Abstract WMP35: Endothelialized 3D Cerebrovascular Modeling: A Novel in vitro Approach to Study Gene Expression in Realistic Vascular Geometry

Abstract

Aberrant flow conditions are implicated in aneurysmal growth or rupture. Current approaches that analyze the effects of flow stress on vascular cells are limited by their simplistic design, lacking patient-specific vascular anatomic features that contribute to disease. Computational fluid dynamics (CFD) is commonly used to characterize the biophysical properties of patient-specific anatomy but neglects the biologic interface between the blood stream and the endothelial surface. The purpose of this study is to develop a new research model for analyzing gene expression influenced by complex-flow stress on endothelial cells using a precision medicine approach that incorporates three-dimensional (3D) patient-specific vascular geometry. Hollow vessel models were created with silicone using 3D printing technology from image data obtained by routine MRA, CTA or rotational angiography obtained in normal clinical practice. The vessel models coated with fibronectin were rotated in 3D with endothelium in culture incubator for cell lining. CFD study was performed to characterize the flow dynamics with specific regions of the vessel models. Viscosity-adjusted culture media was perfused using perfusion conditions calculated by CFD in the circulation with the endothelialized vascular model. After perfusion, RNA was extracted from endothelial cells in the parent artery and the aneurysm and gene expression was examined using quantitative PCR (qPCR). In addition, the morphology of endothelial cells in specific regions of the model were observed with confocal microscopy. Endothelial cells in regions of low wall shear and oscillatory flow within the aneurysm were irregular in shape and size and associated with up-regulation of inflammatory genes compared with cells in the parent artery that exhibited typical spindle shape and aligned with the directionality of flow. This novel in vitro model enables a new research approach to bridge the gap of biophysical flow phenomonology and the biological impact of complex flow patterns on endothelial cells using patient-derived imaging data. Such models are likely to be useful to determine flow-driven biologic changes in vascular endothelium that contribute to aneurysmal growth and rupture.