| Background:The complex microenvironment changes after spinal cord injury limit the ability of endogenous repair and regeneration.Although implanting tissue engineering materials has made some progress in treating spinal cord injury,the ischemia and hypoxia of the local injury site restrict cell survival and seriously affect the transplantation and repair effects of tissue engineering materials.Therefore,scholars have focused their attention on improving local hypoxia,reducing local secondary tissue damage,and promoting nerve repair.Objective:This study developed a new type of compsite oxygen-releasing scaffold based on previous studies.The new composite is constructed to determine its oxygen-releasing characteristics and its effect on cell survival and proliferation and implant it into the injured spinal cord of rats to explore its effect on repairing the spinal cord function.The results provide an experimental basis for the development and clinical transformation of new oxygen-releasing scaffold.Method:1.Construction of a new type of composite oxygen-releasing scaffold:First,the emulsification method was used to construct sustained-release microspheres using CPO and PLGA as raw materials.Subsequently,self-assembled peptide hydrogel was built,and then the oxygen-releasing microspheres were mixed into the hydrogel evenly,according to the ratio.Thus,a new type of composite oxygen-releasing scaffold was developed.The microscopic morphology of the scaffold was observed using a scanning electron microscope,and its oxygen release curve was detemined.2.The effect of oxygen-releasing scaffolds on the survival and proliferation of stem cells(in vitro experiments):Culture oxygen-releasing scaffolds containing GFP-MSCs in a 1%low oxygen incubator to observe the survival of cells;CCK method measures cell viability and proliferation.3.The effect of oxygen-releasing scaffolds on the repair of spinal cord injury in rats(in vivo experiment):First,establish a rat acute spinal cord injury model,implant oxygen-releasing scaffolds in the defect(scaffold group),and perform rats 2 to 12 weeks after surgery,and motor function BBB scores and samples were obtained for histological and immunological testing.Result:1.The diameter of the oxygen-releasing microspheres was approximately 275-600?m,with an average diameter of 329.5 ± 35.2?m Under a light microscope,they were round,opaque,and light yellow.The microspheres were spherical and porous under a scanning electron microscope.CPO can be observed through microdissection.Evenly distributed PLGA scanning electron microscopy revealed that microspheres of different sizes were distributed in the peptide hydrogel to form a composite oxygen-releasing scaffold.2.The new oxygen-releasing scaffold releases oxygen continuously and stably for more than 3 weeks,reaching a plateau after approximately 12 days.3.Under hypoxic culture,it can be seen that GFP-MSCs adhered and distributed on all layers of the scaffold and grew well.On day 7,14,and 21,the cell proliferation activity of the scaffold group was significantly better than that of the hypoxic hydrogel group and hypoxic cell group(P<0.05).4.Twelve weeks after the scaffold was implanted in the spinal cord injury area,the rat's BBB score reached 11.8±1.26,which was better than the SCI group and the hydrogel group(P<0.05).HE staining of the scaffold group showed significant cystic cavity shrinkage.Furthermore,immunofluorescence staining showed that NF increased and GFAP decreased in the scaffold group,and vWF staining showed that microvessels in the scaffold group grew well,which were better than the other two groups(P<0.01).Conclusion:1.The new composite oxygen-releasing scaffold exhibited good oxygen-releasing performance,and the oxygen-releasing time exceeded 3 weeks,which satisfied the requirements of cell proliferation and survival under hypoxia.2.The new composite oxygen-releasing scaffold can relieve local tissue hypoxia and promote the regeneration of nerve fibers and capillaries,thereby improving the motor function of the hind limbs of rats after spinal cord injury. |
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