Extended Data Fig. 5: Permanent hyperplasia of the PF network and functional defects.
(a) Cntn2-positive area is measured on successive transverse sections spaced 140 µm apart. The ventricular lumen is delimitated automatically using the fluorescent background of the tissue at 21 dpi. Cntn2 staining is thresholded after a gaussian blur of 2 µm. The normalized Cntn2 area per section is expressed as the ratio of Cntn2-positive area divided by the luminal perimeter. (b) Plot showing the normalized Cntn2 area along the apico-basal axis (a-j), in Sham (Bleu) and MI (Red) as measured in (a). MI N = 19; Sh N = 17 Error bars: standard deviation. (c) Whole-mount open left ventricles six months after Sham or MI surgery in Cx40-GFP mice. Hyperplasia of the PF network is visible thanks to Cx40-GFP in all 3 MI. (d) The intermediate phenotype in regenerated heats is permanent. Transverse sections of regenerated hearts 6 months post-injury show heterogenous expression of conductive adhesion molecules (Cntn2) and fast-conducting gap junction (Cx40) in the hyperplastic PF network. White arrowheads: PFs, empty arrow heads: intermediate cells. (e) Longitudinal study of cardiac conduction system function thanks to electrocardiogram recordings in leads II at 3dpi, 9dpi, 21 dpi and 6 months post-injury. Note the recovery of the QRS amplitude following myocardium regeneration, however, ventricular conduction velocity remains slow as evidenced by prolonged QRS duration in MI compared to Sham at all stages. MI N = 5; Sh N = 5.
