TGFB1 and persistent truncus arteriosus: Previous studies have demonstrated chronic vascular leakage in the heart after pressure-overload, due to weakening of the blood vascular barrier mediated by TGF-β-induced downregulation of claudin-5 in vascular endothelium.25 In agreement, in our study, at 8 weeks post-TAC, there was increased myocardial vascular permeability, notably in Balb/c mice (see Supplementary material online, Figure S9a), as determined using immunohistochemical detection of extravasated fibrinogen.