摘要
骨髓源性Nkx2-5+心脏祖细胞(bone marrow-derived Nkx2-5+ cardiac progenitor cells)具有高度特异性分化为心肌细胞的潜能,在病理状态下可能参与内源性心肌修复。但在器官缺血、特别在急性心肌缺血病理状态下,该细胞如何被动员的机制尚不清楚。本研究在观察Nkx2-5+心脏祖细胞在骨髓中分布特征的基础上,分析急性心肌缺血对骨髓源性Nkx2-5+心脏祖细胞的动员作用,探讨其细胞动员的可能机制。分别建立小鼠急性心肌缺血及脑、后肢急性缺血动物模型。采用纳米金-银免疫标记透射电镜、免疫荧光标记及分子生物学等检测方法,观察骨髓Nkx2-5+心肌祖细胞的定位及其形态学特征;检测急性心肌缺血后外周血Nkx2-5+细胞比例变化、缺血不同时段骨髓及外周血中Nkx2-5蛋白表达的变化;比较不同器官缺血对Nkx2-5+心脏祖细胞的动员作用;应用SDF-1/CXCR4通路特异性阻断剂AMD3100,分析SDF-1在急性心肌缺血后对Nkx2-5+心脏祖细胞动员作用的影响。结果显示:Nkx2-5+心脏祖细胞呈散在分布于骨髓血窦旁。与对照组相比,急性心肌缺血后,外周血Nkx2-5+心脏祖细胞比例显著增加(P<0.01)。心肌缺血早期(1d),外周血Nkx2-5蛋白表达显著增加(P<0.01),并可持续7d;而此间,骨髓中Nkx2-5蛋白表达立即升高,随后则降低。应用AMD3100阻断剂后,心肌缺血组外周血Nkx2-5蛋白表达受到明显抑制(P<0.05)。脑、后肢缺血后,外周血Nkx2-5蛋白表达显著少于急性心肌缺血组(P<0.01),而与对照组相比无显著差异。上述结果提示,生理状态下,骨髓中存在Nkx2-5+心脏祖细胞亚群;急性心肌缺血对骨髓Nkx2-5+心脏祖细胞具有显著的动员作用,且该动员作用具有显著的器官特异性,SDF-1/CXCR4通路在该动员作用中发挥了重要的趋化作用。
The present study aimed to observe the morphological distribution of bone marrow （BM）-derived Nkx2-5^＋ cardiac progeni- tor cells （CPCs） in bone marrow niche and evaluate the effect of acute myocardial ischemia （AMI） on the mobilizion of BM-derived Nkx2-5^＋ CPCs. Animal models of BALB/c mouse AMI, cerebral and hind-limb ischemia were established. Nanogold labeling method, immunofluorescence and Western blot were used to identify the distribution of BM-derived Nkx2-5^＋ CPCs and the expressions of Nkx2-5 protein in peripheral blood and BM after AMI. Meanwhile, in different ischemia organ models and after AMD3100 （SDF-1/ CXCR4 antagonist） pretreatment in AMI model, Nkx2-5 protein expressions in peripheral blood were also assayed. Nkx2-5^＋ CPCs were found to locate in cavitas medullaris. The percentage of Nkx2-5^＋ CPCs in blood increased immediately after AMI. Nkx2-5 protein expression in peripheral blood was also upregulated at the timepoint of 24 h post-AMI （P〈0.01） and kept stable without further enhancement from day 1 to day 7 post-AMI. In BM, Nkx2-5 protein expression was upregulated immediately after AMI and downregulated afterwards （P〈0.01）. After AMD3100 pretreatment in AMI group, Nkx2-5 protein expression was significantly inhibited in peripheral blood （P〈0.05）. In cerebral and hind-limb ischemia models, Nkx2-5 protein expressions were significantly lower than that in AMI group （P〈0.01）, but with no significant difference to control group. These results suggest that Nkx2-5^＋ CPCs are physiologically resident in BM and AMI initiates mobilization of BM-derived Nkx2-5^＋ CPCs in a predominant organ-specific manner. In the procedure of mobilization, SDF-1 may play a critical role in a chemoattracted manner.
出处
《生理学报》
CAS
CSCD
北大核心
2009年第2期185-193,共9页
Acta Physiologica Sinica
基金
supported by Natural Science Foundation of Education Department of Jiangsu Province, China (No. 05KJD310235)
关键词
心脏祖细胞
骨髓
NKX2-5
动员
心肌缺血
cardiac progenitor cells
bone marrow
Nkx2-5
mobilization
myocardial ischemia
