Avaliação da resposta celular a biomateriais para fins de regeneração óssea

Abstract

Different kinds of biomaterials have been developed over the years for many biomedical applications mainly for bone regeneration purposes. Technological evolution has led to the development of new and better biomaterials. Among the various materials currently, available, available nano-microstructured surfaces and nano and micro-scale materials stand out. Laser beam treatment is a controllable and flexible approach to modifying surfaces that creates a complex surface topography with micro- and nano-scaled patterns. Nano and micro hydroxyapatite (HA) particles are being largely developed due to its properties. Despite many studies carried out to assess differentiation response scant attention has been paid to genotoxic potential of these particles during this process. Therefore, assays to evaluate biocompatibility, including genotoxic studies, should be performed. The behavior of human mesenchymal stem cells (hMSC) during differentiation process was analyzed after exposure to modified laser surface and hydroxyapatite particles. The titanium discs were investigated by scanning electron microscopy, X-ray diffraction, and measurement of contact angles. The surface generated at a fluence of 235 J/cm2 was used in the biological assays: MTT, mineralization, alkaline phosphatase activity and qRTPCR for osteogenic markers. Hydroxyapatite nanoparticles (nanoXIM • HAp102®, Fluidinova, S.A.) and microparticles (Biotal Plasma) commercially available at concentrations of 0.1, 1 and 10 μg / ml were used and analyzed after 1, 3 and 7 days. Data analysis showed that laser-processed titanium surface increased the reduced the proliferation of mesenchymal stem cells, upregulated the expression of the osteogenic markers, and enhanced alkaline phosphatase activity. Particle evaluation showed that these did not affect hMSC viability of (p <0.05), however, higher concentrations used seem to induce an early osteogenic differentiation. This was evidenced by anticipation of maximum levels expected of alkaline phosphatase activity (p <0.05) and extracellular matrix mineralization (p <0.01). No significant changes were observed in the oxidative state and the evaluated genotoxic potential. Interestingly, the frequencies of nucleoplasmic bridges (NPB) and DNA damage by the comet test were higher after 7 days under control conditions, suggesting that these bridges are characteristic of isolated hMSCs and tends to disappear during the differentiation process. Our findings showed that laser-treated titanium surface modulated cellular behavior depending on the cell type and stimulated osteogenic differentiation. In addition, particle data suggest that HA exposure induces a sufficient cellular response to prevent genetic instability and not having in long-term genotoxic effect during osteogenic differentiation. Thus, the biomaterials studied demonstrate potential for its use in regenerative medicine and the particles seems to be safe concerning genotoxicity.