Murasawa Satoshi, Kawamoto Atsuhiko, Horii Miki, Nakamori Shuko, Asahara Takayuki
Department of Regenerative Medicine, Institute of Biomedical Research and Innovation/Stem Cell Translational Research, RIKEN Center for Developmental Biology, Kobe, Japan.
Arterioscler Thromb Vasc Biol. 2005 Jul;25(7):1388-94. doi: 10.1161/01.ATV.0000168409.69960.e9. Epub 2005 Apr 28.
Previous studies from our laboratory have shown therapeutic potential of ex vivo expanded endothelial progenitor cells (EPCs) for myocardial ischemia. Our purpose was to investigate the mechanisms regulating EPC contribution to myocardial regeneration.
To evaluate niche-dependent expression profiles of EPCs in vitro, we performed coculture using cultured EPCs derived from human peripheral blood and rat cardiac myoblast cell line (H9C2). Reverse-transcription polymerase chain reaction (PCR) disclosed the expression of human-specific cardiac markers as well as human-specific smooth muscle markers. Cytoimmunochemistry presented several cocultured cells stained with human specific cardiac antibody. To prove this translineage differentiation in vivo, human cultured EPCs were injected into nude rat myocardial infarction model. Reverse-transcription PCR as well as immunohistochemistry of rat myocardial samples demonstrated the expression of human specific cardiac, vascular smooth muscle, and endothelial markers. We observed the distribution of colors (Qtracker; Quantum Dot Corp) in coculture to detect the fused cells, and the frequency of cell fusion was <1%.
EPCs can contribute to not only vasculogenesis but also myogenesis in the ischemic myocardium in vivo. Transdifferentiation, not cell fusion, is dominant for EPCs commitment to myocardial lineage cells. Ex vivo expanded EPCs transplantation might have enhanced therapeutic potential for myocardial regeneration.
我们实验室之前的研究表明，体外扩增的内皮祖细胞（EPCs）对心肌缺血具有治疗潜力。我们的目的是研究调节EPCs对心肌再生作用的机制。
为了评估体外EPCs的龛位依赖性表达谱，我们使用源自人外周血的培养EPCs和大鼠心肌成肌细胞系（H9C2）进行共培养。逆转录聚合酶链反应（PCR）揭示了人特异性心脏标志物以及人特异性平滑肌标志物的表达。细胞免疫化学显示几个共培养细胞被人特异性心脏抗体染色。为了在体内证实这种跨谱系分化，将人培养的EPCs注射到裸鼠心肌梗死模型中。大鼠心肌样本的逆转录PCR以及免疫组织化学显示了人特异性心脏、血管平滑肌和内皮标志物的表达。我们观察了共培养中颜色（Qtracker；量子点公司）的分布以检测融合细胞，细胞融合频率<1%。
EPCs不仅可促进体内缺血心肌的血管生成，还可促进其肌生成。转分化而非细胞融合在EPCs向心肌谱系细胞的转变中占主导地位。体外扩增的EPCs移植可能对心肌再生具有增强的治疗潜力。
