Injectable Hydrogels of Optimized Acellular Nerve for Injection in the Injured Spinal Cord

Biomed Mater., 2018 · DOI: 10.1088/1748-605X/aaab82 · Published: March 21, 2018

Simple Explanation

Spinal cord injuries are a significant problem with limited treatment options. This study explores a new method using injectable acellular nerve grafts to promote repair after spinal cord injury. The researchers created an injectable solution from decellularized peripheral nerve, which forms a gel at body temperature. This gel retains key chemical cues and has mechanical properties similar to spinal tissue. The injectable nerve graft modulated the inflammatory response after injury and supported axonal growth in rats with spinal cord contusions, suggesting it could be a valuable tool for spinal cord repair.

Study Duration

8 weeks

Participants

Adult Sprague Dawley rats (250–300g)

Evidence Level

Animal study

Key Findings

1
The injectable optimized acellular (iOA) nerve graft retains native chemical cues such as collagens and glycosaminoglycans.
2
iOA solution was compatible with rat Schwann cells in culture, and hydrogel injection into a rat cervical contusion model significantly reduced the ratio of M1:M2 macrophages after one week, favoring regenerative phenotypes (p<0.05).
3
The percentage of axonal coverage increased at the distal tissue interface (p<0.05), suggesting enhanced axonal extension within this region.

Research Summary

This study introduces a novel injectable scaffold derived from optimized acellular nerve scaffold (iOA) for minimally-invasive injection following contusion SCI. The iOA nerve hydrogel was characterized for its composition, mechanics, cell survival in vitro, acute macrophage response in vivo, and functional and tissue regeneration following implantation into a rat model of cervical contusion SCI. The results suggest that iOA nerve hydrogels have the potential to promote neural repair and may be an effective platform for combination SCI therapy.

Practical Implications

Minimally Invasive Treatment

The injectable hydrogel allows for a less invasive approach to treating spinal cord injuries compared to traditional nerve grafts.

Modulation of Inflammatory Response

The hydrogel can shift the macrophage phenotype towards a regenerative state, potentially improving the healing environment in the spinal cord.

Enhanced Axonal Growth

The hydrogel promotes axonal growth at the distal tissue interface, suggesting it can aid in reconnecting damaged neural pathways.

Study Limitations

1
No long-term functional benefit or deficit was observed after iOA injection.
2
The rate of material degradation may explain why injectable nerve alone did not demonstrate observable functional benefits.
3
The material was not observable after 8 weeks, suggesting the material had degraded and/or been remodeled.

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