| Background:The repair of full-thickness skin defects has been the focus of clinical work.Stem cells play an essential role in all stages of the skin and soft tissue regeneration process,However,the utilization of exogenous stem cells is often incomplete.Studies have demonstrated the ability of endogenous stem cells to recruit to the wound bed and actively participate in tissue repair.In skin and soft tissue repair,re-epithelialization is a hallmark of wound healing,and the strategic promotion of stem cell differentiation towards an epithelial-like phenotype represents a promising approach to enhance the process of wound healing.The wound bed presents a complex and dynamic environment,wherein various factors such as inflammation,microorganisms,and exudate can influence the activity of bioactive factors..The application of biomaterials as drug delivery vehicles and cell scaffolds has emerged as a promising strategy to improve the efficacy of therapeutic interventions,additionally,biomaterials can serve as extracellular matrices with tailored mechanical properties,which can regulate stem cell activity and influence tissue regeneration.Objective:In this study,chitosan-gelatin composite hydrogels were prepared with adjustable stiffness and loaded with granulocyte colony-stimulating factor and epidermal growth factor.The aim of this approach is to promote endogenous stem cell recruitment and epithelialization.Adjusting the stiffness of the hydrogel close to the skin provides a suitable matrix mechanical signal for stem cell differentiation,thus promoting wound healing.Methods:1.Chitosan-gelatin hydrogels were prepared using β-glucuronidase and genipin as cross-linking agents,and the stiffness of the hydrogels was adjusted by adjusting genipin content.Observe the microstructure,measure the hydrophilicity and swelling rate.The stress-strain curve and elastic modulus were determined using a universal mechanical testing machine,and the hydrogel close to the skin stiffness was selected.Finally,the ELASA method was used to quantify the effect of hydrogels on the release of G-CSF and EGF.2.To investigate the biological effects of hydrogels loaded with G-CSF and EGF,bone marrow-derived mesenchymal stem cells(BMSCs)were used as experimental subjects.The migratory effect of G-CSF on BMSCs was assessed using scratch wound healing and transwell cell migration assays,meanwhile,the optimal drug concentration was selected.CCK8 method and live-dead staining to verify hydrogel biocompatibility.To evaluate the efficacy of the drug-loaded hydrogel system in promoting the migration and epithelialization of BMSCs,a scratch wound healing assay,transwell cell migration assay,and real-time fluorescence quantitative PCR were conducted.3.The effectiveness of drug-loaded hydrogels in promoting stem cell recruitment was evaluated through in vivo stem cell tracing.Histological analysis was performed to assess the quality of skin soft tissue repair.Results:1.A composite hydrogel with double network and a sparse porous structure was successfully prepared and characterized by its favorable hydrophilicity and swelling properties.Furthermore,the hydrogel exhibited sustained release of G-CSF and EGF.2.The hydrogel was proved to have good biocompatibility,as it was observed to significantly increase the number of transmembrane BMSCs and promote scratch wound healing.Furthermore,the drug-loaded hydrogel was found to upregulate the gene expression of CXCR4 and E-Cadherin.3.In vivo experiments have demonstrated that hydrogels loaded with G-CSF and EGF can effectively recruit stem cells to wounds,promote collagen deposition and stem cell epithelialization,and improve the speed and quality of wound healing.Conclusion:The chitosan-gelatin composite hydrogel has good biocompatibility and promotes the migration of stem cell and the expression of epithelial-like gene expression upon drug loading.In vivo,the drug-loaded hydrogel can recruit stem cells,enhances wound healing,increases the trauma stem cell content,and improves the quality of wound healing. |
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