Glial Cells Found to Regulate Heart Function and Development

Glial cells in the heart help regulate heart rate and rhythm, and drive its development in the embryo, according to a new study published in PLOS Biology. The discovery provides the most detailed portrait yet of a critical population of cells that had been previously poorly understood.

Beginning in zebrafish, they found an abundant group of cells in the heart’s ventricles that produced glial fibrillary acid protein (GFAP), a classic marker of glia. GFAP-positive cells were also found in the hearts of mice and humans. By a variety of methods, including tracking individually labeled cells as they migrated, the researchers showed that the glial cells that take up residence in the outflow tract begin their journey in the neural crest. They termed these cells nexus glia.

When the authors removed the cells, the heart rate increased; when the cells were reduced by depriving them of a key gene that drives their glial development, the resulting heart beat irregularly. A major subdivision of the peripheral nervous system, called the autonomic system, regulates many aspects of physiology, including heart rate, through its two branches, the sympathetic and parasympathetic systems. By treating zebrafish with chemicals that increase the activity of one branch or another, they showed that cardiac glia control heart rate through their modulation of both branches.

The results greatly expand the understanding of the role of glial cells in the heart and suggest that glia may also play critical roles in the development and function of other organs where they have been glimpsed. “Our findings indicate an extensive and under-explored network of organ-associated glia that have functional roles dependent upon the environment,” lead researcher Cody Smith said. “Further understanding of these specialized astroglial populations is therefore necessary, given their potential impact on organ physiology.”