Equal force generation potential of trabecular and compact wall ventricular cardiomyocytes

Area of Science:

• Cardiovascular Development
• Developmental Biology
• Cardiac Anatomy

Background:

• The embryonic ventricular wall primarily consists of trabecular myocardium.
• It was previously hypothesized that fetal compaction transforms weaker trabecular myocardium into stronger compact myocardium.

Purpose of the Study:

• To investigate the mechanisms driving ventricular wall morphogenesis.
• To determine whether myocardial compaction or differential growth shapes the fetal heart.
• To compare the force-generating capacity and protein expression of trabecular and compact myocardium.

Main Methods:

• Analysis of developmental series of human, mouse, and chicken embryos and fetuses.
• Comparative assessment of cardiomyocyte force generation in mice.
• Immunohistochemical analysis of vascular, mitochondrial, and sarcomeric proteins in human myocardium.

Main Results:

• Ventricular morphogenesis is driven by differential growth rates between trabecular and compact layers, not compaction.
• Adult mouse cardiomyocytes from both layers exhibit equal force-generating capacity.
• Human trabecular and compact myocardium show no significant differences in key protein abundance, even in cases of excessive trabeculation.

Conclusions:

• The proportions of trabecular and compact myocardium are established by differential growth, not compaction.
• Both myocardial types are equally capable of force production.
• This finding applies to normal development and congenital malformations like excessive trabeculation.