Islet Cell Transplantation

AIT procedure
After the resection of the pancreas, it is cannulated with an angiocatheter and transported to the laboratory for processing. The excised pancreas is distended with enzyme Liberase solution. The pancreatic tissue is enzymatically and mechanically dissociated in a digestion chamber in the presence of a recirculating cold solution containing collagenase. Once the digestion is complete, the flow is rerouted to a separate collecting flask, where the majority of enzymatic reactions are blocked by diluting the islet-containing solution and lowering the temperature to 7° to 10° C. Routine in vitro staining with Dithizone solution is conducted to discriminate between the remaining exocrine tissue and to determine the optimal timing for stopping the digestion and beginning the dilution process. When the digestion is complete, the islets are purified and infused into the liver, via portal vein injection, using the closed bag system. Islet viability is evaluated immediately pretransplant. Posttransplant, the islet graft embeds into the portal vessels, vascularizes, and within 2 to 3 weeks, incorporates into the hepatic (liver) parenchyma. In the most successful cases, patients are insulin-free with normal glucose tolerance, although some patients with less favorable outcomes require small amounts of insulin to treat hyperglycemia.

Metabolic testing:
Glucose, insulin, and C-peptide levels, as well as insulin and C-peptide response to an arginine and an oral glucose challenge, are measured pretransplant in all islet recipients and then every 6 to 12 months posttransplant. Doing so allows assessment of islet function over time. Immediately posttransplant, a generally mild postprandial (occurring after a meal) hyperglycemia (high blood sugar or glucose) develops. To prevent glucose toxicity to the islet cells, islet recipients are started on an insulin drip either during the AIT, once the pancreas is excised, or immediately after islet infusion. They normally continue to receive exogenous insulin to “rest” the islets and to avoid post- and peritransplant hyperglycemia. Despite initial abnormal glucose values, improved metabolic control is achieved in successfully treated islet recipients within the first few weeks posttransplant. About 40% of islet recipients are completely off insulin after their AIT; the remaining 60% require low doses of insulin.

The most important outcome of AITs is the relief of abdominal pain in a large percentage of recipients. Many (about 58%) no longer require narcotics at all; others experience a marked decrease in their need for analgesics. Use of narcotics is significantly reduced posttransplant (as compared with pretransplant).