Figure 1
From: Cardiac Pacemaker Cells Generate Cardiomyocytes from Fibroblasts in Long-Term Cultures
Emergence of synchronised and spontaneously beating cell clusters and their expansion during culture of adult sinoatrial node cells (SANCs). (A) Typical phase-contrast images of a SANC and its surrounding area after culture for 1 (a), 2 (b) and 3 weeks (c); a synchronised cell cluster with spontaneous beating was formed around the SANC by 1 week of culture (a). Continued culture resulted in gradual expansion of cell cluster sizes (b,c). Spontaneously beating clusters are outlined with white; bar, 100 µm. (B) Time course of the growth of beating cell clusters; a) total beating areas in the culture dish, (b) average areas of the clusters and (c) numbers of clusters in the culture dish; values are expressed as the mean ± standard errors of the mean (S.E.M.; n = 25). Vertical bars denote S.E.M.; Tukey’s test; *P < 0.05, ***P < 0.001. (C) Typical cell images were taken from time-lapse video recordings of morphological changes in SANCs and their surrounding areas during culture for 2–284 h. (a) Spontaneous beating of SANCs was maintained despite partial shrinking at 2 h after starting the culture. (b–e) Fusing of 2 adjacent SANCs was observed occasionally between 12 and 84 h in culture. Migration of fibroblast-like cells started at around 84 h. (f) A spontaneously beating cell cluster had formed and had markedly expanded by 284 h of culture. Beating cells (arrow heads) in cell clusters exhibited distinct morphology compared with neighbouring fibroblast-like flat cells that were outside the beating cluster (thin arrows); bar, 50 µm.
