Heart Study Adds Promise to Heart Tissue Engineering

McGill University investigators have published research that may aid in the study of heart diseases and contribute to the engineering of artificial heart tissue.

The research, published in the Proceedings of the National Academy of Sciences (PNAS), reveals that heart wall myofibers are packed together to form a special minimal surface, the generalized helicoid. They also found that this minimal surface structure can be maintained as the heart beats.

“Current models of myofiber orientation across the heart wall show that they are grouped into sheets or bands, but the precise geometry of bundles of myofibers is unknown,” explain the researchers.

To investigate further, Kaleem Siddiqui and co-investigators used a combination of computer modeling and diffusion tensor magnetic resonance imaging (DTMRI) to reveal the way that the fibers are orientated. They tested their model against DTMRI data from three different mammals: rat, dog, and human.

The researchers report that heart wall myofibers are packed together, while maintaining their helical form, via a unique structural arrangement in which they bundle into a special surface, a generalized helicoid. This model held true across the three species tested.

Their findings also reveal an additional purpose of the generalized helicoid organization; it allows for wall stiffness to be equalized in the plane approximately tangent to the heart wall, giving it mechanical strength.

“You can think of it as analysing a clump of hair instead of an individual strand,” explained Siddiqui. “We’ve discovered that the clump bends and twists in the form of a particular minimal surface, the generalized helicoid – and this is true across species. It’s not particular to just one mammal. The implications of these findings are broad.”

The researchers say that, in tissue bioengineering, understanding the basic structural properties of heart wall myofibers is fundamental. “Their higher-order structural arrangement in generalized helicoids is likely to find application in the design of scaffolds for artificial heart muscle growth,” they say.

Furthermore, the knowledge could be used to help understand the relationship between individual fibers and their laminar organization into sheets, and could aid in the study of myocardial infarction or other heart pathologies that rearrange fiber geometry, the researchers conclude.

By Nikki Withers