

Investigators monitored 48 patients with type 1 labile diabetes who successfully received 90 islet cell transplantations into the portal veins of the liver. After a one-year follow-up, they confirmed that 21 out of 26 patients receiving the full number of islets needed to complete treatment have become insulin-independent and metabolically stable. The research was presented at the Society of Interventional Radiology annual meeting in Salt Lake City in March.

"The technique works well in most patients," said principal investigator Dr. Richard Owen, an interventional radiologist at Alberta Hospital in Edmonton, Canada. "Some of these patients have a very brutal kind of diabetes that really affects their lives."

Patients with type 1 labile diabetes experience abrupt swings in sugar level. They may pass out or even fall into an acute diabetic coma without warning. Many refuse to drive or even go out for fear of hurting themselves or others. The transplantation of insulin-producing islet cells from a healthy pancreas could enable these people to live normal lives, Owen said.

The technique has some pitfalls, however. Complications such as bleeding or long-term function problems have not yet been resolved. Abnormalities seen on follow-up MR studies also create concern among researchers about the long-term effect that islet cell transplantation may have on the liver, Owen said.

Several U.S. and Canadian research centers are conducting trials with islet cell transplantation. Although limited, the results so far show promise. The procedure appears to be relatively safe and minimally invasive, and it does not require a long hospital stay.

If proven effective, the technique could also open a new line of argument in favor of stem-cell research. Organ donation, which is the only way to obtain the islet cells needed for the procedure, is insufficient to treat all patients needing a transplant, Owen said.

The strikingly low number of thrombotic complications and the large number of patients who remain insulin-independent for up to a year-and thus do not suffer from immunologic rejection of the islets-suggest that the authors have made a significant methodological improvement in islet cell transplantation, said Dr. Maikel Peppelenbosch, a specialist in the procedure from the Laboratory for Experimental Internal Medicine at Amsterdam's Academic Medical Center in the Netherlands.

The islet cell transplantation study, one of the largest and most successful performed to date, validates in vivo previous in vitro research that Moberg et al published in the December 2002 issue of The Lancet. The data look hopeful for sufferers from type 1 diabetes, Peppelenbosch said.

Implementing this treatment on a large scale, however, will be difficult. The lack of suitable islet cell donors remains a problem for all transplantations, making it necessary to prioritize the procedure among seriously affected individuals. The experimental procedure is also still too dangerous to justify in all type 1 patients, and it cannot be used to treat type II diabetes patients, Peppelenbosch said.

Recent progress in creating islet cells from the patient's own bone marrow stem cells, however, may help out in this respect. With the proper training, radiologists one day could offer this procedure to their patients, he said.

Further research and analysis will be vital to establish reliable success rates for the procedure, as well as any side effects that may result from it, investigators said.