Effect of pristine and functionalized multiwalled carbon nanotubes on rat renal cortex

The increasing application of carbon nanotubes (CNTs) within environmental, occupational and consumer settings has raised concerns regarding their biosafety and adverse effects on human health. The present study was designed to investigate the possible adverse effect of pristine and functionalized (amylated and polyethelene glycol coated) multi-walled (MW) CNTs on rat kidney with special concern to the histological alterations and the associated oxidative stress, apoptosis and inflammation. Healthy male albino rats (n = 40) were randomly divided into 4 groups: group I (control), group II (pristine MWCNTs), group III (amylated MWCNTs) and group IV [polyethelene glycol (PEG)-coated MWCNTs]. Animals of groups II, III and IV received a single dose of 1 mg/kg body weight of MWCNTs via intra-tracheal (IT) instillation at the beginning of the experiment and all rats were sacrificed after 30 days. Rats in groups II and III showed, nearly similar, renal tissue damage (evidenced by thin collapsed glomeruli, packed mesangial and endothelial cells as well as edematous hemorrhagic glomeruli with apoptotic changes) and functional disruptions (indicated by high serum levels of urea and creatinine) probably through induction of oxidative stress [revealed by high level of the lipid peroxidation marker malondialdehyde (MDA) and lower levels of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx)], apoptosis (indicated by high caspase 3 activity), and inflammation (evidenced by high level of IL1 beta). However, PEG-coated MWCNTs-treated group (group IV) showed nearly normal renal structure and function. It could be concluded that pristine and functionalized amylated MWCNTs have nephrotoxic effect, while PEG-coated MWCNTs had lowest, or none, toxic effects making them safer for therapy and diagnosis of a variety of diseases.