Gelatin-chondroitin-6-sulfate-hyaluronic acid scaffold seeded with vascular endothelial growth factor 165 modified hair follicle stem cells as a three-dimensional skin substitute

Introduction: In the field of skin tissue engineering, gelatin-chondroitin-6-sulfate-hyaluronic acid (Gel-C6S-HA) stents are a suitable bio skin substitute. The purpose was to investigate the effect of genetically-modified hair follicle stem cells (HFSCs), combined with Gel-C6S-HA scaffolds, on the vascularization of tissue-engineered skin. Methods: Three-dimensional (3D) Gel-C6S-HA scaffolds were prepared by freeze-drying. Vascular endothelial growth factor (VEGF) 165 gene-modified rat HFSCs (rHFSCs) were inoculated into the scaffolds and cultured for 7 days. Two bilateral full-thickness skin defects were created on the back of 18 Sprague-Dawley rats. Rats were randomly divided into four groups: Group A, HFSCs transduced with VEGF165 seeded onto Gel-C6S-HA scaffolds; Group B, HFSCs transduced with empty vector seeded onto Gel-C6S-HA scaffolds; Group C, Gel-C6S-HA scaffold only; Group D, Vaseline gauze dressing. These compositions were implanted onto the defects and harvested at 7, 14 and 21 days. Wound healing was assessed and compared among groups according to hematoxylin-eosin staining, CD31 expression, alpha smooth muscle actin (alpha-SMA) and major histocompatibility complex class I (MHC-I) immunohistochemistry, and microvessel density (MVD) count, to evaluate the new blood vessels. Results: SEM revealed the Gel-C6S-HA scaffold was spongy and 3D, with an average pore diameter of 133.23 +/- 43.36 mu m. Cells seeded on scaffolds showed good adherent growth after 7 days culture. No significant difference in rHFSC morphology, adherence and proliferative capacity was found before and after transfection (P > 0.05). After 14 and 21 days, the highest rate of wound healing was observed in Group A (P < 0.05). Histological and immunological examination showed that after 21 days, MVD also reached a maximum in Group A (P < 0.05). Therefore, the number of new blood vessels formed within the skin substitutes was greatest in Group A, followed by Group B. In Group C, only trace amounts of mature subcutaneous blood vessels were observed, and few subcutaneous tissue cells migrated into the scaffolds. Conclusions: Tissue-engineered skin constructs, using 3D Gel-C6S-HA scaffolds seeded with VEGF165-modified rHFSCs, resulted in promotion of angiogenesis during wound healing and facilitation of vascularization in skin substitutes. This may be a novel approach for tissue-engineered skin substitutes.