Gold nanoparticle modifies nitric oxide release and vasodilation in rat aorta

S-nitrosocysteamine-functionalised porous graphene oxide nanosheets as nitric oxide delivery vehicles for cardiovascular applications

Nitric oxide (NO) is a key signalling molecule released by vascular endothelial cells that is essential for vascular health. Low NO bioactivity is associated with cardiovascular diseases, such as hypertension, atherosclerosis, and heart failure and NO donors are a mainstay of drug treatment. However, many NO donors are associated with the development of tolerance and adverse effects, so new formulations for controlled and targeted release of NO would be advantageous. Herein, we describe the design and characterisation of a novel NO delivery system via the reaction of acidified sodium nitrite with thiol groups that had been introduced by cysteamine conjugation to porous graphene oxide nanosheets, thereby generating S-nitrosated nanosheets. An NO electrode, ozone-based chemiluminescence and electron paramagnetic resonance spectroscopy were used to measure NO released from various graphene formulations, which was sustained at >5 × 10-10 mol cm-2 min-1 for at least 3 h, compared with healthy endothelium (cf. 0.5-4 × 10-10 mol cm-2 min-1). Single cell Raman micro-spectroscopy showed that vascular endothelial and smooth muscle cells (SMCs) took up graphene nanostructures, with intracellular NO release detected via a fluorescent NO-specific probe. Functionalised graphene had a dose-dependent effect to promote proliferation in endothelial cells and to inhibit growth in SMCs, which was associated with cGMP release indicating intracellular activation of canonical NO signalling. Chemiluminescence detected negligible production of toxic N-nitrosamines. Our findings demonstrate the utility of porous graphene oxide as a NO delivery vehicle to release physiologically relevant amounts of NO in vitro, thereby highlighting the potential of these formulations as a strategy for the treatment of cardiovascular diseases.

Recent advances on the development of NO-releasing molecules (NORMs) for biomedical applications

Nitric oxide (NO) is an important biological messenger as well as a signaling molecule that participates in a broad range of physiological events and therapeutic applications in biological systems. However, due to its very short half-life in physiological conditions, its therapeutic applications are restricted. Efforts have been made to develop an enormous number of NO-releasing molecules (NORMs) and motifs for NO delivery to the target tissues. These NORMs involve organic nitrate, nitrite, nitro compounds, transition metal nitrosyls, and several nanomaterials. The controlled release of NO from these NORMs to the specific site requires several external stimuli like light, sound, pH, heat, enzyme, etc. Herein, we have provided a comprehensive review of the biochemistry of nitric oxide, recent advancements in NO-releasing materials with the appropriate stimuli of NO release, and their biomedical applications in cancer and other disease control.

Two Methods of AuNPs Synthesis Induce Differential Vascular Effects. The Role of the Endothelial Glycocalyx

AuNPs are synthesized through several methods to tune their physicochemical properties. Although AuNPs are considered biocompatible, a change in morphology or properties can modify their biological impact. In this work, AuNPs (~12 to 16 nm) capping with either sodium citrate (CA) or gallic acid (GA) were evaluated in a rat aorta ex vivo model, which endothelial inner layer surface is formed by glycocalyx (hyaluronic acid, HA, as the main component), promoting vascular processes, most of them dependent on nitric oxide (NO) production. Results showed that contractile effects were more evident with AuNPsCA, while dilator effects predominated with AuNPsGA. Furthermore, treatments with AuNPsCA and AuNPsGA in the presence or absence of glycocalyx changed the NO levels, differently. This work contributes to understanding the biological effects of AuNPs with different capping agents, as well as the key role that of HA in the vascular effects induced by AuNPs in potential biomedical applications.

Effect of gold nanoparticles shape and dose on immunological, hematological, inflammatory, and antioxidants parameters in male rabbit

Background and Aim:

Gold nanorods (AuNRs) have gained much attention recent years due to their promising optical and chemical properties and are hence used in applied research and industrial nanotechnology. This study was designed to investigate the effect of gold nanoparticle shape (Gold nanorods vs. gold nanosphere) on immune response in rabbit.

Materials and Methods:

Thirty New Zealand white rabbits were divided into six groups (n=5 rabbits). The first group is the control negative received an intravenous (IV) injection of normal saline 0.9%; the second group (vaccinated) is the control positive, and the other four groups were vaccinated and received a single-dose or repeated five consecutive IV doses of 300 mg/kg body weight 50 nm AuNRs or 50 nm gold nanosphere (50 nm AuNSs) dissolved in ultrapure water. Blood and serum were collected for the hematological and biochemical analysis.

Results:

White blood cells (WBCs) count, lymphocytes, monocytes, eosinophils, and basophils showed significantly (p<0.05) higher values with the repeated-dose AuNRs. g-globulin levels showed a significant difference after 15 days in the single-dose AuNSs. Single-dose AuNSs significantly (p<0.05) increased the immunoglobulin G (IgG) and significantly (p<0.05) decreased the tumor necrosis factor-alpha. In addition, it elicited a significant (p<0.05) decrease in the malondialdehyde levels and a significant (p<0.05) increase of the superoxide dismutase, glutathione peroxidase, and catalase levels. Moreover, evoked red blood cells count, mean corpuscular volume, and mean corpuscular hemoglobin were significantly (p<0.05) lower than the control group. The platelet count, lysozymes, and nitric oxide were significantly (p<0.05) higher in repeated-dose AuNRs.

Conclusion:

The effect of AuNPs is shape and dose-dependent. The repeated 5 days IV 50 nm AuNRs doses over 15 days showed a significant antioxidant effect, with no considerable toxicity or vascular reactions.

Green Metallic Nanoparticles for Cancer Therapy: Evaluation Models and Cancer Applications

Metal-based nanoparticles are widely used to deliver bioactive molecules and drugs to improve cancer therapy. Several research works have highlighted the synthesis of gold and silver nanoparticles by green chemistry, using biological entities to minimize the use of solvents and control their physicochemical and biological properties. Recent advances in evaluating the anticancer effect of green biogenic Au and Ag nanoparticles are mainly focused on the use of conventional 2D cell culture and in vivo murine models that allow determination of the half-maximal inhibitory concentration, a critical parameter to move forward clinical trials. However, the interaction between nanoparticles and the tumor microenvironment is not yet fully understood. Therefore, it is necessary to develop more human-like evaluation models or to improve the existing ones for a better understanding of the molecular bases of cancer. This review provides recent advances in biosynthesized Au and Ag nanoparticles for seven of the most common and relevant cancers and their biological assessment. In addition, it provides a general idea of the in silico, in vitro, ex vivo, and in vivo models used for the anticancer evaluation of green biogenic metal-based nanoparticles.

Effect of gold nanoparticles (AuNPs) on isolated rat tracheal segments

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AuNPs at 100 μg/mL induce a contractile effect on isolated trachea rings of female and male rats.

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Nitric oxide (NO) is a potential mediator of the AuNPs actions upon the smooth muscle of isolated rat tracheal rings.

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Formation of AuNPs in physiological solution in controls with HAuCl4 trigger similar contractile effects than AuNPs.

The AuNPs have been used in biomedicine as therapeutic tools for cancer. However, its role in the context of respiratory physiology has been little studied. This study aimed to determine the impact of AuNPs on respiratory smooth muscle tone, using a model of isolated tracheal rings from female and male rats precontracted with acetylcholine (ACh). AuNPs exerted a contractile effect only in the concentration of 100 ug/ml. This contractile effect was not modified by gender. The possible mediator ⁺could be nitric oxide (NO), measured in a physiological solution containing the tracheal rings treated with different concentrations of AuNPs. The results obtained in this study show that the AuNPs are bio-inert in a concentration range of 0.1−10 μg/mL; however, 100 μg/mL could trigger airway hyperresponsiveness. Similar effects were obtained in isolated trachea rings treated with 100 μg/mL HAuCl4. An evaluation of HAuCl4 in physiological buffer at various HEPES concentrations (0–20 mM) showed the formation of AuNPs that could explain the contractile effect on the tracheal smooth muscle.

Repeated-oral dose toxicity of polyethylene microplastics and the possible implications on reproduction and development of the next generation

With the increased distribution of microplastics in the environment, the potential for harmful effects on human health and ecosystems have become a global concern. Considering that polyethylene microplastics (PE-MPs) are among the most produced plastics worldwide, we administered PE-MPs (0.125, 0.5, 2 mg/day/mouse) by gavage to mice (10 mice/sex/dose) for 90 days. Compared to control, the body weight gain was significantly reduced in the male mice, and the proportion of neutrophils in the blood stream clearly increased in both sexes of mice. Persistence of a PE-MPs-like material and migration of granules to the mast cell membrane and accumulation of damaged organelles were observed in the stomachs and the spleens from the treated dams, respectively. Additionally, the IgA level in the blood stream was significantly elevated in the dams administered with PE-MPs compared to control, and the subpopulation of lymphocytes within the spleen was altered. Following, we performed an additional study to screen the effects of PE-MPs on reproduction and development (5 mice/sex/dose). Importantly, number of live births per dam, the sex ratio of pups, and body weight of pups was notably altered in groups treated with PE-MPs compared to the control group. Additionally, PE-MPs affected the subpopulation of lymphocytes within the spleen of the offspring, as did in the dams. Therefore, we propose that reproductive and developmental toxicity testing is warranted to evaluate the safety of microplastics. Additionally, we suggest that the IgA level may be used as a biomarker for harmful effects following exposure on microplastics.

Polyvinylpyrrolidone-coated gold nanoparticles inhibit endothelial cell viability, proliferation, and ERK1/2 phosphorylation and reduce the magnitude of endothelial-independent dilator responses in isolated aortic vessels

Background

Gold nanoparticles (AuNPs) demonstrate clinical potential for drug delivery and imaging diagnostics. As AuNPs aggregate in physiological fluids, polymer-surface modifications are utilized to allow their stabilization and enhance their retention time in blood. However, the impact of AuNPs on blood vessel function remains poorly understood. In the present study, we investigated the effects of AuNPs and their stabilizers on endothelial cell (EC) and vasodilator function.

Materials and methods

Citrate-stabilized AuNPs (12±3 nm) were synthesized and surface-modified using mercapto polyethylene glycol (mPEG) and polyvinylpyrrolidone (PVP) polymers. Their uptake by isolated ECs and whole vessels was visualized using transmission electron microscopy and quantified using inductively coupled plasma mass spectrometry. Their biological effects on EC proliferation, viability, apoptosis, and the ERK1/2-signaling pathway were determined using automated cell counting, flow cytometry, and Western blotting, respectively. Endothelial-dependent and independent vasodilator functions were assessed using isolated murine aortic vessel rings ex vivo.

Results

AuNPs were located in endothelial endosomes within 30 minutes’ exposure, while their surface modification delayed this cellular uptake over time. After 24 hours’ exposure, all AuNPs (including polymer-modified AuNPs) induced apoptosis and decreased cell viability/proliferation. These inhibitory effects were lost after 48 hours’ exposure (except for the PVP-modified AuNPs). Furthermore, all AuNPs decreased acetylcholine (ACh)-induced phosphorylation of ERK1/2, a key signaling protein of cell function. mPEG-modified AuNPs had lower cytostatic effects than PVP-modified AuNPs. Citrate-stabilized AuNPs did not alter endothelial-dependent vasodilation induced by ACh, but attenuated endothelial-independent responses induced by sodium nitroprusside. PVP-modified AuNPs attenuated ACh-induced dilation, whereas mPEG-modified AuNPs did not, though this was dose-related.

Conclusion

We demonstrated that mPEG-modified AuNPs at a therapeutic dosage showed lower cytostatic effects and were less detrimental to vasodilator function than PVP-modified AuNPs, indicating greater potential as agents for diagnostic imaging and therapy.

Regulatory mechanisms, prophylaxis and treatment of vascular leakage following severe trauma and shock

Vascular leakage, or increased vascular permeability, is a common but important pathological process for various critical diseases, including severe trauma, shock, sepsis, and multiple organ dysfunction syndrome (MODS), and has become one of the most important causes of death for intensive care units (ICU) patients. Currently, although there has been some progress in knowledge of the pathogenesis of these vascular disorders, the detailed mechanisms remain unclear, and effective prophylaxis and treatment are still lacking. In this study, we aimed to provide a review of the literature regarding the regulatory mechanisms and prophylaxis as well as the treatment of vascular leakage in critical diseases such as severe trauma and shock, which could be beneficial for the overall clinical treatment of vascular leakage disorders.