The role of vascular smooth muscle cell plasticity in arterial remodelling and biomechanical failure

Abstract

Vascular smooth muscle cell (VSMC) plasticity is implicated in extracellular matrix (ECM) turnover and arterial failure. The osteochondrocytic phenotypes of synthetic VSMCs are thought to drive glycosaminoglycan (GAG) accumulation and swelling typically seen in connective tissue disease and hypertension. A central question is whether this phenotype switching under non-homeostatic conditions is a cause or effect of those conditions. We implement a cause–effect association between ECM damage, lost cell mechanosensitivity, and cell phenotype modulation using the Constrained Mixture Model, to simulate the evolution of VSMC population over time. We modelled a cylindrical bi-layer of media and adventitia of a mouse common carotid artery and simulated remodelling in response to initially compromised ECM, concurrent with varying degrees of hypertension. In normo- and moderately hypertensive ECM disruption, physiological remodelling restores mechanical homeostasis to cells with slightly altered mechanical properties. Alternatively, severe hypertension yields complete medial degeneration. Complete loss of stored elastic energy is observed, with stiffened arteries yielding characteristically high pulse wave velocities (PWVs). Early intervention recovering hypertensive to normotensive pressure, as well as enhanced adventitial collagen turnover, are shown to prevent medial degeneration. Our model thus offers a tool to better understand the relationship between ECM damage, arterial failure, and hypertension.