Biochemomechanics of the thoracic aorta in health and disease

Aneurysms and dissections of the thoracic aorta are life threatening events with poorly understood pathophysiologies which may have genetic origins. By starting with an introduction to these pathologies, we focus on the biochemomechanics of the healthy thoracic aorta. Specifically, we describe the microstructure and the mechanics of the aortic tissue since it is known that the microstructure strongly influences the biomechanical behavior. This relationship is then complemented by providing more detailed information on the selected extracellular matrix components (collagen, elastic fibers and proteoglycans) and smooth muscle cells. More specifically, we introduce the roles smooth muscle cells play in the function of the aortic wall: actively (mechanically) with their contractile abilities and passively by regulating the composition of the extracellular matrix they are embedded in, in particular via the transforming growth factor β (TGF-β) pathway. Subsequently, we summarize the microstructural changes in thoracic aortic aneurysms and dissections in connection with selected risk factors and genetic mutations, and couple these changes with the findings on the biomechanical behavior of the pathological tissues. Finally, we provide a summary and concluding remarks.