Dolnikov Katya, Shilkrut Mark, Zeevi-Levin Naama, Danon Asaf, Gerecht-Nir Sharon, Itskovitz-Eldor Joseph, Binah Ofer
Rappaport Institute, Ruth and Bruce Rappaport Faculty of Medicine, Technion, Israel Institute of Technology, Haifa, Israel.
Ann N Y Acad Sci. 2005 Jun;1047:66-75. doi: 10.1196/annals.1341.006.
Regeneration of the diseased myocardium by cardiac cell transplantation is an attractive therapeutic modality. Yet, because the transplanted cardiomyocytes should functionally integrate within the diseased myocardium, it is preferable that their properties resemble those of the host. To determine the functional adaptability of human embryonic stem cell-derived cardiomyocytes (hESC-CM) to the host myocardium, the authors investigated the excitation-contraction (E-C) coupling and the responsiveness to common physiological stimuli. The main findings are: (1) hESC-CM readily respond to electrical pacing and generate corresponding Ca(2+) transients (measured by fura-2 fluorescence) and contractions (measured by video edge detector). (2) In contrast to the mature myocardium, hESC-CM display negative force-frequency relations. (3) The hESC-CM contraction is dependent on Ca(2+) and blocked by verapamil. (4) Surprisingly, ryanodine, the sarcoplasmic-endoplasmic reticulum Ca(2+)-ATPase inhibitor thapsigargin, and caffeine do not affect the Ca(2+) transient or contraction. Collectively, these results indicate that at the developmental stage of 45 to 60 days, the contraction is largely dependent on Ca(2+) rather than on sarcoplasmic reticulum (SR) Ca(2+) stores. The results show for the first time that the E-C coupling properties of hESC-CM differ from the adult myocardium, probably due to immature SR function. Based on these findings, genetic manipulation of hESC-CM toward the adult myocardium should be considered.
通过心脏细胞移植使病变心肌再生是一种有吸引力的治疗方式。然而，由于移植的心肌细胞应在病变心肌内实现功能整合，其特性最好与宿主心肌细胞相似。为了确定人胚胎干细胞衍生的心肌细胞（hESC-CM）对宿主心肌的功能适应性，作者研究了兴奋-收缩（E-C）偶联以及对常见生理刺激的反应性。主要发现如下：（1）hESC-CM对电起搏反应迅速，并产生相应的细胞内钙离子浓度（Ca(2+)）瞬变（通过fura-2荧光测量）和收缩（通过视频边缘检测器测量）。（2）与成熟心肌不同，hESC-CM呈现负性力-频率关系。（3）hESC-CM的收缩依赖于细胞外钙离子浓度（Ca(2+)），并被维拉帕米阻断。（4）令人惊讶的是，ryanodine、肌浆网-内质网Ca(2+)-ATP酶抑制剂毒胡萝卜素和咖啡因并不影响Ca(2+)瞬变或收缩。总体而言，这些结果表明在45至60天的发育阶段，收缩很大程度上依赖于Ca(2+)而非肌浆网（SR）的钙离子储存。研究结果首次表明hESC-CM的E-C偶联特性与成年心肌不同，这可能是由于SR功能不成熟所致。基于这些发现，应考虑对hESC-CM进行向成年心肌方向的基因操作。
