Early postnatal cardiac stress does not influence ventricular cardiomyocyte cell-cycle withdrawal

Congenital heart disease (CHD) is the most common birth defect. After birth, patients with CHD may suffer from cardiac stress resulting from abnormal loading conditions. However, it is not known how this cardiac burden influences postnatal development and adaptation of the ventricles. To study the transcriptional and cell-cycle response of neonatal cardiomyocytes to cardiac stress, we used a genetic mouse model that develops left ventricular volume overload within 2 weeks after birth. The increased volume load caused upregulation of the cardiac stress marker Nppa in the left ventricle and interventricular septum as early as 12 days after birth. Transcriptome analysis revealed that cardiac stress induced the expression of cell-cycle genes. This did not influence postnatal cell-cycle withdrawal of cardiomyocytes and other cell types in the ventricles as measured by Ki-67 immunostaining.