Browsing by Author "Fernandes, S.N."
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- Cyto-genotoxic effects of distinct micro/nanocelluloses in human osteoblastic and mice fibroblastic cellsPublication . Ventura, Célia; Marques, Catarina; Cadete, João; Vilar, Madalena; Pedrosa, J.F.S.; Pinto, P.; Rosa, R.R.; Fernandes, S.N.; Godinho, M.H.; Ferreira, P.J.T.; Louro, Henriqueta; Silva, Maria JoãoThe unique characteristics of micro/nanocelluloses (MNCs) have been boosting their use in a wide variety of industrial and biomedical applications. With the expected decrease of their production cost, it is likely to observe an even faster growing adoption of these materials in the coming years. With the increasing use of MNCs comes an increased likelihood of human exposure to these materials, raising concerns about potential human health effects. The number of studies on the potential adverse effects of MNCs is still scarce and sometimes inconclusive. The aim of the present study is to shed some light on the impact of human exposure to cellulose-based nanomaterials. For that, three MNCs were produced from bleached Eucalyptus kraft pulp using different pretreatments. A microfibrillated (CMF) and a nanofibrillated cellulose (CNF) were respectively obtained by enzymatic and TEMPO-mediated oxidation pretreatments followed by high-pressure homogenization. In addition, cellulose nanocrystals (CNC) were obtained by acid hydrolysis with diluted sulfuric acid. The potential cytotoxicity of the MNCs was evaluated in vitro in two mammalian cell lines (human MG-63 osteoblasts and mice V79 lung fibroblasts) by the MTT and the clonogenic assays, and the genotoxicity was assessed by the micronucleus assay. Cytotoxicity was observed by the clonogenic assay in V79 cells, particularly for CNC, but not by the MTT assay. CNF induced micronuclei in both cell lines and nucleoplasmic bridges in MG-63 cells. CMF and CNC induced micronuclei and nucleoplasmic bridges in MG-63 cells, but not in V79 cells. From the results, it was concluded that under the tested conditions all MNCs present cytotoxicity and genotoxicity, although at different concentration levels, which may be related to their physicochemical differences, to the availability for cell uptake, and to differences in the DNA damage response of the cell model.
- Exploring potential genotoxic effects of nanocelluloses versus multi-walled carbon nanotubes in co-cultures of human lung epithelial cells and monocyte-derived macrophagesPublication . Pinto, Fátima; Ventura, Célia; Teixeira, Sara; Lourenço, Ana Filipa; Fernandes, S.N.; da Rosa, R.R.; Godinho, M.H.; Ferreira, Paulo J.T.; Louro, Henriqueta; Silva, Maria JoãoCellulose nanomaterials (CNMs) are advanced materials exhibiting unique properties for innumerous industrial and biomedical applications. Human exposure to CNMs has been equally growing, which raises some concern, given the similarity of some CNMs size and morphology with that of multiwalled carbon nanotubes (MWCNTs) that induce lung toxicity. The genotoxic effects of three CNMs produced from Eucalyptus globulus bleached kraft pulp through different methods and, hence, harbouring different physicochemical properties (two micro/nano- fibrillated and one nanocrystalline), were investigated in human alveolar (A549) cells co-cultured with monocyte- derived (THP-1) macrophages and in conventional A549 cultures. Two MWCNT differing in diameter, length and flexibility, NM 401 and NM 402 (JRC Repository), were used as references. None of the CNMs was toxic to A549 cells. The results of the in vitro micronucleus assay showed that exposure of A549 cells (1.5 to 50 μg/cm2 48h) to each CNM or to NM 402), either in monoculture or in co-culture, did not produce significant alterations in the frequency of micronucleated binucleated cells (MNBNC), as compared to the control. In contrast, NM-401, the thickest, longest and more rigid nanofiber, was able to significantly increase the frequencies of MNBNC. The cytokinesis-block proliferation index of A549 cells was not affected by CNMs or MWNTs exposure. To conclude, although data from other endpoints is needed, the present in vitro data suggests that the studied CNMs are neither toxic nor genotoxic to lung cells, increasing the weight of evidence in favor of their biocompatibility.