Deﬁning Spatial Relationships Between Spinal Cord Axons and Blood Vessels in Hydrogel Scaffolds

TISSUE ENGINEERING: Part A, 2021 · DOI: 10.1089/ten.tea.2020.0316 · Published: May 28, 2021

Spinal Cord Injury Biomedical Regenerative Medicine & Stem Cells

Simple Explanation

This study investigates how new blood vessels and nerve fibers (axons) grow together in hydrogel scaffolds after a spinal cord injury in rats. The goal was to understand the spatial relationship between the regenerating axons and the newly formed blood vessels. Hydrogel scaffolds containing different substances (Matrigel, Schwann cells, or Schwann cells with a drug called rapamycin) were implanted into the injured spinal cords. The researchers then used advanced imaging techniques to analyze the number, density, and arrangement of axons and blood vessels within the scaffolds. The study found that scaffolds containing Schwann cells promoted better axon and blood vessel regeneration compared to the other groups. The axons also tended to cluster around blood vessels within a certain distance, suggesting an optimal spatial arrangement for neurovascular regeneration.

Study Duration

6 weeks

Participants

Rats with complete spinal cord transection

Evidence Level

Not specified

Key Findings

1
Scaffolds containing Schwann cells (SCs) significantly enhanced axonal regeneration and blood vessel formation compared to Matrigel-only (MG) or SCs with rapamycin (RAPA).
2
Axons tend to cluster around blood vessels, with the highest concentrations located within a specific radius (200–250 mm) from the vessel walls and avoiding a zone immediately adjacent to the vessel (25–30 mm).
3
Higher axonal densities were correlated with smaller vessel cross-sectional areas, suggesting that a dense network of small capillaries supports better axonal regeneration.

Research Summary

This study investigates the spatial relationships between regenerating axons and blood vessels within hydrogel scaffolds implanted into spinal cord injuries in rats. The findings revealed that Schwann cells within the hydrogel channels significantly improved neurovascular bundle regeneration compared to Matrigel alone or Schwann cells combined with rapamycin. The study identified key parameters and correlations, such as vessel diameter, radial diffusion distances, and axonal clustering patterns, which can be used to refine tissue engineering strategies for spinal cord injury repair.

Practical Implications

Optimized Scaffold Design

The study suggests that incorporating Schwann cells into hydrogel scaffolds can improve neurovascular regeneration after SCI.

Targeted Drug Delivery

The findings suggest that rapamycin may not be beneficial for promoting neurovascular regeneration in this context, highlighting the need for careful consideration of drug effects.

Spatial Arrangement Matters

The optimal spatial arrangement of axons and blood vessels for neurovascular regeneration needs to be considered when designing tissue engineering strategies for SCI repair.

Study Limitations

1
The study was performed on rats, and the results may not directly translate to humans.
2
The study focused on a specific type of hydrogel scaffold and injury model, limiting the generalizability of the findings.
3
The study did not explore the underlying mechanisms responsible for the observed spatial relationships between axons and blood vessels.

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