Nerve cells in transplanted pancreatic islets: no effects of cyclosporin or tacrolimus on immediate neuronal survival.

Previous experiments have demonstrated that neuronal cells within pancreatic islets survive the isolation procedure and constitute an integral part of transplanted pancreatic islets. The aim of the present study was to investigate to what extent immunosuppressive drugs affects the acute survival of intra-islet neurons after pancreatic islet transplantation. For this purpose, C57BL/6 mice were syngeneically transplanted with 250 islets under the renal capsule. The animals were treated for 7 consecutive days with subcutaneous injections of cyclosporin, tacrolimus or vehicle. After this, the animals were killed and the grafts were removed, fixed and stained for the presence of the neuron-specific protein PGP 9.5. The number of nerves were then morphologically quantitated. No differences between the experimental groups were seen, and the number of nervous elements were approximately 5 per mm2 in all animals. It is concluded that immunosuppressive treatment does not affect the acute survival of graft neurons after experimental islet transplantation.