The efficacy and toxicity of rapamycin in murine islet transplantation. In vitro and in vivo studies

Transplantation. 1993 Nov;56(5):1137-42. doi: 10.1097/00007890-199311000-00017.

Abstract

We performed an in vivo and in vitro dose-response study of the novel immunosuppressive macrolide antibiotic rapamycin looking at murine islet allograft survival, impact on glucose homeostasis, and possible tissue toxicity. A total of 300 islets were isolated from CBA/J mice (H-2k) and transplanted beneath the renal capsule of streptozotocin-induced diabetic BALB/c (H-2d) recipients. Seven groups of allografted mice received intraperitoneally for 7 days post-transplant: no immunosuppression (n = 8); vehicle only (carboxymethyl-cellulose) (n = 6); or rapamycin at dosages of 0.05 (n = 8), 0.1 (n = 8), 0.3 (n = 8), 1.0 (n = 8), or 5.0 (n = 6) mg/kg/day. Blood glucose was monitored on alternate days, with graft failure defined by the first day of persistently high blood glucose (> 14 mmol/L). The 0.1 and 0.3 mg/kg/day groups showed statistically significant prolongation of diet allograft survival (P < 0.01) when compared to the controls and vehicle-treated mice. Three mice in both the 0.1 and 0.3 mg/kg/day groups and one mouse in the 0.05 mg group reached 100 days normoglycemia and, following nephrectomy of the islet-bearing kidney, returned to hyperglycemia. The 0.05, 1.0, and 5.0 mg/kg/day groups showed no statistically significant prolongation of graft survival. In addition, the higher dosage (1.0 and 5.0 mg/kg/day) groups had erratic blood glucose control. Histologically, there was no evidence of toxicity seen in any of the multiple organ samples. In the in vitro analysis, BALB/c (H-2k) islets cultured in either 0, 10, 30, or 100 ng/ml rapamycin had no significant differences in insulin secretion following a 24-hr culture period; however, there was a significant deterioration in glucose stimulated insulin release after 72 hr culture at high rapamycin concentration (100 ng/ml). Rapamycin significantly prolonged murine islet allograft survival. At doses 10 to 50 times the effective antirejection dosage, we demonstrated adverse impact on glucose homeostasis without histological evidence of end-organ toxicity. We also demonstrated an adverse impact on insulin release in vitro following prolonged culture (72 hr) in a high concentration of rapamycin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Weight / drug effects
  • Culture Techniques
  • Dose-Response Relationship, Drug
  • Glucose / metabolism
  • Graft Survival / drug effects
  • Immunosuppressive Agents / therapeutic use*
  • Insulin / metabolism
  • Insulin Secretion
  • Islets of Langerhans Transplantation*
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred CBA
  • Polyenes / therapeutic use*
  • Polyenes / toxicity
  • Sirolimus

Substances

  • Immunosuppressive Agents
  • Insulin
  • Polyenes
  • Glucose
  • Sirolimus