25Aims. Assessment of preclinical models of vascular disease are paramount in the successful 26 translation of novel treatments. The results of these models have traditionally relied on 2-D 27 histological methodologies. Light sheet fluorescence microscopy (LSFM) is an imaging platform 28 that allows for 3-D visualization of whole organs and tissues. In this study, we describe an 29 improved methodological approach utilizing LSFM for imaging of preclinical vascular injury 30 models while minimizing analysis bias. 31Methods and Results. The rat carotid artery segmental pressure-controlled balloon injury and 32 mouse carotid artery ligation injury were performed. Arteries were harvested and processed for 33 LSFM imaging and 3-D analysis, as well as for 2-D area histological analysis. Artery processing 34 for LSFM imaging did not induce vessel shrinkage or expansion, and was reversible by 35 rehydrating the artery, allowing for subsequent sectioning and histological staining a posteriori. 36By generating a volumetric visualization along the length of the arteries, LSFM imaging provided 37 different analysis modalities including volumetric, area, and radial parameters. Thus, LSFM-38 imaged arteries provided more precise measurements compared to classic histological analysis. 39Furthermore, LSFM provided additional information as compared to 2-D analysis in demonstrating 40 remodeling of the arterial media in regions of hyperplasia and periadventitial neovascularization 41 around the ligated mouse artery. 42
Conclusions. LSFM provides a novel and robust 3-D imaging platform for visualizing and 43quantifying arterial injury in preclinical models. When compared with classic histology, LSFM 44 outperformed traditional methods in precision and quantitative capabilities. LSFM allows for more 45 comprehensive quantitation as compared to traditional histological methodologies, while 46 minimizing user bias associated with area analysis of alternating, 2-D histological artery cross-47
Translational Perspective 49A more reproducible and robust quantitation of vascular pathology in preclinical models is 50 necessary to accelerate translational discovery. Current methodology to assess vascular disease 51 has significant limitations. The methodology described herein employs a modern imaging 52 modality, light sheet fluorescence microscopy (LSFM), to improve assessment of established 53 preclinical vascular injury models. LSFM provides more comprehensive and precise analysis 54 capabilities than classical histological approaches. Hence, LSFM applied to vascular research 55 has the potential to drive new basic discoveries, and ultimately translation of novel therapies. 56 4
I. Introduction 57Cardiovascular disease (CVD) is the leading cause of death and disability in the world 1, 2 . 58Atherosclerosis is the major underlying cause of most CVD. Severe, symptomatic atherosclerosis 59 is treated by percutaneous or surgical revascularization, and the long-term success of both 60 approaches is limited by arterial restenosis 3 . Despite ...