Department of Cardiothoracic Surgery, University College London, London, United Kingdom.
J Thorac Cardiovasc Surg. 2011 Jan;141(1):269-75. doi: 10.1016/j.jtcvs.2010.08.064.
Human subjects and Old World primates have high levels of antibody to galactose-α-1,3 galactose β-1,4-N-acetylglucosamine (α-Gal). Commercially available bioprosthetic heart valves of porcine and bovine origin retain the Gal antigen despite current processing techniques. Gal-deficient pigs eliminate this xenoantigen. This study tests whether binding of human anti-Gal antibody effects calcification of wild-type and Gal-deficient glutaraldehyde-fixed porcine pericardium by using a standard subcutaneous implant model.
Expression of α-Gal was characterized by lectin Griffonia simplicifolia-IB4 staining. Glutaraldehyde-fixed pericardial disks from Gal-positive and Gal-deficient pigs were implanted into 12-day-old Wistar rats and 1.5-kg rabbits with and without prelabeling with affinity-purified human anti-Gal antibody. Calcification of the implants was determined after 3 weeks by using inductively coupled plasma spectroscopy.
The α-Gal antigen was detected in wild-type but not Gal-deficient porcine pericardium. Wild-type disks prelabeled with human anti-Gal antibody exhibited significantly greater calcification compared with that seen in antibody-free wild-type samples (mean ± standard error of the mean: 111 ± 8.4 and 74 ± 9.6 mg/g, respectively; P = .01). In the presence of anti-Gal antibody, a significantly greater level of calcification was detected in wild-type compared with GTKO porcine pericardium (111 ± 8.4 and 55 ± 11.8 mg/g, respectively; P = .005). Calcification of Gal-deficient pericardium was not affected by the presence of anti-Gal antibody (51 ± 9.1 and 55 ± 11.8 mg/g).
In this model anti-Gal antibody accelerates calcification of wild-type but not Gal-deficient glutaraldehyde-fixed pericardium. This study suggests that preformed anti-Gal antibody present in all patients might contribute to calcification of currently used bioprosthetic heart valves. Gal-deficient pigs might become the preferred source for new, potentially calcium-resistant bioprosthetic heart valves.
人类和旧世界灵长类动物的血液中含有高水平的抗半乳糖-α-1,3 半乳糖-β-1,4-N-乙酰氨基葡萄糖（α-Gal）抗体。尽管目前采用了加工技术，但仍保留了 Gal 抗原的猪源和牛源商业生物假体心脏瓣膜。Gal 缺乏的猪能够消除这种异种抗原。本研究通过使用标准皮下植入模型，测试人抗 Gal 抗体是否会影响戊二醛固定的野生型和 Gal 缺乏型猪心包的钙化。
通过凝集素 Griffonia simplicifolia-IB4 染色来鉴定 α-Gal 的表达。Gal 阳性和 Gal 缺乏型猪的戊二醛固定心包片在植入 12 天大的 Wistar 大鼠和 1.5 公斤的兔子体内之前，用亲和纯化的人抗 Gal 抗体进行预标记，并进行植入物 3 周后的钙化测定，采用电感耦合等离子体光谱法。
在野生型猪心包中检测到 α-Gal 抗原，但在 Gal 缺乏型猪心包中未检测到。用抗 Gal 抗体预标记的野生型心包片的钙化程度明显高于未用抗体的野生型样本（平均值±标准误差均值：分别为 111±8.4 和 74±9.6mg/g；P=0.01）。在存在抗 Gal 抗体的情况下，与 GTKO 猪心包相比，野生型心包的钙化程度明显更高（分别为 111±8.4 和 55±11.8mg/g；P=0.005）。Gal 缺乏型心包的钙化程度不受抗 Gal 抗体的影响（分别为 51±9.1 和 55±11.8mg/g）。
在该模型中，抗 Gal 抗体加速了野生型但不加速 Gal 缺乏型戊二醛固定心包的钙化。本研究表明，所有患者体内预先存在的抗 Gal 抗体可能导致目前使用的生物假体心脏瓣膜的钙化。Gal 缺乏型猪可能成为新的、潜在的抗钙生物假体心脏瓣膜的首选来源。
