Human osteoclasts/osteoblasts 3D dynamic co-culture system to study the beneficial effects of glucosamine on bone microenvironment

Glucosamine (GlcN) functions as a building block of the cartilage matrix and its multifaceted roles in promoting joint health has been extensively investigated. On the contrary, the role of GlcN in osteogenesis and bone tissue is poorly understood, mainly due to the lack of adequate experimental models. Consequently, the benefit of GlcN in bone disorders remains controversial. In order to broaden the pharmacological relevance and potential therapeutic/nutraceutic efficacy of GlcN, we investigated the effect of GlcN treatment on human primary osteoclasts (hOCs) and osteoblasts (hOBs) that were grown with 2D traditional methods or co-cultured in a more complex culture system one step closer to the in vivo bone microenvironment, consisting in a three-dimensional (3D) dynamic system (RCCS-4TM bioreactor, Synthecon™). In this condition osteoclastogenesis was supported by hOBs and sizeable self assembling aggregates were obtained. The differentiated osteoclasts were evaluated by the tartrate-resistant acid phosphatase assay (TRAP), osteogenic differentiation was monitored by analyzing both mineral matrix deposition through Alizarin Red staining, and expression of specific osteogenic markers through RT-qPCR. We found that DONA® crystalline glucosamine sulfate (i.e. the original GlcN sulfate product) was effective in decreasing the osteoclastic cell differentiation and function. Osteoclasts from OA donors were more sensitive than those from healthy donors. At the same time, DONA® showed anabolic effects on osteoblasts both in 2D conventional cell culture and in osteoclasts/osteoblasts 3D dynamic co-culture system. Here we demonstrated for the first time, as far as we know, the effectiveness of a 3D dynamic co-culture system to provide useful information on the spectrum of action of GlcN on bone microenvironment. This can pave the way to better define the potential applications of a compound such as GlcN which is positioned between pharmaceuticals and nutraceuticals. Therefore, based on our observations, we hypothesize that GlcN could have potential benefits either in the treatment of osteopenic diseases such as osteoporosis, or in the bone health maintenance.