Construction Of GelMA Macroporous Hydrogel Scaffolds Loaded With Mg Element And Its Application In Bone Tissue Engineering

Bone defect is a common clinical surgical disease.Due to the limited source of autologous bone and allogeneic bone,or the risk of immunity,the use of artificial synthetic materials as bone repair materials has become a clinical development trend.In recent years,hydrogels have attracted widespread attention because of their unique advantages such as high water content,similarity to natural extracellular matrix,and porosity.The macroporous hydrogel has typical structural advantages because the macroporous structure can promote the delivery of nutrients,the discharge of metabolites and the communication between cells,and can be used as excellent tissue engineering scaffold.Pickering emulsions obtained by using ultrafine solid particles as emulsifiers avoid the use of small molecular surfactants,and the emulsions are more stable and have better biocompatibility.Mg element is involved in physiological processes such as bone tissue formation,bone metabolism and bone mineral crystallization Incorporation of trace Mg elements in hydrogel materials can significantly improve the bone repair performance of the material and provide a new path for bone tissue regeneration and repair.First,the GelMA-co-PEG macroporous composite hydrogel loaded with MgO nanoparticles was designed via Pickering emulsion method.The emulsion type and the stability of the emulsion system were evaluated by measuring the water contact angle of MgO nanoparticles and observing the Pickering emulsion with optical microscope,and further to characterize the relationship between the droplet size and the concentration of MgO nanoparticles.The internal morphology,Mg element content,mechanical properties and Mg2+release of the GelMA-co-PEG macroporous composite hydrogel were characterized by field emission scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),dynamic thermomechanical analysis(DMA)and inductively coupled plasma atomic emission spectroscopy(ICP-AES)Then,the hydrogel scaffolds were co-cultured with mouse bone marrow stromal cells(mBMSCs).The results showed that the presence of the macroporous structure of the hydrogel scaffold can promote cell adhesion,spreading,migration and proliferation,while the release of Mg2+ can significantly promote the osteogenic differentiation of stem cellsMoreover,the GelMA-co-PEG macroporous composite hydrogel scaffolds loaded with Mg element were implanted into the SD rat calvarial bone defect model.The results show that the scaffold has the ability to promote host cells to home to the bone defect,as well as improve bone growth and bone conductivity.The scaffold recruits host cells to migrate to the defect site and the inside of the scaffold to provide excellent microenvironment for cells,and further improve the effect of bone repair by continuously delivering Mg2+.In summary,the construction of the GelMA-co-PEG macroporous composite hydrogel scaffold loaded with Mg element can regulate cell migration,proliferation and osteogenic differentiation.And it can be used as multifunctional artificial bone substitute with excellent performance.