JD-312 - A novel small molecule that facilitates cartilage repair and alleviates osteoarthritis progression

Mechanism of chondrocyte injury induced by Benzophenone-3 through modulation of the IL-6/JAK2/STAT3 pathway

Currently, limited research exists on the relationship between osteoarthritis (OA) and Benzophenone-3 (BP-3). This study aims to explore the potential molecular pathways involved, using both in vivo and in vitro biological experiments. In vivo experiments revealed that exposure to BP-3 leads to cartilage damage in the knee joints of rats, suggesting that BP-3 may be a significant risk factor in the development and progression of osteoarthritis. Proteomic sequencing of knee cartilage tissue revealed alterations in multiple inflammatory pathways in the BP-3 group. In vitro cellular experiments further demonstrated the toxic effects of BP-3 on chondrocytes, including inflammatory changes and increased transcriptional levels of IL-6. Cellular transcriptomics sequencing revealed significant changes in multiple intracellular inflammatory pathways, particularly the JAK-STAT pathway. Additional experiments demonstrated that BP-3 enhances STAT3 phosphorylation, promoting the degradation of extracellular matrix (ECM) proteins. Silence of STAT3 alleviated the impaired effects of BP-3 on chondrocytes. Overall, our data suggest that BP-3 exposure may be a significant risk factor for OA development. This study provides substantial evidence and a comprehensive understanding of the impact of BP-3 on OA development.

Kartogenin Enhances Chondrogenic Differentiation of iPSC Derived MSCs (iMSCs) and Improves Outcomes in an Osteochondral Defect Model in Male Rats

Osteochondral defects (OCD) pose a significant clinical challenge due to the limited self-repair capacity of cartilage, leading to pain, joint dysfunction, and progression to osteoarthritis. Cellular implantations of adult mesenchymal stem cells (MSCs) enhanced with treatment of factors, such as small molecule Kartogenin (KGN) to promote chondrogenic differentiation, are promising but these cells often encounter hypertrophy during differentiation, compromising long-term stability. Induced pluripotent stem cell-derived MSCs (iMSCs) offer greater proliferative and differentiation capacity than MSCs and may provide a superior source of cells for cartilage repair. We hypothesized that treatment of iMSCs with TGFβ3 and KGN would enhance chondrogenic differentiation and that implanting these pellets into a rat OCD model would promote de novo cartilage regeneration and reduce pain behavior. We pellet cultured iMSCs derived from articular chondrocytes and treated with various conditions of TGFβ3 and KGN. We then assessed the in vivo performance of the pellets using a trochlear osteochondral defect in male Lewis rats. Co-treatment of iMSC pellets with TGFβ3 and KGN showed more pronounced chondrogenic differentiation than sequential treatment and exhibited stronger expression of chondrogenic genes. Implantation of the TGFβ3/KGN-treated iMSC pellets into OCD resulted in modest repair, as observed via gross morphology, effectively prevented the onset of joint hyperalgesia, and helped to maintain normal gait out to 12 weeks post-implantation compared to untreated OCD rats. Our study highlights the potential of KGN to enhance iMSC pellet chondrogenesis, offering a scaffold-free, cell-based therapy that could simplify clinical translation and improve outcomes for patients with cartilage injuries.

Silk fibroin-based hydrogels for cartilage organoids in osteoarthritis treatment

Osteoarthritis (OA) is a common joint disease characterized by cartilage degeneration. It can cause severe pain, deformity and even amputation risk. However, existing clinical treatment methods for cartilage repair present certain deficiencies. Meanwhile, the repair effect of cartilage tissue engineering is also unsatisfactory. Cartilage organoids are multicellular aggregates with cartilage-like three-dimensional structure and function. On the one hand, cartilage organoids can be used to explore the pathogenesis of OA by constructing disease models. On the other hand, it can be used as filler for rapid cartilage repair. Extracellular matrix (ECM)-like three-dimensional environment is the key to construct cartilage organoids. Silk fibroin (SF)-based hydrogels not only have ECM-like structure, but also have unique mechanical properties and remarkable biocompatibility. Therefore, SF-based hydrogels are considered as ideal biomaterials for constructing cartilage organoids. In this review, we reviewed the studies of cartilage organoids and SF-based hydrogels. The advantages of SF-based hydrogels in constructing cartilage organoids and the iterative optimization of cartilage organoids through designing hydrogels by using artificial intelligence (AI) calculation are also discussed. This review aims to provide a theoretical basis for the treatment of OA using SF-based biomaterials and cartilage organoids.

Sargassum polysaccharide attenuates osteoarthritis in rats and is associated with the up-regulation of the ITGβ1-PI3K-AKT signaling pathway

Background

Osteoarthritis (OA) presents a formidable challenge, characterized by as-yet-unclear mechanical intricacies within cartilage and the dysregulation of bone homeostasis. Our preliminary data revealed the encouraging potential of a Sargassum polysaccharide (SP), in promoting chondrogenesis. The aim of our study is to comprehensively assess the therapeutic effects of SP on OA models and further elucidate its potential mechanism.

Methods

The protective effects of SP were initially evaluated in an inflammation-induced human chondrocyte (C28) cell model. CCK-8 assays, Alcian blue staining, RT-qPCR and Western blotting were used to verify the chondrogenesis of SP in vitro. To assess the efficacy of SP in vivo, surgically induced medial meniscus destabilization (DMM) OA rats underwent an 8-week SP treatment. The therapeutic effects of SP in OA rats were comprehensively evaluated using X-ray imaging, micro-computed tomography (μ-CT), histopathological analysis, as well as immunohistochemical and immunofluorescent staining. Following these assessments, we delved into the potential signaling pathways of SP in inflammatory chondrocytes utilizing RNA-seq analysis. Validation of these findings was conducted through RT-qPCR and western blotting techniques.

Results

SP significantly enhance the viability of C28 chondrocytes, and increased the secretion of acidic glycoproteins. Moreover, SP stimulated the expression of chondrogenic genes (Aggrecan, Sox9, Col2a1) and facilitated the synthesis of Collagen II protein in C28 inflammatory chondrocytes. In vivo experiments revealed that SP markedly ameliorated knee joint stenosis, alleviated bone and cartilage injuries, and reduced the histopathological scores in the OA rats. μ-CT analysis confirmed that SP lessened bone impairments in the medial femoral condyle and the subchondral bone of the tibial plateau, significantly improving the microarchitectural parameters of the subchondral bone. Histopathological analyses indicated that SP notably enhanced cartilage quality on the surface of the tibial plateau, leading to increased cartilage thickness and area. Immunohistochemistry staining and immunofluorescence staining corroborated these findings by showing a significant promotion of Collagen II expression in OA joints treated with SP. RNA-seq analysis suggest that SP's effects were mediated through the regulation of the ITGβ1-PI3K-AKT signaling axis, thereby stimulating chondrogenesis. Verification through RT-qPCR and Western blot analyses confirmed that SP significantly upregulated the expression of ITGβ1, p110δ, AKT1, ACAN, and Col2a1. Notably, knock-down of ITGβ1 using siRNA in C28 chondrocytes inhibited the expression of ITGβ1, p110δ, AKT1, and ACAN. However, these inhibitory effects were not completely reversed by supplemental SP intervention.

Conclusions

In summary, our findings reveal that SP significantly enhances chondrogenesis both in vitro and in vivo, alleviating OA progression both in bone and cartilage. The observed beneficial effects are intricately linked to the activation of the ITGβ1-PI3K-AKT signaling axis.

The translational potential of this article

Our research marks the first instance unveiling the advantageous effects and underlying mechanisms of SP in OA treatment. With its clinical prospects, SP presents compelling new evidence for the advancement of a next-generation polysaccharide drug for OA therapy.