In addition to genetic factors, epigenetic factors play a major role in cardiac morphogenesis, among which the main factor is the early contractile activity of the myocardium. At the same time, changes in hemodynamics during cardiogenesis seriously affect the development of the embryonic heart. The maturation of different myocardial cells occurs at a variable rate, and already in early embryogenesis, a distinct picture of its mosaicism is clearly revealed by the degree of differentiation of cardiomyocytes. First of all, the mosaic nature of the myocardium is manifested in the presence of its compact and trabecular zones, in which the cells differ not only in the degree of differentiation, but also in proliferative activity and sensitivity to damaging factors. Heterogeneity of the morpho-functional state of cardiomyocytes is preserved in the mature myocardium, which is manifested by the mosaic nature of its damage during total ischemia, for example, due to insufficient protection of the myocardium from ischemia during open-heart surgery. The development of the embryonic heart, especially in early cardiogenesis, is seriously affected by changes in hemodynamics and electrical forces, the latter are necessary to maintain the morphology of the cardiac chambers and can be a key epigenetic factor in cardiac remodeling.
The influence of genetic and epigenetic factors on the development of the heart and the occurrence of its anomalies is carried out through a huge number of signal molecules and morphogenetic factors. At the same time, a wide range of genetic anomalies of the heart, including intracardiac conduction disorders, ventricular septal defect, atrial septal defect, Holt–Oram syndrome, Ebstein anomaly, myocardial dysfunction and dilated cardiomyopathy can result from mutations of just one gene – TBX20. Description of the pathways regulating myocardial development in the pre- and early postnatal period, molecular factors involved in this process, as well as the flow of information on the growth, proliferation, migration, differentiation of cardiomyocytes in embryogenesis has been steadily increasing in recent years. This is due to the fact that the mechanisms regulating these phenomena are studied within the framework of rapidly developing modern regenerative medicine.
Despite the fact that the issue of the relevance of studying the mechanism of rapid switching of cardiomyocyte hyperplasia in the embryonic period to hypertrophy after birth is key in the development of methods for myocardial regeneration within the framework of regenerative medicine in case of myocardial damage in the postnatal period, the circumstances of the transition from hyperplasia to hypertrophy of cardiomyocytes after birth are so numerous and diverse that they require in-depth analysis using modern research methods to identify the key factor underlying this phenomenon, which remains unresolved to this day.
