Islet-like cell clusters: viability, cell types, and subretinal transplantation in pancreatectomized cats

We investigated a method for isolating sufficient feline islets of Langerhans to restore normoglycaemia following transplantation into the subretinal space of pancreatectomized cats. Collagenase digestate of feline pancreas was maintained in serum-free tissue culture medium for 1-9 days. Viability of islet-like cell clusters (ICC) was assessed with ethidium bromide and fluorescein diacetate staining; cell types were identified immunohistochemically. After nine days, the ICC were transplanted. We estimated viable ICC in tissue culture at nine days as 3800 +/- 2000 (mean +/- SD) per pancreas. While numbers of beta cells decreased over time in culture, ductal cells increased. Bromodeoxyuridine labelling showed no proliferation of beta cells but extensive proliferation of ductal cells. Subretinal transplants of cultured ICC in the diabetic cats maintained normoglycaemia for up to 12 days, while they provoked massive lymphocyte infiltration indicating rejection. Islet transplantation into the feline subretinal space temporarily restored normoglycaemia. Our current method of culture achieved sufficient reduction of acinar cells but an insufficient yield of insulin-producing cells.