Establishing a new orthotopic composite hemiface/calvaria transplantation model in rabbits

Composite tissue allograft transplantation provides a better reconstructive option for patients who suffer from extensive craniomaxillofacial deformities. However, there is a lack of sufficient experimental data including anatomical and immunologic aspects in larger animals. The purpose of this study was to develop a new orthotopic composite hemiface/calvaria transplantation model in rabbits with which to estimate the feasibility of composite tissue allografts.

A total of 36 rabbits were studied. The anatomical features were explored in six rabbits. Group I (n = 6) represented the autograft group. In the allograft control group (group II, n = 12) and the treatment group (group III, n = 12), orthotopic composite hemiface/calvaria allotransplantations were performed from Dutch to Japanese White rabbits. Recipients in the treatment group received low-dose cyclosporine A/prednisone combination therapy. Evaluation methods included clinical inspection, histologic analysis, immunohistochemistry, and radiography.

The animals in the autograft group survived indefinitely. Four of six nontreated allografts were rejected within 7 to 10 days. In the treatment group, five of six recipients showed no signs of rejection up to the endpoint of the study. Only one recipient died as a result of anorexia, on day 18. The histologic outcomes were well correlated with clinical inspection. Bone biopsy specimens at posttransplant days 7 and 120 revealed viable bone. Radiologic grade at day 120 showed no significant difference between the autograft (10.67 +/- 1.03) and treatment groups (9.2 +/- 1.30).

Low-dose cyclosporine A/prednisone combination therapy does not influence bone viability and healing. A new orthotopic hemiface/calvaria allotransplantation model was established successfully that allows further studies on reconstruction of extensive craniomaxillofacial defects.