Tuscher Robin, Khang Alex, West Toni M, Camillo Chiara, Ferrari Giovanni, Sacks Michael S
Department of Biomedical Engineering, James T. Willerson Center for Cardiovascular Modeling and Simulation, The Oden Institute for Computational Engineering and Sciences, The University of Texas at Austin, Austin, TX, United States.
Department of Surgery, The Seymour Cohn Cardiovascular Research Laboratory, Columbia University, New York, NY, United States.
Front Physiol. 2023 Jun 19;14:1168691. doi: 10.3389/fphys.2023.1168691. eCollection 2023.
Calcific aortic valve disease (CAVD) is characterized by progressive stiffening of aortic valve (AV) tissues, inducing stenosis and insufficiency. Bicuspid aortic valve (BAV) is a common congenital defect in which the AV has two leaflets rather than three, with BAV patients developing CAVD decades years earlier than in the general population. Current treatment for CAVD remains surgical replacement with its continued durability problems, as there are no pharmaceutical therapies or other alternative treatments available. Before such therapeutic approaches can be developed, a deeper understanding of CAVD disease mechanisms is clearly required. It is known that AV interstitial cells (AVICs) maintain the AV extracellular matrix and are typically quiescent in the normal state, transitioning into an activated, myofibroblast-like state during periods of growth or disease. One proposed mechanism of CAVD is the subsequent transition of AVICs into an osteoblast-like phenotype. A sensitive indicator of AVIC phenotypic state is enhanced basal contractility (tonus), so that AVICs from diseased AV will exhibit a higher basal tonus level. The goals of the present study were thus to assess the hypothesis that different human CAVD states lead to different biophysical AVIC states. To accomplish this, we characterized AVIC basal tonus behaviors from diseased human AV tissues embedded in 3D hydrogels. Established methods were utilized to track AVIC-induced gel displacements and shape changes after the application of Cytochalasin D (an actin polymerization inhibitor) to depolymerize the AVIC stress fibers. Results indicated that human diseased AVICs from the non-calcified region of TAVs were significantly more activated than AVICs from the corresponding calcified region. In addition, AVICs from the raphe region of BAVs were more activated than from the non-raphe region. Interestingly, we observed significantly greater basal tonus levels in females compared to males. Furthermore, the overall AVIC shape changes after Cytochalasin suggested that AVICs from TAVs and BAVs develop different stress fiber architectures. These findings are the first evidence of sex-specific differences in basal tonus state in human AVICs in varying disease states. Future studies are underway to quantify stress fiber mechanical behaviors to further elucidate CAVD disease mechanisms.
钙化性主动脉瓣疾病（CAVD）的特征是主动脉瓣（AV）组织逐渐硬化，导致狭窄和关闭不全。二叶式主动脉瓣（BAV）是一种常见的先天性缺陷，其中主动脉瓣有两个瓣叶而非三个，BAV患者发生CAVD的时间比普通人群早数十年。目前CAVD的治疗方法仍然是手术置换，但存在耐久性问题，因为目前尚无药物治疗或其他替代治疗方法。在开发此类治疗方法之前，显然需要更深入地了解CAVD的发病机制。已知AV间质细胞（AVICs）维持AV细胞外基质，在正常状态下通常处于静止状态，在生长或疾病期间转变为活化的、成肌纤维细胞样状态。CAVD的一种可能机制是AVICs随后转变为成骨细胞样表型。AVIC表型状态的一个敏感指标是基础收缩性（张力）增强，因此患病AV的AVICs将表现出更高的基础张力水平。因此，本研究的目的是评估不同人类CAVD状态导致不同生物物理AVIC状态这一假设。为了实现这一目标，我们对嵌入3D水凝胶中的患病人类AV组织的AVIC基础张力行为进行了表征。使用既定方法跟踪应用细胞松弛素D（一种肌动蛋白聚合抑制剂）使AVIC应力纤维解聚后AVIC引起的凝胶位移和形状变化。结果表明，来自三叶式主动脉瓣（TAVs）非钙化区域的患病人类AVICs比来自相应钙化区域的AVICs活化程度明显更高。此外，来自BAVs嵴区域的AVICs比来自非嵴区域的AVICs活化程度更高。有趣的是，我们观察到女性的基础张力水平明显高于男性。此外，细胞松弛素处理后AVIC的整体形状变化表明，来自TAVs和BAVs的AVICs形成了不同的应力纤维结构。这些发现是不同疾病状态下人类AVICs基础张力状态存在性别差异的首个证据。目前正在进行进一步研究以量化应力纤维的力学行为，以进一步阐明CAVD的发病机制。
