The Function of NG2/CSPG4-expressing Cells in the Rat Spinal Cord Injury: An Immunoelectron Microscopy Study

Abstract

Emerging evidence supports an increased role for NG2/CSPG4-expressing cells in the process of neuroregeneration and synaptic plasticity, due to the increased production of multifunctional chondroitin sulfate proteoglycan (NG2/CSPG4). However, the response of NG2/CSPG4-expressing cells in spinal cord injury (SCI) remains to be elcudiated. Expression and distribution of NG2/CSPG4-expressing cells were studied by immunoelectron microscopy in the ventral horns (VH) of an intact and injured rat spinal cord. In the intact spinal cord, NG2/CSPG4 expression was detected on the cell membrane and in the cytoplasm of NG2 glia and was absent in neurons. Large amounts of NG2/CSPG4 were found on myelin membranes. The ability of intact astrocytes to produce NG2/CSPG4 was shown, although to a lesser extent than oligodendrocytes and NG2 glia. At 7 days after SCI at the Th8 level in the reactive glial zone of VH, the expression of NG2/CSPG4 sharply increased in NG2 glia at a distance of 3-5 mm and in reactive astrocytes were observed at all investigated distances caudally from the epicenter of injury. The obtained results indicate the presence of NG2/CSPG4-positive astrocytes in the intact spinal cord, and in the case of damage, an increase in the ability of reactive astrocytes to produce NG2/CSPG4. SCI leads to increased expression of NG2/CSPG4 by NG2 glia in the early stages after injury, which decreases with distance from the epicenter of the injury, as well as at later stages.

Keywords: ALDH1L1; Astrocytes; NG2 glia; NG2/CSPG4; electron microscopy; spinal cord injury.