Avaliação da citotoxicidade e genotoxicidade de microesferas à base de hidroxiapatita nanoestruturada para aplicação na regeneração óssea

Abstract

The current treatments used in bone defects have different limitations, such as immunological rejections and invasive surgical procedures. In regenerative medicine, the development of safe alternatives with an effective applicability to treat these problems is sought. In this context, research into new biomaterials has shown excellent results in the search for solutions to these problems. Among the biomaterials, those whose composition is based on hydroxyapatite (HA), the main inorganic constituent of the bone mineral phase, stand out, as an example the microspheres based on HA. HA allows the incorporation of other elements in its structure to improve its physicochemical and functional characteristics. Thus, substitution with strontium (Sr2+),zinc (Zn2+), fluoride (F-), and carbonate (CO32-) ions can alter the bioactivity of HA. However, changes in HA structure and/or composition lead to the production of new biomaterials that can interact differently with cells, requiring the assessment of their biocompatibility and, consequently, biosafety. In this study, the in vitro cytotoxicity and genotoxicity of different microspheres based on nanostructured HA substituted Sr2+, Zn2+, F- and CO32- were analyzed, by the MTT [3-(4,5-dimethylthiazol-2-yl bromide))-2,5-diphenyltetrazolium] and CBMN (Cytokinesis Blocked Micronucleus) assays, respectively. The MTT allows the evaluation of the viability of cells exposed to an agent by correlating the conversion of the MTT reagent into insoluble formazan crystals, which can be quantified. The CBMN test allows the evaluation of the genotoxic and mutagenic potential of a sample by quantifying the occurrence of chromosomal alterations present in binucleated cells. The results indicated that the biomaterials in question did not significantly affect cell proliferation, nor induce nuclear alterations, suggesting that they could provide a safe system for future clinical applications. Both tests performed are the initial steps and, therefore, will be complemented later with more biocompatibility studies to confirm the biosafety of these microspheres.