Introduction
Degeneration of fibrocartilaginous tissues, such as intervertebral discs (IVDs), is a leading cause of chronic pain and disability. This degeneration is often associated with dysregulated inflammatory signaling mediated by factors including reactive oxygen species (ROS), cell-free nucleic acids (cf-NAs), and epigenetic alterations in immune cells. Current treatments are limited in efficacy, highlighting the need for innovative therapeutic strategies that address these complex inflammatory pathways.
Methods
We developed a self-therapeutic 3D porous hybrid protein (3D-PHP) nanoscaffold designed to modulate key inflammatory mediators involved in IVD degeneration. The 3D-PHP nanoscaffolds were fabricated using a nanomaterial-templated protein assembly (NTPA) strategy, which avoids covalent modification of protein structures. This method involved sequential assembly and diffusion-driven layer-by-layer techniques to achieve the desired scaffold architecture. Enzyme-like 2D nanosheets were incorporated into the nanoscaffolds to enhance their functionality. In vitro studies assessed the scaffolds' ability to scavenge ROS and cf-NAs and support disc cell survival under inflammatory conditions. For in vivo evaluation, 3D-PHP nanoscaffolds loaded with bromodomain and extra-terminal domain (BET) protein inhibitors (BETi) were implanted into a rat nucleotomy disc injury model to assess their effects on inflammation suppression and extracellular matrix (ECM) restoration.
Results
The 3D-PHP nanoscaffolds demonstrated responsiveness to inflammatory stimuli, facilitating controlled drug release. They exhibited disc-mimetic stiffness and excellent biodegradability. In vitro, the incorporation of enzyme-like 2D nanosheets enabled robust scavenging of ROS and cf-NAs, leading to reduced inflammation and enhanced survival of disc cells under inflammatory stress. In the rat nucleotomy model, implantation of BETi-loaded 3D-PHP nanoscaffolds effectively suppressed inflammation and promoted ECM restoration, resulting in significant regeneration of disc tissue and long-term pain reduction.
Discussion
Our findings suggest that the self-therapeutic 3D-PHP nanoscaffold, combined with epigenetic modulation, offers a promising approach to addressing dysregulated inflammatory signaling in IVD degeneration. The scaffold's ability to target multiple inflammatory mediators and support tissue regeneration positions it as a potential therapeutic strategy for degenerative fibrocartilaginous conditions, including intervertebral disc injuries. Future studies should explore the scalability of this approach and its applicability to other degenerative diseases characterized by chronic inflammation.