Geoffrey O'Shea

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Prolonged survival of islet allografts in streptozotocin-induced diabetic rats was achieved by encapsulating individual islets in protective, biocompatible alginate-polylysine-alginate membranes. A single intraperitoneal transplant of encapsulated islets reversed the diabetic state for up to 1 year. In contrast, a single injection of unencapsulated islets(More)
Allogeneic islets obtained from Lewis rats were transplanted into diabetic BB/W rats with or without cyclosporine. In addition, these islets were encapsulated in alginate-poly L-lysine membranes and then transplanted into diabetic BB/W rats with or without immunosuppressive and/or antiinflammatory agents. The agents used were cyclosporine, dexamethasone,(More)
An improved membrane has been developed for the microencapsulation of islets of Langerhans which protects these cells from the immune system. These requirements were accomplished through the optimization of important microencapsulation parameters and through the improved biocompatibility of a new alginate-poly-l-lysine (PLL)-alginate capsule membrane.(More)
Allogeneic islets encapsulated in an alginate/poly-L-lysine membrane and transplanted into diabetic BB/W rats resulted in graft failure within 2 weeks of transplantation. Graft failure was associated with a dense pericapsular infiltrate (PCI) that resulted in necrosis of the encapsulated islets. The PCI could be inhibited by immunosuppressive agents,(More)
Rat islets encapsulated in alginate-polylysine membranes were implanted intraperitoneally into nonimmunosuppressed streptozocin-induced diabetic mice. Diabetes was reversed within 3 days, and the animals remained normoglycemic for up to 144 days, with a mean xenograft survival of 80 days. This was significantly greater than nonencapsulated islets, which(More)
Microcapsules containing insulin crystals or islets of Langerhans were made by extruding a mixture of insulin crystals or islets and sodium alginate into a calcium chloride solution, and then coating it with poly-l-lysine. When these microcapsules were incubated at 37 degrees C, insulin could be detected readily in the medium, indicating that the(More)
Rat islets encapsulated in semipermeable membranes remained viable in culture for 4 months. Multiple allotransplants of islets encapsulated in alginate-polylysine-polyethyleneimine membranes restored normoglycemia in recipient diabetic rats for most of a 90-day experimental period. Each individual transplant restored normal fasting plasma glucose levels for(More)
The present study was undertaken to determine whether the transplantation of encapsulated MHC identical islets into diabetic BB/Wor/BB rats could cure their diabetes. Islets were isolated from diabetes-resistant BB/Wor/WB rats and encapsulated in alginate-polylysine-alginate membranes. Five thousand islets were transplanted into the peritoneal cavity of(More)
This report describes the development of a long-acting insulin accomplished by the slow release of hormone from an implantable, biodegradable matrix. Rats made diabetic with streptozotocin received a single subcutaneous implant of insulin-albumin microbeads that released biologically active insulin for periods up to 3 wk. The mean fasting blood glucose(More)