Pressure overload greatly promotes neonatal right ventricular cardiomyocyte proliferation - a new model for heart regeneration study

Background: Current mammalian model for heart regeneration research is limited in apex amputation or myocardium infarction, both of which are controversy. Moreover, RNAseq demonstrated there were a very limited set of differential expressed genes between sham and operation heart in the myocardium infarction model. Here we investigated whether pressure overload in the right ventricle(RV), a common phenomenon in congenital heart disease children, could be a better animal model for heart regeneration study when consider cardiomyocyte(CM) proliferation as the most important index. Methods and results: Pressure overload was induced by pulmonary artery banding (PAB) on day1 and confirmed by echocardiography and hemodynamic measurements at postnatal day 7(P7). RNAseq analyses of purified RVCM at P7 from PAB and sham-operated rats revealed there were 5469 differential expressed genes between these two groups. GO and KEGG analysis showed that these genes mainly mediated mitosis and cell division. Cell proliferation assay indicates a continuous over-proliferation of RVCM after PAB, in particular for P3. In addition, there were ~2 times-fold increase of Ki67/Phh3 -positive CM in human overload RV compared to non-overload RV. Other features about this model included CM hypotrophy and no fibrosis.. Conclusions: Pressure overload profoundly promotes RVCM proliferation in the neonatal stage both in rats and human beings, activated a regeneration-specific gene program, and may offer a better alternative animal model for heart regeneration research.. Overall design: Purified rat right ventricular cardiomyocytes from Sham and PAB group were generated by deep sequencing, each group contains 6 samples, using Illumina HiSeq 2500.