Do Nanoparticles Affect Neuronal Function? - Establishment of a Microelectrode-Based Assay

Sammanfattning: Nanomaterials are used extensively in industry and daily life but comparatively little is known about the possible health effects. Silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) are two metal nanoparticles that have been intensively studied. AgNPs due to their antibacterial effect and AuNPs due to good intrinsic properties and the fact that they are highly biocompatible. Extracellular recordings of spontaneous electrical activity from in vitro cultured neurons using microelectrode arrays (MEAs) can be used in order to study if AgNPs and AuNPs affect neuronal function. Neuronal cell cultures were exposed to AgNPs and AuNPs with a diameter of either 20 nm or 80 nm in low concentrations (800 particles/cell). To this date, neurotoxicity assessment still relies on in vivo animal testing. However, human induced pluripotent stem cell (hiPSC)-derived neurons (iCell® Neurons commercially) were used in this thesis since animal experiments have several drawbacks and do not always mimic the human physiology. Immunocytochemical analysis of the iCell® Neurons as well as images taken with a scanning electron microscope concludes that the cells develop into functional neuronal networks and attach to electrodes on the MEAs. This provides a good basis for electrophysiological recordings. Significant multiunit extracellular activity associated with spontaneous action potential waveforms was recorded from the iCell® Neurons with the setup presented in this thesis. However, no quantitative analysis of how AgNPs and AuNPs affect the neuronal function was carried out due to a lack of experimental data. Only 10% of the electrodes on the MEAs recorded neuronal activity and further studies are needed in order to develop a fully functioning assay. Nevertheless, hiPSC-derived neurons cultured on MEAs may still enable animal free neurotoxicity testing in the future and could be a valuable tool when studying possible health effects of nanoparticles and other compounds.