Lehmann Sven, Walther Thomas, Kempfert Jörg, Rastan Ardawan, Garbade Jens, Dhein Stefan, Mohr Friedrich W
Department for Heart Surgery, Universität Leipzig, Heart Center, Leipzig, Germany.
Ann Thorac Surg. 2009 Nov;88(5):1476-83. doi: 10.1016/j.athoracsur.2009.07.025.
Mechanical strain may affect aortic valve cusp, leading to an altered extracellular matrix ultrastructure and eventually aortic stenosis. The aim of this study was to evaluate the affect of these potential relationships on human tissue.
Extracellular matrix protein disposition was analyzed on human aortic valve cusp retrieved from 31 patients during routine aortic valve replacement surgery. Samples were immediately fixed in 2-hydroxyethyl methacrylate. Immunohistology and Western blot analysis were used to quantify decorin, tenascin-C, biglycan, alkaline-phosphatase, osteocalcin, and osteopontin content. Fibroblast function was analyzed on interstitial cells derived from aortic valve cups from patients undergoing aortic valve replacement. Cells were grown to confluency in modified Eagle's medium supplemented with 10% fetal calf serum under sterile conditions. Thereafter, mechanical strain was applied for 72 hours and 60 cycles per minute. Elongation of as much as 10% in comparison with no elongation (control group) was applied. All results were correlated to hemodynamic variables.
Decorin and biglycan were mostly located at the inflow aspects of the cusp, tenascin-C in the central layer, and osteopontin, osteocalcin, and alkaline phosphatase were concentrated near the cell populations surrounding calcified areas. The intensity of this protein expression was significantly related to the pressure gradient. Expression levels were twice to five times higher than normal in patients with a preoperative pressure gradient of more than 100 mm Hg. On fibroblasts subjected to mechanical strain, a similar significant increase in the expression for decorin, biglycan, alkaline-phosphatase, tenascin-C, osteocalcin, and osteopontin was found by immunohistology. Western blot analysis confirmed significantly enhanced expressions of two and eight times the normal levels.
A specific pattern of extracellular matrix protein expression was found in relation to mechanical strain on human aortic valve cusp tissue and in mechanically stimulated human valvular fibroblasts. This new insight into the process of aortic valve degeneration may be important for further therapeutic approaches to ameliorate the progression or even the initiation of potential aortic valve stenosis.
机械应变可能影响主动脉瓣叶，导致细胞外基质超微结构改变，最终引发主动脉瓣狭窄。本研究旨在评估这些潜在关系对人体组织的影响。
对31例患者在常规主动脉瓣置换手术中获取的人主动脉瓣叶进行细胞外基质蛋白分布分析。样本立即固定于甲基丙烯酸2-羟乙酯中。采用免疫组织学和蛋白质印迹分析来定量核心蛋白聚糖、肌腱蛋白-C、双糖链蛋白聚糖、碱性磷酸酶、骨钙素和骨桥蛋白的含量。对接受主动脉瓣置换患者的主动脉瓣叶间质细胞进行成纤维细胞功能分析。细胞在补充有10%胎牛血清的改良伊格尔培养基中于无菌条件下生长至汇合。此后，施加机械应变72小时，每分钟60次循环。与无伸长（对照组）相比，施加高达10%的伸长。所有结果均与血流动力学变量相关。
核心蛋白聚糖和双糖链蛋白聚糖主要位于瓣叶的流入面，肌腱蛋白-C位于中间层，骨桥蛋白、骨钙素和碱性磷酸酶集中在钙化区域周围的细胞群附近。这种蛋白质表达的强度与压力梯度显著相关。术前压力梯度超过100 mmHg的患者，其表达水平比正常水平高两倍至五倍。对经受机械应变的成纤维细胞，通过免疫组织学发现核心蛋白聚糖、双糖链蛋白聚糖、碱性磷酸酶、肌腱蛋白-C、骨钙素和骨桥蛋白的表达有类似的显著增加。蛋白质印迹分析证实表达水平显著增强，分别为正常水平的两倍和八倍。
在人主动脉瓣叶组织上的机械应变以及机械刺激的人瓣膜成纤维细胞中，发现了一种与细胞外基质蛋白表达相关的特定模式。这种对主动脉瓣退变过程的新认识可能对进一步改善潜在主动脉瓣狭窄进展甚至起始的治疗方法具有重要意义。
