The heart maintains a careful balancing act; too soft and it won't pump blood, but too hard and it will overtax itself and stop entirely. There is an optimal amount of strain that a beating heart can generate and still beat at its usual rate, once per second.
In a study published in the journal Current Biology, researchers at the University of Pennsylvania have shown that this "sweet spot" depends on the stiffness of the collagen framework that the heart's cells live within. They also have shown that the other biophysical factors that contribute to the strength of the heartbeat adjust alongside the natural stiffening of collagen during embryonic development, keeping the growing heart in this optimal zone.
Taking into account the role that this collagen matrix plays in the optimal heartbeat could help cardiologists repair tissue after a heart attack, where scarring stiffens the heart's collagen.
"If we can understand more clearly the effects on cells of normal and damaged collagen frameworks, then we can develop better treatments for the frameworks as well as the cells within," said Dennis Discher, professor in the Department of Chemical and Biomolecular Engineering in the School of Engineering and Applied Science.
Discher and lead author Stephanie Majkut, a member of his lab and a doctoral candidate in the Department of Physics and Astronomy in Penn's School of Arts and Sciences, conducted the study along with other members of Discher's lab, Joe Swift and Christine Krieger. They collaborated with physics professor Andrea Liu and Timon Idema, a member of her lab.
The study's experiments were conducted on embryonic chick hearts, which are anatomically similar to human hearts during early development. The researchers chemically treated the beating hearts to either stiffen or soften the collagen matrix surrounding the cells. The treatment made it either harder or easier for the cell's molecular motors, proteins
|Contact: Evan Lerner|
University of Pennsylvania