L-NAME promotes foam cell formation and synthetic phenotype marker changes in vascular smooth muscle cells independent of hemodynamic effects

This study investigated whether L-NAME, a nitric oxide synthase (NOS) inhibitor commonly used to model hypertension-associated endothelial dysfunction, can exert direct pro-atherogenic effects on vascular smooth muscle cells (VSMCs) independent of systemic hemodynamic influences. Mouse aortic VSMCs (MOVAS) were treated with non-cytotoxic concentrations of L-NAME (50 µM) or oxidized low-density lipoprotein (ox-LDL, 100 µg/mL), which served as a positive atherogenic control. Lipid accumulation was assessed by Oil Red O staining. The expression of contractile phenotype markers (ACTA2, MYH11, and α-SMA), the synthetic phenotype marker SPP1, and matrix metalloproteinases (MMP-2 and MMP-9) was quantified by qRT-PCR and immunofluorescence. Both L-NAME and ox-LDL treatments caused marked intracellular lipid accumulation in MOVAS cells, consistent with VSMC-derived foam cell formation. L-NAME and ox-LDL reduced the mRNA expression of contractile phenotype markers (ACTA2 and MYH11, p < 0.05) and decreased α-SMA protein expression ( p < 0.001). Conversely, both treatments increased the mRNA expression of the synthetic phenotype marker SPP1 ( p < 0.05) and matrix-remodeling genes MMP-2 and MMP-9 ( p < 0.05). These effects were directionally similar to those induced by ox-LDL. L-NAME directly promotes lipid accumulation and synthetic phenotype-associated marker changes in MOVAS cells under the present in vitro conditions. Because eNOS/NOS activity, intracellular NO levels, rescue pathways, and primary VSMC validation were not assessed, these data should be interpreted as phenotypic evidence that NOS/NO pathway disruption may contribute to VSMC dysfunction rather than definitive proof of a single eNOS-dependent mechanism. Not applicable.