To the surprise of even the researchers who conducted the study, a new type of cell was found in the heart, similar to a glial cell usually found only in the brain and spinal cord. Dubbed “nexus glia” because of their mesh-like appearance around the heart, the team behind the discovery believes these new cells could unlock the way we understand heart disease and defects in the future. The findings were recently published in the journal PLOS BIOLOGY.
Cody Smith, co-author of the study, said, “For me, the definition of great science is something you’ve discovered that opens up more questions. I think it just fits that definition.”
The newly discovered cells look like astrocytes, the star-shaped multitasking cells that our brains are crammed with. These cells play a crucial role in forming and maintaining neural networks in the brain and spine, but they were not thought to be found elsewhere in the body.
It is also unknown why astrocytes, which are very important for neuron function in the brain, are not found in the peripheral nervous system (PNS), that is, in parts of the body that are connected by nerves outside the brain and spinal cord.
“It was surprising to us,” Smith says. “That’s why we looked for glial-like cells in the PNS. [Lead author] Nina came to my office every week with more and more data, and most of it wasn’t convincing to me . it was too much.”
To begin with, the team looked at the zebrafish, an animal quickly favored as a guinea pig by scientists modeling disease in recent years. They discovered a type of cell similar to astrocytes in the zebrafish heart, and cross-species analysis revealed the same cells in human and mouse hearts. Before birth, cells made up of the same group of cells that eventually go on to form our face and smooth muscles are spreading through their exit pathways to the heart, providing an important clue about the function of the nexus glia.
Moreover, when the nexus glia was deprived of an important glial development gene, the heartbeat became irregular. “I thought that if we could find a new cellular piece of the cardiovascular puzzle, it could lay the groundwork for future work,” said Nina Kikel-Coury.
As with many discoveries of this nature, we do not yet know the exact results. Smith cautioned that while the nexus glia “may play a rather important role in regulating the heart”, they “do not yet fully know” their exact functions.
“[Now] we have 100 questions that we didn’t even know existed before, so we’re following them to explore this never-before-studied path,” Smith said. Another example . . . I’m excited for the future.”
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