Osteogenic properties of manganese-doped mesoporous bioactive glass nanoparticles

Mesoporous bioactive glass nanoparticles (MBGNs) based on the SiO₂ -P₂ O₅ -CaO system have demonstrated promising properties for the local delivery of therapeutically active ions with the aim to improve their osteogenic properties. Manganese (Mn) has been identified as a candidate ion for local application in bone tissue engineering applications. It remains unknown how SiO₂ -P₂ O₅ -CaO-based MBGNs influence human bone marrow-derived mesenchymal stromal cells (BMSCs) in terms of viability, proliferation, and differentiation and how these features can be modified by the addition of Mn to the MBGNs' composition. Therefore, in this study, MBGNs (composition in mol%: 50 SiO₂ , 40 CaO, 10 P₂ O₅ ) and its Mn-doped derivate 5Mn-MBGNs (composition in mol%: 50 SiO₂ , 35 CaO, 10 P₂ O₅ , 5 MnO) were applied to a culture of BMSCs in two different concentrations. With increasing concentration, 5Mn-MBGNs supported osteogenic differentiation and enhanced the upregulation of genes encoding for extracellular matrix proteins but also negatively influenced cell viability and proliferation. When applied in lower concentrations, MBGNs showed not only viability- and growth-enhancing effects but also significant pro-osteogenic features-however, these positive properties deteriorated with increasing concentration. Two major conclusions can be drawn from this study: (a) supplementation with Mn enhances the osteogenic properties of MBGNs in a dose-dependent manner and (b) MBGNs constitute an attractive vector for therapeutically active ions since it exhibits an intrinsic pro-osteogenic potential that can be improved and/or modified by incorporation of therapeutically active ions. Future studies should focus on the evaluation of further candidate ions that are known to influence osteogenic differentiation positively.