Optical coherence tomography angiography allows longitudinal monitoring of angiogenesis in the critical-sized defect model

Purpose: This study aims to evaluate the capability of optical coherence tomography angiography (OCTA) for imaging the microvasculature within a critical bone defect, to longitudinally observe vascular alterations, and quantify the microvascular density and morphology in a model of a critical-sized defect.Methods: An OCTA system was used to longitudinally monitor angiogenesis in four rat models presenting critical-sized defects with observations recorded on days 7, 14, and 28 post-defect creation. Simultaneously, angiogenesis in three additional rat models was evaluated through a conventional histological analysis involving hematoxylin and eosin staining.Results: OCTA was successful in acquiring in vivo 3D vascular perfusion mapping within the critical-sized defect, and it allowed for quantitative analysis of the microvasculature's density and morphology. The OCTA imagery of the blood microvasculature revealed a noticeable augmentation in the number and size of vessels, with more extensive vessel convergence observed on day 14 compared to both days 7 and 28. Complementing these observations, quantitative analysis demonstrated that the vessel area density (VAD) and maximum vascular diameter index (MVDI) were significantly larger on day 14 in comparison to measurements taken on days 7 and 28.Conclusion: Leveraging its ability to capture high-resolution images, OCTA facilitated longitudinal monitoring of angiogenesis in models of critical-sized defects. Therefore, it potentially serves as a non-invasive experimental tool beneficial for bone regeneration research.