Engineered metal oxide nanomaterials inhibit corneal epithelial wound healing and .

Journal: NanoImpact
Published Date: Dec 6, 2019

Abstract

Ocular exposure to metal oxide engineered nanomaterials (ENMs) is common as exemplified by zinc oxide (ZnO), a major constituent of sunscreens and cosmetics. The ocular surface that includes the transparent cornea and its protective tear film are common sites of exposure for metal ENMs. Despite the frequency of exposure of the ocular surface, there is a knowledge gap regarding the effects of metal oxide ENMs on the cornea in health and disease. Therefore, we studied the effects of metal oxide ENMs on the cornea in the presence or absence of injury. Cell viability of immortalized human corneal epithelial (hTCEpi) cells was assessed following treatment with 11 metal oxide ENMs with a concentration ranging from 0.5 to 250 μg/mL for 24 hours. An epithelial wound healing assay with a monolayer of hTCEpi cells was then performed using 11 metal oxide ENMs at select concentrations based on data from the viability assays. Subsequently, based on the results, testing of precorneal tear film (PTF) quantity and stability as well as a corneal epithelial wound healing were tested in the presence or absence ZnO or vanadium pentoxide (VO) at a concentration of 50 μg/mL. We found that WO, ZnO, VO and CuO ENMs significantly reduced hTCEpi cell viability in comparison to vehicle control or the other metal oxide ENMs tested. Furthermore, ZnO and VO ENMs also significantly decreased hTCEpi cell migration. Although ZnO and VO did not alter PTF parameters of rabbits , corneal epithelial wound healing was significantly delayed by topical ZnO while VO did not alter wound healing. Finally, hyperspectral images confirmed penetration of ZnO and VO through all corneal layers and into the iris stroma. Considering the marked epithelial toxicity and corneal penetration of ZnO, further investigations on the impact of this ENM on the eye are warranted.

Authors

  • Soohyun Kim
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA.
  • Brooke Gates
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA.
  • Brian C Leonard
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA.
  • Megan Gragg
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA.
  • Kent E Pinkerton
    Center for Health and the Environment, University of California, Davis, CA 95616, USA.
  • Laura Van Winkle
    Center for Health and the Environment, University of California - Davis, Davis, CA, 95616, USA.
  • Christopher J Murphy
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, CA 95616, USA.
  • Georgios Pyrgiotakis
    Center for Nanotechnology and Nanotoxicology, HSPH-NIEHS Nanosafety Center, Department of Environmental Health, Harvard T.H. Chan School of Public School, Harvard University, 665 Huntington Boston, MA 02115, USA.
  • Zhenyuan Zhang
    Center for Nanotechnology and Nanotoxicology, HSPH-NIEHS Nanosafety Center, Department of Environmental Health, Harvard T.H. Chan School of Public School, Harvard University, 665 Huntington Boston, MA 02115, USA.
  • Philip Demokritou
    Center for Nanotechnology and Nanotoxicology, HSPH-NIEHS Nanosafety Center, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Harvard University, 665 Huntington, Boston, MA 02115, USA.
  • Sara M Thomasy
    Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA 95616, USA; Department of Ophthalmology and Vision Science, School of Medicine, University of California, Davis, CA 95616, USA. Electronic address: smthomasy@ucdavis.edu.

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