Association of Bioglass/Collagen/Magnesium composites and low level irradiation: effects on bone healing in a model of tibial defect in rats.

Background and aims: Bioglass (BG) and Magnesium (Mg) composites have been used for bone tissue engineering proposes due to its osteogenic activity and increased mechanical properties respectively. The introduction of Collagen (Col) is a common and efficient approach for bone tissue engineering applications toward cell proliferation. Recently, studies demonstrated that BG/Col/Mg composites presented proper mechanical properties and were non-cytotoxic. Although the osteogenic potential of BG/Col/Mg composites, in specific situations, biomaterials may not be capable of stimulating bone tissue. Therefore, combining biomaterial matrices and effective post-operative therapies (such as low level lasertherapy; LLLT) may be necessary to appropriately stimulate bone tissue. In this context, the aim of this study was to develop intra- and extra-operatively bone regenerative therapeutical strategies, based on the association of Col-enriched BG/Mg composites with LLLT.

Materials and methods: Thereby, an in vivo study, using tibial defect in Wistar rats, was performed in order to investigate the bone regenerative capacity. LLLT treatment (Ga-Al-As laser 808 nm, 30 mW, 2.8 J, 94 s) was performed 3 times a week, in non-consecutive days. Histology, histomorphometry, immunohistochemical analysis and mechanical test were done after 15 and 45 days post-implantation.

Results: The results showed that Col could be successfully introduced into BG/Mg and the association of BG/Mg/Col and LLLT constituted an optimized treatment for accelerating material degradation and increasing bone deposition. Additionally, mechanical tests showed an increased maximal load for BG/Mg + LLLT compared to other groups.

Conclusions: These results lead us to conclude that the Col enriched BG/Mg composites irradiated with LLLT presented superior biological and mechanical properties, demonstrating to be a promising bone graft.