Review of the Essential Roles of SMCs in ATAA Biomechanics

TL;DR

This review emphasizes the critical biomechanical role of smooth muscle cells (SMCs) in the development of ascending thoracic aortic aneurysms (ATAA), highlighting their regulation of stress distribution and homeostasis in arterial walls.

Contribution

It synthesizes current knowledge on SMCs' biomechanical functions and demonstrates their importance in ATAA progression through layer-specific multiscale modeling.

Findings

SMCs actively regulate stress distribution in the aortic wall.

SMC homeostatic tension is key to predicting ATAA initiation.

Mechanosensing in SMCs responds to tension imbalances.

Abstract

Aortic Aneurysms are among the most critical cardiovascular diseases. The present study is focused on Ascending Thoracic Aortic Aneurysms (ATAA). The main causes of ATAA are commonly cardiac malformations like bicuspid aor-tic valve or genetic mutations. Research studies dedicated to ATAA tend more and more to invoke multifactorial eects. In the current review, we show that all these eects converge towards a single paradigm relying upon the crucial biome-chanical role played by smooth muscle cells (SMCs) in controlling the distribution of mechanical stresses across the aortic wall. The chapter is organized as follows. In section 6.2, we introduce the basics of arterial wall biomechanics and how the stresses are distributed across its dierent layers and among the main structural constituents: collagen, elastin, and SMCs. In section 6.3, we introduce the biome-chanical active role of SMCs and its main regulators. We show how SMCs actively regulate the distribution of stresses across the aortic wall and among the main structural constituents. In section 6.4, we review studies showing that SMCs tend to have a preferred homeostatic tension. We show that mechanosensing can be understood as a reaction to homeostasis unbalance of SMC tension. Through the use of layer-specic multiscale modeling of the arterial wall, it is revealed that the quantication of SMC homeostatic tension is crucial to predict numerically the initiation and development of ATAA.