Electron microscopic observations on the formation of elastic fibers in primary cultures of aortic smooth muscle cells

Abstract

Smooth muscle cells were enzymatically isolated from the tunica media of the aorta of 5-day-old rats and grown in culture for 4–28 days. A confluent monolayer was rapidly formed and the cells later grew in multiple overlapping layers. Throughout the period of observation the cells maintained the structure of vascular smooth muscle with numerous myofilaments and a well-developed granular endoplasmic reticulum and Golgi complex. An intercellular matrix with plenty of elastic fibers accumulated already within 1 week of culture. Three partly overlapping stages could be distinguished in the extracellular elastogenesis. First, small bundles of microfibrils appeared. These bundles then became associated with small conglomerates of a dense amorphous material. Finally, in the mature elastic fibers such material had fused into confluent amorphous areas within which no microfibrils were detected. This culture system with early and efficient production of extracellular matrix components may be a useful model for studies on aortic smooth muscle cells under various experimental conditions.