Beyond Rejection: Engineering Immune Responses to Redefine Skin Graft Survival
Summary: Published March 10, 2026 in Frontiers in Immunology (Inflammation section), this mini review from Touro College of Osteopathic Medicine and New York Medical College examines the immunologic landscape governing skin graft outcomes — a topic of direct relevance to wound care practitioners managing patients with burns, chronic ulcers, trauma, and post-excisional defects requiring grafting. The global burden is substantial: WHO estimates 180,000 burn deaths annually and approximately 11 million non-fatal burn injuries, with split-thickness skin graft (STSG) take rates of 70–90% under favorable conditions but lower in resource-limited or high-comorbidity settings. The authors systematically map the immune mechanisms underlying graft rejection: hyperacute rejection is driven by preformed recipient antibodies activating the classical complement cascade, triggering thrombosis and ischemia via MAC formation; early acute rejection involves neutrophil and macrophage recruitment, ROS generation, and NK cell cytotoxicity; acute cellular rejection is mediated by direct and indirect T cell allorecognition pathways (CD4+ Th1 activation driving IFN-γ and macrophage activation; CD8+ cytotoxicity); and chronic rejection involves alloantibody production, MMP-driven ECM degradation, and fibrosis. The review contrasts STSG and full-thickness skin grafts (FTSG) immunologically — FTSGs retain dermal Langerhans cells and are significantly more immunogenic. The therapeutic sections evaluate conventional immunosuppression (tacrolimus, corticosteroids, cyclosporine), bioengineered scaffolds incorporating anti-TNFα or anti-IL-6 agents and antioxidant nanoparticles, 3D bioprinted constructs with immune-evasive materials, and MSC-conditioned media for macrophage polarization toward the M2 repair phenotype. The authors candidly address translational barriers: murine skin models poorly replicate human immunogenetics and skin architecture, phase I/II trial data are limited, and regulatory pathways for bioengineered constructs remain demanding. They advocate for humanized models, longitudinal multicenter trials, and personalized immunotherapy approaches.
Key Highlights:
- STSG take rates 70–90% in ideal conditions; key failure predictors: postoperative infection, hematoma, poor perfusion, diabetes, malnutrition, smoking, immunosuppression
- Rejection mechanisms: hyperacute (preformed antibodies → complement → MAC → thrombosis); acute cellular (T cell allorecognition, CD4+/CD8+ cytotoxicity); chronic (indirect allorecognition → alloantibody, MMP-driven fibrosis); FTSG more immunogenic than STSG due to retained Langerhans cells
- ROS, pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), and MMP-2/MMP-9 amplify tissue injury and interfere with revascularization — but controlled inflammation is also necessary for angiogenesis and M2-driven tissue repair
- Emerging strategies: bioengineered scaffolds with anti-TNFα/anti-IL-6 agents and antioxidant nanoparticles; 3D bioprinted layered constructs using patient-derived keratinocytes and fibroblasts; in-situ portable bioprinting for direct wound deposition; MSC conditioned media for macrophage M2 polarization
- Conventional immunosuppression (tacrolimus, cyclosporine, corticosteroids) reduces rejection but limited by systemic toxicity and impaired wound healing; skin grafts among the most immunogenic tissues, often inadequately controlled by standard systemic regimens
- Translational barriers: murine models diverge from human immunogenetics, skin structure, and microbiome; limited phase I/II human data; regulatory complexity for biomaterial and gene-edited constructs; need for humanized models and stratified multicenter trials
Keywords: skin graft rejection immunology, skin graft survival wound care, bioengineered skin scaffold, split thickness skin graft, immunomodulation wound healing, 3D bioprinting wound repair
Daniela Grinis Jacob Bouzaglou Anish R. Maskey