Spatiotemporal dynamic changes, proliferation, and differentiation characteristics of Sox9-positive cells after severe complete transection spinal cord injury

Studying the spatiotemporal dynamic changes of various cells following spinal cord injury (SCI) is of great significance for understanding the pathological processes of SCI. Changes in the characteristics of Sox9-positive cells, which are widely present in the spinal cord, have rarely been studied following SCI. We found that Sox9-positive cells were widely distributed in the central canal and parenchyma of the uninjured adult spinal cord, with the greatest distribution in the central spinal cord and relatively few cells in the dorsal and ventral sides. Ranging between 14.20% ± 1.61% and 15.60% ± 0.36% of total cells in the spinal cord, almost all Sox9-positive cells were in a quiescent state. However, Sox9-positive cells activated following SCI exhibited different characteristics according to their distance from the lesion area. In the reactive region, Sox9-positive cells highly expressed nestin and exhibited a single-branching structure, whereas in the non-reactive region, cells showed low nestin expression and a multi-branching structure. In response to SCI, a large number of Sox9-positive cells in the spinal cord parenchyma proliferated to participate in the formation of glial scars, whereas Sox9-positive cells in the central canal located near the lesion site accumulated at its broken ends through proliferation. Finally, we found that approximately 6.30% ± 0.35% of Sox9-positive cells differentiated into oligodendrocytes within two weeks after SCI. By examining the spatiotemporal dynamic changes, proliferation and differentiation characteristics of Sox9-positive cells after SCI, our findings provide a theoretical basis for understanding the pathological process of SCI.