Abstract
Bioactive glasses are known to stimulate bone healing, and the incorporation of strontium has the potential to increase their potency. In this study, calcium oxide in the 45S5 bioactive glass composition was partially (50%, Sr50) or fully (100%, Sr100) substituted with strontium oxide on a molar basis. The effects of the substitution on bioactive glass properties were studied, including density, solubility, and in vitro cytotoxicity. Stimulation of osteogenic differentiation was investigated using mesenchymal stromal cells obtained from rat bone marrow. Strontium substitution resulted in altered physical properties including increased solubility. Statistically significant reductions in cell viability were observed with the addition of bioactive glass powders to culture medium. Specifically, addition of ≥ 13.3 mg/ml of 45S5 bioactive glass or Sr50, or ≥ 6.7 mg/ml of Sr100, resulted in significant inhibition. Real‐time PCR analyses detected the upregulation of genes associated with osteoblastic differentiation in the presence of all bioactive glass compositions. Some genes, including Alpl and Bglap, were further stimulated in the presence of Sr50 and Sr100. It was concluded that strontium‐substituted bioactive glasses promoted osteogenesis in a differentiating bone cell culture model and, therefore, have considerable potential for use as improved bioactive glasses for bone tissue regeneration. © 2015 The Authors. Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.
Highlights
Since their development by Larry Hench in the 1960s (Hench, 2006), bioactive glasses have been used extensively in the treatment of bone tissue defects, due to their ability to stimulate healing via dissolution, followed by the formation of a surface layer of hydroxycarbonate apatite
The differential volume distributions showed a peak centred at particle size values within the range 9–13 μm and a tail region which extended to particle sizes < 1 μm for the three bioactive glass powders (Figure 1A)
It was observed that Tg decreased as the level of strontium substitution increased from Sr0 to Sr100 compositions, while both Tc and Tp presented minimum values in the case of Sr50
Summary
Since their development by Larry Hench in the 1960s (Hench, 2006), bioactive glasses have been used extensively in the treatment of bone tissue defects, due to their ability to stimulate healing via dissolution, followed by the formation of a surface layer of hydroxycarbonate apatite. Once the surface modification process has occurred, the hydroxycarbonate apatite layer interacts with collagen fibrils in the damaged tissues, creating a bond. The biological interactions leading to this outcome are thought to include the adsorption of proteins and the attachment of cells, followed by their differentiation.
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