Disparate Hypervariable Region-1 of Mitochondrial DNA Did Not Induce Skin Allograft Rejection in Cloned Porcine Models

IntroductionAlloantigen recognition in skin transplantation is the bane for surgeons. Several studies have mainly focused on the immunogenicity of major histocompatibility (MHC) antigens and H-Y minor histocompatibility antigens. However, the roles of the mitochondrial DNA (mtDNA) encorded miHA have not been identified. Therefore, we sought to address the antigenicity of the hypervariable region 1 (HV-1) of mtDNA in skin transplantation using cloned pig models.MethodsSwine leukocyte antigen and HV-1 of mtDNA were analyzed using sequencing methods. Skin transplantation was performed between MHC-matched, mtDNA-mismatched cloned miniature pigs. Full-thickness skin was grafted between cloned pigs without any immunosuppressants. The grafted tissues were observed for 3 months and evaluated histologically.ResultsThe cloned pigs shared identical MHC but mtDNA mismatched at 9 positions. Skin grafts between the cloned pigs were accepted and hair growth maintained, whereas MHC-mismatched grafts showed acute rejection within 7 days after transplantation and were replaced by hairless scar tissue.ConclusionsHV-1 disparate skin grafts were not recognized as alloantigenic by MHC-matched cloned pigs.