Human vascular smooth muscle in culture. Growth and ultrastructure.

Mixed primary cultures of endothelial and smooth muscle cells were obtained from human umbilical cord vessels after prolonged collagenase digestion of their luminal surfaces. Morphologically homogeneous populations of vascular smooth muscle were then selectively isolated and subcultured for up to 16 weeks. Ultrastructurally, cultured cells were characterized by the presence of bundles of myofilaments with dense bodies similar to native umbilical vessel smooth muscle. Mature cultures developed a distinctive topographical organization consisting of bands of parallel cells and intertwined, multilayered areas. Elaborate intercellular attachments formed along contiguous cell surfaces. Large amounts of extracellular material accumulated, including amorphous substance, elastic fiber microfibrils, and 250- to 300-A,faintly-banded fibrils. In older cultures, focal proliferation, extracellular material secretion and cellular degeneration produced nodular protrusions somewhat resembling atherosclerotic lesions in vivo. Endothelium and smooth muscle cultured from this readily available human source may provide useful comparative material for pathophysiologic studies of vascular disease.