Comparison of the Survival of Fresh or Cultured Pancreatic Islets Pseudoislets and Single Cells Following Allotransplantation Beneath the Kidney Capsule in Non-Immunosuppressed Diabetic Rats

Summary

The purpose of the present study was to examine the effect of culture pretreatment and islet structure on transplantation survival time. Donors for islet isolation were highly inbred male Lewis rats (RT 1¹). Production of single cells was performed by using EDTA and Trypsin. Pseudo-islets were produced by culturing single cell suspensions at 37 ^°C for 12—14 days. Recipients were BDE rats (RT 1^u), made diabetic by streptozotocin injection. 1000—1200 islets (or corresponding amount of single cells or pseudoislets) were transplanted to the subcapsular renal space. Five groups were transplanted. Group 1 (n = 5) received freshly isolated islets of Langerhans. Group 2 (n = 7) received single cells, produced from freshly isolated islets. In group III (n = 7) pseudoislets were transplanted. The animals of group IV received 37^°C cultured islets (12—14 days), while group V received single cells consisting of 12—14 day cultured islets at 37^°C. The median survival times were: gr. I 7 d.; gr. II 5 d.; gr. III 120 d.; gr. IV 11 d.; gr. V 9 d. Group III showed a prolongation of allograft survival that was statistically significant compared to all other groups. 4 from 7 animals showed a long-term acceptance. It can be concluded that neither culturing islets at 37^°C nor producing single cells achieves long-term acceptance. Transplanting pseudoislets resulted in a long-term acceptance of allograft, without immuno-suppression of the host. Three factors may be responsible for this success: Firstly, a reduced number of class-II-antigen positive cells, secondly, metabolic state of rest, and thirdly, the transplantation site.

Key words

Islet Transplantation - Single cells - Pseudo-islets - Class-II-antigen - Allograft survival