Fig. 6: Kyn promotes CM proliferation and cardiac microvascular endothelial cell (CMEC) angiogenesis in vitro on co-culture of CMs and CMECs.

a The experimental procedure for co-culturing primary CMs and CMECs. b–d Kyn concentrations in CMs, CMEC medium, and CMECs detected by HPLC. Relative (Rel.) Kyn concentrations was set as 1 at 0-h group in b (n = 3/group. ***P < 0.001 compared to 0-h group by one-way ANOVA followed by Tukey’s multiple comparisons), and at 24 h group in c, d (n = 4/group in c; n = 3/group in d). *P < 0.05, **P < 0.01, ***P < 0.001 compared to 24-h group by one-way ANOVA followed by Tukey’s multiple comparisons. e Co-immunostaining and quantification of the location and expression of IDO1, AHR, YAP, and KI67 in CMs (TNT staining) treated with IFNγ (50 µM) for 24 h. Bar = 20 µm in e. f–h Representative images and quantification of co-immunostaining of AHR and VEGFA. Rel. IDO1 immunostaining intensity was set as 1 in Control (Ctrl) group. Bar = 50 µm in f, 500 µm in i, and 200 µm in l. i–k Tube formation of CMECs co-cultured with CMs and pretreated with IFNγ. l–m Migration of CMECs co-cultured with CMs and pretreated with IFNγ. *P < 0.05, **P < 0.01, ***P < 0.001, ^# P < 0.05 compared to Ctrl by one-way ANOVA followed by Tukey’s multiple comparisons in e–m (n = 4/group). Data are mean ± SD.