Fig. 6
Enhanced toxicity readouts were observed in T transfected cells. (A) Calcium transients were optically mapped using Fluo-4 staining of cells in the presence or absence of 1 μM doxorubicin in DMSO with an external field stimulation of 1 Hz 35 d after differentiation. T transfection led to calcium transients with greater amplitudes (B) and shorter transient duration width70 (C) with concomitant augmentation of maximum transient upstroke velocity (D) and minimum transient relaxation velocity (E). Cells primed with T showed amplified response to doxorubicin manifesting as an exaggerated calcium transient width70 prolongation (F), greater reduction in transient amplitude (G), and maximum slope decline (H) compared to untransfected cells. To account for differences in maturity, the percent Δ for each parameter was calculated as the percent difference between each cell and the mean of the unexposed doxorubicin cells for each group. I) Propidium iodide staining showed similar dose dependent decline in cell viability with increasing doxorubicin concentration. T + CHIR denotes cells transfected with T that undergo biphasic Wnt modulation for cardiac differentiation. CHIR denotes untransfected cells that are differentiated with Wnt modulation. *p < 0.05, **p < 0.01, ***p < 0.001.
