Understanding the NG2 Glial Scar after Spinal Cord injury

Frontiers in Neurology, 2016 · DOI: 10.3389/fneur.2016.00199 · Published: November 15, 2016

Simple Explanation

NG2 cells, also known as oligodendrocyte progenitor cells, are located throughout the central nervous system and serve as a pool of progenitors to differentiate into oligodendrocytes. In response to spinal cord injury (SCI), NG2 cells increase their proliferation and differentiation into remyelinating oligodendrocytes. In this review, we describe the signaling pathways important for the proliferation and differentiation of NG2 cells, as well as the role of NG2 cells in scar formation and tissue repair.

Study Duration

Not specified

Participants

Not specified

Evidence Level

Review

Key Findings

1
NG2 cells are a major component of the glial scar after SCI and share functional overlap with astrocytes in this region.
2
NG2 cells contribute to axon regeneration failure by expressing CSPGs and forming synaptic structures that prevent further axonal growth.
3
NG2 cells may contribute to neuroinflammation after CNS injury, an area that has been under-appreciated.

Research Summary

The glial scar has been synonymous with reactive astrocytes, but there is substantial evidence indicating that NG2 cells are also a major part of the glial scar, both physically and functionally. Similar to astrocytes, NG2 cells react to SCI by proliferating, becoming hypertrophic, and upregulating CSPG expression. This lineage plasticity of NG2 cells raise the possibility that they can be targeted to promote endogenous repair of the injured spinal cord.

Practical Implications

Therapeutic Target

Targeting NG2 cells could promote endogenous repair of the injured spinal cord due to their lineage plasticity.

Inflammation Control

Modulating NG2 cell activity may offer a means to control neuroinflammation following SCI.

Axon Regeneration

Interfering with CSPG expression and synaptic structure formation by NG2 cells could enhance axon regeneration.

Study Limitations

1
Challenges in definitively identifying NG2+ glial cells due to shared markers with other cell types.
2
Off-target labeling in transgenic mouse lines used for studying NG2 cell fate.
3
Incomplete understanding of the mechanisms underlying NG2 cell differentiation into Schwann cells.

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