Ultra-microskin as cytokine reservoirs promote diabetic wound healing: experimental research

BACKGROUND: Chronic wounds, such as diabetic foot ulcers, are challenging to heal due to persistent inflammatory responses and imbalanced growth factors. Conventional microskin grafting techniques face limitations, including insufficient viability, orientation-dependent survival, and restricted paracrine functions. This study investigates the feasibility of using ultra-microskin grafts (approximately 0.3 mm thick, 0.4 × 0.4 mm in surface dimensions) at expansion ratios of 1:10 to enhance diabetic wound repair. MATERIALS AND METHODS: Ultra-microskins were prepared using an automated skin-cutting device. Viability assessment of ultra-microskin and conventional microskins was performed using CCK-8 assay, LIVE/DEAD staining, transmission electron microscopy, and explant culture. Ultra-microskin was transplanted onto full-thickness defects at 1:10 and 1:20 expansion ratios; the optimal size was determined based on viability results and the "Inter-Graft Spacing Theory." Cytokine release from ultra-microskin was quantified by ELISA. The effects of cytokines in ultra-microskin extracts on the migration, proliferation, and tube formation capabilities of human foreskin fibroblasts (HFB), human umbilical vein endothelial cells (HUVECs), and HaCaT cells were assessed. Ultra-microskin (0.4 mm) was transplanted onto diabetic rat wounds at a 1:10 ratio. Wound healing was evaluated via gross photography, H&E staining, Masson's trichrome staining, and CD31/Ki-67 immunohistochemistry. Proteomic analysis of wound tissues was conducted on posttransplant days 7 and 14. RESULTS: Ultra-microskin sized ≥0.4 mm exhibited viability comparable to or exceeding that of conventional microskins. The optimal size for ultra-microskin was determined to be 0.4 mm. Ultra-microskin significantly enhanced the release of cytokines (TGF-α, EGF, MCP-1, TNF-α, IL-6, IL-10, VEGF-A, TGF-β1, IGF-1) and promoted the functions of wound healing-associated cells (HFB, HUVEC, HaCaT). Transplantation of ultra-microskin significantly attenuated inflammation, promoted vascularization and epithelialization, and accelerated the healing rate of diabetic wounds. CONCLUSION: Ultra-microskin (0.4 mm) dynamically accelerates diabetic wound healing via cytokine release, offering a novel therapeutic strategy for chronic wounds, including diabetic ulcers.