Nondestructive and high‐resolution monitoring of inflammation‐type skull defects regeneration on adult zebrafish with optical coherence tomography

Optimized animal models and effective imaging techniques are exceedingly important to study cranial defects in bone loss due to chronic inflammation. In this study, the assessment procedure on a zebrafish inflammation‐type skull defects model was monitored in vivo with spectral‐domain optical coherence tomography (SD‐OCT), and the efficacy of etidronate disodium in bone regeneration was assessed. An acute skull defect injury model was established in adult zebrafish using a stereotaxic craniotomy device. SD‐OCT imaging was performed immediately following the mechanical injury. Both SD‐OCT and immunohistochemistry results demonstrated an increase in inflammation‐induced skull destruction within 5 days, which was confirmed by pathological experiments. In this study, the efficacy of etidronate in the repair of an inflammatory bone defect was tested in a zebrafish skull defect model, and the in vivo evaluation process was monitored using optical coherence tomography (OCT). Twenty‐four zebrafish were randomly divided into two groups and immersed in water and etidronate solution (25 μg/L) after the formation of skull defects. All zebrafish were examined by OCT immediately after craniotomy and on days 1, 2, 3, 5, 7, 11, and 15 of etidronate disodium treatment. All model fish were euthanized to allow histological evaluation of the skull after 15 days of recovery. OCT images showed that etidronate reduced inflammatory bone resorption within 0–5 days and repaired skull defects within 15 days. (25 μg/L) etidronate disodium may be beneficial to control the inflammatory bone resorption after bone injury and accelerate bone recovery.