Qiliqiangxin Capsule Modulates Calcium Transients and Calcium Sparks in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes

BACKGROUND: The therapeutic effects of Qiliqiangxin capsule (QLQX), a Chinese patent medicine, in patients with chronic heart failure are well established. However, whether QLQX modulates cardiac calcium (Ca(2+)) signals, which are crucial for the heart function, remains unclear. Aim of the Study. This study aimed to evaluate the role of QLQX in modulating Ca(2+) signals in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). MATERIALS AND METHODS: Fluorescence imaging was used to monitor Ca(2+) signals in the cytosol and nuclei of hiPSC-CMs. For Ca(2+) spark measurements, the line-scan mode of a confocal microscope was used. RESULTS: The QLQX treatment substantially decreased the frequency of spontaneous Ca(2+) transients, whereas the amplitude of Ca(2+) transients elicited by electrical stimulation did not change. QLQX increased the Ca(2+) spark frequency in both the cytosol and nuclei without changing the sarcoplasmic reticulum Ca(2+) content. Interestingly, QLQX ameliorated abnormal Ca(2+) transients in CMs differentiated from hiPSCs derived from patients with long-QT syndrome. CONCLUSIONS: Our findings provide the first line of evidence that QLQX directly modulates cardiac Ca(2+) signals in a human cardiomyocyte model.