Microvascular rarefaction: the decline and fall of blood vessels.

The goals of this presentation are two-fold: (1) to briefly sketch the field of vascular rarefaction as a key component of various fibrotic diseases and (2) to illustrate it with four vignettes depicting diverse mechanisms of microvascular rarefaction. Specifically, I shall describe migratory and angiogenic incompetence of endothelial cells under conditions of reduced bioavailability of nitric oxide, role of endothelial-to-mesenchymal cell and mesenchymal stem cell-to-endothelial reprogramming, and potential role of antiangiogenic peptides in the development of graft vascular disease as exemplified by chronic allograft nephropathy.