title: Comparative cellular toxicity of titanium dioxide nanoparticles on human astrocyte and neuronal cells after acute and prolonged exposure.
abstract: Although in the last few decades, titanium dioxide nanoparticles (TiO₂NPs) have attracted extensive interest due to their use in wide range of applications, their influences on human health are still quite uncertain and less known. Evidence exists indicating TiO₂NPs ability to enter the brain, thus representing a realistic risk factor for both chronic and accidental exposure with the consequent needs for more detailed investigation on CNS. A rapid and effective in vitro test strategy has been applied to determine the effects of TiO₂NPs anatase isoform, on human glial (D384) and neuronal (SH-SY5Y) cell lines. Toxicity was assessed at different levels: mitochondrial function (by MTT), membrane integrity and cell morphology (by calcein AM/PI staining) after acute exposure (4-24-48 h) at doses from 1.5 to 250 μg/ml as well as growth and cell proliferation (by clonogenic test) after prolonged exposure (7-10 days) at sub-toxic concentrations (from 0.05 to 31 μg/ml). The cytotoxic effects of TiO₂NPs were compared with those caused by TiO₂ bulk counterpart treatment. Acute TiO₂NP exposure produced (i) dose- and time-dependent alterations of the mitochondrial function on D384 and SH-SY5Y cells starting at 31 and 15 μg/ml doses, respectively, after 24h exposure. SH-SY5Y were slightly more sensitive than D384 cells; and (ii) cell membrane damage occurring at 125 μg/ml after 24h exposure in both cerebral cells. Comparatively, the effects of TiO₂ bulk were less pronounced than those induced by nanoparticles in both cerebral cell lines. Prolonged exposure indicated that the proliferative capacity (colony size) was compromised at the extremely low TiO₂NP doses namely 1.5 μg/ml and 0.1 μg/ml for D384 and SH-SY5Y, respectively; cell sensitivity was still higher for SH-SY5Y compared to D384. Colony number decrease (15%) was also evidenced at ≥0.2 μg/ml TiO₂NP dose. Whereas, TiO₂ bulk treatment affected cell morphology only. TiO₂ internalization in SH-SY5Y and D384 cells was appreciated using light microscopy. These findings indicated, that (i) human cerebral SH-SY5Y and D384 cell lines exposed to TiO₂NPs were affected not only after acute but even after prolonged exposure at particularly low doses (≥ 0.1 μg/ml), (ii) these in vitro critical doses were comparable to literature brain Ti levels detected in lab animal intranasally administered with TiO₂NP and associated to neurotoxic effects. In summary, the applied cell-based screening platform seems to provide effective means to initial evaluation of TiO₂NP toxicity on CNS.
authors.affiliation: Laboratory of Clinical & Experimental Toxicology and Poison Control Center, Toxicology Unit, IRCCS Salvatore Maugeri Foundation and University of Pavia, Pavia, Italy. Electronic address: teresa.coccini@fsm.it.
authors.forename: Teresa
authors.initials: T
authors.lastname: Coccini
authors.affiliation: N.A.M Srl, NANO-Analysis & Materials, Pavia, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Grandi
authors.affiliation: Laboratory of Clinical & Experimental Toxicology and Poison Control Center, Toxicology Unit, IRCCS Salvatore Maugeri Foundation and University of Pavia, Pavia, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Lonati
authors.affiliation: Laboratory of Clinical & Experimental Toxicology and Poison Control Center, Toxicology Unit, IRCCS Salvatore Maugeri Foundation and University of Pavia, Pavia, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Locatelli
authors.affiliation: Laboratory of Clinical & Experimental Toxicology and Poison Control Center, Toxicology Unit, IRCCS Salvatore Maugeri Foundation and University of Pavia, Pavia, Italy.
authors.forename: Uliana
authors.initials: U
authors.lastname: De Simone
mesh_terms: D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D053768:Metal Nanoparticles / Q000633:toxicity*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D018570:Risk Assessment; D013997:Time Factors; D014025:Titanium / Q000378:metabolism / Q000633:toxicity*; D018675:Toxicity Tests / Q000379:methods
chemical_list: C009495:titanium dioxide; D014025:Titanium
keywords: D384 cells; In vitro; Nanomaterials; Neurotoxicity; SH-SY5Y cells; Safety