| Background and ObjectiveTraumatic skull fracture is an acute disease in which the structure of the skull is changed and fractured by external force.In recent years,with the continuous development of construction industry and transportation industry,accidents occur frequently,and the clinical incidence of traumatic skull fractures is increasing.After clinical surgery,inflammation often leads to bone resorption,so the study of bone inflammatory defect regeneration has become a hot topic.Many animal models have been widely used in the study of inflammation in skull defects,including a new biological model,zebrafish.Zebrafish has the advantages of small size,in vitro fertilization development,short development cycle,and high gene homology with human.Phycocyanin,a pigment-protein complex with antioxidant and antiinflammatory properties,inhibits osteoclasts during bone defect recovery by blocking the degradation of cytoplasmic nuclear factor inhibitor proteins.Etidronate disodium is a bisphosphonate compound that reduces bone resorption and prevents bone loss by inhibiting osteoclast activity.At present,the evaluation methods of skull bone defect regeneration based on zebrafish are still mainly based on pathology,so that the progress of related research is slow.Therefore,optimizing animal models and efficient imaging techniques are very important for the study of skull defects with inflammation that may lead to bone loss.Optical coherence tomography(OCT)is an optical imaging technology that uses the principle of low coherence interference to perform highresolution tomographic imaging of biological tissues,with large imaging depth and lossless imaging ability.It is expected to solve the problem of lack of in vivo evaluation tools in zebrafish bone-related research.This article aims to investigate the feasibility of OCT in phycocyanin promoting the regeneration of zebrafish calvaria defects and validate the potential of OCT in evaluating etidronate disodium inhibiting bone inflammatory resorption.Research MethodsAn acute skull defect injury was constructed in adult zebrafish using a stereotaxic crani otomy device.OCT imaging was performed immediately after mechanical injury.In this study,OCT was used to monitor the evaluation procedure of the zebrafish inflammatory skull defect model,including the following two parts:(1)To verify whether the zebrafish inflammatory bone defect model was successfully established by in vivo characterization of phycocyanin promoting the regeneration of zebrafish skull defects,and pathological experimental techniques and professional image processing software were used for processing and analysis.(2)To characterize the zebrafish inflammatory skull defect model in vivo by OCT,to evaluate the efficacy of etidronate disodium in bone regeneration,and to verify the feasibility of OCT in evaluating the adult zebrafish inflammatory skull defect model by immunohistochemistry.Results(1)According to the OCT and histological images,the skull defects of zebrafish immersed in 100 mg/L phycocyanin solution could be recovered after 10 days.At 20 days,there was marked bone hyperplasia at the bone defect joint,and the skull defect was apparently completely closed,but there was some dislocation between the nascent skulls,and there was an enlarged knot at the skull defect joint.(2)On the 5th day,the expression level of pro-inflammatory cytokine TNF-α was decreased in zebrafish treated with etidronate disodium.After treatment with etidronate disodium on day 5,the inflammatory response in the skull defect area was reduced.Both OCT imaging results and immunohistochemical results showed that the inflammatory destruction of the skull increased within 5 days,which was confirmed by pathological experimental results.ConclusionIn this study,a zebrafish inflammatory bone defect model was successfully established.The process of phycocyanin-promoted regeneration of the skull defect and inflammatory destruction of the skull defect in adult zebrafish were visualized in vivo using OCT. |
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