Single-walled carbon nanotubes (SWCNTs) induce vasodilation in isolated rat aortic rings

Pharmacological and toxicological aspects of carbon nanotubes (CNTs) to vascular system: A review

Carbon nanotubes (CNTs) are novel carbon based nanomaterials (NMs) that could be used in many areas ranging from electronics to biotechnology. The present review summarized pharmacological and toxicological aspects of CNTs to vascular systems, because the vascular systems are important targets for CNTs during manufacturing process, daily contact and biomedical uses. Functionalized CNTs could be used as novel nanoplateforms to regulate angiogenesis for cancer therapy, as well as nanocarriers to cross blood brain barrier (BBB), one of the major obstacles to prevent the entering of therapeutic substances into brains. However, it has also been shown that inhalational or intravenous contact with CNTs might induce adverse vascular effects, such as progression of atherosclerotic plaque, vasomotor dysfunction, and changes of blood pressure and/or heart rate in laboratory animals, although currently there are only limited reports obtained from CNT-exposed human beings and the results are inconclusive. The mechanisms associated with the vascular toxicity of CNTs remain poorly understood, and it appears that multiple signaling pathways are likely to be involved. The toxicity of CNTs to vascular systems might be reduced by controlling the physicochemical properties of CNTs, particularly lengths, diameters and surface chemistry. At present, the beneficial and adverse effects of CNTs to vascular systems are still largely unknown and require further extensive studies.

Multi-Walled Carbon Nanotubes (MWCNTs) Activate Apoptotic Pathway Through ER Stress: Does Surface Chemistry Matter?

PURPOSE

Physicochemical properties play a crucial role in determining the toxicity of multi-walled carbon nanotubes (MWCNTs). Recently we found that MWCNTs with longer length and smaller diameters could induce toxicity to human umbilical vein endothelial cells (HUVECs) through the activation of endoplasmic reticulum (ER) stress. In this study, we further investigated the possible contribution of hydroxylation and carboxylation to the cytotoxicity of MWCNTs.

METHODS

The HUVECs were exposed to pristine (code XFM19), hydroxylated (code XFM20; content of hydroxyl groups 1.76 wt%) and carboxylated (code XFM21; content of carboxyl groups 1.23 wt%) MWCNTs, respectively. Then, the internalization, cytotoxicity, oxidative stress and activation of apoptosis-ER stress pathway were measured.

RESULTS

In consequence, all types of MWCNTs could be internalized into the HUVECs, and the cellular viability was significantly reduced to a similar level. Moreover, the MWCNTs increased intracellular reactive oxygen species (ROS) and decreased glutathione (GSH) to similar levels, indicating their capacity of inducing oxidative stress. The Western blot results showed that all types of MWCNTs reduced BCL-2 and increased caspase-3, caspase-8, cleaved caspase-3 and cleaved caspase-8. The expression of ER stress gene DNA damage-inducible transcript 3 (DDIT3) and protein level of chop were only significantly induced by XFM20 and XFM21, whereas protein level of p-chop was promoted by XFM19 and XFM21. In addition, the pro-survival gene XBP-1s was significantly down-regulated by all types of MWCNTs.

CONCLUSION

These results suggested that MWCNTs could induce cytotoxicity to HUVECs via the induction of oxidative stress and apoptosis-ER stress, whereas a low degree of hydroxylation or carboxylation did not affect the toxicity of MWCNTs to HUVECs.

Prolonged exposure to carbon nanoparticles induced methylome remodeling and gene expression in zebrafish heart

Growing black carbon (BC) emission has become one of the major urgent environmental issues facing human beings. Usually, BC or BC-containing carbon nanoparticles (CNPs) were recognized as non-directly toxic components of atmospheric particulate matter. However, epidemiology studies have provided much evidence of the associations of exposure of particulate-containing carbon particles with cardiovascular diseases. There are still no related studies to support the epidemiological conclusions. Hence, in this article we exposed adult zebrafish to CNPs for 60 days, and then explored the heart location and potential adverse effects on cardiac tissues of these nanosized carbon particles. Our results first showed direct visualization of cardiac endothelial uptake and heart deposition of CNPs in zebrafish. In addition, CNPs caused significant ultrastructural alterations in myocardial tissue and induced the expression of inflammatory cytokines in a dose-dependent manner, resulting in sub-endocardial inflammation and cell apoptosis. Moreover, our data demonstrated the perturbations caused by CNPs on DNA methylation, suggesting that DNA methylome remodeling might play a critical role in CNP-induced cardiotoxicity in zebrafish heart. Therefore, this study not only proved a laboratory link between CNP exposure and cardiotoxicity in vivo, but also indicated a possible toxicity mechanism involved.

Overview of Antagonists Used for Determining the Mechanisms of Action Employed by Potential Vasodilators with Their Suggested Signaling Pathways

This paper is a review on the types of antagonists and the signaling mechanism pathways that have been used to determine the mechanisms of action employed for vasodilation by test compounds. Thus, we exhaustively reviewed and analyzed reports related to this topic published in PubMed between the years of 2010 till 2015. The aim of this paperis to suggest the most appropriate type of antagonists that correspond to receptors that would be involved during the mechanistic studies, as well as the latest signaling pathways trends that are being studied in order to determine the route(s) that atest compound employs for inducing vasodilation. The methods to perform the mechanism studies were included. Fundamentally, the affinity, specificity and selectivity of the antagonists to their receptors or enzymes were clearly elaborated as well as the solubility and reversibility. All the signaling pathways on the mechanisms of action involved in the vascular tone regulation have been well described in previous review articles. However, the most appropriate antagonists that should be utilized have never been suggested and elaborated before, hence the reason for this review.