Thein vivoperformance of an alkali‐free bioactive glass for bone grafting,FastOs^®BG, assessed with an ovine model

Abstract

Although bioactive glasses are successfully used as bone substitutes, recent studies have revealed that the high alkali content in these glasses leads to fast in vivo degradation rates that may not match the rate of new bone ingrowth. This prompted us to design and develop novel bioactive glasses that are devoid of alkali but still demonstrate high bioactivity in vitro. This article describes the in vivo performance of an alkali-free bioactive glass with the following composition (Wt %): 13.03 MgO-33.98 CaO-13.37 P O -38.84 SiO -0.77 CaF (labelled as FastOs BG). An animal model was used to assess the in vivo performance of FastOs BG, using 45S5 Bioglass as control. The evaluation was performed through implantation of FastOs BG and 45S5 Bioglass , during one month, in femoral bone defects in sheep. Subcutaneous implantation of both glasses was also performed in order to assess tissue response through a standardized method. Histological and scanning electron microscopy assessment of retrieved subcutaneous and bone samples demonstrated that FastOs BG is biocompatible, osteoconductive, that it can be osteointegrated, and that it is more slowly resorbed than 45S5 Bioglass . These features suggest that FastOs BG is a potential candidate for bone grafting. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 30-38, 2017.

The key Features expected from a Perfect Bioactive Glass –How Far we still are from an Ideal Composition?

“…The effects of such individual or combined substitutions on the relevant properties of the resulting bioactive glasses were investigated and reported in several publications [30][31][32][33].These alkali-free bioactive glasses revealed to have several distinctive features including: moderate degradation rate, accompanied by a fast bio mineralisation rate in vitro with the formation of a hydroxycarbonate apatite (HCA) surface layer after 1 h of immersion in simulated body fluid (SBF) [26,30,32]; the ability to reduce oxidative stress [30,32]; osteogenic activity, inducing the differentiation of hMSCs into bone forming cells even in the absence of osteogenic medium [29]. This osteo induction effect was significantly greater in comparison to that of 45S5 Bioglass® [34]; and excellent bone bonding ability confirmed by in vivo studies using sheep as animal model [35]. Other interesting features of these bioactive glass compositions are the easiness of dispersing the glass powder frits in aqueous suspensions and scaffold fabrication by additive manufacturing techniques [36].…”

Comparison of the effects of 45S5 and 1393 bioactive glass microparticles on hMSC behavior

“…%) a new class of bioactive ceramic materials was created, characterized by their ability to form a strong and stable chemical bond with bone tissue . Bioactive glasses (BAGs) have since attracted immense interest in the field of tissue engineering because of their demonstrated osteoconductive (stimulation of bone growth along its surface) and osteostimulatory (activation of osteoprogenitor cells in the bone environment) properties . Additionally, BAGs facilitate the formation of a carbonated hydroxyapatite layer on their surface when exposed to biological fluids, and resorb over time .…”

Structural changes during crystallization of apatite and wollastonite in the eutectic glass of Ca3(PO4)2‐CaSiO3system

“…Although the incorporation of alkali oxides in bioactive glass is advantageous for their production, as they reduce the melting temperature of the glass, high levels of alkali cations degrade the sintering ability of bioactive glasses by increasing the crystallization tendency of glass . Furthermore, their presence in bioactive glass can reduce the usefulness of the glass in vivo . The incorporation of Na 2 O in parent glass decreased considerably the cell viability due to a fast release of alkali ions at releasing rates faster than that of calcium .…”