The Effect of Microglia
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Microglia are part of the central nervous system and function primarily as immune cells. The role of microglia in a spinal cord injury has remained obscure for decades. Historically, microglial activation was generally perceived as harmful to neurons and glial cells. They were often confused with the role of macrophages.
After a spinal cord injury, blood-derived macrophages invade and adopt many of the markers and behaviors of microglia. However, these two cell types show similarities, but they are different cell populations and have different roles. Microglia rapidly accumulate at the site of injury. There they proliferate extensively shortly after the injury.
What are the new results?
The article from Steve Lacroix´s group at the Laval University, Canada, highlights several aspects. They found that microglia are in fact central in the establishment of the glial scar, allowing for the containment of injury spread.The beneficial effect of microglia occurs during the first week after the injury. Microglia act as an interface between the healthy tissue and the astrocytes that will form the glial scar. The beneficial effect starts when non-active microglia become active and secrete molecules such as Insulin-like Growth factor 1. This leads to the proliferation of astrocytes and the promotion of the astrocytic scar formation.
Finally, the scientists were able to enhance recovery after spinal cord injury by boosting the protective function of microglia via local delivery of a proliferation factor called M-CSF.
These findings might have a translational potential and could give new ideas boosting microglia as a neuroprotective treatment.
This study was supported by Wings for Life and was published in the journal Nature Communications.