血小板源性生长因子A在大鼠移植心脏血管病变及纤维化中的作用

Effect of PDGF-A on cardiac allograft vasculopathy and myocardial fibrosis in rats

目的探讨血小板源性生长因子A（PDGF-A）在移植心脏血管病变及心肌纤维化中的作用。方法选择近交系健康雄性Wistar大鼠及SD大鼠，建立大鼠异位心脏移植模型。实验分为四组，每组8只。正常对照组：取正常Wistar大鼠的心脏作为空白对照。无排斥组：心脏移植的供、受者均为Wistar大鼠，移植后第60天取移植心脏。急性排斥组和慢性排斥组：心脏移植的供者均为Wistar大鼠，受者均为SD大鼠；急性排斥组术后未行免疫抑制治疗，术后第5天取移植心脏；慢性排斥组术后给予环孢素A10mg·kg^-1·d^-1，皮下注射，移植后第60天取移植心脏。采用免疫组织化学染色法检测移植心脏的巨噬细胞浸润（CD68阳性细胞数）情况；逆转录聚合酶链反应（RTPCR）分析PDGF-A mRNA的表达水平。结果正常对照组和无排斥组未见巨噬细胞浸润；急性排斥组巨噬细胞浸润主要见于心肌及冠状血管周围；慢性排斥组巨噬细胞浸润见于心肌及血管周围，在心肌坏死纤维化较严重的区域，巨噬细胞浸润尤为明显；正常对照组、无排斥组、急性排斥组和慢性排斥组移植心组织中PDGF-AmRNA的相对表达量分别为：0．26±0．06、0．31±0．04、0．88±0．12和0．94±0．11，慢性排斥组和急性排斥组中PDGF-A mRNA的相对表达量明显高于正常对照组和无排斥组（P〈0．01）。结论巨噬细胞浸润及血小板源性生长因子表达水平与移植心脏血管病变及心肌纤维化有关。

Objective To investigate the effect of PDGF A on cardiac allograft vasculopathy and myocardial fibrosis in rats. Methods By using inbred Wistar rats as donors, and Sprague Dawley （SD） rats as recipients, heterotopic heart transplantation model was established. Four groups, each having 8 animals, were used. In normal heart group, Wistar rat hearts as blank control; In no rejection group, inbred Wistar rats as donors and recipients without imrnunosuppressive drugs, and grafts were removed on the day 60; In acute rejection group and chronic rejection group, Wistar rats as donors, SD rats as recipients, and the grafts were harvested on the day 5 without imrnunosuppressive drugs in acute rejection group; In chronic rejection group, the grafts were harvested on the day 60 with cyelosporine A （10 mg. kg^-1. d^-1） by hypodermic injection. Immunohistochemistry was used for macrophages （CD68 positive cells） and reverse transcription polymerase chain reaction （RT PCR） assay for expression of PDGF-A mRNA in cardiac allografts. Results Macrophage infiltration was not found in normal heart group and no rejection group. In acute rejection group and chronic rejection group, macrophage infiltration was found around coronary vessels and in myocardial interstitium, especially in myocardial fibrosis area in chronic rejection allografts. The relative content of PDGFA mRNA in normal heart group, no rejection group, acute rejection group, and chronic rejection group was 0.26 ± 0.06, 0.31 ± 0.04, 0.88 ± 0.12, 0.94 ± 0.11 respectively. PEGF-A mRNA was increased in chronic rejection group and acute rejection group significantly as compared with that in normal heart group and no rejection group （P 〈 0. 01）. Conclusion Macrophage infiltration and expression of PDGF-A are associated with cardiac allograft vasculopathy and myocardial fibrosis.