Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) made an invigorating discovery that cells can not only be revived after a heart attack, but they can also still function under low oxygen levels in the event of a heart attack. Using embedded sensors that track heart tissue contractions, studies found “travelers” that are the reason for this life-saving revelation.

Heart attacks are widely known as one of the main causes of death here in America. They occur when blood flow to the heart is blocked. Restoring blood flow was the original solution to a heart attack, but it’s now found that it may cause more damage to the cells in the heart.

The travelers that these researchers discovered are known as EEVs (endothelial-derived extracellular vessels) and were the main focus of the research. They are found within the epithelial cells, which line the surface of blood vessels and are much easier to maintain than stem cells. They are also found within heart tissue and have the ability to “sense” inadequate blood supply. Since they’re derived from heart tissue, researchers hypothesized that they could provide direct protection to the cardiac muscle.

The researchers found that in tissues treated with EEVs, cardiac muscle cells could better adapt to stress conditions and sustain a higher workload. The researchers induced injury to the tissue by three hours of oxygen restrictions, followed by 90 minutes of reoxygenation, and then measured the fraction of dead cells and the contractile force of the tissue. The heart tissue treated with EEVs had half as many dead cells and had a contractile force four times higher than the untreated tissue after injury.

The research was co-authored by Johan U. Lind, a former postdoctoral fellow at SEAS and current Assistant Professor at the University of Copenhagen, Denmark; Herdeline Ann M. Ardoña, a former postdoctoral fellow at SEAS and current Assistant Professor at the University of California Irvine; Sean P. Sheehy, Lauren E. Dickinson, Feyisayo Eweje, Maartje M.C. Bastings, Benjamin Pope, Blakely B. O’Connor, Juerg R. Straubhaar and Bogdan Budnik.