Tat SK et al. (2007) Chondroitin and glucosamine sulfate in combination decrease the pro-resorptive properties of human osteoarthritis subchondral bone osteoblasts: a basic science study. Arthritis Res Ther 9: R117

Osteoarthritis is extremely common, and its symptoms are universally known; however, mechanisms that describe how the complex interplay of inflammatory and other factors cause structural changes in the joint are not yet fully elucidated. While chondroitin sulfate and glucosamine sulfate both have well-documented, beneficial effects in patients with osteoarthritis, the exact molecular actions of these drugs are also unknown.

Tat et al. focused on human subchondral bone and the role of altered osteoblast metabolism in their study, which investigated whether these drugs affect proresorptive activity, or alter levels of osteoprotegerin and receptor activator of nuclear factor κB ligand (RANKL) in affected joints.

Their data showed that 200 µg/ml chondroitin sulfate, 50 µg/ml or 200 µg/ml glucosamine sulfate, or a combination of 200 µg/ml chondroitin sulfate and 200 µg/ml glucosamine sulfate affected neither basal levels nor vitamin-D3-induced release of alkaline phosphatase or osteocalcin. However, both drugs upregulated osteoprotegerin expression in patients with osteoarthritis, irrespective of whether they were receiving vitamin D supplements. Chondroitin sulfate and the combination therapy reduced the expression of RANKL in patients not receiving vitamin D, but in those taking vitamin D, the effect failed to reach significance.

The authors conclude that, while the two drugs do not influence cell integrity or bone biomarkers, chondroitin sulfate either alone or together with glucosamine sulfate increases the expression ratio of osteoprotegerin:RANKL, suggesting they might help slow down the degeneration of subchondral bone in osteoarthritis.