Figure 5.

Visualization of regional Ca²⁺ synchronization in IPS-CM clusters. (A) A brightfield image of a typical IPS-CM cluster in a B-area overlaid with the corresponding fluo4-loaded image. (B) The regional Ca²⁺ synchronization map corresponding to the B-area of IPS-CM depicted in (A). The map is generated from the temporal correlation of Ca²⁺ spikes across the B-area (0.021 mm²) following its sub-division into a 7 × 7 grid of C-areas (i.e., blue box, Figure 4A) as described in Section Materials and Methods. (C) Composite panel of regional Ca²⁺ synchronization in IPS-CM clusters in B-areas over the 4-week experimental matrix. The maximum Ca²⁺ synchronization determined under any condition was 34/49 C-areas (69.4%) which corresponded to a physical area of 14,571 μm². White areas represent regions of the plate devoid of IPS-CM. (D) Color-coded visualization of the mean Ca²⁺ synchronization at each time point and for each condition across the 4-week experimental protocol (Figure 1B). Data are derived from n = 3 plates per time point.