Department of Bioengineering, Cardiovascular Implant Research Laboratory (CIRL), Clemson University, Clemson, South Carolina 29634, USA.
J Biomed Mater Res B Appl Biomater. 2010 Jan;92(1):168-77. doi: 10.1002/jbm.b.31503.
Glutaraldehyde crosslinked bioprosthetic heart valves (BHVs) have two modalities of failure: degeneration (cuspal tear due to matrix failure) and calcification. They can occur independently as well as one can lead to the other causing co-existence. Calcific failure has been extensively studied before and several anti-calcification treatments have been developed; however, little research is directed to understand mechanisms of valvular degeneration. One of the shortcomings of glutaraldehyde fixation is its inability to stabilize all extracellular matrix components in the tissue. Previous studies from our lab have demonstrated that neomycin could be used as a fixative to stabilize glycosaminoglycans (GAGs) present in the valve to improve matrix properties. But neomycin fixation did not prevent cuspal calcification. In the present study, we wanted to enhance the anti-calcification potential of neomycin fixed valves by pre-treating with ethanol or removing the free aldehydes by sodium borohydride treatment. Ethanol treatment has been previously used and found to have excellent anti-calcification properties for valve cusps. Results demonstrated in this study suggest that neomycin followed by ethanol treatment effectively preserves GAGs both in vitro as well as in vivo after subdermal implantation in rats. In vivo calcification was inhibited in neomycin fixed cusps pretreated with ethanol compared to glutaraldehyde (GLUT) control. Sodium borohydride treatment by itself did not inhibit calcification nor stabilized GAGs against enzymatic degradation. Neomycin fixation followed by ethanol treatment of BHVs could prevent both modalities of failure, thereby increasing the effective durability and lifetime of these bioprostheses several fold.
戊二醛交联生物心脏瓣膜（BHV）有两种失效模式：退化（由于基质失效导致瓣叶撕裂）和钙化。它们可以独立发生，也可以相互作用导致共存。钙化失效已经得到了广泛的研究，并且已经开发出了几种抗钙化治疗方法；然而，很少有研究致力于理解瓣膜退化的机制。戊二醛固定的一个缺点是它不能稳定组织中所有的细胞外基质成分。我们实验室之前的研究表明，新霉素可用作固定剂来稳定瓣膜中存在的糖胺聚糖（GAGs），以改善基质特性。但是新霉素固定并不能防止瓣叶钙化。在本研究中，我们希望通过用乙醇预处理或用硼氢化钠处理去除游离醛来增强新霉素固定瓣膜的抗钙化潜力。乙醇处理以前已经被使用过，并被发现对瓣膜瓣叶具有极好的抗钙化特性。本研究的结果表明，新霉素与乙醇处理联合使用，无论是在体外还是在大鼠皮下植入后的体内，都能有效地保存 GAGs。与戊二醛（GLUT）对照组相比，用乙醇预处理的新霉素固定瓣叶的体内钙化得到了抑制。硼氢化钠处理本身并不能抑制钙化，也不能稳定 GAGs 免受酶降解。BHV 的新霉素固定后用乙醇处理可以防止两种失效模式，从而使这些生物假体的有效耐久性和使用寿命增加数倍。
