Glass - Back to the Future!



Presenting Author:
Lucas Souza
<souzalpl@aston.ac.uk>

article posted 31 March 2016


LucasSouza was born in Central-BA, Brazil, has bachelor in physiotherapy and master in Structural and Cellular Biology in the field of Anatomy by University of Campinas (UNICAMP), Campinas, Brazil. Currently he is in the second year of his doctorate in the research area “Development of novel bioactive glasses for biomedical applications” working at School of Engineering and Applied Sciences, Aston Research Centre for Healthy Ageing, University of Aston, Birmingham, UK as an exchange research student.






BIOACTIVITY OF NIOBIUM-DOPED GLASSES: AN IN VIVO AND IN VITRO EXPERIMENTAL STUDY

Lucas P. Souza1,3*, Joćo L. Magalhaes2, Celso A. Bertran2, Richard A. Martin1, José A. Camilli3.
1School of Engineering and Applied Sciences & Aston Research Centre for Healthy Ageing, University of Aston, Birmingham, B4 7ET, UK
2Chemistry Institute, University of Campinas (UNICAMP), Campinas, Brazil
3Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil


Bioactive glasses are widely used as synthetic bone substitutes. They show class A bioactivity meaning they bond to both soft and hard tissue and readily form apatite. Since the development of 45S5 bioglass by Larry Hench there have been various studies assessing the potential impact of incorporating small amounts of metallic oxides to improve the bioactivity. Whilst extensive studies have been conducted on Sr, Mg, Zn, Co and so forth, very few studies have investigated the potential of incorporating niobium dioxide (Nb2O5) which is the focus of this paper. We have investigated the effect of Nb bioglass both in vivo and in vitro experiments. The in vivo trial consisted of treating a critical size femoral defect (4-5mm length) made in rats with niobium-doped glass particles followed by the assessment of osseointegration by both micro-computed tomography (µCT) and histomorphometric analysis. Cytokines relevant to bone repair were quantified by enzyme-linked immunosorbent assay (ELISA). The systemic cytotoxicity of the glass was verified by means of histopathological analysis of H&E stained slides of kidneys, liver and heart. Concomitantly, by culturing osteoblast-like cells on glass discs or in conditioned media, we have been analysing the influence of this glass over cellular viability, apoptosis rate, and cell cycle phase by MTT assays and flow cytometry. In addition, we verified the cell maturation by quantifying the alkalin phosphatase activity, osteocalcin expression, calcium deposition, and cell morphology by scanning electronic microscopy (SEM). Results have shown that the surgical model proposed was successful in producing a critical size femoral defect (shown by µCT images 16 days after the implantation). Furthermore, the MTT assays showed that along 72 hours the medium containing dissolution products of the glass showed non cytotoxicity. So far, our results suggest that this particular glass composition is not cytotoxic and the in vivo model proposed was successful at producing a critical size. Together, these results allow us to begin applying the glass to treat femoral defects and to carry out further analysis.


Figure 1.Femoral segmental defect in rats. (A) Images and quantification of the defect length by µCT 16 after implantation. (B) Photography of the surgery.


Figure 2. Viability of Normal Human Osteoblast-Like Cells (NHOsts) in media containing dissolutions products of two different glass compositions. ns: no significant difference. * all groups were higher than the negative control (Etoposide)