Self-Healing Dynamic Hydrogel as Injectable Shock-Absorbing Artificial Nucleus Pulposus

Area of Science:

• Biomaterials Science
• Spine Biomechanics
• Regenerative Medicine

Background:

• Intervertebral discs (IVDs) provide spinal flexibility and shock absorption.
• The nucleus pulposus (NP) is crucial for IVD adaptive behavior.
• Degeneration of IVDs, particularly the NP, leads to spinal dysfunction.

Purpose of the Study:

• To evaluate an injectable, self-healing dynamic hydrogel (DH) as an artificial NP replacement.
• To investigate the potential of DHs based on gold(I)-thiolate/disulfide (Au-S/SS) exchange for IVD applications.
• To assess the DH's ability to restore biomechanical properties and counteract IVD degeneration.

Main Methods:

• Development of an injectable DH utilizing Au-S/SS dynamic covalent exchange.
• Evaluation of DH self-healing and frequency-dependent stiffness properties.
• Assessment of DH performance in a spine motion segment model with nucleotomized IVDs.

Main Results:

• The DH demonstrated self-healing capabilities and frequency-dependent stiffness, mimicking native NP behavior.
• Injection of DH into nucleotomized IVDs restored full biomechanical properties, unlike conventional covalent hydrogels.
• The DH exhibited long-term persistence and mechanical integrity under cyclic loading, confirmed by tomography.

Conclusions:

• Injectable DHs based on Au-S/SS exchange are effective artificial NP replacements.
• The dynamic properties of DHs are crucial for restoring IVD function and counteracting degeneration.
• DHs show significant potential for long-term treatment of IVD degeneration.