Researchers at the University of Virginia may have discovered a previously unknown repair mechanism at work in the brain. Immune cells called microglia were observed moving beyond their known roles and helping injured neurons heal, potentially paving the way for new treatments for epilepsy and other conditions.
Macrophages are a type of immune cell that patrol the body for anything that doesn’t belong and could be harmful, such as pathogenic microbes, or cancerous or damaged cells. When they find something out of place they engulf and digest the cell to protect the body. Microglia are the resident macrophages in the brain and spinal cord, where they consume damaged neurons, plaque deposits and other debris.
But now, scientists at the University of Virginia have caught them performing a completely new function. The team used an imaging technology called two-photon microscopy to study the brains of mice that had had severe seizures, and found that the microglia weren’t just clearing away damaged neurons as expected – they were healing them.
The microglia began forming tiny pouches, which the scientists have named “microglia process pouches,” around swollen dendrites, the branches that transmit nerve signals between neurons. These pouches were seen to hang around for hours, and the dendrites they targeted appeared to recover much better than those without pouches.
“We did not find microglia to be ‘eating’ the neuronal elements in this context,” says Ukpong Eyo, corresponding author of the study. “Rather, we saw a strong correlation between these interactions and a structural resolution of injured neurons suggestive of a ‘healing’ process.”
The team says that the discovery could be the first step towards developing new seizure treatments. Currently, about a third of epilepsy patients don’t respond to anti-seizure drugs, so finding a way to tap into this new repair mechanism could eventually provide an alternative. However, it’s worth keeping in mind that the study is still in the very early stages.
“There has been mounting generic support for the idea that microglia could be used to ameliorate seizures, but direct, visualized evidence for how they could do this has been lacking,” says Eyo. “Although these findings are exciting, there is yet a lot to follow-up on them. For example, the precise mechanisms that regulate the interactions remain to be identified. Moreover, at present, the ‘healing’ feature is suggested from correlational results and more definitive studies are required to certify the nature of the ‘healing’.”
The research was published in the journal Cell Reports.
Source: University of Virginia