Search

Articular cartilage regeneration remains a major challenge in orthopedics. Noncanonical Wnt5a is a particularly attractive growth factor in this context; Wnt5a inhibits chondrocyte hypertrophy but maintains chondrogenesis. We designed a novel, vertically oriented-collagen scaffold. The effect of Wnt5a on MSCs and chondrocytes and the therapeutic effects of the Wnt5a/oriented-collagen scaffold in terms of osteochondral repair and cartilage integration were evaluated. In vitro, the proliferation, migration, and differentiation of MSCs and chondrocytes treated with Wnt5a, and the mechanisms thereof, were assessed. mRNA microarray analysis was performed to compare the expression profiles of MSCs before and after Wnt5a treatment. In vivo, full-thickness cylindrical osteochondral defects (4 mm in diameter, 3 mm in depth) were created in the patellar grooves of 24 New Zealand white rabbits and implanted with oriented-collagen scaffolds (n = 8), Wnt5a/oriented-collagen scaffolds (n = 8), or nothing (n = 8). After 6 and 12 weeks, integration and tissue responses were evaluated. The proliferation, migration, chondrogenic differentiation, and extracellular matrix formation of/by MSCs and chondrocytes improved greatly after treatment with Wnt5a. Western blotting showed that the PI3K/AKT/JNK signaling pathway was activated. Microarray analysis revealed that the Wnt5a group exhibited a significant upregulation of the PI3K pathway. Reactome GSEA pathway interaction analysis revealed that such upregulation was associated with collagen and extracellular matrix formation. In vivo, the Wnt5a/oriented-collagen scaffold group exhibited optimal interface integration, cartilage regeneration, and collagenous fiber arrangement, accompanied by significantly increased glycosaminoglycan and collagen accumulations in the zones of regeneration and integration, compared to the other groups. Gene expression analysis showed that the levels of mRNAs encoding genes involved in cartilage formation were significantly increased in the Wnt5a/oriented, collagen scaffold group (all P < .05). Wnt5a promoted the proliferation, migration, and chondrogenic differentiation of MSCs and chondrocytes via the activation of the PI3K/AKT/JNK signaling pathway. The Wnt5a/oriented-collagen constructs enhanced the structure-specific regeneration of hyaline cartilage in a rabbit model and may be a promising treatment for the repair of human cartilage defects., (© 2020 Federation of American Societies for Experimental Biology.)

The zone of calcified cartilage (ZCC) is the mineralized region between the hyaline cartilage and subchondral bone and is critical in cartilage repair. A new non-stoichiometric calcium silicate (10% Ca substituted by Mg; CSi-Mg10) has been demonstrated to be highly bioactive in an osteogenic environment in vivo. This study is aimed to systematically evaluate the potential to regenerate osteochondral interface with different amount of Ca-Mg silicate in hydrogel-based scaffolds, and to compare with the scaffolds containing conventional Ca-phosphate biomaterials. Hydrogel-based porous scaffolds combined with 0-6% CSi-Mg10, 6% β-tricalcium phosphate (β-TCP) or 6% nanohydroxyapatite (nHAp) were made with three-dimensional (3D) printing. An increase in CSi-Mg10 content is desirable for promoting the hypertrophy and mineralization of chondrocytes, as well as cell proliferation and matrix deposition. Osteogenic and chondrogenic induction were both up-regulated in a dose-dependent manner. In comparison with the scaffolds containing 6% β-TCP or nHAp, human deep zone chondrocytes (hDZCs) seeded on CSi-Mg10 scaffold of equivalent concentration exhibited higher mineralization. It is noteworthy that the hDZCs in the 6% CSi-Mg10 scaffolds maintained a higher expression of the calcified cartilage zone specific extracellular matrix marker and hypertrophic marker, collagen type X. Immunohistochemical and Alizarin Red staining reconfirmed these findings. The study demonstrated that hydrogel-based hybrid scaffolds containing 6% CSi-Mg10 are particularly desirable for inducing the formation of calcified cartilage.

Reactive oxygen species (ROS)-induced chondrocytes apoptosis plays a key role in osteoarthritis (OA) pathogenesis. Uncoupling protein 4 (UCP4) can protect cells against oxidative stress via reducing ROS production and cell apoptosis. Here, silencing of UCP4 in primary chondrocytes significantly inhibited cell survival, but induced ROS production and cell apoptosis. UCP4 mRNA of cartilage tissues was decreased in osteoarthritis patients, which was negatively correlated with synovial fluid (SF) leptin concentration. Moreover, leptin treatment (5, 10 and 20 ng/ml) of primary cultured chondrocytes significantly decreased mRNA and protein levels of UCP4, but increased ROS production and cell apoptosis in a dose-dependent manner. The effects of leptin treatment (20 ng/ml) on chondrocytes was partially reversed by ectopic expression of UCP4. More importantly, intraarticularly injection of UCP4 adenovirus remarkably alleviate OA progression and cell apoptosis in a rat OA model induced by anterior cruciate ligament transection (ACLT). In conclusion, UCP4, whose expression was suppressed by leptin, may be involved in the ROS production and apoptosis of chondrocytes, thus contributing to the OA pathogenesis.

Objective: Interleukin-1β-mediated production of matrix metalloproteinases (MMPs) plays a pivotal role in the process of osteoarthritis. Crocin, a pharmacologically active component of Crocus sativus L. (saffron), has been used in Chinese traditional medicine. In this study, we aimed to investigate the effects of crocin on MMP-1, MMP-3 and MMP-13 expression in rabbit chondrocytes induced by interleukin-1β (IL-1β) and in an experimental rabbit model induced by anterior cruciate ligament transection., Methods: Chondrocytes isolated from the articular cartilage of 4-week-old rabbits were cultured and passaged. Confluent chondrocytes were treated with various concentrations of crocin in the presence or absence of IL-1β (10 ng/ml) for 24 h. Quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blotting were used to investigate the expression of inducible MMP-1, MMP-3 and MMP-13. In addition, the in-vivo effects of crocin were assessed by morphological and histological analysis., Results: IL-1β markedly upregulated the expression of MMP-1, -3 and -13 in chondrocytes, and this activation was inhibited by co-incubation with crocin in a dose-dependent manner, in contrast with the control group. Moreover, crocin inhibited IL-1β-induced activation of the nuclear factor kappa B pathway through suppressing degradation of inhibitory-kappa-B-α. In-vivo investigations showed that crocin ameliorated cartilage degeneration and that expression of the MMP-1, -3 and -13 genes in cartilage was significantly inhibited by crocin., Conclusion: Taken together, our findings suggest that the anti-inflammatory activity of crocin may be of potential value in the prevention and treatment of osteoarthritis.

[Display omitted] • CAQK targets not only injured brain, but also cartilage. • Successfully developed mRNA-cLNP to enhance cartilage-cartilage integration. • mRNA-cLNP penetrates cartilage and extends residence time. • mRNA-cLNP maintains perifocal cellularity and ECM biosynthesis. • Modified mRNA transfer produced IGF-1 protein with higher anti-apoptosis activity than recombinant IGF-1. Integration of repair tissue with host cartilage is challenging. The persistent and drastic hypocellular interface resulting from perifocal chondrocyte apoptosis, leads to failure of cartilage repair over time. Recombinant insulin-like growth factor-1 (IGF-1) has been shown to inhibit chondrocyte apoptosis in vitro. However, low bioactivity, limited penetration and short retention are its drawbacks. Herein, a cartilage targeting ionizable lipid nanoparticle (LNP) is developed. Messenger RNA (mRNA) encoding IGF-1 is chemically modified and encapsulated by LNP (mRNA-LNP). CAQK, a peptide previously used for targeted delivery to the central nervous system, is introduced to mRNA-LNP (mRNA-cLNP) to bind aggrecan enriched in cartilage. As a result, mRNA-cLNP exhibits improved penetration of cartilage and prolonged retention in the joint cavity. The mRNA-cLNP also showed robust reversal of chondrocyte apoptosis. In a full-thickness chondral defect plus microfracture model, mRNA-cLNP maintained interfacial cellularity and prevented matrix degradation in cartilage-cartilage interface. This study shows that mRNA-cLNP is a promising therapeutic agent for integrative cartilage repair. [ABSTRACT FROM AUTHOR]