Bio-effect of nanoparticles in the cardiovascular system

Editorial of Special Issue: The Toxicity of Nanomaterials and Legacy Contaminants: Risks to the Environment and Human Health

Nanotechnology and the incorporation of nanomaterials (NM) into everyday products help to solve problems in society and improve the quality of life, allowing for major advances in the technological, industrial, and medical fields [...].

Synthesis and Characterization of Rutile TiO2 Nanoparticles for the Toxicological Effect on the H9c2 Cell Line from Rats

The widespread use of titanium dioxide (TiO₂) has raised concerns about potential health risks associated with its cytotoxicity in the cardiovascular system. To evaluate the cytotoxicity of TiO₂ particles, the H9c2 rat cardiomyoblasts were used as a biological model, and their toxicological susceptibility to TiO₂-anatase and TiO₂-rutile particles was studied in vitro. The study examined dose and time exposure responses. The cell viability was evaluated based on metabolic inhibition and membrane integrity loss. The results revealed that both TiO₂-anatase and TiO₂-rutile particles induced similar levels of cytotoxicity at the inhibition concentrations IC₂₅ (1.4-4.4 μg/cm²) and IC₅₀ (7.2-9.3 μg/cm²). However, at more significant concentrations, TiO₂-rutile appeared to be more cytotoxic than TiO₂-anatase at 24 h. The study found that the TiO₂ particles induced apoptosis events, but necrosis was not observed at any of the concentrations of particles used. The study considered the effects of microstructural properties, crystalline phase, and particle size in determining the capability of TiO₂ particles to induce cytotoxicity in H9c2 cardiomyoblasts. The microstress in TiO₂ particles was assessed using powder X-ray diffraction through Williamson-Hall and Warren-Averbach analysis. The analysis estimated the apparent crystallite domain and microstrain of TiO₂-anatase to be 29 nm (ε = 1.03%) and TiO₂-rutile to be 21 nm (ε = 0.53%), respectively. Raman spectroscopy, N₂ adsorption isotherms, and dynamic light scattering were used to identify the presence of pure crystalline phases (>99.9%), comparative surface areas (10 m²/g), and ζ-potential values (-24 mV). The difference in the properties of TiO₂ particles made it difficult to attribute the cytotoxicity solely to one variable.

Magnetic Iron Nanoparticles: Synthesis, Surface Enhancements, and Biological Challenges

This review focuses on the role of magnetic nanoparticles (MNPs), their physicochemical properties, their potential applications, and their association with the consequent toxicological effects in complex biologic systems. These MNPs have generated an accelerated development and research movement in the last two decades. They are solving a large portion of problems in several industries, including cosmetics, pharmaceuticals, diagnostics, water remediation, photoelectronics, and information storage, to name a few. As a result, more MNPs are put into contact with biological organisms, including humans, via interacting with their cellular structures. This situation will require a deeper understanding of these particles’ full impact in interacting with complex biological systems, and even though extensive studies have been carried out on different biological systems discussing toxicology aspects of MNP systems used in biomedical applications, they give mixed and inconclusive results. Chemical agencies, such as the Registration, Evaluation, Authorization, and Restriction of Chemical substances (REACH) legislation for registration, evaluation, and authorization of substances and materials from the European Chemical Agency (ECHA), have held meetings to discuss the issue. However, nanomaterials (NMs) are being categorized by composition alone, ignoring the physicochemical properties and possible risks that their size, stability, crystallinity, and morphology could bring to health. Although several initiatives are being discussed around the world for the correct management and disposal of these materials, thanks to the extensive work of researchers everywhere addressing the issue of related biological impacts and concerns, and a new nanoethics and nanosafety branch to help clarify and bring together information about the impact of nanoparticles, more questions than answers have arisen regarding the behavior of MNPs with a wide range of effects in the same tissue. The generation of a consolidative framework of these biological behaviors is necessary to allow future applications to be manageable.

Oral administration of TiO2 nanoparticles during early life impacts cardiac and neurobehavioral performance and metabolite profile in an age- and sex-related manner

BACKGROUND

Nanoparticles (NPs) are increasingly incorporated in everyday products. To investigate the effects of early life exposure to orally ingested TiO2 NP, male and female Sprague-Dawley rat pups received four consecutive daily doses of 10 mg/kg body weight TiO2 NP (diameter: 21 ± 5 nm) or vehicle control (water) by gavage at three different pre-weaning ages: postnatal day (PND) 2-5, PND 7-10, or PND 17-20. Cardiac assessment and basic neurobehavioral tests (locomotor activity, rotarod, and acoustic startle) were conducted on PND 20. Pups were sacrificed at PND 21. Select tissues were collected, weighed, processed for neurotransmitter and metabolomics analyses.

RESULTS

Heart rate was found to be significantly decreased in female pups when dosed between PND 7-10 and PND 17-20. Females dosed between PND 2-5 showed decrease acoustic startle response and when dosed between PND 7-10 showed decreased performance in the rotarod test and increased locomotor activity. Male pups dosed between PND 17-20 showed decreased locomotor activity. The concentrations of neurotransmitters and related metabolites in brain tissue and the metabolomic profile of plasma were impacted by TiO2 NP administration for all dose groups. Metabolomic pathways perturbed by TiO2 NP administration included pathways involved in amino acid and lipid metabolism.

CONCLUSION

Oral administration of TiO2 NP to rat pups impacted basic cardiac and neurobehavioral performance, neurotransmitters and related metabolites concentrations in brain tissue, and the biochemical profiles of plasma. The findings suggested that female pups were more likely to experience adverse outcome following early life exposure to oral TiO2 NP than male pups. Collectively the data from this exploratory study suggest oral administration of TiO2 NP cause adverse biological effects in an age- and sex-related manner, emphasizing the need to understand the short- and long-term effects of early life exposure to TiO2 NP.

Polyethylenimine-Modified Mesoporous Silica Nanoparticles Induce a Survival Mechanism in Vascular Endothelial Cells via Microvesicle-Mediated Autophagosome Release

Surface-modified mesoporous silica nanoparticles (MSNs) have attracted more and more attention as promising materials for biomolecule delivery. However, the lack of detailed evaluation relevant to the potential cytotoxicity of these MSNs is still a major obstacle for their applications. Unlike the bare MSNs and amino- or liposome-modified MSNs, we found that polyethylenimine-modified MSNs (MSNs-PEI) had no obvious toxicity to human umbilical vein endothelial cells (HUVECs) at the concentrations up to 100 μg/mL. However, MSNs-PEI induced autophagosomes accumulation by blocking their fusion with lysosomes, an essential mechanism for the cytotoxicity of many nanoparticles (NPs). Thus, we predicted that an alternative pathway for autophagosome clearance exists in HUVECs to relieve autophagic stress induced by MSNs-PEI. We found that MSNs-PEI prevented STX17 loading onto autophagosomes instead of influencing lysosomal pH or proteolytic activity. MSNs-PEI induced the structural alternation of the cytoskeleton but did not cause endoplasmic reticulum stress. The accumulated autophagosomes were released to the extracellular space via microvesicles (MVs) when the autophagic degradation was blocked by MSNs-PEI. More importantly, blockade of either autophagosome formation or release caused the accumulation of damaged mitochondria and excessive ROS production in the MSNs-PEI-treated HUVECs, which in turn led to cell death. Thus, we propose here that the MV-mediated autophagosome release, a compensation mechanism, allows the vascular endothelial cell survival when the degradation of autophagosomes is blocked by MSNs-PEI. Accordingly, promoting the release of accumulated autophagosomes may be a protective strategy against the endothelial toxicity of NPs.

Phagocytosis of polymeric nanoparticles aided activation of macrophages to increase atherosclerotic plaques in ApoE-/- mice

The unique physiochemical properties of nanomaterials have been widely used in drug delivery systems and diagnostic contrast agents. The safety issues of biomaterials with exceptional biocompatibility and hemo-compatibility have also received extensive attention at the nanoscale, especially in cardiovascular disease. Therefore, we conducted a study of the effects of poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) on the development of aortic atherosclerotic plaques in ApoE^−/− mice. The particle size of PLGA NPs was 92.69 ± 3.1 nm and the zeta potential were − 31.6 ± 2.8 mV, with good blood compatibility. ApoE^−/− mice were continuously injected with PLGA NPs intravenously for 4 and 12 weeks. Examination of oil red O stained aortic sinuses confirmed that the accumulation of PLGA NPs caused a significantly higher extension of atherosclerotic plaques and increasing the expression of associated inflammatory factors, such as TNF-α and IL-6. The combined exposure of ox-LDL and PLGA NPs accelerated the conversion of macrophages to foam cells. Our results highlight further understanding the interaction between PLGA NPs and the atherosclerotic plaques, which we should consider in future nanomaterial design and pay more attention to the process of using nano-medicines on cardiovascular diseases.

Nonspherical Metal-Based Nanoarchitectures: Synthesis and Impact of Size, Shape, and Composition on Their Biological Activity

Metal-based nanoentities, apart from being indispensable research tools, have found extensive use in the industrial and biomedical arena. Because their biological impacts are governed by factors such as size, shape, and composition, such issues must be taken into account when these materials are incorporated into multi-component ensembles for clinical applications. The size and shape (rods, wires, sheets, tubes, and cages) of metallic nanostructures influence cell viability by virtue of their varied geometry and physicochemical interactions with mammalian cell membranes. The anisotropic properties of nonspherical metal-based nanoarchitectures render them exciting candidates for biomedical applications. Here, the size-, shape-, and composition-dependent properties of nonspherical metal-based nanoarchitectures are reviewed in the context of their potential applications in cancer diagnostics and therapeutics, as well as, in regenerative medicine. Strategies for the synthesis of nonspherical metal-based nanoarchitectures and their cytotoxicity and immunological profiles are also comprehensively appraised.

Adverse effects of amorphous silica nanoparticles: Focus on human cardiovascular health

Amorphous silica nanoparticle (SiNPs) has tremendous potential for a host of applications, while its mass production, broad application and environmental release inevitably increase the risk of human exposure. SiNPs could enter into the human body through different routes such as inhalation, ingestion, skin contact and even injection for medical applications. The cardiovascular system is gradually recognized as one of the primary sites for engineered NPs exerting adverse effects. Accumulating epidemiological or experimental evidence support the association between SiNPs exposure and adverse cardiovascular effects. However, this topic is still in its infancy, and the literature shows high inter-study variability and even contradictory results. New challenges still present in the safety evaluation of SiNPs, and its toxicological mechanisms are poorly understood. Here, scientific papers related to cardiovascular studies of SiNPs in vivo and in vitro were selected, and the updated particle-caused cardiovascular toxicity and potential mechanisms were summarized. Moreover, the understanding of how factors primarily including exposure dose, route of administration, particle size and surface properties, influence the interaction between SiNPs and cardiovascular system was discussed. In particular, the adverse outcome pathway (AOP) framework by which SiNPs cause deleterious effects in the cardiovascular system was described, aiming to provide useful information necessary for the regulatory decision and to guide a safer application of nanotechnology.

Amorphous silica nanoparticles accelerated atherosclerotic lesion progression in ApoE-/- mice through endoplasmic reticulum stress-mediated CD36 up-regulation in macrophage

Background

The biosafety concern of silica nanoparticles (SiNPs) is rapidly expanding alongside with its mass production and extensive applications. The cardiovascular effects of SiNPs exposure have been gradually confirmed, however, the interaction between SiNPs exposure and atherosclerosis, and the underlying mechanisms still remain unknown. Thereby, this study aimed to explore the effects of SiNPs on the progression of atherosclerosis, and to investigate related mechanisms.

Results

We firstly investigated the in vivo effects of SiNPs exposure on atherosclerosis via intratracheal instillation of ApoE^−/− mice fed a Western diet. Ultrasound microscopy showed a significant increase of pulse wave velocity (PWV) compared to the control group, and the histopathological investigation reflected a greater plaque burden in the aortic root of SiNPs-exposed ApoE^−/− mice. Compared to the control group, the serum levels of total triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) were elevated after SiNPs exposure. Moreover, intensified macrophage infiltration and endoplasmic reticulum (ER) stress was occurred in plaques after SiNPs exposure, as evidenced by the upregulated CD68 and CHOP expressions. Further in vitro, SiNPs was confirmed to activate ER stress and induce lipid accumulation in mouse macrophage, RAW264.7. Mechanistic analyses showed that 4-PBA (a classic ER stress inhibitor) pretreatment greatly alleviated SiNPs-induced macrophage lipid accumulation, and reversed the elevated CD36 expression induced by SiNPs.

Conclusions

Our results firstly revealed the acceleratory effect of SiNPs on the progression of atherosclerosis in ApoE^−/− mice, which was related to lipid accumulation caused by ER stress-mediated upregulation of CD36 expression in macrophage.

Graphical abstract

Antibacterial Activity of Silver and Its Application in Dentistry, Cardiology and Dermatology

The problem of antimicrobial resistance is increasingly present and requires the discovery of new antimicrobial agents. Although the healing features of silver have been recognized since ancient times, silver has not been used due to newly discovered antibiotics. Thanks to technology development, a significant step forward has been made in silver nanoparticles research. Nowadays, silver nanoparticles are a frequent target of researchers to find new and better drugs. Namely, there is a need for silver nanoparticles as alternative antibacterial nanobiotics. Silver nanoparticles (AgNPs), depending on their size and shape, also have different antimicrobial activity. In addition to their apparent antibacterial activity, AgNPs can serve as drug delivery systems and have anti-thrombogenic, anti-platelet, and anti-hypertensive properties. Today they are increasingly used in clinical medicine and dental medicine. This paper presents silver antimicrobial activity and its use in dentistry, cardiology, and dermatology, where it has an extensive range of effects.

Exposure to carbon black nanoparticles increases seizure susceptibility in male mice

Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m³) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure.

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.

The size-dependent genotoxic potentials of titanium dioxide nanoparticles to endothelial cells

Despite intensive research activities, there are still many major knowledge gaps over the potential adverse effects of titanium dioxide nanoparticles (TiO₂ -NPs), one of the most widely produced and used nanoparticles, on human cardiovascular health and the underlying mechanisms. In the present study, alkaline comet assay and cytokinesis-block micronucleus test were employed to determine the genotoxic potentials of four sizes (100, 50, 30, and 10 nm) of anatase TiO₂ -NPs to human umbilical vein endothelial cells (HUVECs) in culture. Also, the intracellular redox statuses were explored through the measurement of the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) with kits, respectively. Meanwhile, the protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were also detected by western blot. The results showed that at the exposed levels (1, 5, and 25 μg/mL), all the four sizes of TiO₂ -NPs could elicit an increase of both DNA damage and MN frequency in HUVECs in culture, with a positive dose-dependent and negative size-dependent effect relationship (T100 < T50 < T30 < T10). Also, increased levels of intracellular ROS, but decreased levels of GSH, were found in all the TiO₂ -NP-treated groups. Intriguingly, a very similar manner of dose-dependent and size-dependent effect relationship was observed between the ROS test and both comet assay and MN test, but contrary to that of GSH assay. Correspondingly, the levels of Nrf2 protein were also elevated in the TiO₂ -NP-exposed HUVECs, with an inversely size-dependent effect relationship. These findings indicated that induction of oxidative stress and subsequent genotoxicity might be an important biological mechanism by which TiO₂ -NP exposure would cause detrimental effects to human cardiovascular health.

The interstitium in cardiac repair: role of the immune-stromal cell interplay

Cardiac regeneration, that is, restoration of the original structure and function in a damaged heart, differs from tissue repair, in which collagen deposition and scar formation often lead to functional impairment. In both scenarios, the early-onset inflammatory response is essential to clear damaged cardiac cells and initiate organ repair, but the quality and extent of the immune response vary. Immune cells embedded in the damaged heart tissue sense and modulate inflammation through a dynamic interplay with stromal cells in the cardiac interstitium, which either leads to recapitulation of cardiac morphology by rebuilding functional scaffolds to support muscle regrowth in regenerative organisms or fails to resolve the inflammatory response and produces fibrotic scar tissue in adult mammals. Current investigation into the mechanistic basis of homeostasis and restoration of cardiac function has increasingly shifted focus away from stem cell-mediated cardiac repair towards a dynamic interplay of cells composing the less-studied interstitial compartment of the heart, offering unexpected insights into the immunoregulatory functions of cardiac interstitial components and the complex network of cell interactions that must be considered for clinical intervention in heart diseases.

Biochemical functionality of magnetic particles as nanosensors: how far away are we to implement them into clinical practice?

Magnetic nanosensors have become attractive instruments for the diagnosis and treatment of different diseases. They represent an efficient carrier system in drug delivery or in transporting contrast agents. For such purposes, magnetic nanosensors are used in vivo (intracorporeal application). To remove specific compounds from blood, magnetic nanosensors act as elimination system, which represents an extracorporeal approach. This review discusses principles, advantages and risks on recent advances in the field of magnetic nanosensors. First, synthesis methods for magnetic nanosensors and possibilities for enhancement of biocompatibility with different coating materials are addressed. Then, attention is devoted to clinical applications, in which nanosensors are or may be used as carrier- and elimination systems in the near future. Finally, risk considerations and possible effects of nanomaterials are discussed when working towards clinical applications with magnetic nanosensors.

The safety of tattoo inks: Possible options for a common regulatory framework

Tattoo prevalence has been increasing in the last 25 years, but specific regulations on tattoo inks are still missing. In the European Union, no supranational regulation is available and only few national provisions cover them. In the United States, tattoo inks are classified as cosmetics but are not approved for injection into the dermis. Health risks for consumers may derive from microbiological contamination and the presence of toxic substances or nanomaterials. However, current regulations and non-binding recommendations, where present, only address the microbiological and chemical risks, completely overlooking nanotoxicity. The aim of this paper is to promote awareness of the risks associated with tattoo inks and the nanomaterials contained therein. In particular, the need for a harmonised regulation or, at least, a set of minimal requirements is highlighted to improve the safety of tattoo inks and market surveillance by regulatory authorities.

The size-dependent genotoxicity and oxidative stress of silica nanoparticles on endothelial cells

Concerns over the health risk of the widely distributed, commonly used silica nanoparticles (SiNPs) are increasing worldwide. Yet, up to now, there are still many major knowledge gaps over the potential adverse effects of SiNP exposure on human cardiovascular health and the underlying mechanisms. In this study, comet assay and micronucleus test were employed to determine the genotoxic potentials of four sizes (10, 25, 50, 100 nm) of SiNPs to human umbilical vein endothelial cells (HUVECs) in culture. The intracellular redox statuses were explored through the determination of the levels of reactive oxygen species (ROS) and reduced glutathione (GSH) with kits, respectively. The protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2) were also detected by Western blot. The results showed that at the administrative levels (1, 5, 25 μg/mL), all the four sizes of SiNPs could induce an increase of both DNA damages and MN frequencies in HUVECs in culture, with a positive dose- and negative size-dependent effect relationship (S100 < S50 < S25 < S10). Also, significantly enhanced levels of intracellular ROS, but decreased levels of GSH, were observed in the SiNP-treated groups. Interestingly, a very similar manner of dose- and size-dependent effect relationship was observed between the ROS test and both comet assay and MN test, but contrary to that of GSH assay. Correspondingly, the levels of Nrf2 protein were also enhanced in the SiNP-treated HUVECs, with a negative size-dependent effect relationship. These results implicated that induction of oxidative stress and subsequent genotoxicity may be an important biological mechanism by which SiNP exposure may affect human cardiovascular health.

Molybdenum Disulfide Quantum Dots Attenuates Endothelial-to-Mesenchymal Transition by Activating TFEB-Mediated Lysosomal Biogenesis

A defective lysosome-autophagy degradation pathway contributes to a variety of endothelial-to-mesenchymal transition (EndMT)-related cardiovascular diseases. Molybdenum disulfide quantum dots (MoS₂ QDs) are nanoscale sizes in the planar dimensions and atomic structures of transition metal dichalcogenides (TMDs) materials with excellent physicochemical and biological properties, making them ideal for various biomedical applications. In this study, water-soluble MoS₂ QDs with an average diameter of about 3.4 nm were synthesized by using a sulfuric acid-assisted ultrasonic method. The as-prepared MoS₂ QDs exhibited low cytotoxicity of less than 100 μg/mL in both human umbilical vein endothelial cells and human coronary artery endothelial cells and showed novel biological properties to prevent EndMT and promote angiogenesis in vitro. We found that MoS₂ QDs treatment-induced transcription factor (TFEB) mediated lysosomal biogenesis, which could cause autophagy activation. Importantly, using in vitro transforming growth factor (TGF)-β-induced EndMT model, we demonstrated that the cardiovascular protective effect of MoS₂ QDs against EndMT acted through triggering TFEB nucleus translocation and restoring an impairment of autophagic flux, whereas genetic suppression of TFEB impaired the protective action of MoS₂ QDs against EndMT. Taken together, these results gain novel insights into the mechanisms by which MoS₂ QDs regulate EndMT and facilitate the development of MoS₂-based nanoagents for the treatment of EndMT-related cardiovascular diseases.

The size-dependent apoptotic effect of titanium dioxide nanoparticles on endothelial cells by the intracellular pathway

Concerns over the health risk of the widely distributed, commonly used titanium dioxide nanoparticles (nano-TiO₂ ) are increasing worldwide. Yet, up-to-now, our understanding in their potential effects on the cardiovascular system is very limited and the toxicological mechanisms are still unclear. In the present study, the CCK-8 assay was performed to determine the cytotoxicity of four sizes (10, 30, 50, and 100 nm) of anatase nano-TiO₂ on human umbilical vein endothelial cells (HUVECs) in culture, and the flow cytometry was employed to investigate the potential of these nano-TiO₂ to induce the apoptosis of HUVECs. The apoptotic pathway was also probed through the determination of the protein expression and activation of p53, Bax, Bcl-2, caspases-9, -7, -3, and PARP by western blot. The results showed that at the administrative levels (1, 5, 25 μg/mL), all the four sizes of nano-TiO₂ could significantly inhibit the viability of HUVECs and elicit significant apoptosis in them, compared with the negative control (P < .05, P < .01). Moreover, the apoptotic rates of HUVECs were increased respectively with the elevating levels and decreasing sizes of the administrative nano-TiO₂ , showing a clear dose- and size-dependent effect relationships. Interestingly, the increasing phosphorylation of p53, decreasing ratio of Bcl-2/Bax, and enhancing activation of the downstream proteins caspase-9, -7, -3, and PARP, were also observed with the decreasing sizes of the administrative nano-TiO₂ in the western blot, indicating that the intracellular approach of apoptosis, the p53-caspase pathway, is the major way of the nano-TiO₂ -mediated apoptosis in HUVECs in culture and that the size is an important parameter that may determine the potential of nano-TiO₂ to induce cellular response. In conclusion, these results suggested that high levels of nano-TiO₂ exposure may pose potential risks to human cardiovascular health by inducing cardiovascular EC apoptosis.

Silica nanoparticles induced endothelial apoptosis via endoplasmic reticulum stress-mitochondrial apoptotic signaling pathway

Along with their extensively application, human exposure to amorphous silica nanoparticles (SiNPs) has highly increased. Accumulative toxicological researches have provided the scientific correlation between SiNPs exposure and cardiovascular diseases. Endothelial apoptosis is vital in the initiation and progression of atherosclerosis. However, molecular details between SiNPs and endothelial apoptosis remain unidentified. Here, we investigated the uptake and toxic mechanism of SiNPs using HUVECs (Human umbilical vein endothelial cells). Consequently, at 24-h exposure, SiNPs were located freely or within membrane-bound agglomerates in the cytosol, especially in mitochondrial and endoplasmic reticulum (ER) regions with swelled mitochondria, cristae rupture or aggregated ER. Further, we demonstrated that SiNPs induced endothelial apoptosis as evidenced by the Annexin V/PI staining and flow cytometry determination. In line with the ultrastructure alterations, SiNPs triggered mitochondrial ROS generation, ΔΨm collapse, cytosolic Ca²⁺ overload, as well as ER stress confirmed by enhanced ER staining, up-regulated GRP78/BiP and XBP1 splicing. More notably, in line with the induction of apoptosis, SiNPs-induced ER stress-associated activation of CHOP, caspase-12, and IRE1α/JNK pathways, which may regulate the BCL2 family member as evidenced by a increased proapoptotic BAX while a decline of anti-apoptotic Bcl-2, ultimately facilitate the mitochondria-mediated apoptotic caspase cascade as confirmed by the upregulated expressions of cytochrome c, Caspase-9 and -3. Altogether, our results indicated the activation of ER stress-mitochondria cascade-mediated apoptotic pathways may be a key mechanism among the SiNPs-induced endothelial apoptosis.

Suppression of testosterone production by nanoparticulate TiO2 is associated with ERK1/2-PKA-PKC signaling pathways in rat primary cultured Leydig cells

Background

Nanoparticulate titanium dioxide (nano-TiO₂) enters the body through various routes and causes organ damage. Exposure to nano-TiO₂ is reported to cause testicular injury in mice or rats and decrease testosterone synthesis, sperm number, and motility. Importantly, nano-TiO₂ suppresses testosterone production by Leydig cells (LCs) and impairs the reproductive capacity of animals.

Methods

In an attempt to establish the molecular mechanisms underlying the inhibitory effect of nano-TiO₂ on testosterone synthesis, primary cultured rat LCs were exposed to varying concentrations of nano-TiO₂ (0, 10, 20, and 40 µg/mL) for 24 hours, and alterations in cell viability, cell injury, testosterone production, testosterone-related factors (StAR, 3βHSD, P450scc, SR-BI, and DAX1), and signaling molecules (ERK1/2, PKA, and PKC) were investigated.

Results

The data show that nano-TiO₂ crosses the membrane into the cytoplasm or nucleus, triggering cellular vacuolization and nuclear condensation. LC viability decreased in a time-dependent manner at the same nano-TiO₂ concentration, nano-TiO₂ treatment (10, 20, and 40 µg/mL) decreased MMP (36.13%, 45.26%, and 79.63%), testosterone levels (11.40% and 44.93%), StAR (14.7%, 44.11%, and 72.05%), 3βHSD (26.56%, 50%, and 79.69%), pERK1/2 (27.83%, 63.61%, and 78.89%), PKA (47.26%, 70.54%, and 85.61%), PKC (30%, 50%, and 71%), SR-BI (16.41%, 41.79%, and 67.16%), and P450scc (39.41%, 55.26%, and 86.84%), and upregulated DAX1 (1.31-, 1.63-, and 3.18-fold) in primary cultured rat LCs.

Conclusion

Our collective findings indicated that nano-TiO₂-mediated suppression of testosterone in LCs was associated with regulation of ERK1/2–PKA–PKC signaling pathways.

Mitochondrial dysfunction, perturbations of mitochondrial dynamics and biogenesis involved in endothelial injury induced by silica nanoparticles

As silica nanoparticles (SiNPs) pervade the global economy, however, the followed emissions during the manufacturing, use, and disposal stages inevitably bring an environmental release, potentially result in harmful impacts. Endothelial dysfunction precedes cardiovascular disease, and is often accompanied by mitochondrial impairment and dysfunction. We had reported endothelial dysfunction induced by SiNPs, however, the related mechanisms by which SiNPs interact with mitochondria are not well understood. In the present study, we examined SiNPs-induced mitochondrial dysfunction, and further demonstrated their adverse effects on mitochondrial dynamics and biogenesis in endothelial cells (HUVECs). Consequently, SiNPs entered mitochondria, caused mitochondrial swelling, cristae disruption and even disappearance. Further analyses revealed SiNPs increased the intracellular level of mitochondrial reactive oxygen species, eventually resulting in the collapse of mitochondrial membrane potential, impairments in ATP synthesis, cellular respiration and the activities of three ATP-dependent enzymes (including Na⁺/K⁺-ATPase, Ca²⁺-ATPase and Ca²⁺/Mg²⁺-ATPase), as well as an elevated intracellular calcium level. Furthermore, mitochondria in SiNPs-treated HUVECs displayed a fission phenotype. Accordingly, dysregulation of the key gene expressions (FIS1, DRP1, OPA1, Mfn1 and Mfn2) involved in fission/fusion event further certified the SiNPs-induced perturbation of mitochondrial dynamics. Meanwhile, SiNPs-treated HUVECs displayed declined levels of mitochondrial DNA copy number, PGC-1α, NRF1 and also TFAM, indicating an inhibition of mitochondrial biogenesis triggered by SiNPs via PGC-1α-NRF1-TFAM signaling. Overall, SiNPs triggered endothelial toxicity through mitochondria as target, including the induction of mitochondrial dysfunction, as well as the perturbations of their dynamics and biogenesis.

The size-dependent effects of silica nanoparticles on endothelial cell apoptosis through activating the p53-caspase pathway

With the growing production and applications of silica nanoparticles (SiNPs), human exposure to these nanoparticles continues to increase. However, the possible hazards that SiNP exposure may pose to human cardiovascular system and the underlying mechanisms remain unclear. In the present study, the flow cytometry was employed to investigate the potential of four sizes (10, 25, 50, 100 nm) of SiNPs to induce the apoptosis of human umbilical vein endothelial cells (HUVECs) in culture. The apoptotic pathway was also explored through the determination of the protein expression and/or activation of p53, Bcl-2, Bax, caspases-9, -7, -3, and PARP by western blot. The results showed that all the four sizes of SiNPs could significantly elicit apoptosis in HUVECs at the tested concentrations (1, 5, 25 μg/mL), compared with the negative control (p < 0.05, p < 0.01). Moreover, the apoptotic rates were increased with the elevating levels and decreasing sizes of administrative SiNPs, showing both dose- and size-dependent effect relationships. Interestingly, the enhancing phosphorylation of p53 protein (Ser15), decreasing ratio of Bcl-2/Bax protein, and elevating activation of the downstream proteins, caspase-9, -7, -3 and PARP, were also observed with the decreasing sizes of tested SiNPs, indicating that the p53-caspase pathway is the main way of the SiNP-mediated apoptosis in HUVECs and that the size is an important parameter that determines the SiNPs' potential to induce cellular response.

Evaluation of cardiovascular responses to silver nanoparticles (AgNPs) in spontaneously hypertensive rats

Silver nanoparticles (AgNPs) are used in the medical, pharmaceutical and food industry. Adverse effects and toxicity induced by AgNPs upon cardiac function related to nitric oxide (NO) and oxidative stress (OS) are described. AgNPs-toxicity may be influenced by cardiovascular pathologies such as hypertension. However, the molecules involved under pathophysiological conditions are not well studied. The aim of this work was to evaluate perfusion pressure (PP) and left ventricle pressure (LVP) as physiological parameters of cardiovascular function in response to AgNPs, using isolated perfused hearts from spontaneously hypertensive rats (SHR), and identify the role of NO and OS. The results suggest that AgNPs reduced NO derived from endothelial/inducible NO-synthase and increased OS, leading to increased and sustained vasoconstriction and myocardial contractility. Additionally, the hypertension condition alters phenylephrine (Phe) and acetylcholine (ACh) classic effects. These data suggest that hypertension intensified AgNPs-cardiotoxicity. Nevertheless, the precise mechanism of action is still under elucidation.

The adverse vascular effects of multi-walled carbon nanotubes (MWCNTs) to human vein endothelial cells (HUVECs) in vitro: role of length of MWCNTs

Background

Increasing evidences indicate that exposure to multi-walled carbon nanotubes (MWCNTs) could induce adverse vascular effects, but the role of length of MWCNTs in determining the toxic effects is less studied. This study investigated the adverse effects of two well-characterized MWCNTs to human umbilical vein endothelial cells (HUVECs).

Methods

The internalization and localization of MWCNTs in HUVECs were examined by using transmission electron microscopy (TEM). The cytotoxicity of MWCNTs to HUVECs was assessed by water soluble tetrazolium-8 (WST-8), lactate dehydrogenase (LDH) and neutral red uptake assays. Oxidative stress was indicated by the measurement of intracellular glutathione (GSH) and reactive oxygen species (ROS). ELISA was used to determine the release of inflammatory cytokines. THP-1 monocyte adhesion to HUVECs was also measured. To indicate the activation of endoplasmic reticulum (ER) stress, the expression of ddit3 and xbp-1s was measured by RT-PCR, and BiP protein level was measured by Western blot.

Results

Transmission electron microscopy observation indicates the internalization of MWCNTs into HUVECs, with a localization in nuclei and mitochondria. The longer MWCNTs induced a higher level of cytotoxicity to HUVECs compared with the shorter ones. Neither of MWCNTs significantly promoted intracellular ROS, but the longer MWCNTs caused a higher depletion of GSH. Exposure to both types of MWCNTs significantly promoted THP-1 adhesion to HUVECs, accompanying with a significant increase of release of interleukin-6 (IL-6) but not tumor necrosis factor α (TNFα), soluble ICAM-1 (sICAM-1) or soluble VCAM-1 (sVCAM-1). Moreover, THP-1 adhesion and release of IL-6 and sVCAM-1 induced by the longer MWCNTs were significantly higher compared with the responses induced by the shorter ones. The biomarker of ER stress, ddit3 expression, but not xbp-1s expression or BiP protein level, was significantly induced by the exposure of longer MWCNTs.

Conclusions

Combined, these results indicated length dependent toxic effects of MWCNTs to HUVECs in vitro, which might be associated with oxidative stress and activation of ER stress.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0318-x) contains supplementary material, which is available to authorized users.

Effect of silver nanoparticles upon the myocardial and coronary vascular function in isolated and perfused diabetic rat hearts

Silver nanoparticles (AgNPs) are promising antibacterial nanomaterials for diagnostic and treatment of diabetes. However, toxicity and adverse cardiac responses induced by AgNPs related to nitric oxide (NO) and oxidative stress (OS) are described. Moreover, little is known about the diabetes influence upon AgNPs-toxicity. The aim of this work was to evaluate cardiovascular function in response to AgNPs through measuring perfusion pressure (PP) and left ventricle pressure (LVP), using perfused hearts from streptozotocin (STZ)-induced diabetic rats and identify the role of NO and OS. High concentrations but not the lower concentrations of AgNPs, promotes increases in PP and LVP, as well as increased OS. Additionally, diabetes alters the classic effects of phenylephrine (Phe) and acetylcholine (ACh). These data suggest that diabetes may intensify AgNPs-cardiotoxicity. Nevertheless, the precise mechanism of action is still under elucidation.

Multifunctional and biomimetic fish collagen/bioactive glass nanofibers: fabrication, antibacterial activity and inducing skin regeneration in vitro and in vivo

The development of skin wound dressings with excellent properties has always been an important challenge in the field of biomedicine. In this study, biomimetic electrospun fish collagen/bioactive glass (Col/BG) nanofibers were prepared. Their structure, tensile strength, antibacterial activity and biological effects on human keratinocytes, human dermal fibroblasts and human vascular endothelial cells were investigated. Furthermore, the Sprague Dawley rat skin defect model was used to validate their effect on wound healing. The results showed that compared with pure fish collagen nanofibers, the tensile strength of the Col/BG nanofibers increased to 21.87±0.21 Mpa, with a certain degree of antibacterial activity against Staphylococcus aureus. It was also found that the Col/BG nanofibers promoted the adhesion, proliferation and migration of human keratinocytes. Col/BG nanofibers induced the secretion of type one collagen and vascular endothelial growth factor by human dermal fibroblasts, which further stimulated the proliferation of human vascular endothelial cells. Animal experimentation indicated that the Col/BG nanofibers could accelerate rat skin wound healing. This study developed a type of multifunctional and biomimetic fish Col/BG nanofibers, which had the ability to induce skin regeneration with adequate tensile strength and antibacterial activity. The Col/BG nanofibers are also easily available and inexpensive, providing the possibility for using as a functional skin wound dressing.

The endoplasmic reticulum stress inducer thapsigargin enhances the toxicity of ZnO nanoparticles to macrophages and macrophage-endothelial co-culture

It was recently shown that exposure to ZnO nanoparticles (NPs) could induce endoplasmic reticulum (ER) stress both in vivo and in vitro, but the role of ER stress in ZnO NP induced toxicity remains unclear. Because macrophages are sensitive to ER stress, we hypothesized that stressing macrophages with ER stress inducer could enhance the toxicity of ZnO NPs. In this study, the effects of ER stress inducer thapsigargin (TG) on the toxicity of ZnO NPs to THP-1 macrophages were investigated. The results showed that TG enhanced ZnO NP induced cytotoxicity as revealed by water soluble tetrazolium-1 (WST-1) and neutral red uptake assays, but not lactate dehydrogenase (LDH) assay. ZnO NPs dose-dependently enhanced the accumulation of intracellular Zn ions without the induction of reactive oxygen species (ROS), and the presence of TG did not significantly affect these effects. In the co-culture, exposure of THP-1 macrophages in the upper chamber to ZnO NPs and TG significantly reduced the viability of human umbilical vein endothelial cells (HUVECs) in the lower chamber, but the release of tumor necrosis factor α (TNFα) was not induced. In summary, our data showed that stressing THP-1 macrophages with TG enhanced the cytotoxicity of ZnO NPs to macrophages and macrophage-endothelial co-cultures.

Biosilver nanoparticle interface offers improved cell viability

Silver nanoparticles (AgNP) are promising candidates for fighting drug-resistant infections because of their intrinsic antimicrobial effect. The design of high-yield antimicrobial molecules may inadvertently cause variation in host cells' biological responses. While many factors affect AgNPs' efficacy, their surface is exposed to the biological environment and thus plays a critical role in both the preservation of antimicrobial efficacy against pathogens and the modulation of host cells cytotoxicity. This work investigated an engineered biomimetic interface approach to controlling AgNP surface properties to provide them a competitive advantage in a biological environment. Here, a fusion protein featuring a silver-binding peptide (AgBP) domain was engineered to enable self-assembly and track assembly by a green fluorescent protein (GFP) reporter. Following AgNP functionalisation with GFP-AgBP, their antimicrobial and cytotoxic properties were evaluated. GFP-AgBP binding affinity to AgNPs was evaluated using localized surface plasmon resonance sensing. The GFP-AgBP biomimetic interface on AgNPs' surfaces provided sustained antibacterial efficacy at low concentrations based on bacterial growth inhibition assays. Viability and cytotoxicity measurements in fibroblast cells exposed to GFP-AgBP protein-functionalised AgNPs showed significant improvement compared to controls. Biointerface engineering offers promise towards tailoring AgNP antimicrobial efficacy while addressing safety concerns to maintain optimum cellular interactions.