Preparation Of Hyaluronic Acid Nanocomposite Hydrogel And Its Application In Cartilage Damage Repair

Cartilage damage and degradation resulting from violent sports and senility have become common issues in orthopedics clinics.There are no blood vessels and lymph in cartilage tissues,limiting the self-healing ability of cartilage after injury.However,many repairing methods of cartilage damage applied in clinics could not achieve long-term satisfactory outcomes.In recent years,cartilage tissue engineering(CTE)technology provides a promising method to repair cartilage damage.As the important component of cartilage tissue,hyaluronic acid(HA)is widely used to construct hydrogel scaffolds in CTE due to its excellent biocompatibility,biodegradability and easy modification.The traditional hyaluronic acid hydrogel scaffolds often exhibit poor mechanical peoperties thanks to the simple physical and chemical crosslinking,which makes them unable to meet the requirements of CTE.Therefore,the nanocomposite hydrogels were developed by incorporating multifunctional nanostructures into hydrated polymeric networks through physical or covalent crosslinking,which offers an effective method to improve the mechanical properties of hydrogel scaffolds.As a kind of sustainable biomass nanomaterials,cellulose nanofibrils(CNFs)are widely used as reinforcing fillers due to their outstanding mechanical properties,high surface activity,biodegradable,and large specific surface area.In this study,a CNFs enhanced HA-based nanocomposite hydrogel scaffold was engineered to provide a suitable biological and physical microenvironment for the proliferation and differentiation of stem cells with the aim of cartilage damage repairing.The main research works and the obtained results can be summarized as follows:Firstly,methacrylated HA and CNFs were synthesized by the esterification reaction between methacrylic anhydride and the hydroxyl groups of HA and CNFs.Then,a series of nanocomposite hydrogels composed of HA and CNFs were prepared by UV crosslinking in the presence of a photoinitiator.The microscopic morphology,rheological and mechanical properties of nanocomposite hydrogels were controlled by the UV irradiation time and the concentration of CNFs.The results demonstrated that the nanocomposite hydrogel(20s irradiation and 2%(w/v)methacrylated CNFs)had the most suitable pore size,high storage modulus(10633±584 Pa)and compressive modulus(0.46±0.05 MPa),which meets the requirements of CTE.Subsequently,the cyclic compression,stress relaxation,swelling,degradation and thermal stability properties of the CNFs/HA nanocomposite hydrogel were also studied.Secondly,the biological performance of nanocomposite hydrogel was further evaluated using bone marrow mesenchymal stem cells(BMSCs)in vitro.The proliferation and distribution of BMSCs in the nanocomposite hydrogel were evaluated through WST-1 assay and Live/Dead staining.The results demonstrated that the nanocomposite hydrogel scaffold could provide a suitable microenvironment for BMSCs survival and proliferation.The q RT-PCR was used to assess the m RNA expression levels of chondrogenic-related genes.The results proved that this nanocomposite hydrogel provided a well 3D microenvironment to support the chondrogenesis of BMSCs.In addition,the cartilaginous specific matrix gradually increased with the extending of culture time.Finally,in vivo model of cartilage repair was built in SD rat,the capability of BMSCs-laden nanocomposite hydrogel for CTE was evaluated.The regenerated cartilage tissue was examined by histological staining(H&E,Safranin-O,and Toluidine blue),macroscopic and histological scoring.The results demonstrated that BMSCs and transforming growth factor-β1(TGF-β1)co-laden nanocomposite hydrogel scaffold could promote the deposition of cartilage specific matrix and formation of hyaline cartilage,which cause further realize of the regeneration and repair of articular cartilage tissue.