Cells involved in extracellular matrix remodeling after acute myocardial infarction

Objective Evaluate the effects of VEGF165 gene transfer in the process of remodeling of the extracellular matrix after an acute myocardial infarct. Methods Wistar rats were submitted to myocardial infarction, after the ligation of the left descending artery, and the left ventricle ejection fraction was used to classify the infarcts into large and small. The animals were divided into groups of ten, according to the size of infarcted area (large or small), and received or not VEGF165 treatment. Evaluation of different markers was performed using immunohistochemistry and digital quantification. The primary antibodies used in the analysis were anti-fibronectin, anti-vimentin, anti-CD44, anti-E-cadherin, anti-CD24, anti-alpha-1-actin, and anti-PCNA. The results were expressed as mean and standard error, and analyzed by ANOVA, considering statistically significant if p≤0.05. Results There was a significant increase in the expression of undifferentiated cell markers, such as fibronectin (protein present in the extracellular matrix) and CD44 (glycoprotein present in the endothelial cells). However, there was decreased expression of vimentin and PCNA, indicating a possible decrease in the process of cell proliferation after treatment with VEGF165. Markers of differentiated cells, E-cadherin (adhesion protein between myocardial cells), CD24 (protein present in the blood vessels), and alpha-1-actin (specific myocyte marker), showed higher expression in the groups submitted to gene therapy, compared to non-treated group. The value obtained by the relation between alpha-1-actin and vimentin was approximately three times higher in the groups treated with VEGF165, suggesting greater tissue differentiation. Conclusion The results demonstrated the important role of myocytes in the process of tissue remodeling, confirming that VEGF165 seems to provide a protective effect in the treatment of acute myocardial infarct.

研究目的 评估VEGF165基因转染在急性心肌梗死后细胞外基质重塑过程中的作用效果。实验方法 通过结扎左前降支动脉构建Wistar大鼠心肌梗死模型，采用左心室射血分数将梗死灶划分为大面积梗死与小面积梗死亚组。根据梗死区域大小，将大鼠分为10只/组的组别，分别接受VEGF165治疗或不予治疗。采用免疫组织化学法与数字化定量技术对多种标志物开展检测分析，本次实验所用一抗包括抗纤连蛋白（anti-fibronectin）、抗波形蛋白（anti-vimentin）、抗CD44、抗E-钙粘蛋白（anti-E-cadherin）、抗CD24、抗α-1-肌动蛋白（anti-alpha-1-actin）以及抗增殖细胞核抗原（anti-PCNA）。实验结果以均值±标准误表示，采用方差分析（ANOVA）进行统计学检验，以P≤0.05为差异具有统计学意义。实验结果 未分化细胞标志物（如纤连蛋白，即细胞外基质相关蛋白；CD44，即内皮细胞表面糖蛋白）的表达量显著升高。但经VEGF165治疗后，波形蛋白与增殖细胞核抗原（PCNA）的表达量有所降低，提示细胞增殖过程可能受到抑制。分化细胞标志物包括E-钙粘蛋白（心肌细胞间黏附蛋白）、CD24（血管相关蛋白）以及α-1-肌动蛋白（心肌细胞特异性标志物），其在基因治疗组中的表达水平均高于未治疗组。VEGF165治疗组中α-1-肌动蛋白与波形蛋白的比值约为未治疗组的3倍，提示组织分化程度更高。研究结论 本实验结果明确了心肌细胞在组织重塑过程中的重要作用，证实VEGF165在急性心肌梗死治疗中可发挥保护性作用。