Aortic, pulmonic, mitral, and tricuspid (n = 4 for each valve type) VICs were isolated from hearts valves explanted from patients undergoing cardiac transplantation. Cells were cultured and grown to confluence in passage 2–6 before treatment with Lipopolysaccharide (LPS) (100–200 ng/mL) for 24 or 48 h. Cells were characterized by immunofluorescent staining. TLR-4 expression was analyzed (immunoblotting, flow cytometry). Bone morphogenetic protein 2 and intercellular adhesion molecule 1 production were determined (immunoblotting). Monocyte chemoattractant protein 1 levels were determined by enzyme-linked immunosorbent assay. Statistics were by Mann–Whitney U test.
TLR-4 stimulation induced bone morphogenetic protein 2 production only in aortic VICs (P < 0.05). Intra-cellular adhesion molecule 1 production and monocyte chemoattractant protein 1 secretion increased in a similar fashion among TLR-4-stimulated VICs from all four valves.
Proinflammatory stimulation induces an osteogenic phenotype in aortic VICs but not mitral, pulmonic, or tricuspid VICs. We conclude that this differential osteogenic response of aortic VICs contributes to the pathogenesis of calcific aortic stenosis.