Mechano-genetics of the cardiac development in embryonic medaka

Cardiovascular morphogenesis during embryonic development is influenced by the interplay between mechanical forces sensed by endothelial cells and the subsequent genetic response. A perturbation to this mechano-genetic interplay would lead to cardiovascular malformations. To investigate the hemodynamic cues that lead to altered gene expressions, we conduct a qPCR analysis on synthesized cDNA from medaka embryos starting at 12 hours post fertilization (hpf) to 12 days post fertilization (dpf). Five genes (FGF8, BMP4, NKX2.5, SMYD1 and HOX6b6) that contribute to early cardiac development were investigated. Concomitantly, the embryonic heart was imaged under a microscope from 3 dpf (after onset of circulation) to 14 dpf. PIV analysis was conducted on the images to calculate the velocity fields in the heart by cross-correlating red blood cell patterns. Hemodynamic metrics like flow velocity magnitude, pressure drop across ventricle, wall shear stress and cardiac wall strain were quantified and correlated to the gene expression in each dpf. This integrated mechano-genetic framework will further enhance knowledge about the developmental biology of the species.