In vitro Osteogenesis in Autologous and IPS-derived Canine Mesenchymal Stromal Cells is Modulated by Dexamethasone and Bone Morphogenic Protein-2

Introduction: Mesenchymal stromal cells (MSCs) represent promising agents for bone repair. However, osteogenic culture conditions must be optimized. The objective of this study was to determine the effect of varying the concentration and time-of-delivery of dexamethasone and BMP-2 on early- and late-stage osteogenesis of both autologous and IPS-derived cMSCs.

Materials and Methods: cMSCs were cultured under control and osteogenic conditions in the presence of varying concentrations of BMP-2 and dexamethasone. Cultures were assayed for alkaline phosphatase activity (ALP) at day 7 and Alizarin Red staining (ALZ) at day 21. Data were reported as mean ± SD and analyzed using two-way ANOVA with Tukey’s tests.

Results: Increasing concentrations of dexamethasone with low levels of BMP-2 reduced ALP activity in both marrow and IPS cMSCs. This effect was attenuated at high concentrations of BMP-2 in autologous but not IPS cMSCs. In late-stage assays, higher dexamethasone and BMP-2 concentrations, provided at day 1, enhanced osteogenesis in marrow cMSCs. In contrast, dexamethasone impaired osteogenesis of IPS-cMSCs.

Discussion/Conclusion: In vitro osteogenesis of cMSCs can be modulated by varying the timing and concentration of osteogenic factors. The mechanisms underlying osteogenesis of IPS-derived cMSCs may be different as compared with autologous cMSCs. Further work is necessary to identify the mechanistic underpinnings of these differences. This work represents an important first step for development of optimal osteogenic cMSC culture conditions that are tailored to individual preparations of cMSCs.

Acknowledgment: No proprietary interest. Funded by the AKC-CHF and the Bone & Joint Fund.