Figure 1.

hIPSC-Derived CSs

(A) Immunostained images of differentiated human induced pluripotent stem sell (hiPSC)–derived cardiomyocytes (CMs) before metabolic selection. (B) Immunostained images of differentiated hiPSC-derived CMs after metabolic selection. Note that most of the cells are α-actinin–positive CMs. Scale bars represent 200 μm in upper panels and 100 μm in lower panels. (C) hiPSC-derived CMs are positive for MLC2a (myosin light chain 2a), indicating immature CMs, at day 21 (upper panel). Most of purified hiPSC-derived CMs become positive for MLC2v, indicating ventricular CMs, at 50 days (lower panel). Scale bars represent 100 μm. (D) Differentiation efficiency is ∼80%. (E) After purification, the proportion of cardiac troponin T–positive CMs is >98%. (F) Cardiac spheroids (CSs) are generated from hiPSC-derived CMs in microwell plates. (G) Systolic and diastolic movements of beating CMs are analyzed by Cell Motion Imaging System SI8000. Stimulation of β-adrenoreceptor significantly increased the beats rate of hiPSC-derived CSs (p < 0.001) (n = 5). ∗∗ p < 0.01.