Islet transplantation for brittle type 1 diabetes: the UIC protocol.

This prospective phase 1/2 trial investigated the safety and reproducibility of allogeneic islet transplantation (Tx) in type I diabetic (T1DM) patients and tested a strategy to achieve insulin-independence with lower islet mass. Ten C-peptide negative T1DM subjects with hypoglycemic unawareness received 1-3 intraportal allogeneic islet Tx and were followed for 15 months. Four subjects (Group 1) received the Edmonton immunosuppression regimen (daclizumab, sirolimus, tacrolimus). Six subjects (Group 2) received the University of Illinois protocol (etanercept, exenatide and the Edmonton regimen). All subjects became insulin- independent. Group 1 received a mean total number of islets (EIN) of 1460 080 +/- 418 330 in 2 (n = 2) or 3 (n = 2) Tx, whereas Group 2 became insulin- independent after 1 Tx (537 495 +/- 190 968 EIN, p = 0.028). All Group 1 subjects remained insulin free through the follow-up. Two Group 2 subjects resumed insulin: one after immunosuppression reduction during an infectious complication, the other with exenatide intolerance. HbA1c reached normal range in both groups (6.5 +/- 0.6 at baseline to 5.6 +/- 0.5 after 2-3 Tx in Group 1 vs. 7.8 +/- 1.1 to 5.8 +/- 0.3 after 1 Tx in Group 2). HYPO scores markedly decreased in both groups. Combined treatment of etanercept and exenatide improves islet graft function and facilitates achievement of insulin-independence with less islets.

Improved outcomes in islet isolation and transplantation by the use of a novel hemoglobin-based O2 carrier.

During isolation, islets are exposed to warm ischemia. In this study, intraductal administration of oxygenated polymerized, stroma-free hemoglobin-pyridoxalated (Poly SFH-P) was performed to improve O2 delivery. Rat pancreata subjected to 30-min warm ischemia were perfused intraductally with collagenase in oxygenated Poly SFH-P/RPMI or RPMI (control). PO2 was increased by Poly SFH-P (381.7 +/- 35.3 mmHg vs. 202.3 +/- 28.2, p = 0.01) and pH maintained within physiological range (7.4-7.2 vs. 7.1-6.6, p = 0.009). Islet viability (77% +/- 4.6 vs. 63% +/- 4.7, p = 0.04) was improved and apoptosis lower with Poly SFH-P (caspase-3: 34,714 +/- 2167 vs. 45,985 +/- 1382, respectively, p = 0.01). Poly SFH-P improved islet responsiveness to glucose as determined by increased intracellular Ca2+ levels and improved insulin secretion (SI 5.4 +/- 0.1 vs. 3.1 +/- 0.2, p = 0.03). Mitochondrial integrity was improved in Poly SFH-P-treated islets, which showed higher percentage change in membrane potential after glucose stimulation (14.7% +/- 1.8 vs. 9.8 +/- 1.4, respectively, p < 0.05). O2 delivery by Poly SFH-P did not increase oxidative stress (GSH 7.1 +/- 2.9 nm/mg protein for Poly SFH-P vs. 6.8 +/- 2.4 control, p = 0.9) or oxidative injury (MDA 1.8 +/- 0.9 nmol/mg protein vs. 6.2 +/- 2.4, p = 0.19). Time to reach normoglycemia in transplanted diabetic nude mice was shorter (1.8 +/- 0.4 vs. 7 +/- 2.5 days, p = 0.02), and glucose tolerance improved in the Poly SFH-P group (AUC 8106 +/- 590 vs. 10,863 +/- 946, p = 0.03). Oxygenated Poly SFH-P improves islet isolation and transplantation outcomes by preserving mitochondrial integrity.

Intra-ductal glutamine administration reduces oxidative injury during human pancreatic islet isolation.

Oxidative stress during islet isolation induces a cascade of events injuring islets and hampering islet engraftment. This study evaluated islet isolation and transplantation outcomes after intra-ductal glutamine administration. Human pancreata deemed unsuitable for pancreas or islet transplantation were treated with either a 5 mM solution of l-glutamine (n = 6) or collagenase enzyme alone (n = 6) through the main pancreatic duct. Islet yield, viability, in vitro function; markers of oxidative stress [malondialdehyde (MDA) and Glutathione (GSH)] and apoptosis were assessed. Islet yields were significantly increased in the glutamine group compared to controls (318, 559 +/- 25, 800 vs. 165, 582 +/- 39, 944 mean +/- SEM, p < 0.01). The amount of apoptotic cells per islet was smaller in the glutamine group than the control. The percentage of nude mice rendered normoglycemic with glutamine-treated islets was higher than the controls (83% n = 10/12 vs. 26% n = 6/23; p < 0.01), and the time to reach normoglycemia was decreased in the glutamine group (1.83 +/- 0.4 vs. 7.3 +/- 3 days; p < 0.01). Glutamine administration increased GSH levels (7.6 +/- 1.7 nmol/mg protein vs. 4.03 +/- 0.5 in control, p < 0.05) and reduced lipid-peroxidation (MDA 2.45 +/- 0.7 nmol/mg of protein vs. 6.54 +/- 1.7 in control; p < 0.05). We conclude that intra-ductal administration of glutamine reduces oxidative injury and apoptosis and improves islet yield and islet graft function after transplantation.

Restoration of phosphaturia in phosphate-deprived rats in the presence of both parathyroid hormone and phosphate infusion.

The present study tested the hypothesis that the combination of parathyroid hormone and phosphate infusion would be phosphaturic in phosphate-deprived rats. Clearance experiments were performed in Sprague-Dawley rats fed a low-phosphate diet for 4 days. The animals were first given a phosphate infusion and then administered parathyroid hormone. The reverse experiment was also performed in a second group of rats by giving the hormone first followed by a phosphate infusion. There was no increase in phosphate excretion in response to phosphate infusion or parathyroid hormone given alone. However, the combination of parathyroid hormone and phosphate infusions, given in either order, was phosphaturic in phosphate-deprived rats.