Multifunctional ADM Hydrogel Containing Endothelial Cell-Exos For Diabetic Wound Healing

Objectives:Difficulty wound healing is a common complication of diabetes,and there is still a lack of effective treatment.Studies have found that oxidative stress injury,bacterial infection,cell dysfunction,and severe inflammatory reaction are important reasons for wound nonunion in diabetes.Acellular Dermal Matrix（ADM）is a wound dressing with a natural extracellular matrix structure,which has been used to treat the burn,diabetes,and other wounds.The complex(Fe³⁺@PA)composed of protocatechualdehyde（PA）and trivalent iron ion(Fe³⁺)has antioxidant and antibacterial properties.In this study,ADM modified by Fe³⁺@PA complex and photocurable gelatin（Gel MA）formed a dual hydrogel network,and carried exosomes secreted from HUVECs（HUVEC-Exos）derived from umbilical vein endothelial cell line to develop ADM composite hydrogel system(ADM-Fe³⁺@PA-Exos/Gel MA)with antioxidant,antibacterial and cell promoting functions for the treatment of diabetic wounds.The antioxidant,antibacterial,and biological safety of ADM composite hydrogel were investigated through in vitro experiments;To study the protective effect of ADM composite hydrogel on diabetes cell damage;The therapeutic effect of ADM composite hydrogel on diabetes wound healing was evaluated through animal experiments.Methods:The double network ADM composite hydrogel was prepared by photocrosslinking and Schiff base bonding,and its gel time,water content,swelling ratio,biodegradability,rheological mechanics,scanning electron microscope observation,pore size analysis,and Fe³⁺@PA complex absorption spectrum were characterized.The biocompatibility of ADM composite hydrogel was evaluated by cell death staining,CCK8test,and the blood compatibility test.DPPH·test was used to verify the extracellular antioxidant activity of hydrogel.The cell model of diabetes was established by methylglyoxal（MGO）,and the intracellular antioxidant capacity of ADM composite hydrogel was verified by SOD and GSH-Px kits.The protective effect of ADM composite hydrogel on MGO-mediated cell damage was explored through CCK8,Transwell cell migration experiments,and Ed U staining experiments;The antibacterial properties of ADM composite hydrogel were verified by the experiments of bacterial clone formation,bacteriostatic ring,turbidimetry and live dead staining;Establish a mouse diabetes wound model and evaluate the effect of ADM composite hydrogel on diabetes wound healing through wound healing,HE staining,Masson staining,immunofluorescence staining and immunohistochemical staining.Results:ADM composite hydrogel has good biocompatibility.It can reduce oxidative stress injury of diabetes cells by eliminating reactive oxygen species,and promote cell proliferation and migration function recovery after MGO-mediated cell injury.At the same time,ADM composite hydrogel showed excellent antibacterial performance against Staphylococcus aureus and Escherichia coli.In vivo experiments have proved that ADM composite hydrogel can improve the function of wound cells,reduce oxidative stress injury,inhibit inflammation,prevent bacterial infection,accelerate collagen deposition and angiogenesis,and then promote the healing of diabetic wounds.Conclusion:In this study,ADM-Fe³⁺@PA Exos/Gel MA composite hydrogel system was constructed,which has good antioxidant and antibacterial properties,and can effectively restore cell function in diabetes and promote the healing of diabetic wounds.This study improved and broke through the function of ADM materials,and provided a new idea for the clinical transformation of ADM in the application of diabetes wounds.