Dynamics of Cell Generation and Turnover in the Human Heart

Area of Science:

• Cardiovascular Biology
• Cellular Dynamics
• Human Physiology

Background:

• The contribution of cell generation to physiological heart growth and maintenance in humans has been difficult to establish.
• Previous studies have yielded controversial findings regarding cell turnover in the adult human heart.

Purpose of the Study:

• To determine the lifespan cell dynamics of cardiomyocytes, endothelial cells, and mesenchymal cells in the human heart.
• To establish a comprehensive model of cell generation and turnover throughout the human lifespan.

Main Methods:

• Utilized nuclear bomb test-derived carbon-14 (14C) dating to quantify cell proliferation and turnover.
• Analyzed cell populations in myocardial tissue across various human age groups.
• Integrated data to model cell generation rates and renewal throughout life.

Main Results:

• The complete set of cardiomyocytes is established perinatally and remains stable throughout life.
• Endothelial and mesenchymal cell numbers increase significantly from birth to early adulthood.
• Endothelial cells exhibit high turnover (>15% per year) throughout life, while mesenchymal cells show limited renewal (<4% per year in adulthood).
• Cardiomyocyte exchange is highest in early childhood (<1% per year in adulthood).

Conclusions:

• Human heart growth is primarily driven by increases in endothelial and mesenchymal cells, not cardiomyocyte proliferation.
• Endothelial cells are continuously renewed throughout life, suggesting a dynamic cardiovascular system.
• The study provides a quantitative model for cell turnover in the human heart, resolving long-standing controversies.