Aix Marseille Univ, INSERM, Marseille Medical Genetics, U1251, 13005 Marseille, France.
Aix Marseille Univ, CNRS, IRPHE, UMR7342, 13013 Marseille, France.
Int J Cardiol. 2021 Jan 15;323:220-228. doi: 10.1016/j.ijcard.2020.08.074. Epub 2020 Aug 25.
Endothelial cells covering the aortic and ventricular sides of the aortic valve leaflets are exposed to different stresses, in particular wall shear stress (WSS). Biomechanical stimuli actively regulate valve tissue structure and induce remodeling events leading to valve dysfunction. Endothelial to mesenchymal transformation (EndMT), for example, has been associated with aortic valve disease. The biomechanical response of cells at different sides of the leaflets has not been clearly characterized. To analyze the mechanical response of valve endothelial cells (VECs) we developed a unique fluid activation device that applies physiologically relevant pulsatile WSS. We characterized the morphology and function of adult porcine aortic VECs derived from the opposite sides of aortic valve leaflets following exposure to different pulsatile WSS. We found that elongation and orientation of cells in response to pulsatile WSS depends on their side of origin. Quantification of gene expression confirms phenotypic differences between aortic and ventricular VECs. Aortic VECs exposed to pulsatile WSS similar to that in vivo at the tip of aortic side of the valve leaflet upregulated pro-EndMT (ACTA2, Snail, TGFβ1) and inflammation (ICAM-1, VCAM-1) genes, whereas expression of endothelial markers like PECAM-1 was decreased. Conversely, ventricular-VECs showed strong increase of PECAM-1 expression and no activation of pro-EndMT marker. Finally, we found that stress-induced genes are upregulated in both cell types, at higher levels in ventricular compared to aortic VECs. Application of physiological shear stress levels using a fluid activation device therefore reveals functional differences in VECs derived from opposite sides of the aortic valve leaflets.
覆盖主动脉瓣叶主动脉侧和心室侧的内皮细胞会受到不同的压力，尤其是壁面切应力（WSS）。生物力学刺激会主动调节瓣膜组织的结构，并诱导重塑事件，导致瓣膜功能障碍。例如，内皮细胞向间充质转化（EndMT）与主动脉瓣疾病有关。瓣叶两侧细胞的生物力学反应尚未得到明确描述。为了分析瓣膜内皮细胞（VECs）的力学反应，我们开发了一种独特的流体激活装置，该装置施加生理相关的脉动 WSS。我们对来自主动脉瓣叶相对侧的成年猪主动脉 VECs 在暴露于不同脉动 WSS 后的形态和功能进行了表征。我们发现，细胞对脉动 WSS 的伸长和定向取决于它们的起源侧。基因表达的定量分析证实了主动脉和心室 VECs 之间的表型差异。在瓣膜主动脉侧尖端处类似于体内的脉动 WSS 下，暴露于脉动 WSS 的主动脉 VECs 上调了前 EndMT（ACTA2、Snail、TGFβ1）和炎症（ICAM-1、VCAM-1）基因，而内皮标志物如 PECAM-1 的表达则降低。相反，心室-VECs 表现出 PECAM-1 表达的强烈增加，而前 EndMT 标志物没有被激活。最后，我们发现，在两种细胞类型中，应激诱导的基因都被上调，心室 VECs 的上调水平高于主动脉 VECs。使用流体激活装置施加生理剪切应力水平，因此揭示了来自主动脉瓣叶相对侧的 VECs 之间的功能差异。
