The team from Thomas Jefferson University has completed the first three-dimensional map of neurons in the human heart. The team says the information sheds light on neurons and heart attacks and other heart diseases. Although the brain is the primary controller of the heart, the heart also has its own “small brain”, known as the inner nervous system (ICN), the team said. ICN supports heart health and protects the heart muscle in the event of a heart attack, but it is unclear how it does these effects.
Understanding ICNis is poor, and scientists don’t know where they are in the heart, how they connect, or what their molecular properties are. Now, scientists at the university have been able to answer these questions in detail. The researchers worked with scientists from different research groups and industry partners to create a two-pronged approach.
One approach involves a new imaging technique called a knife-edge scanning microscope, in which researchers can build three precise models of the entire rodent heart. The study marks the first time the technology has been used in heart research. The second method uses a technique called laser capture microanatomy to analyze and sample individual neurons for gene expression and accurately map locations within the three-dimensional structure of the heart.
The 3D map created reveals the previously unknown complexity of icN. The researchers found that the neurons that make up icN form a coherent band cluster on the base of the heart, where the heart’s veins and arteries enter and leave. ICN also extends along the length of the left atrium to the back of the heart. They are also located close to certain key heart structures, such as atrial knots.
The team compared the hearts of male and female rats and found gender differences in spatial tissue and gene expression in these neurons. Scientists say that because they know the location of neurons to the structure of the heart, they can now ask questions such as whether stimulating a position or selectively stimulating a particular neuron can make a difference in heart function. The team says they have created the basis for future research.