OBJECTIVETo explore the synergistic protective effect of co-transplanted testicular cells expressing FasL and CsA on survival of islet allografts.

METHODSThe allogeneic islets and testicular cells were co-transplanted into the renal subcapsular space of the diabetic recipients with or without CsA after operation. Allografts survival period and the testicular cells or islets function were analyzed.

RESULTSThe mean survival period of control group was 4.6 +/- 1.1 days. When CsA was administered after transplantation, the mean survival period of islet allografts, (21.8 +/- 4.7) days, was significantly longer than that of control group (P < 0.01). When islets were co-transplanted together with 1 x 10(7) testicular cells (group A), a significant prolongation of graft survival was found (more than 57.5 +/- 4.0 days; P < 0.01 vs. control). But if 1 x 10(7) testicular cells expressing FasL were cultured with FasL-mAb for 30 minutes before co-transplantation (group B), the mean survival period of islet allografts (5.8 +/- 2.6 days), was similar to that in control group, but significantly shorter than that in group A (P < 0.01). When islets and 1 x 10(5) testicular cells were co-transplanted separately into the bilateral renal subcapsular space with CsA (group C), the survival of islet allografts was significantly prolonged in comparison with control group (more than 55.0 +/- 6.5 days; P < 0.01 vs. control), and similar to islets co-transplanted together with 1 x 10(7) testicular cells (group A). When islets were co-transplanted separately with 1 x 10(6) testicular cells without CsA (group D), the mean survival period (11.5 +/- 3.1 days) was shorter than that in group C, but prolonged in comparison to control group (P < 0.05).

CONCLUSIONThe co-transplanted testicular cells expressing FasL with administering CsA post-transplantation can jointly inhibit immune rejection of islet allografts by different mechanism and play a systemic and synergistic protective role to islet allografts.