Rejection and regeneration in peripheral nerve homografts in rats after withdrawal of cyclosporin: Morphological and immunohistochemical assessment

Peripheral nerve homografts 35 mm long were inserted in rats to study rejec tion and regeneration of nerves after suspension of an immunosuppressant (c yclosporin), and the correlation between the Schwann cells of the host and the donor during the course of regeneration. Sciatic nerve homografts from 36 ACI-RTa rats were transplanted into Lewis-RT1(1) rats, Isografts were ta ken from 24 Lewis rats. Cyclosporin 5 mg/kg/day was given subcutaneously fo r II weeks, In the homograft group the myelinated axons that regenerated wh ile the immunosuppressant was being given were covered mainly with Schwann cells from the donor, and after the immunosuppressant was withdrawn both Sc hwann cells of the donor and axons were rejected. However, while the cyclos porin was being given the Schwann cells of the host migrated into the nerve graft together with a few myelinated axons that escaped rejection, and unm yelinated axons that regenerated after rejection were myelinated by the Sch wann cells of host.