Protective effects of ugonin K on hydrogen peroxide-induced osteoblast cell damage

Bone Health and Natural Products- An Insight

Bone metabolism involves a complex balance between matrix deposition, mineralization, and resorption. Numerous evidences have revealed that dietary components and phytoconstituents can influence these processes, through inhibition of bone resorption, thus exhibiting beneficial effects on the skeleton. Various traditional herbal formulae in ayurvedic and Chinese medicine have shown demonstrable benefits in pharmacological models of osteoporosis. The present review discusses normal bone metabolism and disorders caused by bone disruption, with particular reference to osteoporosis and current therapeutic treatment. Furthermore the effects of constituents from natural products on bone tissue are explained, with relevant evidences of efficacy in various experimental models.

The Effects of Cerium Valence States at Cerium Oxide Coatings on the Responses of Bone Mesenchymal Stem Cells and Macrophages

Ideal orthopedic coatings should trigger good osteogenic response and limited inflammatory response. The cerium valence states in ceria are associated with their anti-oxidative activity and anti-inflammatory property. In the study, we prepared two kinds of plasma sprayed CeO₂ coatings with different Ce⁴⁺ concentrations to investigate the effects of Ce valence states on the response of bone mesenchymal stem cells (BMSCs) and macrophage RAW264.7. Both the coatings (CeO₂-A and CeO₂-B) were characterized via XRD, SEM, and X-ray photoelectron spectroscopy. The CeO₂ coatings enhanced osteogenic behaviors of BMSCs in terms of cellular proliferation, alkaline phosphatase (ALP) activity and calcium deposition activity in comparison with the Ti substrate. In particular, the CeO₂-B coating (higher Ce⁴⁺ concentration) elicited greater effects than the CeO₂-A coating (higher Ce³⁺ concentration). RT-PCR and western blot results suggested that the CeO₂-B coating promoted BMSCs osteogenic differentiation through the SMAD-dependent BMP signaling pathway, which activated Runx2 expression and subsequently enhanced the expression of ALP and OCN. With respect to either CeO₂-A coating or Ti substrate, the CeO₂-B coating exerted greater effects on the macrophages, increasing the anti-inflammatory cytokines (IL-10 and IL-1ra) expression and suppressing the expression of the pro-inflammatory cytokines (TNF-α and IL-6) and ROS production. Furthermore, it also upregulated the expression of osteoinductive molecules (TGF-β1 and BMP2) in the macrophages. The regulation of cerium valence states at plasma sprayed ceria coatings can be a valuable strategy to improve osteogenic properties and alleviate inflammatory response.

Cerium Oxide-Incorporated Calcium Silicate Coating Protects MC3T3-E1 Osteoblastic Cells from H2O2-Induced Oxidative Stress

Oxidative stress regulates cellular functions in multiple pathological conditions, including bone formation by osteoblastic cells. In this work, the protective effects of cerium oxide (CeO₂)-incorporated calcium silicate (CeO₂-CS) coating on the response of osteoblasts to H₂O₂-induced oxidative stress and the related mechanism were examined. CeO₂ incorporation significantly improved osteoblast viability and reduced cell apoptosis caused by H₂O₂ when compared with the control. H₂O₂-induced reduction of differentiation marker alkaline phosphatase (ALP) was recovered in the presence of the CeO₂-CS coating. The above effects were mediated by the antioxidant effect of CeO₂. The CeO₂-CS coating immersed in 0.1 mM H₂O₂ aqueous solution was able to degrade 64 % of it in 1 week. In addition, CeO₂ incorporation decreased reactive oxygen species (ROS) production and suppressed malondialdehyde (MDA) formation in H₂O₂-treated osteoblasts. Taken together, CeO₂-CS biomedical coatings with antioxidant property would be promising for bone regeneration under oxidative stress.

Plasma sprayed cerium oxide coating inhibits H2O2-induced oxidative stress and supports cell viability

Oxidative stress is a risk factor in the pathogenesis of osteoporosis, and plays a major role in bone regeneration of osteoporotic patients. Cerium oxide (CeO2) ceramics have the unique ability to protect various types of cells from oxidative damage, making them attractive for biomedical applications. In this study, we developed a plasma sprayed CeO2 coating with a hierarchical topography where ceria nanoparticles were superimposed in the micro-rough coating surface. The protective effects of the CeO2 coating on the response of osteoblasts to H2O2-induced oxidative stress have been demonstrated in terms of cell viability, apoptosis and differentiation. The CeO2 coating reversed the reduced superoxide dismutase activity, decreased reactive oxygen species production and suppressed malondialdehyde formation in H2O2-treated osteoblasts. It indicated that the CeO2 coating can preserve the intracellular antioxidant defense system. The cytocompatibility of the CeO2 coating was further assessed in vitro by cell viability assay and scanning electron microscopy analysis. Taken together, the CeO2 coating could provide an opportunity to be utilized as a potential candidate for bone regeneration under oxidative stress.