Proteoglycan synthesis by the neointimal smooth muscle cells cultured from rabbit aortic explants following de-endothelialization.

Proteoglycans (PGs), the essential component of the extracellular matrix, are implicated in the pathogenesis of atherosclerosis. In an experimental model of injury, PGs accumulate in the neointimal tissue parallel with lipid deposition. However, it is still not clear whether the PG accumulation is from active smooth muscle cell (SMC) production or is a consequence of trapping within neointima covered by endothelium. To study the effect of endothelial injury on PG synthesis, SMCs were cultured from normal aorta (N-SMC), neointima covered by regenerated endothelium (W-SMC) and neointima without endothelium (B-SMC). Using [35S]-Na2SO4, as a precursor in an in vitro incubation, the kinetics of PG synthesis were determined. PG synthesis by all three cell types increases as a function of time. It is significantly higher in the SMCs cultured from endothelium-denuded aortic explants (W- and B-SMC) than N-SMC. This finding indicates that endothelial injury stimulates PG synthesis by SMCs.