Teo Ailing, Morshedi Amir, Wang Jen-Chieh, Zhou Yufeng, Lim Mayasari
Schools of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore.
Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
J Ultrasound Med. 2017 Aug;36(8):1693-1706. doi: 10.7863/ultra.16.12042. Epub 2017 Apr 25.
Low-intensity ultrasound (LIUS) has been shown to enhance bone and cartilage regeneration from stem cells. The ease of its incorporation makes it an attractive mechanical stimulus for not only osteogenesis and chondrogenesis, but also cardiomyogenesis. However, to date, no study has investigated its effects on cardiomyogenesis from embryonic stem cells.
In this study, murine embryonic stem cells were differentiated via embryoid body formation and plating, and after 3 days they were subjected to daily 10 minutes of LIUS treatment with various conditions: (1) low-pulsed (21 mW/cm , 20% duty cycle), (2) low-continuous, (3) high-pulsed (147 mW/cm , 20% duty cycle), and (4) high-continuous LIUS.
Low-pulsed and high-continuous LIUS had improved beating rates of contractile areas as well as increased late cardiac gene expressions, such as α- and β-myosin heavy chain and cardiac troponin T, showing its benefits on cardiomyocyte differentiation. Meanwhile, an early endodermal marker, α-fetoprotein, was significantly attenuated after LIUS treatments.
With these observations, it is demonstrated that LIUS simulation could enhance cardiomyogenesis from embryonic stem cells and increase its selectivity toward cardiomyocytes by reducing spontaneous differentiation.
低强度超声（LIUS）已被证明可促进干细胞的骨和软骨再生。其易于整合的特点使其不仅成为骨生成和软骨生成，而且也是心肌生成的一种有吸引力的机械刺激。然而，迄今为止，尚无研究调查其对胚胎干细胞心肌生成的影响。
在本研究中，小鼠胚胎干细胞通过形成胚状体并接种进行分化，3天后在不同条件下每天接受10分钟的LIUS治疗：（1）低脉冲（21 mW/cm²，20%占空比），（2）低连续，（3）高脉冲（147 mW/cm²，20%占空比），以及（4）高连续LIUS。
低脉冲和高连续LIUS提高了收缩区域的搏动率，并增加了晚期心脏基因的表达，如α和β肌球蛋白重链以及心肌肌钙蛋白T，表明其对心肌细胞分化有益。同时，LIUS治疗后早期内胚层标志物甲胎蛋白显著减弱。
基于这些观察结果，证明LIUS模拟可增强胚胎干细胞的心肌生成，并通过减少自发分化提高其对心肌细胞的选择性。
