Figure 4.

Observation of double-layered human iPS cell-derived cardiac cell sheets by optical coherence tomography (OCT). At 15 min cultivation after centrifugation, while the double-layered cardiac cell sheets did not continuously beat synchronously ((a-1) and (a-3)), the occasional synchronous beating was detected in the cell sheets (a-2). However, within 45 min cultivation, the cardiac cell sheets beat synchronously ((b-1)–(b-6)). Beating areas within the cell sheet are shown with green colors. The time-intervals between (a-1) and (a-3) or (b-1) and (b-6) were 4 s or 1 s, respectively. Three experiments were performed independently and all of them showed similar results. The other two double-layered cardiac cell sheets also synchronized within 45 min after centrifugation. An OCT system (IVS-2000) was used in this study.