Building-Block Size Mediates Microporous Annealed Particle Hydrogel Tube Microenvironment Following Spinal Cord...

Area of Science:

• Biomaterials Science
• Neuroscience
• Regenerative Medicine

Background:

• Spinal cord injury (SCI) causes significant sensory and motor function loss.
• Current biomaterial therapies for SCI regeneration face limitations in size and shape adaptability.
• Microporous annealed particles (MAPs) offer a tunable platform for neural tissue engineering.

Purpose of the Study:

• To investigate the impact of bead size in microporous annealed particle (MAP) tubes on spinal cord regeneration and functional recovery.
• To evaluate the ability of MAP tubes with varying polyethylene glycol (PEG) bead sizes to bridge spinal cord defects and promote axonal growth.
• To assess the influence of MAP tube geometry on glial scarring, immune cell infiltration, and inflammatory responses post-SCI.

Main Methods:

• Fabrication of MAP tubes using 20-, 40-, and 60-micron polyethylene glycol (PEG) beads.
• Implantation of MAP tubes into a T9-10 murine hemisection model of spinal cord injury.
• Assessment of glial and fibrotic scarring, immune cell density, and inflammatory phenotypes.
• Evaluation of locomotor function, axonal regeneration, and remyelination at 8 weeks post-injury.

Main Results:

• MAP tubes attenuated glial and fibrotic scarring, with effects dependent on bead size.
• Tubes made from 60-micron PEG beads increased chronic macrophage density while not affecting neutrophil infiltration.
• Implantation of 60-micron PEG bead MAP tubes led to enhanced locomotor function, significant axonal ingrowth, and remyelination.

Conclusions:

• Bead size is a critical design parameter for MAP-based biomaterials in SCI.
• Polyethylene glycol (PEG) MAP tubes demonstrate potential as an effective biomaterial therapy for promoting regeneration and functional recovery after spinal cord injury.
• Optimized MAP tube architecture can guide axonal regeneration and improve outcomes in SCI models.