Matching mechanical heterogeneity of the native spinal cord augments axon infiltration in 3D-printed scaffolds

Biomaterials, 2023 · DOI: 10.1016/j.biomaterials.2023.122061 · Published: April 1, 2023

Simple Explanation

This study explores how mimicking the natural differences in stiffness between the gray and white matter of the spinal cord can improve the success of implanted scaffolds designed to promote axon regeneration after spinal cord injury. The researchers used a specialized 3D printing technique called digital light processing (DLP) to create scaffolds that match the varying mechanical properties of spinal cord tissue. The results showed that these mechanically heterogeneous scaffolds enhanced axon infiltration and growth compared to scaffolds with uniform stiffness, suggesting a promising approach for spinal cord injury repair.

Study Duration

2 weeks

Participants

Nine female Sprague-Dawley rats (225–250 g)

Evidence Level

Not specified

Key Findings

1
Bulk spinal cord mechanics differ along anatomical level due to variations in the ratio of white and gray matter.
2
Scaffolds recreating the heterogeneity of spinal cord tissue mechanics must account for the disparity between gray and white matter.
3
Scaffolds matching the mechanical heterogeneity of white and gray matter improve the effectiveness of biomaterials transplanted within the injured spinal cord.

Research Summary

This study demonstrates that the bulk mechanical properties of the spinal cord change along its length, and that these changes are due to variations in the relative amounts of gray and white matter. The researchers developed a modified digital light processing (DLP) technique to fabricate scaffolds with heterogeneous mechanical properties that mimic the difference in stiffness between gray and white matter. Transplantation experiments in an acute transection rat model indicated that scaffolds with heterogeneous mechanical properties resulted in greater axon infiltration compared to homogeneous scaffolds.

Practical Implications

Improved Scaffold Design

Designing spinal cord scaffolds to mimic the mechanical heterogeneity of native tissue, particularly the stiffness differences between gray and white matter, can enhance axon regeneration and improve functional outcomes after spinal cord injury.

Advanced 3D Printing Techniques

Utilizing DLP and similar techniques to create complex, mechanically heterogeneous biomaterials opens new avenues for tissue engineering and regenerative medicine.

Personalized Treatment Strategies

Tailoring scaffold mechanical properties to match individual patient spinal cord characteristics may further improve the efficacy of biomaterial implants.

Study Limitations

1
The GelMA scaffolds are primarily elastic, while native spinal cord tissue exhibits viscoelastic properties.
2
The study focuses on short-term (2-week) axon infiltration and regrowth, without assessing long-term functional recovery.
3
The mechanism underlying increased axon infiltration in heterogeneous scaffolds compared to homogenous controls is unclear.

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