免疫抑制剂降低同种带瓣主动脉移植后钙含量的观察

Observations on the effect of immunosuppressive agents on the reduction in the occurrence of calcification in cardiovalve homograft

探讨在同种带瓣主动脉移植后早期使用免疫抑制剂降低钙含量的机制和效果。成年SD大鼠为供体;Wistar大鼠为受体,行同种异体带瓣主动脉腹主动脉的异位移植,实验组移植后给予环孢素A(CsA)15mg/kg·d,共2周。对照组不做任何处理。同基因组行同一种系的近交系大鼠同种带瓣主动脉移植。各组随机分为5组,每组8只,分别于术后2、4、8、12、16周使用流式细胞仪测定大鼠CD25、CD71的表达,移植物进行光镜和电镜观察,免疫组化测定CD40的表达,同时测定钙含量。对照组移植后CD25、CD71和CD40表达的高峰时间段主要在移植后早期(2～4周),此后的表达水平逐渐回落,12周后维持在低水平。CsA组在移植后2～4周CD25、CD71和CD40的表达明显低于对照组(P<0.01),但是在8周后的表达水平与对照组无差别(P>0.05)。对照组的钙含量从4周开始升高,随着时间的推移,逐渐升高,在12周达到高峰,此后进入平台期。CsA组在移植后4、8、12、16周4个不同时间点的钙含量显著低于对照组(P<0.01)。移植后早期,实验组的内皮细胞脱落和平滑肌细胞的坏死情况较对照组减轻。同种瓣移植后早期使用免疫抑制剂具有抗钙化作用,其机制在于抑制移植后早期的免疫排斥,减轻了内皮细胞和平滑肌细胞所受到的免疫攻击,保护了内皮细胞和平滑肌细胞;但是否能改善同种瓣功能和血流动力学尚需进一步观察。

To evaluate the effect of immunosuppressive agents on the cardiovalve allograft durability and its effect on the reduction of occurrence of calcification in the valve homograft, aortic value homograft was heterotopically allografted into the abdominal aorta in which the adult SD rats were chosen as donor and adult Wistar rats as recipients. The recipient rats were divided into 3 groups, in which the test group of rats was treated with cyclosporine A (CsA) in a dose of 0.15 mg/kg, the isogenic group of rats consisted of the isogenic donors and recipients, and the control group of rats received no any treatment except the valve homograft transplantation. All the rats were sacrificed in batches at 2, 4, 8, 12 and 16 weeks after transplantation and blood samples were taken to access the expressions of CD25 and CD71 by flow cytometry. Meanwhile, the changes in endothelial cells and smooth muscle cells were observed with transmission and electron microscopy, the expression of CD40 was determined by immunohistochemical assay and the content of calcium was measured with the related method. As demonstrated in the control group, the maximal expression level of CD25, CD71 and CD40 occurred almost at the early stage after transplantation (2～4 weeks), and then it gradually dropped down, remaining at low level 12 weeks afterwards. In case of the test group with CsA, the expressions of CD25, CD71 and CD40 were comparatively lower than that of control group at 2～4 weeks after transplantation. But at 8 weeks, the expression levels of these molecules showed no significant difference with that of control group. The content of calcium in control group began to rise from 4 weeks, gradually increasing afterwards and reaching its highest level at 12 weeks after tansplantation, however, there was no difference in the calcium content in the isogenic group in comparison with that before transplantation. Meanwhile, the calcium content in the test group was comparatively lower than that of control group at 4～16 weeks after transplantation. It is concluded that CsA treatment can reduce the occurrence of calcification in cardiovalve homograft, because it can inhibit the development of immune responses at early stage after transplantation. But its mechanism of action needs further investigation.