Embryonic endothelial cells transdifferentiate into mesenchymal cells expressing smooth muscle actins in vivo and in vitro

MC DeRuiter, RE Poelmann, JC VanMunsteren… - Circulation …, 1997 - Am Heart Assoc
MC DeRuiter, RE Poelmann, JC VanMunsteren, V Mironov, RR Markwald…
Circulation research, 1997Am Heart Assoc
All blood vessels are lined by endothelium and, except for the capillaries, surrounded by
one or more layers of smooth muscle cells. The origin of the embryonic vascular smooth
muscle cell has until now been described from neural crest and locally differentiating
mesenchyme. In this study, we have substantial evidence that quail embryonic endothelial
cells are competent in the dorsal aorta of the embryo to transdifferentiate into subendothelial
mesenchymal cells expressing smooth muscle actins in vivo. At the onset of smooth muscle …
Abstract
All blood vessels are lined by endothelium and, except for the capillaries, surrounded by one or more layers of smooth muscle cells. The origin of the embryonic vascular smooth muscle cell has until now been described from neural crest and locally differentiating mesenchyme. In this study, we have substantial evidence that quail embryonic endothelial cells are competent in the dorsal aorta of the embryo to transdifferentiate into subendothelial mesenchymal cells expressing smooth muscle actins in vivo. At the onset of smooth muscle cell differentiation, QH1-positive endothelial cells were experimentally labeled with a wheat germ agglutinin–colloidal gold marker (WGA-Au). No labeled subendothelial cells were observed at this time. However, 19 hours after the endothelial cells had endocytosed, the WGA-Au–labeled subendothelial mesenchymal cells were observed in the aortic wall. Similarly, during the same time period, subendothelial cells that coexpressed the QH1 endothelial marker and a mesenchymal marker, α-smooth muscle actin, were present. In such cells, QH1 expression was reduced to a cell membrane localization. A similar antigen switch was also observed during endocardial-mesenchymal transformation in vitro. Our results are the first direct in vivo evidence that embryonic endothelial cells may transdifferentiate into candidate vascular smooth muscle cells. These data arouse new interpretations of the origin and differentiation of the cells of the vascular wall in normal and diseased vessels.
Am Heart Assoc