Researchers uncover healing potential of tiny particles found in the fluid that surrounds the heart

Researchers at the University of Calgary's Cumming School of Medicine have discovered that tiny particles found in the fluid that surrounds the heart—the pericardial fluid—may help protect and repair heart tissue after a heart attack.

The particles, called extracellular vesicles (EVs), are released by cells and carry a variety of biological molecules that facilitate communication between cells.

The work was co-led by Dr. Vaibhav Patel, PhD, and Dr. Paul Fedak, MD, PhD, alongside co-first-authors Dr. Ali Fatehi Hassanabad, MD, PhD'25, PGME'25; Megan Meechem, a doctoral candidate; and Dr. Anshul Jadli, PhD, a research associate at UCalgary. 

“We discovered that tiny particles in the fluid surrounding the human heart carry powerful repair signals,” says Fedak. “In an experimental model of heart attack, they reduced scarring and improved heart function, suggesting the heart may contain its own tools for healing.”

Little was previously known about how EVs affect the heart, so, to better understand their impact, the researchers isolated different-sized EVs from the pericardial fluid of patients with coronary artery disease. They then investigated whether those EVs could help protect the heart from damage. 

Researchers found the small EVs from patients with coronary artery disease had beneficial effects on endothelial cells, the cells that line blood vessels. The EVs cause the endothelial cells to grow, migrate and form new blood vessel-like structures. These changes suggest the EVs may help support blood-vessel growth and repair.

Researchers then asked whether these effects could translate to the heart after a heart attack. They found that injecting the EVs into the pericardial space of mouse models reduced scarring and improved heart function. Further analysis suggests pathways involved in promoting new blood-vessel growth, reducing scarring and limiting cell death, are behind the protective effect. 

Although more work needs to be done to validate the findings, the study is a preliminary step towards a potential therapy for various cardiovascular diseases that uses the heart’s own repair mechanisms.  

“This work is exciting, because it may lead to EV-derived therapies for patients,” says Patel. 

According to Meechem, one of the biggest advantages to working in the Patel lab is its collaborative nature. By working with clinician-researchers, the lab has access to patient samples.

“This type of collaboration is challenging, but very rewarding,” she says.

Fatehi Hassanabad agrees.

“The University of Calgary benefits from world-class field experts and cutting-edge technology,” he says. “I am proud of the significant progress we have made in this area of cardiovascular research through strong and effective collaborations.” 

This research was funded by the Libin Cardiovascular Institute’s Michael and Terry Wilson Grant, the Canadian Institutes of Health Research, Alberta Innovates, the Heart and Stroke Foundation of Canada, and the Natural Sciences and Engineering Research Council of Canada.

The results are published in Biomedicine & Pharmacotherapy.