Vascularization Of Mesenchymal Stem Cells In RGD Modified Chitosan Based Injectable Nano-Composite Thermosensitive Hydrogels

With the development of tissue engineering technology,three-dimensional scaffolds have shown increasing potential in tissue and organ repair.However,traditional stent implantation into the human body leads to more trauma and repeated infections,so injectable stents have emerged.After tissue and organ implantation in the body,it often takes several weeks to complete capillary invasion to generate blood vessels,and the lack of oxygen and nutrient supply leads to graft implantation failure.Therefore,for the purpose of angiogenesis in tissue repair.We have prepared a chitosan(CS)/?-glycerophosphate(?-GP).Injectable hydrogels of gelatin(Ge)and arg-gly-asp(RGD)peptides,and by encapsulating mesenchymal stem cells(MSCs)and the carrier factor VEGF(angiogenic factor)/ SDF-1(stromal cell derived)Factors)to promote vascularization and tissue repair.By comparing the material properties of CS/?-GP/Ge and CS/?-GP/Ge-RGD temperature-sensitive hydrogels,it was found that the addition of RGD to the temperature-sensitive hydrogel did not change the gelation properties and viscoelasticity of the hydrogel.The CS/?-GP/Ge-RGD thermosensitive hydrogel still has excellent injectability and a gelatinization temperature of 30 °C.The results of SEM electron microscopy showed that the gel exhibited a porous network structure with a pore size of about 35 ?m,which was beneficial to the cells to maintain physiological functions.Infrared results show that the structure of the RGD peptide and gelatin is well maintained in the hydrogel.Chitosan/fucoidan nanoparticle loaded growth factor,can control the factor release.Mesenchymal stem cells(MSCs)were seeding on the surface of CS/?-GP/Ge-RGD thermosensitive hydrogel loaded with different loading factors,and it was found that MSCs maintained good cell proliferation activity and spread well.The MSCs were seeding into the hydrogel and subjected to fluid shearing force.It was found that MSCs differentiated into the endothelium,which provided a basis for further MSCs seeding in the CS/?-GP/Ge-RGD thermosensitive hydrogel for in situ treatment of vascularization.Successfully constructed a chicken embryo allantoic sac model(CAM),injected with factor-loaded nanoparticles CS/?-GP/Ge-RGD thermosensitive hydrogel and loaded with MSCs/loading factor nanoparticles CS/?-GP/Ge-RGD thermosensitive hydrogel It was found that loading MSCs in the hydrogel effectively promoted angiogenesis.The rat myocardial infarction model was successfully constructed.It was found that the carrier-loaded nanoparticle CS/?-GP/Ge-RGD thermosensitive hydrogel has a positive effect on the repair and regeneration of myocardial infarction tissue,and has significant effects on post-infarction ventricular remodeling and microangiogenesis.In vivo experiments provide evidence for the positive effects of MSCs loading on CS/?-GP/Ge-RGD thermosensitive hydrogels for vascular in situ treatment.In summary,RGD modified chitosan-based injectable nanocomposite thermosensitive hydrogel has the ability to promote angiogenesis after encapsulation of MSCs,and has potential application value in tissue engineering repair,organ tissue regeneration,and ischemic disease treatment.