Substituted Borosilicate Glasses with Improved Osteogenic Capacity for Bone Tissue Engineering

Borosilicate bioactive glasses (BBGs) have shown capacity to improve the new bone formation when compared to silicate bioactive glasses. Herein, we assessed the capacity of BBGs to induce the osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs), as a function of their substituted divalent cations (Mg2+, Ca2+, Sr2+). To this purpose, we synthesized BBG particles by melt quench. The cell viability, proliferation and morphology, (i.e. PrestoBlue®, PicroGreen®, and DAPI and Phalloidin stainings, respectively) as well as protein expression (of ALP, osteopontin and osteocalcin) of BM-MSCs in contact with the BBGs were evaluated for 21 days. We observed an enhanced expression of bone-specific proteins (ALP, OP and OC) and high mineralization of BM-MSCs under BBG-Mg and BBG–Sr conditioned osteogenic media for concentrations of 20 and 50 mg/ml with low cytotoxic effects. Moreover, BBG-Sr at a concentration of 50 mg/ml was able to increase the mineralization and expression of bone-specific proteins even under basal media conditions. These results indicated that the proposed BBGs improved the osteogenic differentiation of BM-MSCs. Therefore, showing their potential as relevant biomaterials for bone tissue regeneration, not only by bonding to bone tissue, but also by stimulating new bone formation.