186 The effects of different concentrations of MgSO₄ in osteogenic differentiation

Abstract

Tissue engineering offers a viable alternative to bone grafts in repairing large bone defects. Magnesium-based materials are biocompatible in vivo, and it is possible to determine the degradation period according to the necessities (Farraro et al. 2014 J. Biomech. 47, 1979-1986). Magnesium (Mg) is part of many physiological processes, and it promotes the osteogenesis of mesenchymal stem cells (Díaz-Tocados et al. 2017 Sci. Rep. 7, 7839.). Moreover, Mg up-regulates important genes associated with the osteogenic differentiation (Yoshizawa et al. 2014 Acta Biomater. 10, 2834-2842). The aim of this study was to evaluate the effect of different Mg concentrations in the osteogenic medium on the number of nodules of bone. Swine adipose stem cells (ASC) were previously isolated as described (Monaco et al. 2009 Open Tissue Eng. Regen. Med. J. 2, 20-33). In this in vitro study, ASC were cultured during 4 weeks in osteogenic medium with addition of 0.1, 0.2, 1, 2, 10, or 20 mM MgSO₄. The medium was changed twice a week. Alizarin Red and Von Kossa staining were performed to evaluate the formation of nodules by mineralization of extracellular matrix (ECM), evidenced by dark red nodules and calcium deposit. The experiment was replicated 3 times in triplicate. Data were analysed using the generalized linear model (GLM) procedure, and Bonferroni’s post hoc test was used to perform statistical multiple comparison (SPSS Inc./IBM Corp., Chicago, IL, USA). The results showed enhanced nodule formation with 2 mM Mg in the osteogenic medium (35.6 v. 15.3, respectively for 2 mM and Control). This result confirms the ability of magnesium to act in bone formation. There was no statistical difference among the different groups when we evaluated the Von Kossa staining results, indicating that the quality of the new formations was comparable to that of the control group even in an elevated nodule formation. In conclusion, a higher concentration of magnesium can improve nodule formation into osteogenic differentiation in vitro; the 2 mM concentration showed the best nodule formation compared with the other groups. These results showed the value of magnesium in bone physiology.