Dietary supplementation with chondroitin sulfate and glucosamine HCL does not slow down articular cartilage erosion in biglycan/fibromodulin deficient mice

Aim of the study: The effects of oral glucosamine HCl/chondroitin sulfate on preservation of articular cartilage in the biglycan/fibromodulin doubledeficient mouse (DKO) were studied to determine if this new animal model of osteoarthritis (OA) would be suitable to test the in vivo efficacy of structure modifying compounds. Results: Supplementation with glucosamine/chondroitin sulfate did not slow down cartilage erosion in DKO. Articular cartilage was similarly eroded below the tidemark in both DKO groups while being intact in WT groups. This observation was confirmed by measurements of Coll2-1 and C2C biomarkers. The mean serum concentrations of Coll2-1 and C2C in control WT were significantly lower than in control DKO (see Table) but no differences were found between treated and control groups except for higher coll2-1 levels found in WT control group at day 81 (245±40 vs 204±37 nM, p=0.007) and in DKO control group at day 95 (362±60 vs 293±55, p=0.007). Conclusions: While glucosamine and chondroitin sulfate have been shown to slow down cartilage erosion in surgically induced OA in rabbits, this supplementation failed to show any benefit in the DKO. The higher serum levels of coll2-1 in DKO vs WT suggest that this new biomarker, which is specific for a peptide of the α-helical region of type II collagen, could be useful to monitor collagen degradation in joint diseases. Material and methods Two groups of 15 wild-type (WT) mice and 2 groups of 15 biglycan/fibromodulin double-deficient mice (DKO) were fed from weaning (day 21) with a regular diet, supplemented or not with 1.2% chondroitin sulfate and 1.5% glucosamine HCl. Serum levels of the C2C (i.e Coll 2 3/4 C Long, IBEX, Montreal, Canada) and coll2-1 type II collagen biomarkers were determined at day 66 and 141 and at day 49, 81, 95 and 141, respectively. Mice were sacrificed at day 141 and preservation of the articular cartilage in the knees was assessed by histology.