Colloidal Gold Nanoparticles Induce Changes in Cellular and Subcellular Morphology

Abstract

Exposure of cells to colloidal nanoparticles (NPs) can have concentration-dependent harmful effects. Mostly, such effects are monitored with biochemical assays or probes from molecular biology, i.e., viability assays, gene expression profiles, etc., neglecting that the presence of NPs can also drastically affect cellular morphology. In the case of polymer-coated Au NPs, we demonstrate that upon NP internalization, cells undergo lysosomal swelling, alterations in mitochondrial morphology, disturbances in actin and tubulin cytoskeleton and associated signaling, and reduction of focal adhesion contact area and number of filopodia. Appropriate imaging and data treatment techniques allow for quantitative analyses of these concentration-dependent changes. Abnormalities in morphology occur at similar (or even lower) NP concentrations as the onset of reduced cellular viability. Cellular morphology is thus an important quantitative indicator to verify harmful effects of NPs to cells, without requiring biochemical assays, but relying on appropriate staining and imaging techniques.

Analyse quantitativer Partikelaufnahme von Zellen über verschiedene Messmethoden

“…Wenn dies nicht ordentlich durchgeführt wird, führt es zu falsch‐positiven Signalen, insbesondere wenn man mit Partikeln arbeitet, die eine schwache Fluoreszenz haben und in kleiner Menge dosiert werden. Die Unterscheidung von internalisierten und extrazellulären Partikeln ist möglich mit den bereits erwähnten Methoden der pH‐sensitiven Fluorophore und der Korrelation mit Immunfärbungen . In diesem Fall werden nur die Fluoreszenzen der Partikel gewertet, die lateral mit der Fluoreszenz der immungefärbten intrazellulären Organellen (Endosome/Lysosome) überlappen .…”

“…Die Unterscheidung von internalisierten und extrazellulären Partikeln ist möglich mit den bereits erwähnten Methoden der pH‐sensitiven Fluorophore und der Korrelation mit Immunfärbungen . In diesem Fall werden nur die Fluoreszenzen der Partikel gewertet, die lateral mit der Fluoreszenz der immungefärbten intrazellulären Organellen (Endosome/Lysosome) überlappen . Der Grad der Colokalisation kann über Manders‐Koeffizienten quantifiziert werden .…”

Cellular localization and biological effects of 20nm‐gold nanoparticles

“…Poly(methacrylic acid) HUVEC and HeLa Upon NP internalization, the lysosomal swelling, disturbances in actin and tubulin cytoskeletons, changes in mitochondrial morphology, reduction of focal adhesion contact area and number of filopodia were observed in both cell types. 20 NPs are incorporated by cells mainly via endocytic pathways and accumulated inside acidic intracellular vesicles. The decreases in cell proliferation at NP concentrations below 1 nM were found in both cells, whereas the effect of AuNPs on cell viability varied according to cell types.…”

“…The use of AuNPs in inflammatory joint disorders, such as rheumatoid arthritis, in which new vasculature plays an important role in the disease progression, also formed a basis for the investigation of the effect of these particles on angiogenesis. Studies have shown that AuNPs can selectively inhibit the efficacy of heparin‐binding cytokines such as vascular endothelial growth factor (VEGF 165 ) and basic fibroblast growth factor (bFGF), which take an active role in the angiogenesis process . Furthermore, AuNPs of about 20 nm in size reduced VEGF‐ and bFGF‐induced endothelial cell proliferation more effectively compared to particles with size of 5 and 10 nm .…”

“…Studies have shown that AuNPs can selectively inhibit the efficacy of heparin‐binding cytokines such as vascular endothelial growth factor (VEGF 165 ) and basic fibroblast growth factor (bFGF), which take an active role in the angiogenesis process . Furthermore, AuNPs of about 20 nm in size reduced VEGF‐ and bFGF‐induced endothelial cell proliferation more effectively compared to particles with size of 5 and 10 nm . Moreover, 20 nm AuNPs were effective at lower concentrations.…”