大鼠心包膜组织对其缺血心肌的保护和再生作用

目的 研究心包膜组织中是否有干细胞现象,能否对梗死后的心肌起到保护和修复作用.方法 结扎Wistar大鼠冠状动脉左前降支(LAD)制作心肌梗死(简称心梗)模型.术中分别保留完整心包组织(+PC组,n=8)和去除心包组织(-PC组,n=10).心梗7d以后用超声心动图分析大鼠的心功能恢复情况;2,3,5-氯化三苯基四氮唑(TTC)染色测定梗死区的成活心肌组织;溴脱氧尿苷(BrdU)掺入实验检测新生的心肌细胞;免疫组化检测心包膜组织中心脏干细胞特征蛋白的免疫表象(SCA-1,c-kit和KDR).结果 超声心动图分析结果显示,+PC组左室射血分数、左室短轴缩短率均高于-PC组(52±12比37 +12,36±14比25±13,均P＜0.05).TTC染色发现,心包组的再生心肌组织明显多于无心包组,这些细胞＞90％为BrdU阳性心肌细胞(新生细胞).免疫组化显示:心外膜和心包膜组织中存在大量的Ki67阳性的分裂活跃细胞.心外膜和心包膜组织中的SCA-1和c-kit阳性细胞少,主要为KDR(flk-1)的阳性细胞,这些细胞呈克隆样增生,同一区域同时存在大量的cTnT阳性细胞,并发现部分KDR阳性细胞向心肌组织中迁移,提示这些心包起源的细胞可能参与了心脏的修复过程.结论 心包膜组织在心脏自我修复过程中能起重要作用,其主要机制可能与心包膜KDR阳性心脏干细胞有关.

Protective role of pericardial tissue on injured myocardium in rats

Objective To define the protective role of pericardial tissue and identify the subcellular population with potential contribution to cardiac protection after injury in a rat model.Methods Myocardial infarction (MI) was created by the ligation of left anterior descending artery (LAD) in rats while the pericardial sac was either completely removed ( - PC,n =10) or surgically closed after ligation ( + PC,n =8 ).The follow-up functional and structure benefits were analyzed by echocardiography and 2,3,5- triphenyl tetrazoliumch(TTC) and bromodeoxyuridine (BrdU)staining.The contributions of cardiac stem cells (sca-1,c-kit and KDR) were evaluated by immunohistochemistry.Results The integrity of poricardial sac showed significant benefits of cardiac contractile function (ejection fraction and short axis fractional shortening) in comparison to the controls (52 ± 12 vs 37 ± 12 and 36 ± 14 vs 25 + 13,both P ＜0.05).The observed functional amelioration after MI was obvious based on structural repair examined by TTC staining and BrdU incorporation,showing significantly more de novo cardiomyocytes in + PC rats.Interestingly,we have immunohistologically identified a sub-population of KDR + (flk-1 + ) cells in pericardial tissue which clonegenically distributed and mildly expressed cardiac specific proteins (cTnT).It suggested that the KDR + cells might act as cardiac progenitors and therefore play an important role in cardiac repair.Meanwhile,rare SCA-1 and c-kit positive cells were detected in pericardial tissue.Conclusion The intact pericardial tissue exerts protective effects after MI.It may be related with a specific cell population of KDR + cells from pericardial tissue.