Increased Hemodynamic Load in Early Embryonic Stages Alters Endocardial to Mesenchymal Transition

Abstract

Normal blood flow is essential for proper heart formation during embryonic development, as abnormal hemodynamic load (blood pressure and shear stress) results in cardiac defects seen in congenital heart disease. However, the progressive detrimental remodeling processes that relate altered blood flow to cardiac defects remain unclear. Endothelial–mesenchymal cell transition is one of the many complex developmental events involved in transforming the early embryonic outflow tract into the aorta, pulmonary trunk, interventricular septum, and semilunar valves. This study elucidated the effects of increased hemodynamic load on endothelial–mesenchymal transition remodeling of the outflow tract cushions in vivo. Outflow tract banding was used to increase hemodynamic load in the chicken embryo heart between Hamburger and Hamilton stages 18 and 24. Increased hemodynamic load induced increased cell density in outflow tract cushions, fewer cells along the endocardial lining, endocardium junction disruption, and altered periostin expression as measured by confocal microscopy analysis. In addition, 3D focused ion beam scanning electron microscopy analysis determined that a portion of endocardial cells adopted a migratory shape after outflow tract banding that is more irregular, elongated, and with extensive cellular projections compared to normal cells. Proteomic mass-spectrometry analysis quantified altered protein composition after banding that is consistent with a more active stage of endothelial–mesenchymal transition. Outflow tract banding enhances the endothelial–mesenchymal transition phenotype during formation of the outflow tract cushions, suggesting that endothelial–mesenchymal transition is a critical developmental process that when disturbed by altered blood flow gives rise to cardiac malformation and defects.

Removing vessel constriction on the embryonic heart results in changes in valve gene expression, morphology, and hemodynamics

“…As stated earlier, several studies have reported the fact that perturbation of hemodynamics in the embryonic heart leads to a spectrum of congenital heart / valve defects (Hu and Clark, 1989; Hogers et al, 1997; Hogers et al, 1999; Reckova et al, 2003; Stekelenburg-de et al, 2003; Lucitti et al, 2005; Menon et al, 2015; Ford et al, 2017; Midgett et al, 2017). We recently showed that altering intracardiac hemodynamics by partial OFT constriction via banding, has consequences at the cellular and genetic level (Menon et al, 2015).…”

“…This fact is well documented by numerous studies, which demonstrate that altering hemodynamics through the developing heart, leads to a spectrum of congenital heart defects (Hu and Clark, 1989; Hogers et al, 1997; Hogers et al, 1999; Hove et al, 2003; Reckova et al, 2003; Stekelenburg-de et al, 2003; Lucitti et al, 2005; Menon et al, 2015; Ford et al, 2017; Midgett et al, 2017). Our laboratory recently reported on the genetic / cellular consequences of altering hemodynamics by increasing shear stress by banding in the embryonic chick heart (Menon et al, 2015); adding to the growing body of research that emphasizes the importance of maintaining normal hemodynamics during development.…”

Contractile and hemodynamic forces coordinate Notch1b-mediated outflow tract valve formation

“…Further increases in contractility and WSS led to valve leaflet hyperplasia, in part mediated by increased endocardial differentiation into valve-forming cells via EndoMT ( Figure 6). Rugonyi et al showed that cardiac contractility and hemodynamic load increase EndoMT in the OFT of developing chick embryos (33). Butcher and Merryman et al further demonstrated shear stress-and myocardial contractility-mediated EndoMT in vitro (34,35).…”

Stem Cell Therapy of Myocardial Infarction: A Promising Opportunity in Bioengineering

“…Midgett et al. also found that altered hemodynamics leads to changes in the myofibrils and reorganization of mitochondria in the cardiac outflow tract of chicken embryos . Rogers et al used a biomimetic cardiac tissue model to adapt hiPSC‐derived CMs to physiological hemodynamic loads.…”