Dynamic Diversity of Glial Response Among Species in Spinal Cord Injury

Following spinal cord injury (SCI), glial cells form a scar, primarily composed of microglia, NG2 glia, and astrocytes. This glial scar has a complex role, both hindering axonal regeneration and limiting lesion spread. Different species respond differently to SCI. Amphibians and fishes show limited scarring, while mammals develop a well-defined scar. Even within mammals, the timing of glial activation varies, with rodents showing earlier microglia activation than primates. A better understanding of glial activation and scar formation is crucial for developing targeted therapies. These therapies aim to promote functional recovery by specifically modulating glial cell activity at the appropriate time after injury.

• 1
  In mice, immune cell recruitment precedes microglial and astrocytic responses. A complex molecular crosstalk orchestrates the formation of a well-defined and dense glial scar.
• 2
  Rats exhibit similar glial response dynamics to mice, but the immune cell response occurs earlier. Cavities, a characteristic of human SCI, are observed in rats but not typically in mice.
• 3
  Nonhuman primates do not form a major astrocytic scar after SCI, and their astrocytic response is slower than in rodents. The inflammatory response is also generally slower.