Lucas P. Souza
 <lpls2002@hotmail.com>

Mr. Souza was born in Central-BA, Brazil. He has a BSc in physiotherapy and MSc in Structural and Cellular Biology in the field of Anatomy by University of Campinas (UNICAMP), Campinas, Brazil. Currently he is in the fourth year of his doctorate in the research area “Development of novel bioactive glasses for biomedical applications” working at the Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas-SP, Brazil.

Therapeutic Potential Of Niobium- Doped Bioactive Glass For Treatment Of Bone Disorders: An In Vitro And In Vivo Experimental Study
Lucas P. Souza1,3*, João 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, UK2Chemistry Institute, University of Campinas (UNICAMP), Campinas, Brazil3Department of Structural and Functional Biology, Institute of Biology, University of Campinas (UNICAMP), Campinas, Brazil

 In order to improve the treatment of large fractures we investigated the potential of incorporating niobium dioxide (Nb2O5) into the composition of the Bioglass®45S5. We tested the biological effects of Nb- doped bioglass by performing both in vivo and in vitro The in vivo trial consisted of an 8 week cross-sectional experimental study. Critical sized calvarial defects (4-5mm length) made in rats, were treated with Nb-doped glass particles followed by the assessment of osseointegration by micro-computed tomography (µCT) analysis. We also investigated the systemic biocompatibility of the glasses by means of the quantification of the hepatic (TGO, TGP, GAMA GT), renal (Urea, Creatinine), and cardiac (CK) biochemical markers, as well as by the histopathological analysis of these same organs. In order to comprehend the mechanism by which the materials could have aided bone regeneration, we used ELISA kits to quantify a series of cytokines related to inflammation (TNF- α, IL-1β, IL-6), angiogenesis (VEGF), bone remodelling (RANK, RANKL, OPG), and bone differentiation and maturation (FAC e OSC) in the blood serum of rats. In the in vitro trial, Mesenchymal Stem Cells (MSCs) were isolated from the adipose tissue of rats to test the material’s cytocompatibility by means of MTT analysis and live/dead assay. Results have shown an outstanding regeneration of the fractures treated with Nb-containing glass after 8 weeks of implantation, when compared to the control groups (treated with BG45S5 and with no treatment). No glass composition elicited any damage to highly metabolic organs, attesting their biocompatibility. The biocompatibility was also shown in the in vitro experimentation. So far, our results suggest that this particular glass composition is not toxic and shows increased osteostimulative performance.  Together, these results strongly suggest that this composition of niobium-doped glass is suitable for use in biomedical applications that aim to reconstitute bone anatom

Figure 1. Microtomographies of critical size calvarial defects (4-5mm length) taken after 8 postoperative weeks. A: Control group (no treatment, empty defect); B: Treated with Bioglass®45S5; C: Treated with Nb-doped glass. Results showed a significant bone regeneration in those fractures treated with nb-doped glasses.

Figure 2. Biocompatibility of Nb-doped glass. A-C: Photomicrographs of Live/Dead assay of Mesenchymal Stem Cells (MSCs) treated with different media for 4 days (100x magnification). A: Control Group (DMEM with no glass); B: MSCs treated with Nb-doped glass conditioned media; C: Negative Control Group (killed with DMSO). Scale bar = 100um. Results showed no sign of cytotoxicity. D-F: Photomicrographs of histological sections of liver after 8 weeks of implantation stained with Haematoxylin & Eosin (200x magnification). D: Control Group (no treatment); E: Rat treated with Nb-doped glass; F: Rat treated with Bioglass 45S5. G-I: Photomicrographs of histological sections of kidney after 8 weeks of implantation stained with Haematoxylin & Eosin (200x magnification). G: Control Group (no treatment); H: Rat treated with Nb-doped glass; I: Rat treated with Bioglass 45S5. There is no histological sign of damage to these two highly metabolic organs attesting the systemic biocompatibility of the tested bioactive glasses.