Pressure overload induces early morphological changes in the heart

Area of Science:

• Cardiovascular Biology
• Cardiac Physiology
• Pathology

Background:

• Cardiac hypertrophy, both pathological and physiological, causes significant heart changes.
• Early physiological hypertrophy's morphological and physiological shifts are understudied.
• Pathological hypertrophy events are better documented than early physiological changes.

Purpose of the Study:

• To define acute cardiac remodeling events following transverse aortic constriction (TAC).
• To track temporal changes in hypertrophy, collagen, capillary density, and cell populations.
• To understand the rapid morphological and physiological adaptations in the early stages of cardiac hypertrophy.

Main Methods:

• Induction of cardiac hypertrophy via transverse aortic constriction (TAC) in mice.
• Assessment of cardiac remodeling using heart weight, myocyte width, and wall thickness.
• Analysis of collagen deposition (Picrosirius staining), cell populations (immunostaining, flow cytometry), and capillary density.

Main Results:

• Cardiac hypertrophy was detected by day 2 and peaked by day 7 post-TAC.
• Increased collagen deposition and fibroblast populations were observed by day 7.
• Capillary density decreased at day 2 but recovered by day 7, with increased pericytes noted at day 2.
• Gene expression indicated coordinated responses in growth, extracellular matrix, and angiogenic factors.

Conclusions:

• Morphological changes in response to cardiovascular injury occur rapidly.
• Early cardiac hypertrophy involves swift remodeling, including fibroblast proliferation and collagen deposition.
• Pericytes may play a role in the angiogenic transition during early cardiac hypertrophy.