First-Ever 3D Map of the Heart's Neurons

Scientists have established a new technological pipeline that enabled them to print a full 3D version of neurons in a rat's heart.

Your heart beats and pumps thanks to the body's control center telling it to — the brain. It does so thanks to an intricate network of nerves. However, when something goes wrong in this signaling system, serious issues can arise, such as cardiac arrest or heart disease. 

When this happens, the heart has another option to function, and that's by using the intracardiac nervous system (ICN) to try and correct any local problems. It's been widely unknown how the ICN functions with these roles, up until a groundbreaking study that was been published in iScience on Tuesday. 

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"The first comprehensive roadmap of the heart's nervous system"

Researchers from Thomas Jefferson University developed this phenomenal study of the heart. 

"The ICN represents a big void in our understanding that falls between neurology and cardiology," said co-senior author James Schwaber, director of the Daniel Baugh Institute for Functional Genomics and Computational Biology and co-senior author of the study. "Our goal was to bridge that gap by providing an anatomical framework of the ICN."

"The only other organ for which such a detailed high-resolution 3-D map exists is the brain," explained co-senior author Raj Vadigepalli, Professor of Pathology, Cell Biology and Anatomy. "In effect what we have created is the first comprehensive roadmap of the heart's nervous system that can be referenced by other researchers for a range of questions about the function, physiology, and connectivity of different neurons in the ICN."

The team explained they were troubleshooting into the dark as they went along with their research, as this had never yet been done. Their 3D map displayed an unknown complexity of the ICN. The researchers found a coherent band of clusters on the base of the heart (which is in fact the top), that also extends to the bottom of the left atrium on the back of the heart, near the sinoatrial node — something that was until now unknown. 

The team found more diversity as they kept looking: "We found that there are several different types of neuromodulators and receptors present," explained Dr. Vadigepalli. "This means that we don't just have neurons in the heart that shut on and off activity, but also those that can fine-tune the activity of the ICN."

Dr. Vadigepalli went on to say "Now that we know where neurons are located in relation to heart structures, we can ask questions like—does stimulating in one location, or even selectively stimulating specific neurons make a difference?" 

It's a fantastic moment in science, as a better understanding of the heart's functions will only lead to improved treatments. There's plenty more still to discover.

"Eventually the hope is to create a 3-D map for the human heart, both in health and disease," said Dr. Schwaber. "We've created the foundation for an endless possibility of future studies."