SURVIVAL AND MATURATION OF HETEROTOPIC FETAL BRAIN-STEM XENOGRAFTS AFTER TREATMENT WITH 2-CHLORODEOXYADENOSINE AND CYCLOSPORINE-A

Brain stem halves from fetal rabbits were transplanted to the caudate nucleus area of adult rats. The animals were treated postoperatively w ith cyclosporine A (CsA) and 2-chlorodeoxyadenosine (CdA) for three da ys, and with CdA alone for the next 13 days. The treatment started at the day of implantation, and in some animals it was repeated starting at day 36 after grafting (at the time when signs of a light inflammato ry reaction appeared in some grafts). Grafts survived and matured hist ologically, and no signs of acute rejection were observed up to the 90 th day. In some grafts we recorded phasic neuronal activities similar to the respiratory-related neural activities characteristic for the ad ult brain stem. Immunosuppression with CdA and CsA deserves further ev aluation in fetal brain grafting.