Improvement And Biological Application Of Chitosan Based Injectable Nano-composite Hydrogel

In recent years,tissue engineering has shown more and more potential in tissue and organ defect repair,and the research based on three-dimensional scaffolds has become a hot topic for researchers.Traditional scaffold materials can cause large trauma and secondary infection in the process of repair.Injectable hydrogels emerge as the times require,which makes it possible to solve these problems.However,the effects of these synthetic materials on angiogenesis and tissue repair ability in tissue rerepair are not well studied.Based on the above,the chitosan based injectable nanocomposite hydrogel was used as the target material.However,cell adhesion and proliferation can not be well spread and proliferated in the gel.As a common peptide sequence that stimulates cell adhesion,RGD can provide adhesion sites for cells,so the modified nano-composite hydrogel can be obtained by adding RGD to the gel.The growth of endothelial cells(ECs)and mesenchymal stem cells(MSCs)were studied.At the same time,the vascularization of nano-composite hydrogels and the promotion of tissue repair were studied by using animal models.EC were inoculated on the surface of chitosan based nano-hydrogel.The effect of proliferation of EC was studied and the results of AO staining showed that the morphology of the cells in the gel was spherical and the results of cck-8 showed that the cells could proliferate in nano-hydrogel.At the same time,the migration of EC in nano-hydrogel was studied.The results showed that nano-hydrogel could promote the migration of EC.The cell growth in modified hydrogel was studied by adding different concentration of RGD into the chitosan based hydrogel.The results of AO staining showed that the cell spread when RGD concentration was 2000ug/ml and the results of cck-8 showed that the addition of RGD could promote the proliferation of the cells compared with the blank hydrogel.Therefore,the concentration of RGD used in EC was set to 2000 ugml.Effects of chitosan based Nano-Hydrogel on Endothelial Cell growth after adding 2000ug/ml RGD was studyed,the results showed that EC could be widely spread in RGD modified nanocomposite hydrogels and cocultured with smooth muscle cell(SMCs)to form tubular structures.Further study on the effect of MSC on the growth in chitosan based hydrogel modified with different concentrations of RGD,the result of stain with phalloidin showed that the MSC spreading at the RGD concentration is 1000ug/ml,and cck-8 results show that RGD can promote the proliferation of MSC.When MSC were inoculated into chitosan based hydrogel modified by 1000ug/ml RGD,the results showed that MSC could be widely spread in hydrogel and cocultured with smooth muscle cells can form tubular structure.The chick chorioallantoic membrane(CAM)model was successfully constructed and stained with HE.The results showed that the nano-hydrogel material could promote the migration of cells and the formation of blood vessels in tissues.CD68 Ly6 g and Collagen I immunohistochemical staining were performed on rat skin test.The results showed that the inflammatory reaction of the tissue to hydrogel was relatively small and collagenization appeared in the nano-hydrogel.Further,the myocardial infarction model of rats was established.The results of ultrasound showed that the cardiac function of nano-hydrogel group recovered well,the results of HE and Masson staining showed that nano-hydrogel could promote myocardial infarction repair,and the results of KI67 showed that the cardiomyocytes had proliferative activity in nano hydrogel group.In conclusion,the modified chitosan based nano-hydrogel has good biological properties and the properties of promote cell spread and cell proliferation,and it has the function of promoting angiogenesis and tissue repair.This experiment provides a theoretical basis for the application of chitosan-based nanocomposite hydrogels in the future.