Avaliação dos potenciais osteogênico e genotóxico de microesferas à base de hidroxiapatita nanoestrutura contendo zinco

Abstract

A wide range of biomaterials is currently being studied as new alternatives in the field of bone regeneration. Among them, hydroxyapatite (HA) stands out as a mineral component present in the inorganic phase of bones. HA, in addition to being biocompatible, exhibits suitable physicochemical characteristics and allows for ionic substitutions that can enhance its performance for various applications. Nano-structured HA (nHA) microspheres with different compositions have been developed, including the incorporation of zinc ions (Zn²⁺), which are notable for their ability to increase cell viability and promote bone mineralization. However, any alteration to HA results in the production of a new biomaterial that, in addition to confirming its osteogenic capabilities, must undergo biosafety testing. Thus, in this study, we evaluated the ability of Zn²⁺- containing nHA-based microspheres to promote osteogenic differentiation using human Wharton's jelly mesenchymal stem cells (hWJ-MSCs) isolated from umbilical cord tissue.The cytotoxicity results, assessed using the MTT assay (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), showed that the samples did not significantly reduce the ability of hWJ-MSCs to metabolize MTT, indicating that the samples are not cytotoxic under the tested conditions. The results of bone mineralization, alkaline phosphatase (ALP) activity, and gene expression, quantified by qRT-PCR, indicated that the samples, under the tested conditions, exhibited osteogenic activity, as evidenced by increased extracellular matrix mineralization, ALP activity, and the expression of genes related to osteogenesis in hWJ-MSCs. Considering potential clinical applications, we also evaluated the genotoxic potential of these materials. The genotoxicity results, obtained through the Comet assay and the CBMN assay (cytokinesis-block micronucleus), showed that the samples do not exhibit genotoxic potential under the tested conditions. Therefore, it is expected that this biomaterial could have applications in bone regeneration.