Altered haemodynamics causes aberrations in the epicardium

Area of Science:

• Developmental Biology
• Cardiovascular Research
• Embryology

Background:

• The epicardium is crucial for heart development, contributing cells for cardiac formation.
• While a heartbeat is known to be essential for epicardium formation, the impact of hemodynamic changes remains unexplored.
• Congenital heart defects often have unknown etiologies, suggesting potential environmental influences like altered hemodynamics.

Purpose of the Study:

• To investigate the effects of altered hemodynamics on epicardium development and function.
• To explore the potential role of hemodynamic changes in the etiology of congenital heart defects.

Main Methods:

• Outflow tract (OFT) banding was performed on chick embryos (HH21) to alter heart hemodynamics.
• Epicardial morphology and function were assessed using various techniques at different developmental stages (HH29, HH35).
• Gene expression analysis focused on extracellular matrix (ECM) related genes.

Main Results:

• Altered hemodynamics led to abnormal epicardial morphology by HH29, despite normal cell migration.
• Severe changes in ECM structure and differential expression of ECM genes (e.g., DDR2, collagen XII, collagen I, TCF21) were observed.
• Epicardial thinning at HH35 suggested increased tension, indicating a direct impact of blood flow on the epicardium.

Conclusions:

• Altered hemodynamics significantly impact epicardial structure and molecular expression during embryonic heart development.
• These findings provide a potential mechanistic link between hemodynamic alterations and congenital heart defects.
• The epicardium's sensitivity to blood flow highlights its importance in normal cardiogenesis.