Engineering miRNA-223 nanocomplexes via bioorthogonal self-assembly for precision therapy of intervertebral disc degeneration.

Intervertebral disc degeneration (IVDD) is characterized by inflammation-driven pyroptosis of nucleus pulposus (NP) cells. While oligonucleotide-based gene therapy holds promise for precision intervention, its clinical translation is hindered by inefficient cellular delivery and rapid lysosomal degradation. Here, we identified miRNA-223 as a pivotal regulator of IVDD, where its overexpression mitigated the inflammatory extracellular matrix (ECM) metabolic imbalance in NP cells in vitro. To overcome delivery barriers in vivo, we engineered an injectable multifunctional cell-penetrating peptide (CPP), R9-DOPA-DBCO, which spontaneously self-assembles with azido-modified miRNA-223 via bioorthogonal click chemistry to form nanocomplexes (R9-DOPA-miRNA223). These nanoparticles not only exhibited superior cell membrane penetration and lysosomal escape capabilities but also exhibited significant therapeutic efficacy in mitigating NP cell pyroptosis and restoring ECM metabolic homeostasis via the MKNK2/eIF4E/NOD-like signaling pathway, concomitantly attenuating IVDD progression in rat models. This direct and efficient delivery strategy not only has transformative potential for IVDD therapy but also broadens the conceptual and methodological framework for precision miRNA-based therapeutics.