The purpose of this study was to examine the effects of hyaluronic acid supplementation on chondrocyte metabolism in vitro. The clinical benefits of intra-articular hyaluronic acid injections are thought to occur through improved joint lubrication. Recent findings have shown that exogenous hyaluronic acid is incorporated into articular cartilage where it may have a direct biological effect on chondrocytes through CD44 receptors.Bovine articular chondrocytes were isolated and seeded into alginate constructs. These were cultured in medium containing hyaluronic acid at varying concentrations. Samples were assayed for biochemical and histological changes. There was a dose-dependent response to the exposure of hyaluronic acid to bovine articular chondrocytes in vitro. Low concentrations of hyaluronic acid (0.1 mg/mL and 1 mg/mL) significantly increase DNA, sulphated glycosaminoglycan and hydroxyproline synthesis. Immunohistology confirmed the maintenance of cell phenotype with increased matrix deposition of chondroitin-6-sulphate and collagen type II. These findings confirm a stimulatory effect of hyaluronic acid on chondrocyte metabolism.

Nicotine has an overall detrimental effect on NP disc cells cultured in vitro. There was significant inhibition of cell proliferation and extracellular matrix synthesis. Nicotine in tobacco smoke may have a role in pathogenesis of disc degeneration.