Browsing by Author "Dusting, Gregory"

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    Electrical Stimulation Promotes Cardiac Differentiation of Human Induced Pluripotent Stem Cells
    (Hindawi Publishing Corporation, 2016) Hernandez, Damian; Millard, Rodney; Sivakumaran, Priyadharshini; Wong, Raymond; Crombi, Duncan; Hewitt, Alex; Liang, Helena; Hung, Sandy; Pebay, Alice; Shepherd, Robert; Dusting, Gregory; Lim, Shiang
    Background.Human induced pluripotent stemcells (iPSCs) are an attractive source of cardiomyocytes for cardiac repair and regeneration. In this study, we aim to determine whether acute electrical stimulation of human iPSCs can promote their differentiation to cardiomyocytes. Methods. Human iPSCs were differentiated to cardiac cells by forming embryoid bodies (EBs) for 5 days. EBs were then subjected to brief electrical stimulation and plated down for 14 days. Results. In iPS(Foreskin)-2 cell line, brief electrical stimulation at 65mV/mm or 200mV/mm for 5 min significantly increased the percentage of beating EBs present by day 14 after plating. Acute electrical stimulation also significantly increased the cardiac gene expression of ACTC1, TNNT2, MYH7, and MYL7. However, the cardiogenic effect of electrical stimulation was not reproducible in another iPS cell line,CERA007c6. Beating EBs from control and electrically stimulated groups expressed various cardiac-specific transcription factors and contractile muscle markers. Beating EBs were also shown to cycle calcium and were responsive to the chronotropic agents, isoproterenol and carbamylcholine, in a concentration-dependent manner. Conclusions. Our results demonstrate that brief electrical stimulation can promote cardiac differentiation of human iPS cells.The cardiogenic effect of brief electrical stimulation is dependent on the cell line used.
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    Influence of continuous electrical stimulation on development of human cardiomyocytes from induced pluripotent stem cells
    (Conditioning Medicine, 2018-11) Hernandez, Damian; Millard, Rodney; Sivakumaran, Priyadharshini; Kong, Anne; Mitchell, Geraldine; Pebay, Alice; Shepherd, Robert; Dusting, Gregory; Lim, Shiang
    Regeneration of cardiac tissue remains an ideal approach to restore cardiac function after myocardial infarction. The ability of human induced pluripotent stem cells (iPSCs) to differentiate into bona fide cardiomyocytes also provides a platform for cardiac disease modeling, drug discovery and pharmacological safety testing of new drugs. One of the major limitations for the use of cardiomyocytes derived from iPSCs is that they resemble fetal cardiomyocytes and are immature compared to adult cardiomyocytes. Considering that the developing heart grows in an electric field, we investigated whether electrical stimulation can promote maturation of cardiomyocytes derived from human iPSCs. Two-dimensional cultures of immature cardiomyocytes at day 22 post-differentiation were subjected to continuous electrical stimulation at 200 mV/mm for 7 days using a custom-made electrical stimulator. This long-term electrical stimulation significantly increased the percentage of cardiomyocytes with organized sarcomeres and promoted alignment of cardiomyocytes parallel to the electric field. Electrical stimulation also decreased the circularity index of cardiomyocytes suggesting a more rod-like morphology. In conclusion, long-term continuous electrical stimulation promotes maturation of cardiomyocytes derived from human iPSCs. Mature cardiomyocytes can better recapitulate the pathophysiological conditions of the human heart for more accurate disease modeling and drug testing. Mature cardiomyocytes can also provide a substrate for cardiac regeneration and repair by tissue engineering in the future.