Adventitia and perivascular cells.

Abstract

The past few years have seen significant advances in our understanding of the multiple and dynamic roles of the adventitia and its companion perivascular tissues for vessel wall homeostasis and disease. It is now becoming clear that signals originating from within the adventitia and from perivascular cells play essential roles in regulation of vascular development, physiology, artery wall remodeling, immune surveillance, and vascular disease.1–4 The adventitia is in contact with and completely surrounds the media and is the interface between the vessel wall and its neighboring tissues. It contains many different interacting cell types including fibroblasts, microvascular endothelium, nerves, resident macrophages, T cells, B cells, mast cells, and dendritic cells.5–9 The adventitia is also home to resident vascular progenitor cells whose formation and maintenance depend, in part, on sonic hedgehog signaling.1,10–12 Perivascular cells are in close contact with the adventitia, particularly for the aorta and coronary arteries. Perivascular tissue includes adipocytes, lymphatic vessels, perivascular nerves, and stromal cells exhibiting mesenchymal stem cell–like properties.3,13 The adventitia and periadventitial cells function in concert. They are linked by microvessels, nerves, and migratory cells to regulate vascular physiology, homeostasis, structural remodeling, and exert major influences on the progression or regression of vascular disease. Crosstalk between intima, media, and adventitia further links the adventitia-periadventitial unit to the rest of the vessel wall. Much of the work advancing our concepts of the adventitia and periadventitial tissues has been published in ATVB , and some of those key studies are discussed in this highlights article. In the following summary, areas that have attracted the most interest over the past 2 years in ATVB are reviewed including the multiple roles of perivascular adipose tissue (PVAT) on control of vascular physiology and remodeling, adventitial progenitor …