Direct Lineage Reprogramming of Fibroblasts into Functional Keratinocyte-Like Cells via BMI1 and FGFR2b for Diabetic Wound Repair

The limited regenerative capacity of epidermal cells following tissue injury impairs wound healing in diabetic foot ulcers (DFUs), contributing to elevated rates of amputation and mortality. Recent advances have demonstrated that somatic cells can be reprogrammed into diverse cell types through the application of defined reprogramming factors. This study aims to develop a safe, efficient, and clinically translatable strategy for skin regeneration via direct lineage reprogramming. We established a novel reprogramming approach using a combination of two factors, BMI1 and FGFR2b (termed B2), to induce fibroblast-to-keratinocyte-like cells (iKCs) conversion in vitro and delivered via adeno-associated virus 9 (AAV9) in vivo. Molecular and functional characteristics of iKCs were evaluated by qRT-PCR, Western blot, immunofluorescence, transcriptomic analysis, and in vitro differentiation assays. A diabetic (db/db) mouse skin wound model was used to assess the regenerative potential and therapeutic effects. Statistical significance was determined using Student's t-test or one-way ANOVA. iKCs-B2 (Keratinocyte-like cells form from B2-infected L929) exhibited both morphological and functional characteristics comparable to primary keratinocytes. In vivo, AAV9-mediated delivery of B2 factors significantly promoted wound closure, reconstructed stratified epithelium, restored barrier function, and markedly reduced the mortality rate. This study presents a safe and effective direct reprogramming strategy for skin regeneration, bypassing the pluripotent stage and avoiding cell transplantation. The B2 combination provides a novel molecular tool for wound repair and offers translational potential for treating non-healing wounds such as DFUs.