Development of a novel in vitro model to study the tryptic : endothelial cells, monocytes and flow

Abstract

This thesis describes the development of a novel in vitro model of monocytes transmigration under flow and use in the study of early molecular events of atherogenesis. In this work, we focused on how endothelial dysfunction, specifically mediated by disturbed flow from atherosusceptible regions of the vasculature, is both communicated to recruited monocytes as they reside in the subendothelial matrix, and how reciprocally, monocytes may exacerbate the endothelial dysfunctional state. We built and integrated our in vitro model to a unique flow apparatus that can precisely replicate atheroprone and atheroprotective shear stress waveforms. We carefully characterized the model that relies on a fibronectin-coated collagenous matrix seeded with a confluent monolayer of endothelial cells co-cultured with THP- 1 monocytes under flow. We used the model to draw biological insight from endothelial:monocyte co-cultures under flow. We found that monocytes preferentially accumulate on endothelial monolayers exposed to atheroprone flow. We also observed the upregulation of IL-1[beta] in endothelial cells exposed to atheroprone flow when co-cultured with monocytes but not in endothelial cells alone, in each of three independent experiments; yet the aggregated results are not statistically relevant due to variability. Flow-driven dysfunctional endothelium recruits and interacts with monocytes that soon after transmigration become dysfunctional foam cells. Our novel in vitro model that congregates endothelial cells, monocytes and flow responds to the pressing need to understand the interplay between these protagonist cells during atherogenesis, and allowed us to define further monocyte- and flow-mediated transition of endothelium from normal to dysfunctional to diseased states. Harnessing the power of a versatile platform of transmigration under flow may foster the discovery of novel targets for atherogenesis and the development of original therapeutic strategies.