Prednisone, azathioprine, and cyclosporine a toxicity on human fetal pancreas

Abstract

The limited clinical success of human fetal pancreas (HFP) transplantation may be related to graft toxicity caused by immunosuppressant agents. This study describes the effects of prednisone (PRED), azathioprine (AZA), and cyclosporine A (CSA) on HFP tissue in vitro and in vivo. To assess in vitro function, fresh HFP explants (1–2 mm 3; 16–21 weeks gestational age) were prepared and cultured 72 hr in supplemented Ham's medium containing varying concentrations of each drug. Insulin release in response to high glucose (17 m M) and theophylline (10 m M) challenge was determined and compared to basal release in low glucose (3 m M) buffer. No significant difference in insulin release was observed between culture control tissue and drug-cultured tissue throughout the concentration range (10 −8-10 −4 M; P > 0.05). To assess in vivo function, cyropreserved HFP explants were transplanted under the kidney capsule of streptozotocin-induced diabetic nude mice. Mice were immunosuppressed with PRED (1 mg/kg), AZA (1 mg/kg), CSA (30 mg/kg), or combined triple drug therapy (COMBO), and glucose levels followed weekly. Hyperglycemia reversal and insulin withdrawal were observed in all drug groups [PRED ( 4 6 ), AZA ( 4 6 ), CSA ( 2 4 ), COMBO, ( 2 4 )] and were not statistically different from control ( 5 8 ; P > 0.8). Time to insulin withdrawal was significantly different from control (12.2 ± 2.2 weeks; P < 0.05) only for AZA (10 ± 0 weeks; PRED, 12.3 ± 2.6 weeks; CSA, 11 ± 0 weeks; COMBO, 15 ± 0 weeks). Additionally, oral glucose tolerance tests in all groups were equivalent to nondiabetic controls. We were unable to demonstrate PRED, AZA, or CSA toxicity on HFP. Future investigation of HFP graft failure should be directed toward causes other than direct drug toxicity.