A double-network hydrogel for the dynamic compression of the lumbar nerve root

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Neurosurgery

Background:

• Existing animal models for lumbar disc herniation lack dynamic compression, unlike the actual disease process.
• Current models fail to replicate the dynamic mechanical forces experienced by nerve roots during herniation.

Purpose of the Study:

• To develop and characterize a chitosan/polyacrylamide double-network hydrogel for simulating dynamic nerve root compression in lumbar disc herniation models.
• To evaluate the hydrogel's mechanical properties, biocompatibility, and efficacy in an animal model.

Main Methods:

• A chitosan/polyacrylamide double-network hydrogel was synthesized using a two-step method.
• The hydrogel's swelling ratio, compressive strength, modulus, and porous structure were analyzed.
• Biocompatibility was assessed using an MTT assay.
• The hydrogel was implanted to dynamically compress the L4 nerve root in a sand rat model.

Main Results:

• The hydrogel exhibited a swelling ratio of 140 and demonstrated good mechanical properties (compressive strength 53.6 MPa, modulus 0.34 MPa).
• Scanning electron microscopy confirmed a porous, crosslinked structure.
• The MTT assay indicated good biocompatibility with no significant cytotoxicity.
• In vivo, the hydrogel successfully induced dynamic compression, leading to temporary nerve root edema that resolved within 3 weeks.

Conclusions:

• The developed chitosan/polyacrylamide hydrogel possesses suitable mechanical and biocompatibility characteristics for creating dynamic nerve root compression.
• This hydrogel represents a promising new biomaterial for advancing animal models of lumbar disc herniation, offering a more physiologically relevant simulation.