Piero Marchetti

Insulin Independence After Islet Transplantation Into Type I Diabetic Patient

Effective clinical trials of islet transplantation have been limited by the inability to transplant enough viable human islets into patients with type I (insulin-dependent) diabetes mellitus to eliminate their exogenous insulin requirement. We report the first type I diabetic patient with an established kidney transplant on basal cyclosporin immunosuppression who was able to eliminate the insulin requirement after human islet transplantation into the portal vein. We successfully isolated ∼800,000 islets that were 95% pure from 1.4 cadaver pancreases containing 121 U of insulin. Islets were proven viable by in vitro insulin response to glucose challenge. After 7 days of 24°C culture, the islets were transplanted into the portal vein under local anesthesia. Seven days of Minnesota antilymphoblast globulin (20 mg/kg) administration followed the islet transplantation, with maintenance of the cyclosporin. Blood glucose was kept under strict control via intravenous insulin for 10 days posttransplantation, when all insulin therapy was stopped. Off insulin, the average 24-h blood glucose level remained <150 mg/dl, with the fasting glucose level at 115 ± 6 mg/dl and the 2-h postprandial level at 141 ±8 mg/dl for 22 days posttransplantation (the time of this study). The C-peptide values post-Sustacal testing, although initially rising slower, exceeded the normal range, with peak values of 1.0–1.8 pmol/ml. This preliminary result represents the first essential step required to determine the feasibility of islet transplantation by future clinical trials.

Results of our first nine intraportal islet allografts in type 1, insulin-dependent diabetic patients.

With the first demonstration of insulin independence following intraportal islet transplantation into a patient with type 1 diabetes, a new era of clinical islet transplantation will begin. This report provides our initial experience of clinical islet transplantation with a total of nine consecutive portal vein islet transplants in seven diabetic recipients. The first three transplants were done in nonrenal failure diabetics (NRFI) using 6319 +/- 2173 islets/kg body weight with islets processed from single pancreas and cultured for 7 days at 24 degrees C. Prednisone, azathioprine, and cyclosporine were initiated prior to transplant. While all three recipients demonstrated C-peptide function posttransplant, all three rejected their grafts at 2 weeks. Five days of OKT3 treatment failed to recover more than 10% of their rejecting islet grafts. The studies were then shifted to established kidney transplant recipients (EKI) maintaining their basal immunosuppression while adding 7 days of Minnesota antilymphoblast globulin (MALG) to the recipient using islets from single donor pancreas that had been cultured for 7 days at 24 degrees C. There were an average of 6161 +/- 911 islets transplanted intraportally into three EKI recipients. All three had C-peptide response from the transplant, but none achieved insulin independence. While the first patient rejected his graft at 2 weeks, two recipients demonstrated long-term islet function up to 10 months posttransplant. Sustacal challenge testing demonstrated C-peptide responsiveness, but in a delayed pattern suggesting insufficient islet mass had been transplanted. The next three kidney transplant recipients received islets from more than one donor pancreas averaging 13,916 +/- 556 islets/kg body weight. The first of these was the first to achieve insulin independence from 10 to day 25 posttransplant when she appeared to have a rejection episode. The second and third recipients were retransplanted with islets from multiple donors having achieved partial islet function from single pancreas donor. The first patient on triple immunosuppression is demonstrating long-term partial function at 184 days but is not insulin independent. The third patient on prednisone and azathioprine received one half his islets after 7-day culture and the other half after 7-day culture combined with cryopreservation. He is continuing to demonstrate insulin independence for 154 days post-transplant with a glycated hemoglobin value of 5.6%. Sustacal challenge data demonstrate a total stimulated C-peptide response of 155 rhomol/ml at 4 months post-transplant compared with 148 +/- 12 rhomol/ml for normal controls (NC) and 425 rhomol/ml for nondiabetic, established kidney transplant recipients on triple immunosuppression.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulsatile Insulin Secretion from Isolated Human Pancreatic Islets

Insulin secretion from the pancreas is pulsatile. The precise site and function of the pacemaker that regulates insulin periodicity in humans have not been determined. We isolated human pancreatic islets from five cadaver organ donors by collagenase digestion and density gradient purification. After 24 h of culture in CMRL-1066 medium at 37°C, aliquots of 200 islets were perifused (1 ml/min for 120 min) with glucose and other secretagogues in oxygenated Krebs-Ringer bicarbonate solution at 37°C. Samples for insulin measurement were taken every minute, and insulin secretion was analyzed by the Clifton and Steiner cycle detection technique. With 3.3 mM glucose (n = 17), insulin oscillations were demonstrated with a periodicity of 9.8 ± 0.1 min (means ± SE), mean amplitude was 16.8 ± 1.8 pM, and overall mean insulin release was 43.8 ± 4.2 pM. With 16.7 mM glucose (n = 14), no change of insulin periodicity was observed (10.2 ± 0.9 min), mean amplitude was 41.4 ± 10.2 pM (P < 0.01 vs. 3.3 mM glucose), and mean insulin release was 118.2 ± 19.2 pM (P < 0.01 vs. 3.3 mM glucose). Both at 3.3 and 16.7 mM glucose, the addition of 1.4 mM glucagon (n = 4), 15 mM arginine (n = 4), or 100 µg/ml tolbutamide (n = 4) caused no change of insulin periodicity but enhanced mean amplitude and mean insulin release compared with glucose alone. These results show that a pacemaker is located within the islets that regulates pulsatile insulin secretion in humans; the pacemaker is remarkably stable, because its periodicity is not affected by factors altering insulin secretion.