Spinal Cord Injury Results in Chronic Mechanical Stiffening

JOURNAL OF NEUROTRAUMA, 2020 · DOI: 10.1089/neu.2019.6540 · Published: February 1, 2020

Spinal Cord Injury Neurology Biomechanics

Simple Explanation

After a spinal cord injury (SCI), scar tissue forms which can prevent nerve regeneration. This study uses atomic force microscopy to measure the stiffness of spinal cord tissue after SCI. The study found that chronically injured spinal cord tissue is stiffer than healthy tissue. They also found that glial cells are sensitive to the stiffness of their environment. Finally, they used nanoparticles to reduce scarring and found that this also reduced the stiffness of the spinal cord tissue, indicating that scar tissue contributes to the increased stiffness.

Study Duration

12 weeks

Participants

Female C57BL/6 wild-type mice

Evidence Level

Not specified

Key Findings

1
Chronically injured mouse spinal cord is stiffer than healthy tissue.
2
Glial cells from both mouse and human sources respond to changes in substrate stiffness within the biological range of injured/uninjured spinal tissue.
3
Pathological stiffening of spinal cord tissue after injury is due to the presence of the chronic spinal scar.

Research Summary

This study provides quantitative evidence of chronic mechanical stiffening after SCI using atomic force microscopy microindentation. The study assessed the sensitivity of both mouse and human astrocytes in vitro and determined that they are mechanosensitive within the range of substrate stiffness observed in the injured/uninjured spinal cord. The results identify chronic mechanical stiffening as a critically important aspect of the complex lesion milieu after SCI.

Practical Implications

Clinical Interventions

Mechanical stiffening should be considered when assessing and developing potential clinical interventions for SCI.

Targeted Therapies

Targeting fibrosis may reduce stiffening and improve outcomes after SCI.

In Vitro Models

Physiologically relevant stiffness ranges should be used in in vitro models studying glial cell behavior.

Study Limitations

1
Lack of direct mechanical property measurements of chronically injured human spinal cord tissue.
2
The hemisection injury model replicates only a small portion of the injuries observed in human patients.
3
Different experimental methods have unique strengths and limitations and operate at divergent length scales.

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