Silver and gold nanoparticles exposure to in vitro cultured retina--studies on nanoparticle internalization, apoptosis, oxidative stress, glial- and microglial activity

PLoS One. 2014 Aug 21;9(8):e105359. doi: 10.1371/journal.pone.0105359. eCollection 2014.

Abstract

The complex network of neuronal cells in the retina makes it a potential target of neuronal toxicity--a risk factor for visual loss. With growing use of nanoparticles (NPs) in commercial and medical applications, including ophthalmology, there is a need for reliable models for early prediction of NP toxicity in the eye and retina. Metal NPs, such as gold and silver, gain much of attention in the ophthalmology community due to their potential to cross the barriers of the eye. Here, NP uptake and signs of toxicity were investigated after exposure to 20 and 80 nm Ag- and AuNPs, using an in vitro tissue culture model of the mouse retina. The model offers long-term preservation of retinal cell types, numbers and morphology and is a controlled system for delivery of NPs, using serum-free defined culture medium. AgNO3-treatment was used as control for toxicity caused by silver ions. These end-points were studied; gross morphological organization, glial activity, microglial activity, level of apoptosis and oxidative stress, which are all well described as signs of insult to neural tissue. TEM analysis demonstrated cellular- and nuclear uptake of all NP types in all neuronal layers of the retina. Htx-eosin staining showed morphological disruption of the normal complex layered retinal structure, vacuole formation and pyknotic cells after exposure to all Ag- and AuNPs. Significantly higher numbers of apoptotic cells as well as an increased number of oxidative stressed cells demonstrated NP-related neuronal toxicity. NPs also caused increased glial staining and microglial cell activation, typical hallmarks of neural tissue insult. This study demonstrates that low concentrations of 20 and 80 nm sized Ag- and AuNPs have adverse effects on the retina, using an organotypic retina culture model. Our results motivate careful assessment of candidate NP, metallic or-non-metallic, to be used in neural systems for therapeutic approaches.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Glial Fibrillary Acidic Protein
  • Gold* / chemistry
  • Metal Nanoparticles / administration & dosage*
  • Metal Nanoparticles / chemistry
  • Metal Nanoparticles / ultrastructure
  • Mice
  • Nerve Tissue Proteins / metabolism
  • Neuroglia / drug effects
  • Neuroglia / metabolism
  • Oxidative Stress / drug effects
  • Particle Size
  • Retina / drug effects*
  • Retina / metabolism*
  • Retina / pathology
  • Silver* / chemistry
  • Tissue Culture Techniques

Substances

  • Glial Fibrillary Acidic Protein
  • Nerve Tissue Proteins
  • glial fibrillary astrocytic protein, mouse
  • Silver
  • Gold

Grants and funding

This work was supported by grants from the Crafoord Foundation, VELUX stiftung, Clas Groschinskys Foundation, Kronprinsessan Margaretas Arbetsnämnd för synskadade (KMA), Magnus Bergvall Foundation, Greta and Johans Kock Foundation, Signhild Engqvist Foundation, The Royal Physiographic Society in Lund and the Nanometer Consortium at Lund University. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.