Differential effects of single-walled carbon nanotubes on cell viability of human lung and pharynx carcinoma cell lines

Carbon Nanotubes as Carriers in Drug Delivery for Non-Small Cell Lung Cancer, Mechanistic Analysis of Their Carcinogenic Potential, Safety Profiling and Identification of Biomarkers

Non-small cell lung cancer (NSCLC) is a global burden leading to millions of deaths worldwide every year. Nanomedicine refers to the use of materials at the nanoscale for drug delivery and subsequent therapeutic approaches in cancer. Carbon nanotubes (CNTs) are widely used as nanocarriers for therapeutic molecules such as plasmids, siRNAs, antisense agents, aptamers and molecules related to the immunotherapy for several cancers. They are usually functionalized and loaded with standard drug molecules to improve their therapeutic efficiency. Functionalization and drug loading possibly decrease the genotoxic and carcinogenic potential of CNTs. In addition, the targeted cytotoxic properties of the drug improve and undesired toxicity decreases after drug loading and/or conjugation with proteins, including antibodies. For intended drug delivery, a lysosomal pH of 5.5 is more suitable and effective for the slow and extended release of cytotoxic drugs than a physiological of pH 7.4. Remarkably, CNTs possess intrinsic antitumor properties and are usually internalized by endocytosis. After being internalized, several mechanisms are involved in the therapeutic and carcinogenic effects of CNTs. They are generally safe for therapy, and their toxicity profile remains dependent on their physicochemical properties. Moreover, the dose, route, duration of exposure, surface properties and degradative potential determine the toxicity outcomes of CNTs locally or systemically. In summary, the use of CNTs in drug delivery and NSCLC therapy, as well as their genotoxic and carcinogenic potential and the possible mechanisms, has been discussed in this review. The therapeutic index is generally high for NSCLC cells treated with drug-loaded CNTs; therefore, they are effective carriers in implementing targeted therapy for NSCLC.

Effect of single-walled carbon nanotubes on cytochrome P450 activity in human liver microsomes in vitro

Single-walled carbon nanotubes (SWCNTs) are made from a rolled single sheet of graphene with a diameter in the nanometer range. SWCNTs are potential carriers for drug delivery systems because antibodies or drugs can be loaded on their surface; however, their effect on the activities of cytochrome P450 (CYP) remains unclear. The aim of this study was to investigate the effect of two kinds of SWCNTs with different lengths (FH-P- and SO-SWCNTs) on human CYP activity. In addition, other nano-sized carbon materials, such as carbon black, fullerene-C₆₀ , and fullerene-C₇₀ were also evaluated to compare their effects on CYP activities. Ten CYP substrates (phenacetin, coumarin, bupropion, paclitaxel, tolbutamide, S-mephenytoin, dextromethorphan, chlorzoxazone, midazolam, and testosterone) were used. Testosterone 6β-hydroxylation and midazolam 1'-hydroxylation, which are catalysed by both CYP3A4 and CYP3A5 in liver microsomes, were decreased by 25% and 45%, respectively, in the presence of 0.1 mg/ml SO-SWCNT. Dextromethorphan O-demethylation, which is catalysed mainly by CYP2D6, was decreased by 40% in the presence of SO-SWCNT. Other CYP activities, however, were not attenuated by SO-SWCNT. FH-P-SWCNT, carbon black, fullerene-C₆₀ , and fullerene-C₇₀ at 0.1 mg/ml had no effect on CYP activities. The K_i values for testosterone 6β-hydroxylation, midazolam 1'-hydroxylation, and dextromethorphan O-demethylation in liver microsomes were 136, 34, and 56 μg/ml, respectively. SO-SWCNT was determined to be a competitive inhibitor of CYP3A4, CYP3A5, and CYP2D6. These results suggest that the effect of SO-SWCNT differs among CYP isoforms, and that the inhibition potency depends on the physicochemical properties of the nanocarbons.

Carbon nanotubes physicochemical properties influence the overall cellular behavior and fate

The unique properties of single walled carbon nanotubes (SWCNTs) make them viable candidates for versatile implementation in the next generation of biomedical devices for targeted delivery of chemotherapeutic agents or cellular-sensing probes. Such implementation requires user-tailored changes in SWCNT's physicochemical characteristics to allow for efficient cellular integration while maintaining nanotubes' functionality. However, isolated reports showed that user-tailoring could induce deleterious effects in exposed cells, from decrease in cellular proliferation, to changes in cellular adhesion, generation of reactive oxygen species or phenotypical variations, just to name a few. Before full implementation of SWCNTs is achieved, their toxicological profiles need to be mechanistically correlated with their physicochemical properties to determine how the induced cellular fate is related to the exposure conditions or samples' characteristics. Our study provides a comprehensive analysis of the synergistic cyto- and genotoxic effects resulted from short-term exposure of human lung epithelial cells to pristine (as manufactured) and user-tailored SWCNTs, as a function of their physicochemical properties. Specifically, through a systematic approach we are correlating the nanotube uptake and nanotube-induced cellular changes to the sample's physicochemical characteristics (e.g., metal impurities, length, agglomerate size, surface area, dispersion, and surface functionalization). By identifying changes in active hallmarks involved in cell-cell connections and maintaining epithelial layer integrity, we also determine the role that short-term exposure to SWCNTs plays in the overall cellular fate and cellular transformation. Lastly, we assess cellular structure-function relationships to identify non-apoptotic pathways induced by SWCNTs exposure that could however lead to changes in cellular behavior and cellular transformation. Our results show that the degree of cell transformation is a function of the physicochemical properties of the SWCNT, with the nanotube with higher length, higher metal content and larger agglomerate size reducing cell viability to a larger extent. Such changes in cell viability are also complemented by changes in cell structure, cycle and cell-cell interactions, all responsible for maintaining cell fate.

[Effects of Xenobiotics on Drug Pharmacokinetics and Safety]

The use of nanotechnology has increased over the past 10 years, and various nanomaterials with a wide range of applications have been developed. Carbon nanotubes (CNTs), which are cylindrical molecules consisting of hexagonally arranged carbon atoms, are nanomaterials with high utility. Recently, applications of single-walled CNT (SWCNT) in the medical field for drug-delivery and as gene-delivery agents have been proposed. Due to its structural characteristics and physicochemical properties, the inhalation of SWCNT could be considered as one route for targeted drug delivery into the lungs. Therefore, it is necessary to investigate the effects of SWCNT on the physiological state and response of the cells upon delivery into the lung. We clarified the different response of two carcinoma cell lines to SWCNT exposure, and determined these differences may be due to different cell functions. Furthermore, SWCNT exposure resulted in a global downregulation of stress-responsive genes in normal human bronchial epithelial cells, thereby indicating that the factors involved in the stress responses were not activated by SWCNT. We then tried to ascertain the possible effect of SWCNT on the fate of drugs delivered with SWCNT. Exposure to SWCNT down-regulated the mRNA expression and enzymatic activity of CYP1A1 and CYP1B1 by preventing the binding of activated aryl hydrocarbon receptors to the enhancer region of these genes. This review provides basic information for the prediction of human responses to SWCNT exposure by inhalation, and in its use as a drug delivery carrier.

Enhanced human bone marrow mesenchymal stem cell functions in novel 3D cartilage scaffolds with hydrogen treated multi-walled carbon nanotubes

Cartilage tissue is a nanostructured tissue which is notoriously hard to regenerate due to its extremely poor inherent regenerative capacity and complex stratified architecture. Current treatment methods are highly invasive and may have many complications. Thus, the goal of this work is to use nanomaterials and nano/microfabrication methods to create novel biologically inspired tissue engineered cartilage scaffolds to facilitate human bone marrow mesenchymal stem cell (MSC) chondrogenesis. To this end we utilized electrospinning to design and fabricate a series of novel 3D biomimetic nanostructured scaffolds based on hydrogen (H2) treated multi-walled carbon nanotubes (MWCNTs) and biocompatible poly(L-lactic acid) (PLLA) polymers. Specifically, a series of electrospun fibrous PLLA scaffolds with controlled fiber dimension were fabricated in this study. In vitro MSC studies showed that stem cells prefer to attach in the scaffolds with smaller fiber diameter. More importantly, the MWCNT embedded scaffolds showed a drastic increase in mechanical strength and a compressive Young's modulus matching to natural cartilage. Furthermore, our MSC differentiation results demonstrated that incorporation of the H2 treated carbon nanotubes and poly-L-lysine coating can induce more chondrogenic differentiations of MSCs than controls. After two weeks of culture, PLLA scaffolds with H2 treated MWCNTs and poly-L-lysine can achieve the highest glycosaminoglycan synthesis, making them promising for further exploration for cartilage regeneration.

Evaluation of cytotoxicity, biophysics and biomechanics of cells treated with functionalized hybrid nanomaterials

Hybrids consisting of carboxylated, single-walled carbon nanotube (c-SWNT)-silver nanoparticles (AgNPs)-DNA-poly vinyl alcohol (PVA) are synthesized via sequential functionalization to mimic the theragnostic (therapy and diagnosis) system. Carboxylation of SWNT has minimized the metal impurities with plenty of -COOH groups to produce hybrid (c-SWNT-AgNPs). The hybrid is further wrapped with DNA (hybrid-DNA) and encapsulated with PVA as hybrid composite (HC). Materials were tested against human alveolar epithelial cells (A549), mouse fibroblasts cells (NIH3T3) and human bone marrow stromal cells (HS-5). The composition-sensitive physico-chemical interactions, biophysics and biomechanics of materials-treated cells are evaluated. The cell viability was improved for HC, hybrid-PVA and c-SWNT when compared with SWNT and hybrid. SWNT and hybrid showed cell viability less than 60% at high dose (40 µg ml(-1)) and hybrid-PVA and HC retained 80% or more cell viability. The treatment of hybrid nanomaterials considerably changed cell morphology and intercellular interaction with respect to the composition of materials. Peculiarly, PVA-coated hybrid was found to minimize the growth of invadopodia of A549 cells, which is responsible for the proliferation of cancer cells. Surface roughness of cells increased after treatment with hybrid, where cytoplasmic regions specifically showed higher roughness. Nanoindentation results suggest that changes in biomechanics occurred owing to possible internalization of the hybrid. The changes in force spectra of treated cells indicated a possible greater interaction between the cells and hybrid with distinct stiffness and demonstrated the surface adherence and internalization of hybrid on or inside the cells.

Combination of single walled carbon nanotubes/graphene oxide with paclitaxel: a reactive oxygen species mediated synergism for treatment of lung cancer

Heterogeneity in tumors has led to the development of combination therapies that enable enhanced cell death. Previously explored combination therapies mostly involved the use of bioactive molecules. In this work, we explored a non-conventional strategy of using carbon nanostructures (CNs) [single walled carbon nanotube (SWNT) and graphene oxide (GO)] for potentiating the efficacy of a bioactive molecule [paclitaxel (Tx)] for the treatment of lung cancer. The results demonstrated enhanced cell death following combination treatment of SWNT/GO and Tx indicating a synergistic effect. In addition, synergism was abrogated in the presence of an anti-oxidant, N-acetyl cysteine (NAC), and was therefore shown to be reactive oxygen species (ROS) dependent. It was further demonstrated using bromodeoxyuridine (BrdU) incorporation assay that treatment with CNs was associated with enhanced mitogen associated protein kinase (MAPK) activation that was ROS mediated. Hence, these results for the first time demonstrated the potential of SWNT/GO as co-therapeutic agents with Tx for the treatment of lung cancer.