A new type of cell has been identified in the heart of several organisms, from the zebrafish to mouse and human hearts.
This new type of cell, called “nexus-glia” by its discoverers, as it forms a net around the heart, not only appears to possess some characteristics from these cells, but it is also related to producing the right heartbeats.
Glial cells are the ugly sibling of neurons in the central nervous system, or at least they were, because recently new interesting roles for these cells are being discovered which show that they are not just there to feed, supply, and support neurons. What’s more, findings like this of the nexus-glia show that glial cells might not be restricted to the central nervous system (brain and spine) after all.
Going back to these nexus-glia found in the heart, which resemble astrocytes (star shaped cells), the lead author of the paper published in PLoS Biology 1, Nina L. Kikel-Coury, found such a cell in zebrafish, and comparing the gene expression profiles of mouse, human and zebrafish hearts, she found common gene signatures for an astroglia-like cell that appears to have been conserved throughout evolution.
Usually, evolution tends to conserve things which serve a purpose, and in this case, it seems that these cells might be implied in the regularity of the heartbeat. Actually, the research team obtained evidence of its involvement in heart function from two directions: one, if they inhibited the development of these glial cells by tampering with specific genes, the heartbeat became irregular; two, these glial-like cells derive from an embryonic cell population which has been associated with up to 30% of congenital heart defects.
However, despite the promise of these results, there is no functional data yet, and therefore, many questions remain open like: how do these cells interact with other heart cells to regulate beating, do they work together with the pacemakers or the actual muscle cells?
All in all, this is an interesting example of the surprises our nervous systems hold on store for us, and how everything we learned at school 10-20 years ago will be overwritten in due time. Because science is an ever-going process, and no dogma is set in stone.