Study On Cartilage Repair Drug-loading System With Gradient Pores

Cartilage is a connective tissue without blood vessels,nerves or lymphatic vessels,and this relatively closed environment causes it to lack the ability to repair itself.If cartilage defects occur due to trauma or chronic diseases,it is difficult for cartilage tissue to complete self-repair.At present,the main clinical treatment methods for cartilage defects are microfracture,autologous cartilage transplantation,autologous chondrocyte transplantation,etc.,but these methods lack the guiding ability of chondrocytes to varying degrees,making it difficult for the repaired cartilage tissue to recover original structure and function.In this study,we designed and fabricated a dual drug-loaded cartilage repair system with gradient pores.The system consists of two parts.Silk fibroin(SF)and polylactic acid(PLA)are selected as materials to prepare the fiber layer,and Kartogenin(KGN)is loaded for coaxial spinning to achieve sustained release.At the same time,the natural gelatin(Gel)was methacrylated,and the methacrylated gelatin(Gel MA)formed by cross-linking was used as the gel layer,and the sodium aescinate(SA)was loaded by electrostatic adsorption.The specific research contents are as follows:1.Coaxial fiber membranes were prepared from SF and PLA by coaxial electrospinning,and the coaxial spinning conditions were screened by the stability of the spinning process.The morphology,diameter distribution,porosity,hydrophilic properties,tensile properties and degradation properties of SF/PLA coaxial fiber membranes were characterized.The results show that the SF/PLA coaxial fiber membrane combines the advantages of the two materials and can be used as a component material for cartilage repair systems.2.Gel was acylated using methacrylic anhydride(MA),and orthogonal experiments were designed to screen the acylation conditions.The effects of different mass fractions of Gel MA on the morphology,pore size distribution,porosity,swelling properties,mechanical properties and degradation properties of hydrogels were investigated.According to the experimental results,10.0 wt% Gel MA was selected as the constituent material of the cartilage repair system.3.The drug-loaded double-layer cartilage repair system was prepared by two materials,SF/PLA coaxial fiber and Gel MA hydrogel,and the physicochemical properties were characterized.The release behavior of the two drugs in the cartilage repair system was characterized.The results show that the cartilage repair system meets the requirements of cartilage defect implants,and the loaded two drugs can be released at different release rates.4.The cells were co-cultured with the material extracts of each part of the cartilage repair system,the cytotoxicity of the materials was evaluated,and the cell growth was observed by staining.The results showed that the materials in each group had no cytotoxicity to cells,and the cells grew well.After the annulus fibrosus cells were seeded on the double drug-loaded cartilage repair system for 5 days,the growth state of the cells in the cartilage repair system was observed by various methods.The results showed that the cartilage repair system provided sufficient space for cell growth and effectively promoted the formation of cartilage tissue.In conclusion,this study prepared and characterized a drug-loaded cartilage repair system with gradient pores,in which the structure of gradient pores can effectively induce chondrocytes to rebuild a hierarchical structure like that of native cartilage tissue.And for different stages of cartilage repair,control the release rate of the two drugs,in the early and middle and late stages of repair,respectively,to inhibit the inflammatory response at the cartilage defect and promote the differentiation of stem cells into chondrocytes.Cartilage defect repair has a good promotion effect.