Abstract 380: Shear Stress Affects Smooth Muscle Cells Through Pulmonary Arterial Endothelial Cell Mechanotransduction
Introduction: Pulmonary hypertension is associated with increased flow shear stress (FSS), endothelial dysfunction and vascular remodeling. Our previous study found that increased FSS upregulated endothelial vasodilator expression and downregulated endothelial vasoconstrictor expression. In this study, we assess the hypothesis that the influence of FSS on pulmonary artery smooth muscle cells (PASMC) is through mechanotransduction of pulmonary arterial endothelial cell (PAEC).
Methods: We use cell signal and co-culture techniques to examine PASMC response to the flow through PAEC mechanotransduction. In cell signal studies, bovine PAECs are subject to a laminar FSS profile ranging from normal physiological (10, 20, 60 dynes/cm2) to high-pathological (90, 120 dynes/cm2) FSS. Flow-conditioned PAEC media is used to culture PASMCs. SM-α-actin and PCNA expression are determined. A static condition is used as the control. In co-culture studies, PASMC are cultured in collagen matrix and with PAEC. PASMC F-actin, SM a-actin and proliferation are studied with a confocal microscope. PAEC F-actin and VE-Cadherin expression is evaluated to study mechanotransduction of flow through PAEC.
Results: In cell signal studies, SM-α-actin expression did not significantly increase in flow media exposed to 20 dynes/cm2 compared to the static condition, but increased in those exposed to 60, 90 and 120 dynes/cm2. PCNA marker did not show significant changes with FSS. In co-culture studies, SMC F-actin expression and proliferation significantly increased with flow compared to the static condition. Compared to the static condition, F-actin in PAEC was enhanced within the physiological FSS range (20 and 60 dynes/cm2), but decreased at 120 dynes/cm2. VE-cadherin assay showed a continuous linear pattern on PAEC along the peripheral intercellular junction under the static condition. At 20 and 60 dynes/cm2, VE-cadherin was redistributed: greater stain in the cytoplasm and around the nuclear membrane. At 90 and 120 dynes/cm2, it exhibited a more disorganized pattern.
Conclusions: We conclude that high FSS may play an important role in pulmonary vascular remodeling through PAEC transduction of FSS information via both cytoskeletal and cytokine-secretion pathways.