Avaliação da genotoxicidade e do potencial osteogênico de polissacarídeos sulfatados de algas marinhas

Abstract

Problems related with bone defects continue to motivate the search for more effective therapies. Thus, the combination of biomaterials, stem cells and bioactive molecules is part of the tools used by regenerative medicine to achieve this goal. Several studies have already shown the osteogenic potential of sulfated polysaccharides (SPs) extracted from marine macroalgae. Among them, fucoidan, isolated from brown algae Fucus vesiculosus, is the most studied, and is already commercialized by some companies. Green algae are also a source of SPs, but these are even more unexploited in the scope of bone regeneration. In general, the clinical applications of SPs from algae are very limited, because studies on their effects are scarce, for example, their genotoxic effects are unknown in most cases. Thus, in this work, we evaluated the osteogenic activity of Fucoidan from F. vesiculosus (an extract commercialized by Sigma), 2) SPs-rich samples obtained from subfractionation of commercial fucoidan, and 3) SPs-enriched extract from green algae Caulerpa Sertularioides, using human mesenchymal stem cells isolated from the Wharton jelly of umbilical cords (CTMH-GW) as cell model. It was also studied the genotoxic potential of the total extracts of F. vesiculosus and C. sertularioides, using the cytokinesis block micronucleus assay (CBMN) in the line CHO-K1. The genotoxicity of fucoidan’s subfraction that presented greater osteogenic potential was also evaluated. The MTT reduction assays showed that SPs-enriched samples did not show significant cytotoxicity over 72 h, up to 10 μg.mL-1. Alkaline phosphatase (ALP) activity and mineralization assays suggest that SPs-enriched samples have different osteogenic activities: fucoidan subfraction FUC 0.5 (5 μg.mL-1) showed the best result, increasing 124% the ALP activity in relation to the positive control (cells maintained in osteogenic medium). The total extract of C. sertularioides (5 μg.mL-1) increased the ALP activity by 192%. In addition, all samples tested induced calcium accumulation in the extracellular matrix. Concerning to genotoxicity, CBMN assay results suggest that, under the tested conditions, these samples are not genotoxic, indicating their potential as alternative bone regeneration therapy.