Biology of Injury – Spinal Cord Injury

Introduction

Spinal cord injury (SCI) sets off a complex series of biological events that extend far beyond the initial moment of trauma. While the primary insult disrupts neural pathways, much of the lasting functional loss results from ongoing cellular and molecular processes. Understanding these processes is central to developing meaningful therapeutic approaches.

• Primary Injury

The primary phase involves direct mechanical disruption of neural tissue, including axonal shearing, compression, vascular rupture, and immediate loss of conduction pathways.

• Secondary Injury Cascade

After the initial trauma, secondary biological processes expand the lesion and limit recovery.

• Inflammation and Immune Activation

Activation of microglia and immune infiltration release cytokines and reactive oxygen species, intensifying damage.

• Excitotoxicity

Excess glutamate and ionic imbalance harm neurons and oligodendrocytes.

• Oxidative Stress

Reactive oxygen species promote lipid peroxidation and membrane injury.

• Apoptosis and Oligodendrocyte Loss

Oligodendrocyte death contributes to demyelination and impaired signal conduction.

• Vascular Dysfunction

Ischemia and edema restrict metabolic support to neural tissue.

• Glial Scar Formation and Inhibitory Environment

Reactive gliosis forms a glial scar that contains inflammation but also creates barriers to axonal regrowth through inhibitory extracellular matrix molecules such as CSPGs.

• Chronic Phase

The chronic stage features persistent inflammation, cyst formation, long-term demyelination, inhibitory extracellular matrix, and reduced neuronal regenerative capacity.

• Implications for Therapeutic Development

Each phase reveals actionable targets: inflammation, excitotoxicity, oligodendrocyte loss, scar-associated inhibition, and chronic ECM barriers.

Key References

• Anjum A, et al. Spinal Cord Injury: Pathophysiology and Therapeutic Approaches. 2020.
• Zhang Y, et al. Deciphering the Glial Scar after Spinal Cord Injury. 2021.
• Mensah EO, et al. Traumatic Spinal Cord Injury: A Review of the Current State. 2025.
• Hellenbrand DJ, et al. Inflammation After Spinal Cord Injury. 2021.
• Clifford T, et al. Current Advancements in Spinal Cord Injury Research. 2023.
• Shafqat A, et al. Tackling the Glial Scar in Spinal Cord Regeneration. 2023.