Lower range of molecular weight of xanthan gum inhibits apoptosis of chondrocytes through MAPK signaling pathways

LRWXG has previously been reported to have a protective effect on chondrocytes, preventing apoptosis induced by oxidative stress. In this study, we were aimed at determining whether LRWXG exerts its anti-apoptotic activity through the MAPK signaling pathways in chondrocytes. Our results show that, at the cellular level, apoptosis of chondrocytes in the groups treated by LRWXG decreases compared with groups treated by inhibitors alone and model group under conditions of oxidative stress in a dose-dependent manner. Mechanistically at the molecular level, LRWXG regulates the MAPK pathway induced by oxidative stress: The levels of phosphorylation of JNK and p38 proteins in the groups treated by LRWXG are lower than model group, while compared with corresponding groups of inhibitors, there are no significant difference; For other related proteins, LRWXG reduces the levels of the apoptosis-related proteins BAX and cleaved caspase-3, and increases the level of anti-apoptotic protein BCL2. In addition, LRWXG can significantly reduce the levels of inflammatory-related factors such as COX2, PEG2, TNFα and IL1β, and inhibits the expression of MMPs, increasing the content of type II collagen. The results of this research strongly suggest that LRWXG exerts its anti-apoptotic activity via regulating the MAPK signaling pathways in vitro.

Injectable and 3D Bioprinted Polysaccharide Hydrogels: From Cartilage to Osteochondral Tissue Engineering

Biomechanical performance of functional cartilage is executed by the exclusive anisotropic composition and spatially varying intricate architecture in articulating ends of diarthrodial joint. Osteochondral tissue constituting the articulating ends comprise superfical soft cartilage over hard subchondral bone sandwiching interfacial soft-hard tissue. The shock-absorbent, lubricating property of cartilage and mechanical stability of subchondral bone regions are rendered by extended chemical structure of glycosaminoglycans and mineral deposition, respectively. Extracellular matrix glycosaminoglycans analogous polysaccharides are major class of hydrogels investigated for restoration of functional cartilage. Recently, injectable hydrogels have gained momentum as it offers patient compliance, tunable mechanical properties, cell deliverability, and facile administration at physiological condition with long-term functionality and hyaline cartilage construction. Interestingly, facile modifiable functional groups in carbohydrate polymers impart tailorability of desired physicochemical properties and versatile injectable chemistry for the development of highly potent biomimetic in situ forming scaffold. The scaffold design strategies have also evolved from single component to bi- or multilayered and graded constructs with osteogenic properties for deep subchondral regeneration. This review highlights the significance of polysaccharide structure-based functions in engineering cartilage tissue, injectable chemistries, strategies for combining analogous matrices with cells/stem cells and biomolecules and multicomponent approaches for osteochondral mimetic constructs. Further, the rheology and precise spatiotemporal positioning of cells in hydrogel bioink for rapid prototyping of complex three-dimensional anisotropic cartilage have also been discussed.

Xanthan gum protects rabbit articular chondrocytes against sodium nitroprusside-induced apoptosis in vitro

We have previously reported that intra-articular injection of xanthan gum (XG) could significantly ameliorate the degree of joint cartilage degradation and pain in experimental osteoarthritis (OA) model in vivo. In this present study, we evaluated the protective effect of XG against Sodium nitroprusside (SNP)-induced rabbit articular chondrocytes apoptosis in vitro. Rabbit articular chondrocytes were incubated with various concentrations of XG for 24h prior to 0.5mmol/L SNP co-treatment for 24h. The proliferation of chondrocytes was analyzed using MTT assay. The chondrocytes early apoptosis rates were evaluated using Annexin V-FITC/PI flow cytometry. The morphology of apoptosis chondrocytes were observed by scanning electron microscopy (SEM). The loss/disruption of mitochondrial membrane potential was detected using rhodamin 123 by confocal microscope. The concentration of prostaglandin E2 (PGE2) in cell culture supernatants was evaluated using ELISA assay. The results showed that XG could significantly reverse SNP-reduced cell proliferation and inhibited cell early apoptosis rate in a dose-dependent manner. XG alleviated loss/disruption of mitochondrial membrane potential and decreased the PGE2 level of chondrocytes cell culture supernatants in SNP-induced chondrocytes. These results of the present research strongly suggest that XG can protect rabbit articular chondrocytes against SNP-induced apoptosis in vitro.