Stimulation of proliferation in stationary primary cultures of monkey aortic smooth muscle cells. Part 2. Effect of varying concentrations of hyperlipemic serum and low density lipoproteins of varying dietary fat origins.

The outgrowth of medial explants of thoracic aorta from Rhesus monkeys has used to study the influence of hyperlipemic serum on cell proliferation. After 5-6 weeks of rapid growth in BME plus 10% normal serum, the cultures reach a stationary phase during which they show little mitotic activity. When it replaces 5% of the normal serum in the media, hyperlipemic serum induces another proliferative phase in the cultures, as measured by [3H1thymidine incorporation and increase in culture area. Low density lipoprotein (LDL) has the greatest stimulatory effect, while high density lipoprotein (HDL) has no effect. Hyperlipemic serum or its LDL still stimulates the cells even when diluted to achieve cholesterol levels comparable to the values with normal serum or LDL. Normal LDL has no effect, even when concentrated to increase its cholesterol level in the media. Thus it appears that hyperlipemic LDL has a stimulatory effect on arterial smooth muscle cells which does not depend on its higher lipid or cholesterol level.