Extended Data Fig. 1: Representative images showing cardiomyocyte proliferation after in vitro treatment with regenerative growth factors, as determined by BrdU incorporation assay.

Cardiomyocytes were identified by cardiac Troponin I (cTnI) staining and analysed by immunofluorescence for DNA synthesis (BrdU incorporation assay). White arrows point to proliferating cardiomyocytes; scale bars 50 μm.