Immunologic Pretreatment of Donor Tissue in Vascularized Composite Allotransplantation: A Systematic Review

Vascularized composite allotransplantation (VCA) holds significant promise for patients with complex structural defects, providing solutions unattainable through traditional methods. Despite technical successes, graft rejection and ischemia-reperfusion injury (IRI) present major challenges, with high rejection rates even under modern immunosuppression protocols. This review synthesizes current literature on immunologic pretreatments (IPTs) designed to mitigate these issues, focusing on interventions applied to donor tissues between procurement and transplantation.

A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines identified 11 relevant studies, categorizing IPTs into donor tissue modification (DTM), deoxygenated perfusate, and oxygenation methods.

DTM, the most common IPT method, shows promise in reducing immunogenicity and prolonging graft survival, primarily through techniques such as recipient bone marrow-derived cell conditioning and MHC-I knockdown using small interfering RNA (siRNA). Deoxygenated perfusate studies highlighted mitomycin C's potential in reducing immune response and extending graft viability. Oxygenation methods, aimed at minimizing IRIs, utilized perfusion techniques to maintain graft viability ex vivo.

Although IPTs for extending graft survival have seen moderate clinical translation, those targeting immunogenicity remain largely experimental. This review underscores the potential of these IPT modalities to improve VCA outcomes by reducing rejection and IRIs. However, it also highlights the need for further research, particularly multi-center clinical trials, to validate these techniques for broader clinical adoption. This comprehensive synthesis aims to guide future studies and enhance clinical strategies for VCA, ultimately improving patient outcomes.