Fig. 4: LncBAR overexpression enhances cardiomyocyte proliferation after AR injury.

a Schematic depiction of AR experiments. Adeno-associated virus serotype 9 (AAV9) with LncBAR overexpression driven by cardiac specific promoter cTnT (AAV9-cTnT-LncBAR) or control virus expressing GFP (AAV9-cTnT-GFP) were intramyocardially injected into the neonatal mice hearts. The PBS group was used as a non-viral control. AR surgery was performed at P8, echo and histology samples were collected at AR7 and AR21. b Quantification analysis of the transduction efficiency of adeno-associated viruses by the percentage of GFP+ cells. Scale bars, 200 µm. c RT-qPCR analysis showing the expression level of LncBAR in hearts receiving AAV9-cTnT-LncBAR virus. AAV9-cTnT-GFP injected hearts were used as control. PBS injected hearts were used as non-viral control (n = 5 mice). Representative confocal z-stack images and quantification of Ki67+ cTnT+ CMs (d), and pH3+ cTnT+ CMs (e) in the cryosection of apex zone of hearts receiving AAV9-cTnT-LncBAR or AAV9-cTnT-GFP or PBS injection at AR7. White arrows indicate proliferating CMs (n = 15 fields, 3 mice/group). Scale bars, 20 µm. Masson’s trichrome staining and quantification of cardiac fibrosis in heart sagittal sections from AAV9-cTnT-LncBAR, AAV9-cTnT-GFP and PBS mice at AR7 (f) and AR21 (g) (n = 5 mice). Scale bars, 1 mm. h Echocardiography assessing left ventricular function at AR21 in mice treated with AAV9-cTnT-LncBAR, AAV9-cTnT-GFP, or PBS. Quantification of left ventricular ejection fraction (i) and fractional shortening (j) at 3 weeks after AR in AAV9-cTnT-LncBAR and control mice (n = 3 mice for sham groups and n = 5 mice for AR groups). Data are presented as mean ± SEM. Statistical significance was determined by one-way or two-way ANOVA with Tukey’s multiple comparisons test. **P < 0.01, ***P < 0.001.