Severity- and Time-Dependent Activation of Microglia in Spinal Cord Injury

A spinal cord injury (SCI) initiates a number of cascades of biochemical reactions and intercellular interactions, the outcome of which determines the regenerative potential of the nervous tissue and opens up capacities for preserving its functions. The key elements of the above-mentioned processes are microglia. Many assumptions have been put forward, and the first evidence has been obtained, suggesting that, depending on the severity of SCI and the post-traumatic period, microglia behave differently. In this regard, we conducted a study to assess the microglia behavior in the model of mild, moderate and severe SCI in vitro for various post-traumatic periods. We reported for the first time that microglia make a significant contribution to both anti- and pro-inflammatory patterns for a prolonged period after severe SCI (60 dpi), while reduced severities of SCI do not lead to prolonged activation of microglia. The study also revealed the following trend: the greater the severity of the SCI, the lower the proliferative and phagocytic activity of microglia, which is true for all post-traumatic periods of SCI.