Shradhanjali Akankshya, Riehl Brandon D, Lee Jeong Soon, Ha Ligyeom, Lim Jung Yul
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588, USA; The Graduate School of Dentistry, Kyung Hee University, Seoul, South Korea.
Biochem Biophys Res Commun. 2017 Jul 8;488(4):590-595. doi: 10.1016/j.bbrc.2017.05.092. Epub 2017 May 17.
The cardiac milieu is mechanically active with spontaneous contraction beginning from early development and persistent through maturation and homeostasis, suggesting that mechanical loading may provide a biomimetic myocardial developmental signal. In this study, we tested the role of cyclic mechanical stretch loading in the cardiomyogenesis of pluripotent murine embryonic (P19) stem cells. A Flexcell tension system was utilized to apply equiaxial stretch (12% strain, 1.25 Hz frequency) to P19 cell-derived embryoid bodies (EBs). Interestingly, while control EBs without any further stimulation did not exhibit cardiomyogenesis, stretch stimulation alone could induce P19-derived EBs to become spontaneously beating cardiomyocytes (CMs). The beating colony number, average contracting area, and beating rate, as quantified by video capturing and framed image analysis, were even increased for stretch alone case relative to those from known biochemical induction with 5-Azacytidine (5-Aza). Key CM differentiation markers, GATA4 and Troponin T, could also be detected for the stretch alone sample at comparable levels as with 5-Aza treatment. Stretch and 5-Aza co-stimulation produced in general synergistic effects in CM developments. Combined data suggest that stretch loading may serve as a potent trigger to induce functional CM development in both beating dynamics and genomic development, which is still a challenge for myocardial regenerative medicine.
心脏环境具有机械活性，从早期发育开始就有自发收缩，并持续到成熟和稳态，这表明机械负荷可能提供一种仿生的心肌发育信号。在本研究中，我们测试了周期性机械拉伸负荷在多能小鼠胚胎（P19）干细胞心肌生成中的作用。利用Flexcell张力系统对P19细胞来源的胚状体（EBs）施加等轴拉伸（12%应变，1.25Hz频率）。有趣的是，未经任何进一步刺激的对照EBs未表现出心肌生成，而仅拉伸刺激就能诱导P19来源的EBs成为自发跳动的心肌细胞（CMs）。通过视频捕获和帧图像分析量化，仅拉伸组的跳动集落数、平均收缩面积和跳动率相对于用5-氮杂胞苷（5-Aza）进行的已知生化诱导组甚至有所增加。仅拉伸样本中也能检测到关键的CM分化标志物GATA4和肌钙蛋白T，其水平与5-Aza处理相当。拉伸和5-Aza共同刺激在CM发育中总体上产生协同效应。综合数据表明，拉伸负荷可能是诱导功能性CM在跳动动力学和基因组发育方面发育的有效触发因素，这对心肌再生医学来说仍然是一个挑战。
