Koyanagi Masamichi, Brandes Ralf P, Haendeler Judith, Zeiher Andreas M, Dimmeler Stefanie
Molecular Cardiology, Department of Internal Medicine III, University of Frankfurt, Germany.
Circ Res. 2005 May 27;96(10):1039-41. doi: 10.1161/01.RES.0000168650.23479.0c. Epub 2005 May 5.
The regeneration of new myocardium by stem or progenitor cells is an important therapeutic option. Cellular or nuclear fusion is considered as an alternative to cell reprogramming by transdifferentiation. However, the generation of hybrid cells may also be a consequence of a transient transmembrane exchange of proteins and organelles between cells. Therefore, we investigated the formation of intercellular connections, which may allow the transport of macromolecular structures between labeled adult human endothelial progenitor cells (EPC) and GFP-expressing neonatal rat cardiomyocytes (CM) in a coculture system. FACS analysis revealed that, 6 days after initiation of coculture, 2.1+/-0.4% of the cells stained positive for GFP and Dil-ac-LDL. 6 hours after initiation of the coculture, ultrafine intercellular structures between Dil-ac-LDL-labeled EPC and GFP-expressing CM were observed. The number of EPC, which established nanotubular connections with CM increased from 0.5+/-0.2% after 6 hours to 2.6+/-0.3% after 24 hours of coculture. The intercellular connections had a diameter from 50 to 800 nm, a length of 5 to 120 mum, and were only transiently established. To determine whether the nanotubular structures allowed the transport of organelles, we labeled CM with a mitochondrial live tracker (MitoTracker). Using time-lapse video microscopy, we observed the transport of stained complexes between CM and EPC resulting in up-take of MitoTracker-positive structures in EPC. Thus, the present study shows a novel type of cell-to-cell communication between progenitor cells and CM in vitro, which may contribute to the acquisition of a cardiomyogenic phenotype independent of permanent cellular or nuclear fusion.
利用干细胞或祖细胞使新的心肌再生是一种重要的治疗选择。细胞融合或核融合被认为是细胞转分化重编程的一种替代方式。然而，杂交细胞的产生也可能是细胞间蛋白质和细胞器短暂跨膜交换的结果。因此，我们研究了细胞间连接的形成，这种连接可能允许在共培养系统中标记的成人内皮祖细胞（EPC）和表达绿色荧光蛋白（GFP）的新生大鼠心肌细胞（CM）之间进行大分子结构的运输。流式细胞术分析显示，共培养开始6天后，2.1±0.4%的细胞对GFP和DiI-ac-LDL染色呈阳性。共培养开始6小时后，观察到DiI-ac-LDL标记的EPC和表达GFP的CM之间有超细微的细胞间结构。与CM建立纳米管连接的EPC数量从共培养6小时后的0.5±0.2%增加到24小时后的2.6±0.3%。细胞间连接的直径为50至800纳米，长度为5至120微米，且只是短暂形成。为了确定纳米管结构是否允许细胞器运输，我们用线粒体活细胞追踪剂（MitoTracker）标记CM。使用延时视频显微镜，我们观察到CM和EPC之间有染色复合物的运输，导致EPC摄取MitoTracker阳性结构。因此，本研究显示了祖细胞和CM在体外一种新型的细胞间通讯方式，这可能有助于获得独立于永久性细胞融合或核融合的心肌生成表型。
