Background: Advances in transplantation immunology opened the discussion on routine clinical applicability of the composite tissue allografts (CTAs). The most challenging, but most rewarding, would be restoration of the composite facial and/or scalp component. Here we introduced the feasible and applicable face/scalp allograft transplant model across MHC barrier in rat. Material and Methods: Anatomic studies on facial/scalp harvesting technique (n=6) and pilot isograft transplants (n=14) in Lewis (LEW;RT1^l) rats revealed that the composite face/scalp flap can be successfully transplanted. Nonvascular isograft (LEW ® LEW) and allograft rejection controls (LBN(F1); RT1^l+n ®LEW) (n=4); and vascularized isograft (LEW®LEW;n=4) and allograft transplantations (LBN®LEW;n=7) across MHC barrier were studied. Allograft recipients were treated with Cyclosporine-A (CsA) tapered from 16 to 2 mg/kg/day and maintained at this level. Results: Nonvascularized grafts resulted in facial flap necrosis within 5 to7 days posttransplantation. Long term survivals include, isograft controls (survival; 190 and 190 days) and CsA treated allografts (survival 20, 165 and 250 days). Flow cytometric assessment of chimerism at day 120 post-transplant showed 1.2 % of CD8+/RT1ⁿ⁺ positive cells in the peripheral blood of recipients. The MLR assay at day 120 post-transplant reveled hyporesponsiveness to the host, but increased reactivity to the donor and third-party (ACI; RT1^a) alloantigens. The immunostaining of frozen skin sections with FITC-conjugated mouse-anti rat CD25 monoclonal antibodies revealed CD25+ positive cells in skin obtained from the recipients of face allograft transplants. Conclusion: To the best of our knowledge this is the first report on composite face/scalp transplantation in animal model. This model will allow studying the pattern of acute and chronic rejection and tolerance including strategies in the face/scalp allograft transplants. Once tolerance is induced application of this procedure in the clinical scenario will be more justified in humans.
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