Increased efficacy of CSA following rearterialization in the rat OLTX model

Many investigators presently use a rat orthotopic liver transplant (OLTX) model without rearterialization of the graft. Rearterialization has been demonstrated to have a variable effect on the rejection response in various strain combinations. However, there are little data on the effects in a model with immunosuppression. The influence of rearterialization on the efficacy of cyclosporine (CSA) in such a model was examined, with the hypothesis that rearterialization may alter the rejection response and efficacy of cyclosporine. OLTX was performed between adult male D Agouti rats and Lewis rats. Rearterialization was performed between the recipient and donor celiac axis, and CSA was delivered at 1 mg/kg/day by continuous infusion for 14 days postoperatively. Treatment groups consisted of no rearterialization/no CSA, rearterialization/no CSA, no rearterialization/CSA, and rearterialization/CSA. Survival time and histology of liver grafts were measured. Rearterialization itself did not prolong survival in this strain combination (median survival no rearterialization/no CSA is 11 days versus median survival rearterialization/no CSA is 10 days). The addition of CSA at this dose without rearterialization also did not prolong survival (median survival no rearterialization/CSA is 15.5 days). The combination of CSA with rearterialization did prolong survival significantly (median survival rearterialization/CSA is 22 days; P < 0.05 versus the other three groups). The mechanism of this increased efficacy is unknown, but may involve altered MHC antigen expression, altered metabolism of CSA, decreased toxicity of CSA, or decreased nonspecific inflammation in the rearterialized grafts.