Bone Regeneration by Novel Bioactive Glasses Containing Strontium and/or Magnesium: A Preliminary In-Vivo Study

Abstract

In this work, a set of novel bioactive glasses have been tested in vivo in an animal model. The new compositions, characterized by an exceptional thermal stability and high in vitro bioactivity, contain strontium and/or magnesium, whose biological benefits are well documented in the literature. To simulate a long-term implant and to study the effect of the complete dissolution of glasses, samples were implanted in the mid-shaft of rabbits’ femur and analyzed 60 days after the surgery; such samples were in undersized powder form. The statistical significance with respect to the type of bioactive glass was analyzed by Kruskal–Wallis test. The results show high levels of bone remodeling, several new bone formations containing granules of calcium phosphate (sometimes with amounts of strontium and/or magnesium), and the absence of adverse effects on bone processes due to the almost complete glass dissolution. In vivo results confirming the cell culture outcomes of a previous study highlighted that these novel bioglasses had osteostimulative effect without adverse skeletal reaction, thus indicating possible beneficial effects on bone formation processes. The presence of strontium in the glasses seems to be particularly interesting.

Injectable bioactive glass-based pastes for potential use in bone tissue repair

“…Generally, after one month of implantation, formation of new bone was more advanced in the experimental group (Table 4) compared to the control group (Figure 7b) due to weak osteogenesis of the latter with presence of loose connective tissue in the area of the defect, incomplete filling of the cavity and rarefaction. Importantly, in the experimental group, bone repair in the form of woven bone appears in intimate contact with bone graft surface; this is consistent with previous observations by other authors who investigated different bioactive glass compositions [46][47][48]. After 2 months, further resorption of the bioactive material followed by osteointegration can be observed (Figure 7c).…”

“…The following histological scoring scale for the presence and intensity of bone formation was used for statistical analysis [29,30]: 1. no osteogenesis, 2. weak osteogenesis, 3. medium-low osteogenesis, 4 medium-high osteogenesis, 5. good-low osteogenesis, 6. good-high osteogenesis, 7. perfect osteogenesis. For this purpose, each slide of histopathological sections was divided into four segments to be observed in detail while the average of the scores of the four quadrants represents the score given to the slide [29].…”

Human Mesenchymal Stem Cell Combined with a New Strontium-Enriched Bioactive Glass: An ex-vivo Model for Bone Regeneration

“…The cracks and fractures on the granules’ surface after 1 and 3 days in SBF (Figure 2a,b) are ascribable to the drying and subsequent delamination of a silica gel film, whose formation is among the initial steps of the process which leads to the precipitation of hydroxyapatite on bioactive glasses, according to the model originally proposed by L.L. Hench [5] and subsequently confirmed by several studies both in vitro and in vivo [33,34,35,36]. The findings here discussed, regarding the BGMS10 bioactivity, are analogous to those previously reported about bioactive glasses of different compositions containing strontium and/or magnesium, further confirming that the presence of these elements have negligible negative effects on the samples’ bioactivity [13].…”

P2O5-Free Cerium Containing Glasses: Bioactivity and Cytocompatibility Evaluation

“…Our research focuses on the addition of therapeutic ions, such as zinc, fluoride, gold, copper, gallium, and cerium to these bioglasses [8,9,10,11,12,13,14,15,16]. The resulting glasses are bioactive and their behavior is comparable to Hench and Kokubo bioglasses.…”