Toxicity Studies
We use a range of in vitro and in vivo tests to assess the possible toxic behaviour of a range ofnanoparticles. Combined, these tests provide a powerful tool to assess therelative toxicity of the nanoparticles we study as well as the most sensitivereceptors, environmental or human.
Ecotoxicity
We experiment with differentanimals in vivo, in order to compareimplications of different biological traits. Our test organisms are: Mytilus galloprovincialis, Scrobiculariaplana, Corbula amruensis, Macoma balthica, Lymnea stagnalis, Hydrobia ventrose,Peringia ulvae, Nereis diversicolor, Capitella capitata and Danio rerio. Microscopy and the sub-cellular fractionation are amongst the techniques used to determine the internalisation of nanomaterials. Oxidative stress, metallothionein synthesis, lysosomal membrane destabilization and histopathology are used as indicators of stress. If organisms show such responses to bioavailable nanomaterials, in vivo, it is unequivocal evidence that nanomaterial uptake causes the organisms response. Visual evidence of internal nanomaterials, evaluation of internal dissolution and manipulation of experimental design isused to determine if responses are due to internal dissolution of the metaloxide particle or due to disruption by the particle itself. Different partners employ different tests or use different animals, but with the same particles, thus avoiding overlap. Biodynamic parameters are used to screen different particle types. Longer term bioavailability and effects tests will focus on those particles deemed of potentially greatest risk.
Complimentary to the in vivo studies are short term in vitro experiments with mussel haemocytes and gill cells using the same selected setof particles. This two pronged approach allows our eco-tox group to gain both toxic and mechanistic understanding of nanomaterials.
Toxicity
Weinvestigate the cellular and molecular reactivity of the selected metalnanoparticles in a) primary mammalian and human cells and b) in a panel ofestablished human cell lines. The chosen cells will reflect likely nanoparticle exposure routes.
Cellular models: Our cellular models incorporate a host of human and mammalian cell types derived from a number of different organs (lung, skin, vasculature, brain, gut etc.). These include structural tissue cells like epithelial and endothelial cells and immune cells such as macrophages and circulating blood monocytes. Where possible, we use primary cells taken from tissue samples, but we also use a variety of cell lines in our studies.
We use endpoints that measure basal toxicity/cell viability (necrosis, apoptosis), inflammatory response (e.g. cytokine release, cell signalling) and oxidative stress (e.g. GSH flux). We also study the specific in vitro organ toxicity of selected nanomaterials. We examine features unique to specific organs/cell types e.g. phagocytosis (macrophages), beat frequency (heart cells),antigen presenting cells (monocytes, macrophages and dendritic cells),transepithelial electrical resistance and epithelial adsorption (Caco-2 and MDCK), where appropriate and where it will add to understanding the relationship between the physicochemical nature of each type/group of nanoparticles and their reactivity.
We also investigate the genotoxic and carcinogenic effects of nanoparticles. We use tests to analyse chromosome breakage and chromosome loss, DNA strand breaks insingle cells, Balb/3T3 cell transformation, cell division/proliferation and possible oxidative effects of metal nanoparticles and inhibition of cell proliferation. Some in vivo tests employing mussels and zebrafish also address carcinogenicity.
