Fig. 4: EC proliferation in vitro.

a Representative photographs of EC colonies. 5 × 10³ ECs isolated from each organ as indicated were cultured on OP9 feeder cells for 10 days and stained with anti-CD31 antibody. Scale bar, 3 mm (low-power field) and 200 μm (high-power field). The mean vascular area generated by ECs from each organ (n = 5 per group) was quantified. Data are presented as mean ± SEM. b Representative photographs of EC colonies. 5 × 10³ ECs isolated from each organ as indicated were cultured with or without (control) fetal brain cells on OP9 feeder cells for 10 days and stained with anti-CD31 antibody. Scale bar, 3 mm (low-power field) and 200 μm (high-power field). The mean vascular area generated by ECs from each organ (n = 5 per group) was evaluated. The vascular area with brain cells was compared to that without (control) brain cells. Data are presented as mean ± SEM. c Representative photographs of EC colonies. 5 × 10³ ECs isolated from each organ as indicated were cultured with or without (control) the culture supernatant of fetal brain cells on OP9 feeder cells for 10 days and stained with anti-CD31 antibody (d). Scale bar, 3 mm. The mean vascular area generated by ECs from each organ (n = 5 per group) was evaluated. The vascular area with the culture supernatant of brain cells were compared to that without supernatant. Data are presented as mean ± SEM. d Representative photographs of EC colonies. 5 × 10³ ECs isolated from each organ as indicated were cultured with or without (control) astrocytes from fetal brain cells on OP9 feeder cells for 10 days and stained with anti-CD31 antibody. Scale bar, 3 mm. The mean vascular area generated by ECs from each organ (n = 5 per group) was evaluated. The vascular area generated with astrocytes were compared to that without astrocytes. Data are presented as mean ± SEM. **, P < 0.01; ***, P < 0.001; ****, P < 0.0001; ns not significant. EC endothelial cell.