Effects of Polyamidoamine Dendrimers on a 3-D Neurosphere System Using Human Neural Progenitor Cells

Abstract

The practical application of engineered nanomaterials or nanoparticles like polyamidoamine (PAMAM) dendrimers has been promoted in medical devices or industrial uses. The safety of PAMAM dendrimers needs to be assessed when used as a drug carrier to treat brain disease. However, the effects of PAMAM on the human nervous system remain unknown. In this study, human neural progenitor cells cultured as a 3D neurosphere model were used to study the effects of PAMAM dendrimers on the nervous system. Neurospheres were exposed to different G4-PAMAM dendrimers for 72 h at concentrations of 0.3, 1, 3, and 10 μg/ml. The biodistribution was investigated using fluorescence-labeled PAMAM dendrimers, and gene expression was evaluated using microarray analysis followed by pathway and network analysis. Results showed that PAMAM dendrimer nanoparticles can penetrate into neurospheres via superficial cells on them. PAMAM-NH2 but not PAMAM-SC can inhibit neurosphere growth. A reduced number of MAP2-positive cells in flare regions were inhibited after 10 days of differentiation, indicating an inhibitory effect of PAMAM-NH2 on cell proliferation and neuronal migration. A microarray assay showed 32 dendrimer toxicity-related genes, with network analysis showing 3 independent networks of the selected gene targets. Inducible immediate early gene early growth response gene 1 (Egr1), insulin-like growth factor-binding protein 3 (IGFBP3), tissue factor pathway inhibitor (TFPI2), and adrenomedullin (ADM) were the key genes in each network, and the expression of these genes was significantly down regulated. These findings suggest that exposure of neurospheres to PAMAM-NH2 dendrimers affects cell proliferation and migration through pathways regulated by Egr1, IGFBP3, TFPI2, and ADM.

Applications and Limitations of Dendrimers in Biomedicine

“…PAMAM G4 dendrimers and biotinylated PAPAM dendrimers exhibit toxic effects on blood–brain barrier cell cultures [ 261 ]. PAMAM dendrimers had negative effects on the proliferation and migration of human neural progenitor cells in an in vitro experiment [ 262 ]. In vivo studies on mice revealed a neurotoxic effect via the measurement of neuronal biomarkers after the intranasal administration of a PAMAM dendrimer [ 263 ].…”

Neurotoxicity of Nanomaterials: An Up-to-Date Overview

“…The effects on a 3D neurosphere system using human neural progenitor cells after exposure to polyamidoamine dendrimers were evaluated. Results showed that higher concentrations induced significant inhibition of cell proliferation and migration [82]. Furthermore, dendrimers of different generations were used in zebrafish embryos and larvae to assess the associated toxic effects.…”

Suitability of 3D human brain spheroid models to distinguish toxic effects of gold and poly-lactic acid nanoparticles to assess biocompatibility for brain drug delivery

“…Taking in account the advantages of 3D organotypic cultures, increasing number of studies have used variety of such models to study nanotoxicity and NP neurotoxicity [39–43]. Hoelting and collaborators developed an in vitro 3D neuronal model derived from human embryonic stem cell (hESC) and showed that polyethylene NPs (PE-NP) penetrated into the neurospheres and impacted gene expression at non-cytotoxic concentrations [42].…”

“…Hoelting and collaborators developed an in vitro 3D neuronal model derived from human embryonic stem cell (hESC) and showed that polyethylene NPs (PE-NP) penetrated into the neurospheres and impacted gene expression at non-cytotoxic concentrations [42]. In the same way, Zeng and collaborators developed an in vitro 3D model of human neural progenitor cells and showed that different types of polyamidoamine dendrimers NPs can penetrate into neurospheres, affecting cell proliferation and migration through different pathways [43]. To the best of our knowledge, toxicity of gold and PLA-NP were not extensively studied in 3D brain models.…”