The aorta is the largest vascular conduit in humans, comprising three layers and a multitude of varying cell types collectively maintaining homeostasis and normal aortic wall function. Amongst these layers, the tunica adventitia is the external-most layer, where microvessels, termed vasa vasorum, can be found. These comprise pericytes and endothelial cells (ECs) and provide nourishment to the tunica adventitia and the outer media layers in the thoracic aorta. Adjacent to these microvessels, stem/progenitor group populations can be found, together forming a perivascular niche. Eventually, however, many of these cells and components can become dysregulated and contribute to development of thoracic aortic aneurysm (TAA). The purpose of this narrative review is to evaluate the recent literature related to marker gene expression in tunica adventitia pericytes, as well as the contribution of these populations to the development of aneurysm in the thoracic aorta. Pericytes in TAA generally exhibit phenotypic changes, which could be driven, in part, by loss of fibroblast growth factor (FGF) signaling. These changes eventually lead to vasa vasorum remodeling in the thoracic aorta, in turn contributing to the development of TAA.
Stougiannou et al. (Tue,) studied this question.