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Objectives and questions: Bone is increasingly recognized as an endocrine organ influencing systemic metabolism. Osteocytes regulate bone remodeling and secrete signaling molecules implicated in adipose tissue regulation, including sclerostin (SOST) and bone morphogenetic protein 7 (BMP7). However, direct osteocyte–adipocyte interaction remains insufficiently characterized. The objective of this experimental study was to establish a functional osteocyte–adipocyte co-culture model and to investigate osteocyte-derived signaling relevant to bone–fat communication.

Material and methods: An experimental in vitro co-culture system was established using osteocyte-enriched bone fragments and freshly isolated mature visceral adipocytes obtained from rats. After enzymatic digestion and preparation, adipocytes were co-cultured with bone fragments for 14 days under controlled conditions. Cell viability was assessed using live/dead fluorescence assays and brightfield microscopy. Histological analyses were performed to evaluate SOST and BMP7 expression in bone fragments. Analyses were descriptive. Further molecular characterization including RNA sequencing is ongoing to investigate differential gene expression associated with osteocyte–adipocyte interaction.

Results: The co-culture model was successfully established and demonstrated sustained metabolic activity and viability of both adipocytes and bone fragments for at least 14 days. Live/dead assays confirmed maintained cell integrity in both populations. Histological evaluation showed increased SOST and BMP7 expression in co-cultured bone fragments compared with monoculture controls. These findings indicate active osteocyte-derived signaling within the co-culture environment and suggest a functional role of osteocytes in modulating adipocyte-related pathways.

Discussion and conclusions: A stable osteocyte–adipocyte co-culture system was successfully developed, enabling direct investigation of cellular bone–fat crosstalk. The observed modulation of SOST and BMP7 expression supports the concept of osteocyte-mediated regulation of adipocyte signaling. This experimental platform provides a translational framework for identifying molecular targets relevant to osteoporosis and metabolic disease. Future work will extend this model to paired human bone and adipose tissue samples to validate the observed signaling mechanisms in a clinically relevant setting.