Raghavan Devanathan, Simionescu Dan T, Vyavahare Naren R
Cardiovascular Implant Research Laboratory (CIRL), Department of Bioengineering, Clemson University, 401 Rhodes Engineering Center, Clemson, SC 29634, USA.
Biomaterials. 2007 Jun;28(18):2861-8. doi: 10.1016/j.biomaterials.2007.02.017. Epub 2007 Mar 13.
Bioprosthetic heart valves (BHVs) derived from glutaraldehyde crosslinked porcine aortic valves are frequently used in heart valve replacement surgeries. However, BHVs have limited durability and fail either due to degeneration or calcification. Glycosaminoglycans (GAGs), one of the integral components of heart valve cuspal tissue, are not stabilized by conventional glutaraldehyde crosslinking. Previously we have shown that valvular GAGs could be chemically fixed with GAG-targeted chemistry. However, chemically stabilized GAGs were only partially stable to enzymatic degradation. In the present study an enzyme inhibitor was incorporated in the cusps to effectively prevent enzymatic degradation. Thus, neomycin trisulfate, a known hyaluronidase inhibitor, was incorporated in cusps via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) chemistry followed by glutaraldehyde crosslinking (NEG). Controls included cusps crosslinked with either EDC/NHS followed by glutaraldehyde (ENG) or only with glutaraldehyde (GLUT). NEG group showed improved resistance to in vitro enzymatic degradation as compared to GLUT and ENG groups. All groups showed similar collagen stability, measured as a thermal denaturation temperature by differential scanning calorimetry (DSC). The cusps were implanted subdermally in rats to study in vivo degradation of GAGs. NEG group preserved significantly more GAGs than ENG and GLUT. NEG and ENG groups showed reduced calcification than GLUT.
源自戊二醛交联猪主动脉瓣的生物人工心脏瓣膜（BHVs）常用于心脏瓣膜置换手术。然而，BHVs的耐久性有限，会因退变或钙化而失效。糖胺聚糖（GAGs）是心脏瓣膜尖组织的重要组成部分之一，传统的戊二醛交联无法使其稳定。此前我们已表明，瓣膜GAGs可用靶向GAG的化学方法进行化学固定。然而，化学稳定的GAGs对酶降解仅部分稳定。在本研究中，将一种酶抑制剂掺入瓣膜尖以有效防止酶降解。因此，通过1-乙基-3-(3-二甲基氨基丙基)碳二亚胺/N-羟基琥珀酰亚胺（EDC/NHS）化学方法将已知的透明质酸酶抑制剂硫酸新霉素掺入瓣膜尖，随后进行戊二醛交联（NEG）。对照组包括用EDC/NHS随后戊二醛交联的瓣膜尖（ENG）或仅用戊二醛交联的瓣膜尖（GLUT）。与GLUT和ENG组相比，NEG组对体外酶降解的抵抗力有所提高。通过差示扫描量热法（DSC）以热变性温度衡量，所有组的胶原蛋白稳定性相似。将瓣膜尖皮下植入大鼠体内以研究GAGs的体内降解情况。NEG组保留的GAGs明显多于ENG组和GLUT组。NEG组和ENG组的钙化程度低于GLUT组。
