Extracellular Vesicles from Human Cardiac Fibroblasts Modulate Calcium Cycling in Human Stem Cell-Derived...

Area of Science:

• Cardiovascular Biology
• Cellular and Molecular Medicine
• Extracellular Vesicles Research

Background:

• Cardiac fibroblasts are crucial in regulating cardiomyocyte phenotype and cardiac remodeling during disease.
• Cardiomyocyte calcium (Ca2+) cycling is fundamental to cardiac function and is altered in various heart conditions.
• The role of fibroblast-secreted extracellular vesicles (EVs) in modulating cardiomyocyte Ca2+ handling remains largely unexplored.

Purpose of the Study:

• To investigate the impact of extracellular vesicles (EVs) secreted by human cardiac fibroblasts on cardiomyocyte Ca2+ cycling.
• To determine if fibroblast-derived EVs can alter fundamental Ca2+ handling mechanisms in cardiomyocytes.

Main Methods:

• Human cardiac ventricular fibroblasts were cultured, and their secreted extracellular vesicles (EVs) were purified using centrifugation, ultrafiltration, and size-exclusion chromatography.
• EVs were characterized using dot blot analysis and electron microscopy to confirm their presence and phenotype.
• Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were treated with purified fibroblast-secreted EVs, and intracellular Ca2+ transients were analyzed.

Main Results:

• Purified fibroblast-secreted EVs exhibited a characteristic EV phenotype with specific markers (CD9, CD63, CD81) identified.
• Treatment with fibroblast-secreted EVs led to a significant abbreviation in the time to peak and time to 50% decay of Ca2+ transients in hiPSC-CMs compared to controls.
• EV fractions were separated from soluble contaminating proteins, ensuring the observed effects were attributable to the EVs themselves.

Conclusions:

• Extracellular vesicles (EVs) secreted by human cardiac fibroblasts are novel mediators of fibroblast-cardiomyocyte interactions.
• Fibroblast-derived EVs enhance the efficiency of Ca2+ handling in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs).
• This study reveals a new mechanism by which cardiac fibroblasts influence cardiomyocyte function, with potential implications for understanding and treating cardiac diseases.