Single vs. repeated matrix metalloproteinase-13 knockdown with intra-articular short interfering RNA administration in a murine osteoarthritis model

Engineering approaches for RNA-based and cell-based osteoarthritis therapies

Osteoarthritis (OA) is a chronic, debilitating disease that substantially impairs the quality of life of affected individuals. The underlying mechanisms of OA are diverse and are becoming increasingly understood at the systemic, tissue, cellular and gene levels. However, the pharmacological therapies available remain limited, owing to drug delivery barriers, and consist mainly of broadly immunosuppressive regimens, such as corticosteroids, that provide only short-term palliative benefits and do not alter disease progression. Engineered RNA-based and cell-based therapies developed with synthetic chemistry and biology tools provide promise for future OA treatments with durable, efficacious mechanisms of action that can specifically target the underlying drivers of pathology. This Review highlights emerging classes of RNA-based technologies that hold potential for OA therapies, including small interfering RNA for gene silencing, microRNA and anti-microRNA for multi-gene regulation, mRNA for gene supplementation, and RNA-guided gene-editing platforms such as CRISPR-Cas9. Various cell-engineering strategies are also examined that potentiate disease-dependent, spatiotemporally regulated production of therapeutic molecules, and a conceptual framework is presented for their application as OA treatments. In summary, this Review highlights modern genetic medicines that have been clinically approved for other diseases, in addition to emerging genome and cellular engineering approaches, with the goal of emphasizing their potential as transformative OA treatments.

Chondroitin sulfate modified chitosan nanoparticles as an efficient and targeted gene delivery vehicle to chondrocytes

Conventional treatments for osteoarthritis (OA), including drug delivery and tissue engineering approaches, could not offer a high yield of cartilage repair due to the compact and exclusive structure of cartilage. Targeted and high-efficiency delivery of gene sequences is necessary to rebalance the lost homeostatic properties of the cartilage in OA. Herein, we synthesized chitosan (CH)-chondroitin sulfate (CS) nanoparticles (NPs) as a platform for delivering gene sequences. These new nanoparticles benefit from two natural polymers that minimize the toxicity, and the presence of CS can be in favor of targeted delivery. The CAG-GFP plasmid was used as a gene sequence model, and the nanoparticles could successfully encapsulate approximately all of them in their structure. Loaded nanoparticles were characterized in terms of morphology, size, zeta potential, the efficiency of encapsulation and, DNA release pattern. Cell viability and uptake of new nanoparticles were compared to the chitosan nanoparticles and Lipofectamine. After substituting TPP with CS, NPs exhibited a significant decrease in size. In addition, there was little difference in zeta potential between nanoparticles. Furthermore, a tremendous increase in plasmid uptake and cell viability was observed by CH-CS NPs compared to CH-TPP NPs and Lipofectamine. In the final stage, the knockdown level of MMP13 was evaluated with real-time RT-PCR for confirming the potential uptake of CH-CS NPs. The results revealed cellular uptake of siRNA loaded NPs and effective knockdown of MMP13 in chondrocytes. In conclusion, CH-CS nanoparticles can be considered as a candidate for gene therapy purposes in cartilage diseases.

Epigenetic Regulation of Chondrocytes and Subchondral Bone in Osteoarthritis

The aim of this review is to provide an updated review of the epigenetic factors involved in the onset and development of osteoarthritis (OA). OA is a prevalent degenerative joint disease characterized by chronic inflammation, ectopic bone formation within the joint, and physical and proteolytic cartilage degradation which result in chronic pain and loss of mobility. At present, no disease-modifying therapeutics exist for the prevention or treatment of the disease. Research has identified several OA risk factors including mechanical stressors, physical activity, obesity, traumatic joint injury, genetic predisposition, and age. Recently, there has been increased interest in identifying epigenetic factors involved in the pathogenesis of OA. In this review, we detail several of these epigenetic modifications with known functions in the onset and progression of the disease. We also review current therapeutics targeting aberrant epigenetic regulation as potential options for preventive or therapeutic treatment.

Top-Down Fabricated microPlates for Prolonged, Intra-articular Matrix Metalloproteinase 13 siRNA Nanocarrier Delivery to Reduce Post-traumatic Osteoarthritis

Post-traumatic osteoarthritis (PTOA) associated with joint injury triggers a degenerative cycle of matrix destruction and inflammatory signaling, leading to pain and loss of function. Here, prolonged RNA interference (RNAi) of matrix metalloproteinase 13 (MMP13) is tested as a PTOA disease modifying therapy. MMP13 is upregulated in PTOA and degrades the key cartilage structural protein type II collagen. Short interfering RNA (siRNA) loaded nanoparticles (siNPs) were encapsulated in shape-defined poly(lactic-co-glycolic acid) (PLGA) based microPlates (μPLs) to formulate siNP-μPLs that maintained siNPs in the joint significantly longer than delivery of free siNPs. Treatment with siNP-μPLs against MMP13 (siMMP13-μPLs) in a mechanical load-induced mouse model of PTOA maintained potent (65-75%) MMP13 gene expression knockdown and reduced MMP13 protein production in joint tissues throughout a 28-day study. MMP13 silencing reduced PTOA articular cartilage degradation/fibrillation, meniscal deterioration, synovial hyperplasia, osteophytes, and pro-inflammatory gene expression, supporting the therapeutic potential of long-lasting siMMP13-μPL therapy for PTOA.

Candidates for Intra-Articular Administration Therapeutics and Therapies of Osteoarthritis

Osteoarthritis (OA) of the knee is a disease that significantly decreases the quality of life due to joint deformation and pain caused by degeneration of articular cartilage. Since the degeneration of cartilage is irreversible, intervention from an early stage and control throughout life is important for OA treatment. For the treatment of early OA, the development of a disease-modifying osteoarthritis drug (DMOAD) for intra-articular (IA) injection, which is attracting attention as a point-of-care therapy, is desired. In recent years, the molecular mechanisms involved in OA progression have been clarified while new types of drug development methods based on gene sequences have been established. In addition to conventional chemical compounds and protein therapeutics, the development of DMOAD from the new modalities such as gene therapy and oligonucleotide therapeutics is accelerating. In this review, we have summarized the current status and challenges of DMOAD for IA injection, especially for protein therapeutics, gene therapy, and oligonucleotide therapeutics.

Applications of RNA interference in the treatment of arthritis

RNA interference (RNAi) is a cellular mechanism for post-transcriptional gene regulation mediated by small interfering RNA (siRNA) and microRNA. siRNA-based therapy holds significant promise for the treatment of a wide-range of arthritic diseases. siRNA selectively suppresses the expression of a gene product and can thus achieve the specificity that is lacking in small molecule inhibitors. The potential use of siRNA-based therapy in arthritis, however, has not progressed to clinical trials despite ample evidence for efficacy in preclinical studies. One of the main challenges to clinical translation is the lack of a suitable delivery vehicle to efficiently and safely access diverse pathologies. Moreover, the ideal targets in treatment of arthritides remain elusive given the complexity and heterogeneity of these disease pathogeneses. Herein, we review recent preclinical studies that use RNAi-based drug delivery systems to mitigate inflammation in models of rheumatoid arthritis and osteoarthritis. We discuss a self-assembling peptide-based nanostructure that demonstrates the potential of overcoming many of the critical barriers preventing the translation of this technology to the clinic.