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 have been extensively investigated. However, the role of GlcN in osteogenesis and bone tissue is poorly understood, mainly due to the lack of adequate experimental models. As a result, the benefit of GlcN application in bone disorders remains controversial. In order to further elucidate the pharmacological relevance and potential therapeutic/nutraceutic efficacy of GlcN, the effect of GlcN treatment was investigated in human primary osteoclasts (hOCs) and osteoblasts (hOBs) that were cultured with two‑dimensional (2D) traditional methods or co‑cultured in a 3D dynamic system more closely resembling the bone microenvironment. Under these conditions, osteoclastogenesis was supported by hOBs and sizeable self‑assembling aggregates were obtained. The differentiated hOCs were evaluated using tartrate‑resistant acid phosphatase assays and osteogenic differentiation was monitored by analyzing mineral matrix deposition via Alizarin Red staining, with expression of specific osteogenic markers determined via reverse transcription‑quantitative PCR. It was found that crystalline GlcN sulfate was effective in decreasing osteoclastic cell differentiation and function. hOCs isolated from patients with OA were more sensitive compared with those from healthy donors. Additionally, GlcN exhibited anabolic effects on hOCs both in 2D conventional cell culture and in hOC/hOB 3D dynamic co‑culture. The present study demonstrated for the first time the effectiveness of a 3D dynamic co‑culture system for characterizing the spectrum of action of GlcN on the bone microenvironment, which may pave the way for more fully determining the potential applications of a compound such as GlcN, which is positioned between pharmaceuticals and nutraceuticals. Based on the present findings, it is hypothesized that GlcN may have potential benefits in the treatment of osteopenic diseases such as osteoporosis, as well as in bone maintenance.