Effects of whole greenshell mussel (Perna canaliculus) powder on macrophage, osteoblast, and chondrocyte cell models of metabolic osteoarthritis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Health Sciences at Massey University, Palmerston North, New Zealand
Osteoarthritis (OA) is a chronic, painful disorder of synovial joints in the hands, knees, hips, and spine. It is characterized by articular cartilage degeneration, subchondral bone sclerosis, and synovium inflammation. Obesity is an important risk factor, by exerting additional mechanical loading on the joints and by increasing the hormone leptin (LEP). LEP, an adipokine produced by white adipose tissue, is important in regulating the metabolic activities of inflammatory, cartilage and bone cells in OA pathogenesis. OA has no cure and is conventionally managed with painkilling medications. Oil from New Zealand GreenshellTM mussel (GSM) is also used to treat OA, but its mechanism of action is unclear, and it is not known whether peptides and other components in whole GSM may have additional health benefits in OA. This study investigated the effects of whole GSM using novel in vitro models of OA. LEP-stimulated J774A.1 macrophages, MC3T3-E1 pre-osteoblasts and differentiated osteoblasts, and ATDC5 pre-chondrocytes and differentiated chondrocytes modelled the behaviour of synovial macrophages, subchondral bone, and cartilage cells during OA. Blue mussel (BM) and GSM extracts were used to optimise macrophage assay conditions. Two whole GSM extracts were further tested in the in vitro models at non-cytotoxic concentrations. RT-qPCR was used to quantify biomarkers; chemical and staining assays were used to assess alkaline phosphatase activity and mineralization, proteoglycan, and collagen synthesis. LEP-induced inflammatory cytokine expression in macrophages peaked at 4 and was dose-dependent; neither mussel type ameliorated inflammation but BM alone significantly induced IL-1β, IL-6, TNF-α and IL-10 expression. GSM significantly increased osteoblast proliferation, mineral deposition, and expression of osteogenic markers Alp, Osx, Col10α1 and Runx2. In chondrocytes, GSM significantly blocked LEP-induced hypertrophic differentiation by suppressing alkaline phosphatase, Col10α1 and mineralized nodules and increasing Sox9 expression. This project developed simple but effective in vitro models of inflammatory, bone, and cartilage cells that mimic the physiological response to LEP and the pathological changes observed in OA and demonstrated that whole GSM may prevent OA by acting directly on bone and cartilage rather than acting through well recognized anti-inflammatory pathway, indicating novel protective effects of whole GSM on all three cell types.
Osteoarthritis, Alternative treatment., Perna, Therapeutic use, Biological models
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