Clinical outcomes and insulin secretion after islet transplantation with the Edmonton protocol.

Islet transplantation offers the prospect of good glycemic control without major surgical risks. After our initial report of successful islet transplantation, we now provide further data on 12 type 1 diabetic patients with brittle diabetes or problems with hypoglycemia previous to 1 November 2000. Details of metabolic control, acute complications associated with islet transplantation, and long-term complications related to immunosuppression therapy and diabetes were noted.

Conservation of phosphorylation state of cardiac phosphofructokinase during in vitro hypothermic hypoxia.

We investigated the metabolic effects of buffering agents alpha-amino-4-imidazole-propionic acid (Histidine), N, N-bis(2-hydroxyethyl)glycine (bicine), N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) on anaerobic energy production (via glycolysis) and conservation of key regulatory enzyme activity, and phosphofructokinase (PFK) throughout prolonged hypothermic hypoxia in porcine hearts. Hearts from 35 to 40 kg pigs were flushed with one of the following five solutions: St. Thomas' Hospital solution (STHS); modified University of Wisconsin (UW) solution; and three solutions containing modified UW plus 90 mM of histidine, bicine, or BES.

Single injection of insulin delays the recurrence of diabetes in syngeneic islet-transplanted diabetic NOD mice.

Background: Insulin has been implicated in the pathogenesis of type 1 diabetes and oral administration of insulin has been shown to delay the onset of diabetes in NOD mice. In this study we determined whether a single footpad injection of insulin will protect syngeneic islet grafts from autoimmune destruction when placed under the kidney capsule of diabetic NOD mice.

Methods: Five hundred islets were transplanted under the kidney capsule of diabetic female NOD mice in conjunction with a single footpad injection of either pork insulin in saline or mixed with incomplete Freund's adjuvant (IFA).

Gene gun transfection of human glioma and melanoma cell lines with genes encoding human IL-12 and GM-CSF.

We used particle-mediated gene transfer by a custom-built gene gun to transfect two well-established human glioma (D54MG and U251) and melanoma (SK mel 28 and Ed 141) cell lines, as well as two glioma lines locally established from primary patient tumors (Ed 147 and Ed 149). Using beta-galactosidase as a reporter gene, D54MG, U251, Ed 141 and SK mel 28 showed an average transfection efficiency of 15-40%, whereas Ed 147 and Ed 149 had mean transfection efficiencies of 3% and 5% respectively. Twenty-four hours after transfection with the gene encoding human interleukin-12 (IL-12), ELISA was performed on cell supernatants (mean of n = 12 for each cell line).

Islet transplantation in seven patients with type 1 diabetes mellitus using a glucocorticoid-free immunosuppressive regimen.

Background: Registry data on patients with type 1 diabetes mellitus who undergo pancreatic islet transplantation indicate that only 8 percent are free of the need for insulin therapy at one year.

Methods: Seven consecutive patients with type 1 diabetes and a history of severe hypoglycemia and metabolic instability underwent islet transplantation in conjunction with a glucocorticoid-free immunosuppressive regimen consisting of sirolimus, tacrolimus, and daclizumab. Islets were isolated by ductal perfusion with cold, purified collagenase, digested and purified in xenoprotein-free medium, and transplanted immediately by means of a percutaneous transhepatic portal embolization.

Microencapsulation of neonatal porcine islets: protection from human antibody/complement-mediated cytolysis in vitro and long-term reversal of diabetes in nude mice.

Background: Recently, we have developed a simple and reliable method to efficiently isolate large numbers of neonatal porcine islets (NPI). We and others have shown that NPI are susceptible to cytolysis by the activation of human complement in vitro. Microencapsulation of islets may be one strategy to protect NPI from this form of rejection.

The role of protein kinase A in anaerobic energy production during liver storage.

Background/aim: During cold liver storage in University of Wisconsin solution, glycolysis is inhibited by declining intracellular pH and a reduction in glycogen phosphorylase activity. The current study investigated the effects of a histidine-buffered, modified University of Wisconsin solution with cyclic-AMP analogue plus phosphodiesterase inhibitors to optimize both pH and PK A-mediated limits on glycolytic energy production.

Methods: In an isolated rodent-liver system, dioctanoyl-cAMP was supplemented with each phosphodiesterase inhibitor (isobutylmethylxanthine, papaverine, Ro 20-1724, dipyridamole).

Secretion from islets and single islet cells following cryopreservation.

The ability to cryopreserve pancreatic islets has allowed the development of low-temperature banks that permit pooling of islets from multiple donors and allows time for sterility and viability testing. However, previous studies have shown that during cryopreservation and thawing there is a loss of islet mass and a reduction in islet function. The aim of this study was to measure and compare insulin secretion from cultured nonfrozen and frozen-thawed canine islets and beta-cells.

Frontiers in transplantation of insulin-secreting tissue for diabetes mellitus.

Transplantation of insulin-secreting tissue represents a physiologic approach to reverse diabetes mellitus. Pancreas transplants yield a remarkable enhancement in quality of life and appear to modify the devastating neurovascular complications of diabetes. A more attractive approach is transplantation of insulin-secreting cells, a procedure of low invasiveness with the exciting prospect of modulating graft immunogenicity before transplantation, so as to minimize requirements for toxic immunosuppressive drugs.

Intraductal collagenase delivery into the human pancreas using syringe loading or controlled perfusion.

Effective intraductal delivery of the enzyme collagenase into the pancreas is crucial to the subsequent ability to isolate viable islets. Most clinical islet transplant centers load the enzyme into the pancreas by retrograde injection using a syringe following cannulation of the pancreatic duct. An alternative approach is to perfuse the pancreas via the pancreatic duct with collagenase solution using a recirculating perfusion device system.

Long-term effects of in vivo angioplasty in normal and vasospastic canine carotid arteries: pharmacological and morphological analyses.

Object: A canine model of hemorrhagic vasospasm of the high cervical internal carotid artery (ICA) was used to study the long-term effects of transluminal balloon angioplasty (TBA) on the structure and function of the arterial wall.

Methods: Forty dogs underwent surgical exposure of both distal cervical ICAs, followed by baseline angiographic studies on Day 0. Dogs in Group A (20 animals) underwent simple exposure of one ICA and placement of a silicone elastomer cuff around a segment of the opposite artery.

Effects of hypothermic hypoxia on anaerobic energy metabolism in isolated anuran livers.

Many lower vertebrates (reptilian and amphibian species) are capable of surviving natural episodes of hypoxia and hypothermia. It is by specific metabolic adaptations that anurans are able to tolerate prolonged exposure to harsh environmental stresses. In this study, it was hypothesized that livers from an aquatic frog would possess an inherent metabolic ability to sustain high levels of ATP in an isolated organ system, providing insight into a metabolic system that is well-adapted for low temperature in vitro organ storage.

Surgical research in Canada: synopsis of a consensus conference.

Canadian surgical research requires careful nurturing if it is to flourish in tomorrow's environment. A consensus conference organized by the Research Development Committee of the Canadian Association of Surgical Chairs has addressed a number of issues to promote Canadian surgical research. This synopsis is a summary of the proceedings of that conference.

Effect of cryopreservation on the survival and function of murine islet isografts and allografts.

We compared the efficacy of fresh and frozen/thawed islets by determining the minimum number required to consistently reverse diabetes in mice. Defined numbers of islets, isolated from Balb/c (H-2d) and CBA/J (H-2k) mice, were transplanted into streptozotocin-induced diabetic Balb/c mice. Frozen/thawed grafts were cooled slowly to -40 degrees C, stored at -196 degrees C, and thawed rapidly.

Improved survival of biolistically transfected mouse islet allografts expressing CTLA4-Ig or soluble Fas ligand.

Background: Pancreatic islet transplantation is limited because of immune rejection of the transplanted tissue. Long-term survival of allogeneic pancreatic islet grafts in the absence of systemic immunosuppressive agents should be possible by transfecting the islets directly with DNA encoding immunoregulatory molecules. Localized production of these molecules should affect only the immune cells that come into the vicinity of the foreign tissue.

Metabolic adaptations of a lower vertebrate to long-term hypothermic hypoxia provide clues to successful clinical liver preservation.

This study was designed to determine whether the metabolic adaptations developed by frogs to tolerate natural events of hypothermic hypoxia would precondition its liver for ex vivo organ storage. The metabolic responses of the frog, Rana castabiena, were compared to those of a mammalian system (rat) throughout a prolonged period of organ storage. Livers from rats and frogs were flushed and stored in UW solution at 5 degrees C for periods of 24-96 h.

Investigation of a primary requirement of organ preservation solutions: supplemental buffering agents improve hepatic energy production during cold storage.

Background: This study was designed to investigate the effects of a modified University of Wisconsin (UW) solution supplemented with one of four buffering agents (histidine, bicine [N,N-bis(2-hydroxyethyl)glycine], tricine [N-tris(hydroxymethyl)methylglycine], and Tris) on liver metabolism during cold ischemic storage.

Methods: Rat livers were flushed and stored for a maximum period of 24 hr at 4 degrees C, and tissue energetics, substrate, and anaerobic end-products were assessed; the group exhibiting the best results during storage was recovered in a 60-min period of warm reperfusion. Relative buffering capacities of the experimental solutions (measured over physiological pH range, in mM H+/L) were: UW, 4.

Survival and function of syngeneic rat islet grafts placed within the thymus versus under the kidney capsule.

The role of the thymus in the ongoing acquisition of tolerance to self antigens has made it an attractive site for islet transplantation. Several studies have reported survival of rodent islet allografts in the thymus without requiring the long-term use of immunosuppressive agents; however, the degree of glucose homeostasis in the intrathymic islet transplant recipients has not been examined. We transplanted 500, 1000, or 2000 syngeneic islets into the thymus of streptozotocin-induced diabetic Wistar-Furth rats, and compared the metabolic response of these recipients with animals receiving 2000 syngeneic islets under the kidney capsule.