Swine hemi-facial composite tissue allotransplantation: a model to study immune rejection

Partial face composite tissue allotransplantation was recently achieved in a human subject. However, the side effects of long-term immunosuppression and chronic rejection area still need concerning. This preliminary study investigated the reproducibility of swine hemi-facial transplantation for preclinical studies.

Eleven out-bred miniature swine underwent hemi-facial transplant. The hemi-facial orthotopic transplant consisted of ear cartilage, auricular nerve, parotid gland and lymphoid tissue, muscle with surrounding hemi-facial skin paddle supplied by the carotid artery, and external jugular vein transplanted to recipient swine. Three different experimental designs were studied, as follows: group I (n = 4): autologous hemi-facial transplantation as a normal control; group II (n = 4): hemi-facial allotransplantation without treatment; group III (n = 3): hemi-facial allotransplantation with cyclosporine-A treatment for 4 wk. The transplanted face was observed daily for signs of rejection. Biopsy of donor skin, gland lymphoid tissue, and cartilage were obtained at specified predetermined time (d 7, 14, 28), or at the time of clinically evident rejection.

The results indicated the survival of group I following autologous hemi-facial transplant was 100% and indefinite until sacrifice. Group II without treatment as the controls revealed allograft rejection by d 7 to 28. The allograft with short-term cyclosporine-A treatment revealed delayed rejection by d 38 to 49 postoperatively. The histological examination in group I revealed abundant lymphocyte infiltration, especially in lymphoid gland and alloskin at 1 wk and sacrifice. In contrast, the cyclosporine treatment group showed no significant rejection signs in 4 wk posttransplants. These results demonstrated that lymphoid tissue and alloskin are both susceptible to early rejection.

The experimental results revealed this model is suitable to investigate the new strategies for preclinical facial allotransplantation studies. Monitoring and modulation of early rejection in alloskin and gland lymphoid tissue is a useful strategy to evaluate composite tissue allotransplantation survival.