Suppression of NF-κB activity via nanoparticle-based siRNA delivery alters early cartilage responses to injury

Abstract

Osteoarthritis (OA) is a major cause of disability and morbidity in the aging population. Joint injury leads to cartilage damage, a known determinant for subsequent development of posttraumatic OA, which accounts for 12% of all OA. Understanding the early molecular and cellular responses postinjury may provide targets for therapeutic interventions that limit articular degeneration. Using a murine model of controlled knee joint impact injury that allows the examination of cartilage responses to injury at specific time points, we show that intraarticular delivery of a peptidic nanoparticle complexed to NF-κB siRNA significantly reduces early chondrocyte apoptosis and reactive synovitis. Our data suggest that NF-κB siRNA nanotherapy maintains cartilage homeostasis by enhancing AMPK signaling while suppressing mTORC1 and Wnt/β-catenin activity. These findings delineate an extensive crosstalk between NF-κB and signaling pathways that govern cartilage responses postinjury and suggest that delivery of NF-κB siRNA nanotherapy to attenuate early inflammation may limit the chronic consequences of joint injury. Therapeutic benefits of siRNA nanotherapy may also apply to primary OA in which NF-κB activation mediates chondrocyte catabolic responses. Additionally, a critical barrier to the successful development of OA treatment includes ineffective delivery of therapeutic agents to the resident chondrocytes in the avascular cartilage. Here, we show that the peptide–siRNA nanocomplexes are nonimmunogenic, are freely and deeply penetrant to human OA cartilage, and persist in chondrocyte lacunae for at least 2 wk. The peptide–siRNA platform thus provides a clinically relevant and promising approach to overcoming the obstacles of drug delivery to the highly inaccessible chondrocytes.

Post-Traumatic Osteoarthritis in Mice Following Mechanical Injury to the Synovial Joint

“…Other studies have shown an acute chondrocyte necrosis and apoptosis in response to blunt trauma to cartilage43. Our findings of apoptosis in the injured cartilage are in line with our previous observations102021 and with other studies45. Furthermore, our unpublished data suggest that apoptosis begins as early as 12 h post-loading (Duan X, Rai MF, Sandell LJ).…”

“…The right knee underwent one of three separate loading forces following our established procedure102021. Briefly, mice were anesthetized using 2.5% isoflurane inhalation in 4-L/min of oxygen.…”

Emerging potential of gene silencing approaches targeting anti-chondrogenic factors for cell-based cartilage repair

“…In addition to polymers, cell penetrating/permeable peptides in the form of NPs have been explored as carriers for RNAi delivery. Yan et al generated and delivered peptidic NPs complexed to NF-kB siRNA as a therapeutic approach to mediate chondroprotective effect by preserving cartilage homeostasis in chondrocytes from patients with osteoarthritis (OA) via NF-kB suppression [43].…”

Genome Engineering for Personalized Arthritis Therapeutics

“…Articular injection of siRNA-peptide nanoparticles penetrated deep within murine articular cartilage and reduced tissue degradation relative to controls. [123] Future exploration of intra-articular delivery of CRISPR-Cas9 may involve delivery of nanoparticles carrying sgRNA and Cas9 protein. [124]…”