Purpose: We used total body irradiation (TBI) as conditioning for cord blood transplantation studies in pigtailed macaques. In these studies, different doses of TBI were explored to obtain optimal myelosuppression with acceptable radiation-related side effects.
Methods: Four macaques received TBI ranging from 800 to 1320 cGy, followed by standard post-transplant care. Hematopoietic recovery was monitored by CBC and donor contribution by variable number of tandem repeats analysis.
Results: Animals receiving 800 or 1020 cGy TBI tolerated the irradiation well with autologous recovery of neutrophils within 24 days. At a dose of 1200 cGy, neither autologous recovery nor extramedullary toxicity was observed. A fourth animal received 1320 cGy of TBI and suffered significant toxicity necessitating termination of the study.
Conclusions: We conclude that previously considered myeloablative doses of TBI allowed for autologous recovery in the pigtailed macaque, and that a dose of 1200 cGy may be most appropriate, providing both myeloablation and acceptable non-hematopoietic toxicities.