Synergistic Organelle-Microenvironment Regulation Strategy for Intervertebral Disc Degeneration Therapy by Reinforcing Mitochondrial Outer Membrane Stability and Sequestering exDNA
Free extracellular DNA (exDNA) accumulation within the cytoplasm is closely associated with chronic inflammation in intervertebral disc degeneration (IVDD). While numerous minimally invasive treatments targeting the various etiologies of IVDD have been developed, there remains a lack of systematic approaches to address the chronic inflammation caused by both intracellular and extracellular nucleic acids. In this study, we propose a novel strategy for treating IVDD that involves dual nucleic acid clearance. This approach targets and regulates mitochondrial DNA (mtDNA) release while clearing exDNA from the microenvironment, working synergistically to block the inflammatory cascade. We first analyzed the mechanism of chronic inflammation mediated by intracellular and extracellular nucleic acids during the progression of IVDD using single-cell sequencing and clinical sample analysis. Next, we developed a composite delivery system consisting of engineered nanovesicles with mitochondrial targeting functions (BNPMT) and a nucleic acid clearance hydrogel (H-P gel). BNPMT achieves targeted delivery to nucleus pulposus cells via membrane modification with triphenylphosphonium (TPP), while encapsulated BAI1, a small molecule drug, specifically inhibits mitochondrial outer membrane permeabilization (miMOMP). This reduces mitochondrial DNA (mtDNA) leakage into the cytoplasm, thereby blocking the mtDNA-cGAS/STING signaling pathway-mediated inflammatory response in nucleus pulposus cells. The H-P gel, crosslinked by Schiff base reactions and using G3-PAMAM dendrimers as functional crosslinkers, efficiently captures exDNA from the intervertebral disc microenvironment. This inhibits cfDNA-induced M1 macrophage polarization and the release of inflammatory cytokines. In an IVDD rat model, this dual-modal system demonstrated synergistic therapeutic advantages, significantly reversing the progression of IVDD over 8 weeks. This targeted nucleic acid clearance strategy provides a novel approach for treating IVDD and offers a theoretical framework for addressing other nucleic acid-related inflammatory diseases. Overall design: RNA-seq profiling of wildtype Nucleus pulposus cells and Doxorubicin-induced senescence of nucleus pulposus cells and BNPMT intervention in senescence of nucleus pulposus cells