Fig. 5

Ccn2a promotes cardiomyocyte proliferation and heart regeneration post-injury. (A) Schematic of the experimental procedures. Post-cryoinjury, wild-type and ccn2a-overexpressing transgenic animals were subjected to daily 1 h heat shock. CM proliferation was assessed at 7 dpci and scarring at 30 dpci. (B) Representative maximum intensity projections of confocal images of 10 μm sagittal cryosections of 7 dpci heart expressing DsRed in CM nuclei, immunostained for EGFP (cyan; marks cells expressing ectopic Ccn2a), stained for EdU (yellow; marks proliferating cells) and stained with DAPI (white; marks all nuclei). Arrowheads indicate EdU+/DsRed+ cells. (C) CM proliferation quantified in wild-type and ccn2a-overexpressing (hsp70:ctgfa) hearts at 7 dpci (n=8 each). At least two sagittal sections of each heart were analyzed for quantification. (D) Representative bright-field images of 12 μm sagittal paraffin sections of 30 dpci wild-type and hsp70:ctgfa hearts stained with AFOG (muscle, yellowish red; fibrin, brick red; collagen, blue). (E) Semi-quantitative analysis of scarring in wild-type and ccn2a-overexpressing (hsp70:ctgfa) hearts at 30 dpci (n=7 each). The histological section with the largest area covered by collagen in each heart was considered for scar quantification. Color-coded bar chart indicates degree of regeneration: green, complete; blue, moderate; red, very poor. Data indicate the percentage of total hearts represented by each score and the statistical significance of differences was evaluated by a wound-recovery χ2 test. (F) Dot plot shows highest area covered by collagenous scar on a tissue section from each heart. Data are mean±s.e.m. in C,F.