Zilla Peter, Bezuidenhout Deon, Human Paul
Chris Barnard Division of Cardiothoracic Surgery, Cape Heart Center, University of Cape Town, Cape Town, South Africa.
Ann Thorac Surg. 2005 Mar;79(3):905-10. doi: 10.1016/j.athoracsur.2003.12.026.
Bifunctional amines were previously found to act as bridging molecules between the terminal ends of incomplete glutaraldehyde (GA) cross-links. The additional cross-links thus formed between -NH2 groups of tissue were seen to significantly inhibit bioprosthetic calcification. In the current study, the potential ability of alpha-amino oleic acid (AOA) to act as a bridging molecule between -NH2- and COOH-dependent cross-links was hypothesized to similarly augment the anticalcification effect of the AOA molecule.
Porcine aortic wall tissue from Medtronic Freestyle valve bioprostheses incorporating the AOA anticalcification process additionally underwent carboxyl-group cross-linking with Jeffamine (poly[propylene glyco]-bis-[aminopropyl ether]) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). Tissue was subdermally implanted into 5-week-old Long-Evans rats for 60 days. Standard 0.2% GA-fixed tissue served as a control. To further assess the impact of storage solution on AOA tissue, samples were either stored in GA (0.2%GA) or EDC (25 mmol/L carbodiimide) before implantation. Tissue calcification was assessed by atomic absorption spectroscopy and histochemical staining.
Aldehyde end-capping with AOA achieved only a modest reduction of calcification in GA-treated aortic wall tissue (-20.0%; p < 0.05). Replacing GA with EDC as a storage solution led to a further 32.4% (p < 0.01) mitigation of calcification in Freestyle tissue. Incorporating an intermediate EDC/Jeffamine cross-linking step achieved a distinct additional reduction of calcification by 40.4% (p < 0.05). Overall, aortic wall calcification was 59.7% (p < 0.0001) lower if commercial Freestyle tissue underwent an additional EDC/Jeffamine cross-linking step and subsequent storage in EDC. Relative to control GA-fixed tissue, this represented a 67.8% (p < 0.0001) reduction. Incorporation of AOA was essential for the beneficial effect of the additional EDC/Jeffamine cross-linking step.
Potentially utilizing both the amino- and the carboxyl moieties of AOA for tissue binding dramatically reduces aortic wall calcification of GA-fixed tissue.
先前发现双功能胺可作为不完全戊二醛（GA）交联末端之间的桥连分子。由此在组织的-NH₂基团之间形成的额外交联可显著抑制生物假体钙化。在本研究中，假设α-氨基油酸（AOA）作为-NH₂和COOH依赖性交联之间的桥连分子的潜在能力可类似地增强AOA分子的抗钙化作用。
将采用AOA抗钙化工艺的美敦力自由式瓣膜生物假体的猪主动脉壁组织，另外使用1-乙基-3-（3-二甲基氨基丙基）碳二亚胺（EDC）与聚醚胺（聚[丙二醇]-双-[氨丙基醚]）进行羧基交联。将组织皮下植入5周龄的Long-Evans大鼠体内60天。标准的0.2% GA固定组织用作对照。为进一步评估储存溶液对AOA组织的影响，样品在植入前要么储存在GA（0.2% GA）中，要么储存在EDC（25 mmol/L碳二亚胺）中。通过原子吸收光谱法和组织化学染色评估组织钙化情况。
用AOA进行醛封端仅使GA处理的主动脉壁组织中的钙化适度减少（-20.0%；p < 0.05）。用EDC替代GA作为储存溶液可使自由式组织中的钙化进一步减轻32.4%（p < 0.01）。加入中间的EDC/聚醚胺交联步骤可使钙化明显额外减少40.4%（p < 0.05）。总体而言，如果商用自由式组织经过额外的EDC/聚醚胺交联步骤并随后储存在EDC中，主动脉壁钙化降低59.7%（p < 0.0001）。相对于对照GA固定组织，这代表降低了67.8%（p < 0.0001）。加入AOA对于额外的EDC/聚醚胺交联步骤的有益效果至关重要。
潜在地利用AOA的氨基和羧基部分进行组织结合可显著降低GA固定组织的主动脉壁钙化。
