Antisense oligonucleotides to stromelysin mRNA inhibit injury-induced proliferation of arterial smooth muscle cells

Smooth muscle cell migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. To make this possible, the smooth muscle ce ll has to change from a contractile to an activated repair cell with capaci ty to synthesize DNA and extracellular matrix components. There is now cons iderable evidence that the extracellular matrix has important functions in modulating the phenotypic properties of smooth muscle cells, but less is kn own about the role of the matrix metalloproteinases. The present study inve stigates the role of stromelysin in the modulation of rat aortic smooth mus cle cell morphology and function following mechanical injury in vitro and i n vivo. Antisense mRNA oligonucleotides were used to investigate the role o f stromelysin expression in injury-induced phenotypic modulation and the su bsequent migration and proliferation of vascular smooth muscle cells. Cultu red rat aortic smooth muscle cells and balloon-injured rat carotid arteries were used as experimental models. Light- and electron microscopy were used to follow changes in smooth muscle cell phenotype and lesion formation and incorporation of H-3-thymidine to detect DNA synthesis. Injury-induced DNA synthesis and migration in vitro were inhibited by 72% and 36%, respective ly, by adding stromelysin antisense oligonucleotides to the medium prior to injury. In primary cultures, 67% of the smooth muscle cells treated with s tromelysin antisense were retained in a contractile phenotype as judged by analysis of cell fine structure, compared to 15% untreated cells and 40% in cells treated with mismatched oligonucleotides. Examination of the carotid arteries one week after balloon injury likewise demonstrated a larger frac tion of contractile cells in the inner parts of the media in vessels treate d with antisense oligonucleotides compared to those treated with mismatched oligonucleotides. The neointima was also distinctly thinner in antisense-t reated than in mismatched-treated and control arteries at this time. These findings indicate that stromelysin mRNA antisense oligonucleotides inhibite d phenotypic modulation of rat arterial smooth muscle cells and so caused a decrease in migration and proliferation and neointima formation in respons e to vessel wall injury.