Effects of polycyclic aromatic hydrocarbons on proliferation, collagen secretion and viability of arterial smooth muscle cells in culture

Abstract

Previous reports have suggested a role for polycyclic aromatic hydrocarbons in the pathogenesis of atherosclerosis. Therefore, the effects of benzpyren (BP) and dimethylbenzanthracene (DMBA) on the arterial smooth muscle cell (SMC) in culture were studied. DMBA increased the proliferation of bovine and rabbit SMC but not of human embryonal fibroblasts or human SMC. BP did not significantly influence the cell number of bovine SMC. The secretion of newly synthesized collagen was always decreased when SMC were exposed to BP or DMBA. When BP or DMBA were added to SMC in plasma with high lipid levels compared to low levels, a decrease in total cellular DNA was seen together with a relatively higher collagen secretion. The same effects were noted when SMC had been preincubated with platelet factors compared to serum free medium, i.e. diminished cellular DNA and increased collagen secretion after BP or DMBA exposure. Cell death, measured as release of prelabelled 3H-thymidine from cell layers, was increased after exposure to BP 10 micrograms/ml while DMBA 0.05-0.1 microgram/ml led to a significantly lesser cell death compared to controls in serum free media. It was also shown that SMC exposed to DMBA might release mitogenic factors to conditioned media. It is concluded that, depending on the mode of administration, the polycyclic aromatic hydrocarbons BP and DMBA may induce different effects on arterial SMC in vitro as increased or decreased toxicity and collagen secretion, and increased proliferation and that these effects might be of importance in the pathogenesis of atherosclerosis