title: Titanium Dioxide Nanoparticles Trigger Loss of Function and Perturbation of Mitochondrial Dynamics in Primary Hepatocytes.
abstract: Titanium dioxide (TiO2) nanoparticles are one of the most highly manufactured and employed nanomaterials in the world with applications in copious industrial and consumer products. The liver is a major accumulation site for many nanoparticles, including TiO2, directly through intentional exposure or indirectly through unintentional ingestion via water, food or animals and increased environmental contamination. Growing concerns over the current usage of TiO2 coupled with the lack of mechanistic understanding of its potential health risk is the motivation for this study. Here we determined the toxic effect of three different TiO2 nanoparticles (commercially available rutile, anatase and P25) on primary rat hepatocytes. Specifically, we evaluated events related to hepatocyte functions and mitochondrial dynamics: (1) urea and albumin synthesis using colorimetric and ELISA assays, respectively; (2) redox signaling mechanisms by measuring reactive oxygen species (ROS) production, manganese superoxide dismutase (MnSOD) activity and mitochondrial membrane potential (MMP); (3) OPA1 and Mfn-1 expression that mediates the mitochondrial dynamics by PCR; and (4) mitochondrial morphology by MitoTracker Green FM staining. All three TiO2 nanoparticles induced a significant loss (p < 0.05) in hepatocyte functions even at concentrations as low as 50 ppm with commercially used P25 causing maximum damage. TiO2 nanoparticles induced a strong oxidative stress in primary hepatocytes. TiO2 nanoparticles exposure also resulted in morphological changes in mitochondria and substantial loss in the fusion process, thus impairing the mitochondrial dynamics. Although this study demonstrated that TiO2 nanoparticles exposure resulted in substantial damage to primary hepatocytes, more in vitro and in vivo studies are required to determine the complete toxicological mechanism in primary hepatocytes and subsequently liver function.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, NE, 68588, United States of America.
authors.forename: Vaishaali
authors.initials: V
authors.lastname: Natarajan
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, NE, 68588, United States of America.
authors.forename: Christina L
authors.initials: CL
authors.lastname: Wilson
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, NE, 68588, United States of America.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Hayward
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Nebraska-Lincoln, NE, 68588, United States of America; Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, NE, 68588, United States of America; Mary and Dick Holland Regenerative Medicine Program, University of Nebraska Medical Center, NE, 68198, United States of America.
authors.forename: Srivatsan
authors.initials: S
authors.lastname: Kidambi
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000067493:Dynamic Light Scattering; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D063154:Mitochondrial Dynamics / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014025:Titanium / Q000737:chemistry*
chemical_list: D017382:Reactive Oxygen Species; C009495:titanium dioxide; D014025:Titanium; D013482:Superoxide Dismutase