A DNA Nanomachine Reverses Mitochondrial Dysfunction by Cascaded Drug Release to Treat Osteoarthritis

Abstract Mitochondrial dysfunction in chondrocytes is closely associated with osteoarthritis (OA) progression. However, the underlying mechanism remains elusive, and targeted OA therapies are lacking. Here, it is demonstrated that mitochondrial calcium (mito‐Ca 2+ ) content and energy metabolism are dysregulated in OA. Accordingly, a DNA nanomachine (DNM) is developed for OA treatment by reversing the mitochondrial dysfunction. The DNM used a programmable tetrahedral framework and incorporated dual targeting, switching, and therapeutic motifs. The targeting motifs contained a collagen II‐targeting peptide and an adenosine triphophate (ATP) aptamer to enable precise delivery into cartilage and mitochondria, respectively. Overexpressed matrix metalloproteinases (MMPs) in OA microenvironment triggered the MMP‐cleavable peptide switch and induced the release of mitochondrial open reading frame of the 12S rRNA‐c to promote ATP production. This result further triggered the release of DS16570511 conjugated to a sequence partially hybridized with ATP aptamer, inhibiting mito‐Ca 2+ uniporter and mitigating mito‐Ca 2+ overload under chronic inflammation. By leveraging sequential roles in delivery targeting, switch triggering, and therapeutic release, the DNM synergistically promoted cellular energy metabolism, inhibited mito‐Ca 2+ overload, and maintained extracellular matrix homeostasis. Consequently, cartilage degradation is significantly delayed in an OA model after treatment. This approach paves avenues for developing novel strategies to combat OA progression.