Normal reproductive function in dogs with islet autografts

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Effect of cyclosporin treatment on metabolic and hormonal responses to mixed meal plus oral glucose in dogs with intrasplenic pancreatic islet autograft.

We evaluated the effect of immunosuppressive concentrations of cyclosporin A (CsA), given intramuscularly, on the levels of glucose, insulin, C-peptide, glucagon, pancreatic polypeptide (PP), lactate, alanine and β-hydroxy-butyrate in a group of pancreatectomized mongrel dogs with intrasplenic islet autografts, given mixed meal and oral glucose, while on or off CsA therapy. In whole blood, HPLC-measured drug levels ranged from 412 to 803 ng/ml. Basal glucose and insulin concentrations did not differ significantly between non-pancreatectomized, control dogs and transplanted animals, whether on or off CsA. After the meal challenge, glucose levels were significantly higher in transplanted animals than in normal dogs, and no additional deleterious effect of CsA was observed. Similar insulin and C-peptide responses were found in animals either on or off CsA treatment. Fasting and post-meal concentrations of glucagon, PP and intermediate metabolites were not affected by the drug. These results suggest that intramuscular CsA, given at doses known to sustain islet allograft function, has no detrimental effect on the hormonal and metabolic responses to mixed meal and oral glucose in dogs with intrasplenic islet autografts. © 1994 Springer-Verlag

Factors affecting in vitro and in vivo function of isolated porcine islets

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Effects of cyclosporine on insulin secretion and insulin sensitivity in dogs with intrasplenic islet autotransplants

Abstract: Concern about cyclosporine causing adverse effects on glucose metabolism is based mainly on in vitro studies and in vivo data in rodents. However, data on large mammals and humans are much more controversial. Because the drug is used as therapy accompanying pancreatic or isolated islet transplantations, studies in large animals are needed to assess whether cyclosporine inhibits beta-cell function and causes glucose intolerance. To address these issues, we examined intravenous glucose tolerance, islet beta-cell function, and insulin sensitivity in a group of adult mongrel dogs with intrasplenic islet autografts, with and without cyclosporine treatment. Similar fasting plasma glucose and insulin values were found before and after pancreatectomy and islet transplantation. After intravenous glucose, plasma glucose values decreased more slowly in dogs that had undergone transplantation, but not additional adverse effect as a result of cyclosporine was observed. During euglycemic clamp studies, performed at both physiologic and pharmacologic insulin concentrations, the drug had no effect on the total amount of metabolized glucose, and glucose production was unaffected by cyclosporine treatment. Thus intramuscular cyclosporine therapy does not seem to inhibit insulin secretion from heterotopic islets or to affect peripheral and hepatic insulin sensitivity in dogs with intrasplenic islet autografts

Anti-CD4 antibody treatment in xenografts of differently immunomodulated porcine islets

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Effect of different temporary immunosuppressive therapies and low-temperature culture on pancreatic islet xenograft survival (pig-to-mouse)

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Glucose metabolism, insulin sensitivity, and glucagon secretion in dogs with intraportal or intrasplenic islet autografts

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Prolonged survival of discordant porcine islet xenografts

Abstract: Purified porcine islets were prepared by collagenase digestion and density gradient purification, and transplanted under the kidney capsule of C57B/B6 mice with streptozotocin-induced diabetes which were receiving varying temporary immunosuppressive therapies. Islets that had been cultured for 1 day at 37 degrees C were rejected after: 9 +/- 0.1 (mean +/- SE) days in control mice; 14 +/- 3 days in mice receiving mouse antilymphocyte serum (MLS) plus porcine antilymphocyte serum (PLS) on day of transplant (day 0); 43 +/- 8 days in mice treated for 1 week with anti-CD4 antibody (aCD4); 36 +/- 4 days in mice given aCD4 for 1 week plus PLS on days 0 and 7; 47 +/- 3 days in mice treated with aCD4 for 1 week plus MLS and PLS on day 21. Porcine islet survival in these latter three groups was significantly (P<0.01) and similarly longer than in the control and MLS plus PLS groups. Then, we transplanted islets that had been either cultured at 24 degrees C for 7 days or cryopreserved into 7-day aCD4-treated mice, to evaluate whether low temperature culture or the freezing-thawing procedure could affect survival. Neither 7-day, low temperature culture (mean survival time: 37 +/- 2 days) nor cryopreservation (mean survival time: 39 +/- 2 days) prolonged islet function further. Thus, the present study demonstrates that prolonged survival can be achieved with discordant porcine islet xenografts, and shows the greater efficacy of aCD4 treatment, which was not improved by the additional immunosuppressive therapies we tested, nor by culture or cryopreservation of the islets

Cryogenic storage of isolated, purified porcine pancreatic islets

Abstract: Highly purified islets of Langerhans were prepared in the present study from adult pigs by collagenase digestion and density gradient purification. After overnight culture, the tissue was equilibrated with DMSO at 25 degrees C, supercooled to -7.5 degrees C, nucleated, slowly cooled at 0.25 degrees C/min to -40 degrees C, and stored at -130 degrees C. Then, after variable periods of storage, the islets were rapidly thawed at 37 degrees C. Postthaw actual islet and islet equivalent (150-mu m sized islets) recovery were 75+/-7% and 66+/-4%, respectively. The frozen-thawed porcine islets maintained good morphology on histological staining by hematoxylin-eosin and aldehyde-fuchsin. Upon perifusion, basal insulin secretion was 43+/-10 and 67+/-18 pmol/L from noncryopreserved, control islets, and cryopreserved islets, respectively (P=0.2). Peak insulin release at 16.7 mmol/L glucose was 85+/-28 pmol/L from noncryopreserved islets and 157+/-48 pmol/L from the frozen-thawed islets (P=0.1). When 10 mmol/L theophylline was added to 16.7 mmol/L glucose, the secretion of the hormone peaked to 221+/-83 (control islets) and 479+/-140 pmol/L (cryopreserved islets, P=0.1). Total insulin secretion differed significantly for the noncryopreserved and the cryopreserved islets at both 16.7 mmol/L (1412+/-306 vs. 3756+/-764 pmol/L, respectively, P=0.007) and 16.7 mmol/L glucose plus 10 mmol/L theophylline (2161+/-371 vs. 7505+/-2075 pmol/L, respectively, P=0.011). Normoglycemia was restored within 7 days from implantation in temporarily immunosuppressed (aL3T4 antibody) mice with streptozotocin-induced diabetes by transplanting 1500-2000 cryopreserved porcine islets under the kidney capsule. Mean survival time of frozen-thawed islet xenografts (39+/-3 days) was similar to that of noncryopreserved islet xenografts (43+/-6 days). This study demonstrates that cryogenic storage is feasible of isolated porcine islets, with the frozen-thawed pancreatic endocrine tissue maintaining morphological integrity and both in vitro and in vivo viability. Further studies are needed to define the effect of cryopreservation on the immunogenic properties of porcine islets