Injectable,Self-healing And Antibacterial Hydrogel Loaded With Adhesive Liposomes For Osteogenesis

Objective:To construct injectable,self-healing and antibacterial hydrogel(A-LIP-PEG)mixed with adhesive liposomes(A-LIP)which loaded with bone morphogenetic protein 2(BMP-2)for osteogenesis.Methods:The A-LIP loaded with BMP-2 was prepared by thin film dispersion method,and the composite hydrogel was prepared by blending A-LIP with 4SH-PEG and crosslinking with Ag+.A-LIP and A-LIP-PEG were characterized by dynamic light scattering particle size dispersion(DLS),transmission electron microscope(TEM),scanning electron microscope(SEM),fourier transform infrared spectroscopy(FTIR)and inverted fluorescence microscope.The release of BMP-2 in vitro was investigated by full-wavelength enzyme labeling instrument and BMP-2 protein kit.The adhesion ability of A-LIP and A-LIP isolated from hydrogel to rat bone marrow mesenchymal stem cell(BMSCs)was investigated by viscous experiment.The inhibitory effect of the composite hydrogel on Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)was evaluated by bacteriostatic zone method,plate colony count method and bacterial living/dead staining.The retention ability of A-LIP isolated from A-LIP-PEG in the abdominal cavity of C57BL mice was evaluated by in vivo fluorescence imaging system.The effects of composite hydrogel on the proliferation and differentiation of BMSCs were studied by CCK-8 method,alkaline phosphatase staining(ALP),calcium nodule staining and polymerase chain reaction(PCR).The osteogenic ability of the composite hydrogel in vivo was evaluated by rat osteoporotic fracture model.The osteogenic ability of the composite hydrogel was studied by Micro-CT,H&E staining,Safranin O Fast Green staining and MASSON staining.Results:A-LIP released from A-LIP-PEG had obvious adhesion to BMSCs and the abdominal cavity of C57BL mice.The inhibition rates of composite hydrogels on S.aureus and E.coli were 89.7±2.3%and 96.2 ±1.4%,respectively.The composite hydrogel has excellent injectable and self-healing properties.Co-cultured with BMSCs,the cells grew well,and the expression of ALP and the content of calcium nodules in the composite hydrogel group were significantly higher than those in the control group.In the PCR test,OPN,OSX and COL-1 in the A-LIP-PEG group were significantly higher than those in the control group.In the model of osteoporotic fracture,BV/TV of the A-LIP-PEG group was much higher than that of the control groupConclusion:the composite hydrogel can be directly injected into the osteoporotic fracture site and adjacent to the bone marrow cavity,locally release A-LIP,improve the retention of BMP-2 in the fracture site,and show a good osteogenic effect.Therefore,the composite hydrogel drug loading system provides a new method for the treatment of bone cavity injury and disease.