NG2 Glia and Cellular Crosstalk in Health and Disease: Focus on Spinal Cord Injury.

NG2 glia, also known as oligodendrocyte progenitor cells, represent a unique population of glial cells characterized by dynamic morphology and the ability to extend branched processes that actively contact neurons and other cellular elements. These structural and functional interactions enable NG2 glia to contribute to the regulation of axonal excitability, electrical activity, and axonal architecture. Unlike most other glial cells, NG2 glia receive direct synaptic input from neurons and can generate action potentials, defining their distinctive physiological status. A particularly important feature of this cell population is the expression of the chondroitin sulfate proteoglycan NG2/CSPG4, which serves as a key molecular marker and plays an essential role in intercellular interactions. Following spinal cord injury (SCI), NG2 glia rapidly become activated, undergo phenotypic changes, and engage in extensive interactions with neurons, astrocytes, microglia, and endothelial cells. These interactions form a complex regulatory network that influences both the severity of secondary injury and the effectiveness of remodeling and repair processes. Mechanisms of particular importance include the secretion of chondroitin sulfate proteoglycans and alterations in extracellular matrix properties. Finally, this review highlights potential therapeutic approaches aimed at modulating NG2 glial activity and their intercellular interactions. The focus is on strategies designed to reduce the inhibitory effects of proteoglycans while enhancing the remyelinating and neuroprotective potential of these cells, thereby opening new perspectives for regenerative therapies after SCI.