Engineered nanoparticles toxicity on adipose tissue derived mesenchymal stem cells: A preliminary investigation

Nanoscience and nanotechnologies have recently gained importance in several fields, such as industry and medicine. A big issue of the increasing application of nanomaterials is the poor literature regarding their potential toxicity in humans and animals. Recently, adult stem cells have been proposed as putative targets of nanoparticles (NPs). This study aims to investigate the effects of zerovalent-metallic NPs on isolated and amplified equine Adipose tissue derived Mesenchymal Stem Cells (eAdMSCs). Cells were treated with Cobalt (Co-), Iron (Fe-), and Nickel (Ni-) nanoparticles (NPs) at different concentrations and were characterized for the cytotoxic and genotoxic effects of exposure. Treatment with NPs resulted in reduced cell viability and proliferative capability in comparison with untreated cells. However, this did not influence eAdMSCs potency, as treated cells were able to differentiate towards the adipogenic and osteogenic lineages. Ni- and Fe-NPs showed cytoplasmic localization, while Co-NPs entered the nucleus and mitochondria, suggesting a potential genotoxic activity. Regarding p53 expression, it was enhanced in the first 48 h after treatments, with a drastic reduction of expression within 72 h. Higher p53 expression was reported in the case of Co-NP treatment, suggesting the tumorigenic potential of these NPs. Telomerase activity was enhanced by Fe- and Ni-NP treatments in a concentration- and time-dependent way. This was not true for Co-NP treated samples, suggesting a reduced replicative capacity of eAdMSCs upon Co-NP exposure. The present study is a preliminary investigation of the influence exerted by NPs on eAdMSC physiological activity in terms of cytotoxic and genotoxic effects. The present results revealed eAdMSC physiology to be strongly influenced by NPs in a dose-, time- and NP-dependent way.

Multimodal Potentials of Gold Nanoparticles for Bone Tissue Engineering and Regenerative Medicine: Avenues and Prospects

Osseous tissue repair has advanced due to the introduction of tissue engineering. The key elements required while engineering new tissues involve scaffolds, cells, and bioactive cues. The macrostructural to the nanostructural framework of such complex tissue has engrossed the intervention of nanotechnology for efficient neo-bone formation. Gold nanoparticles (GNPs) have recently gained interest in bone tissue regeneration due to their multimodal functionality. They are proven to modulate the properties of scaffolds and the osteogenic cells significantly. GNPs also influence different metabolic functions within the body, which directly or indirectly govern the mechanism of bone regeneration. Therefore, this review highlights nanoparticle-mediated osteogenic development, focusing on different aspects of GNPs ranging from scaffold modulation to cellular stimulation. The toxic aspects of gold nanoparticles studied so far are critically explicated, while further insight into the advancements and prospects of these nanoparticles in bone regeneration is also highlighted.

Histological Injury to Rat Brain, Liver, and Kidneys by Gold Nanoparticles is Dose-Dependent

Gold nanoparticles (GNPs) possess various interesting plasmonic properties that can provide a variety of diagnostic and therapeutic functionalities for biomedical applications. Compared to other inorganic metal nanoparticles (NPs), GNPs are less toxic and more biocompatible. However, the in vivo toxicity of gold nanoparticles on humans can be significant due to the size effect. This work aims to study the effect of multiple doses of small-size (≈20 nm) GNPs on the vital organs of Wistar rats. The study includes the oxidative stress in vital organs (liver, brain, and kidney) caused by GNPs and histopathology analysis. The rats were given a single caudal injection of NPs dispersed in PBS at 25, 50, 100, and 250 mg/kg of body weight. After sacrifice, both plasma and organs were collected for the determination of oxidant/antioxidant markers and histological studies. Our data show the high sensitivity of oxidative stress parameters to the GNPs in the brain, liver, and kidneys. However, the response to this stress is different between the organs and depends upon the antioxidant defense, where GSH levels control the MDA and PCO levels. Histological alterations are mild at 25, 50, and 100 mg/kg but significant at higher concentrations of 250 mg/kg. Therefore, histological impairments are shown to be dependent on the dose of GNPs. The results contribute to the understanding of oxidative stress and cellular interaction induced by nanoparticles.

Green Synthesis of Gold Nanoparticles Using Upland Cress and Their Biochemical Characterization and Assessment

This research focuses on the plant-mediated green synthesis process to produce gold nanoparticles (Au NPs) using upland cress (Barbarea verna), as various biomolecules within the upland cress act as both reducing and capping agents. The synthesized gold nanoparticles were thoroughly characterized using UV-vis spectroscopy, surface charge (zeta potential) analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), atomic force microscopy (AFM), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results indicated the synthesized Au NPs are spherical and well-dispersed with an average diameter ~11 nm and a characteristic absorbance peak at ~529 nm. EDX results showed an 11.13% gold content. Colloidal Au NP stability was confirmed with a zeta potential (ζ) value of -36.8 mV. X-ray diffraction analysis verified the production of crystalline face-centered cubic gold. Moreover, the antimicrobial activity of the Au NPs was evaluated using Gram-negative Escherichiacoli and Gram-positive Bacillus megaterium. Results demonstrated concentration-dependent antimicrobial properties. Lastly, applications of the Au NPs in catalysis and biomedicine were evaluated. The catalytic activity of Au NPs was demonstrated through the conversion of 4-nitrophenol to 4-aminophenol which followed first-order kinetics. Cellular uptake and cytotoxicity were evaluated using both BMSCs (stem) and HeLa (cancer) cells and the results were cell type dependent. The synthesized Au NPs show great potential for various applications such as catalysis, pharmaceutics, and biomedicine.

Nanomaterial Shape Influence on Cell Behavior

Nanomaterials are proven to affect the biological activity of mammalian and microbial cells profoundly. Despite this fact, only surface chemistry, charge, and area are often linked to these phenomena. Moreover, most attention in this field is directed exclusively at nanomaterial cytotoxicity. At the same time, there is a large body of studies showing the influence of nanomaterials on cellular metabolism, proliferation, differentiation, reprogramming, gene transfer, and many other processes. Furthermore, it has been revealed that in all these cases, the shape of the nanomaterial plays a crucial role. In this paper, the mechanisms of nanomaterials shape control, approaches toward its synthesis, and the influence of nanomaterial shape on various biological activities of mammalian and microbial cells, such as proliferation, differentiation, and metabolism, as well as the prospects of this emerging field, are reviewed.

Functions and applications of metallic and metallic oxide nanoparticles in orthopedic implants and scaffolds

Bone defects and diseases are devastating, and can lead to severe functional deficits or even permanent disability. Nevertheless, orthopedic implants and scaffolds can facilitate the growth of incipient bone and help us to treat bone defects and diseases. Currently, a wide range of biomaterials with distinct biocompatibility, biodegradability, porosity, and mechanical strength is used in bone-related research. However, most orthopedic implants and scaffolds have certain limitations and diverse complications, such as limited corrosion resistance, low cell proliferation, and bacterial adhesion. With recent advancements in materials science and nanotechnology, metallic and metallic oxide nanoparticles have become the subject of significant interest as they offer an ample variety of options to resolve the existing problems in the orthopedic industry. More importantly, these nanoparticles possess unique physicochemical and mechanical properties not found in conventional materials, and can be incorporated into orthopedic implants and scaffolds to enhance their antimicrobial ability, bioactive molecular delivery, mechanical strength, osteointegration, and cell labeling and imaging. However, many metallic and metallic oxide nanoparticles can also be toxic to nearby cells and tissues. This review article will discuss the applications and functions of metallic and metallic oxide nanoparticles in orthopedic implants and bone tissue engineering.

Gold nanoparticles biosynthesized by Nocardiopsis dassonvillei NCIM 5124 enhance osteogenesis in gingival mesenchymal stem cells

Gold nanoparticles are widely used for biomedical applications owing to their biocompatibility, ease of functionalization and relatively non-toxic nature. In recent years, biogenic nanoparticles have gained attention as an eco-friendly alternative for a variety of applications. In this report, we have synthesized and characterized gold nanoparticles (AuNPs) from an Actinomycete, Nocardiopsis dassonvillei NCIM 5124. The conditions for biosynthesis were optimized (100 mg/ml of cell biomass, 2.5 mM tetrachloroauric acid (HAuCl₄) at 80 °C and incubation time of 25 min) and the nanoparticles were characterized by TEM, SAED, EDS and XRD analysis. The nanoparticles were spherical and ranged in size from 10 to 25 nm. Their interactions with human gingival tissue-derived mesenchymal stem cells (GMSCs) and their potential applications in regenerative medicine were evaluated further. The AuNPs did not display cytotoxicity towards GMSCs when assessed by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay, DNA fragmentation patterns and Annexin V/propidium iodide staining techniques. These AuNPs induced faster cell migration when monitored by the in vitro wound healing assay. The effect of these nanoparticles on osteogenesis of GMSCs was also studied. Based on the results obtained from alkaline phosphatase, Von Kossa staining and Alizarin Red S staining, the AuNPs were seen to positively affect differentiation of GMSCs and enhance mineralization of the synthesized matrix. We therefore conclude that the biogenic, non-toxic AuNPs are of potential relevance for tissue regeneration applications.

X-ray computed tomography in life sciences

Recent developments within micro-computed tomography (μCT) imaging have combined to extend our capacity to image tissue in three (3D) and four (4D) dimensions at micron and sub-micron spatial resolutions, opening the way for virtual histology, live cell imaging, subcellular imaging and correlative microscopy. Pivotal to this has been the development of methods to extend the contrast achievable for soft tissue. Herein, we review the new capabilities within the field of life sciences imaging, and consider how future developments in this field could further benefit the life sciences community.

In vitro evaluation of magnetite nanoparticles in human mesenchymal stem cells: comparison of different cytotoxicity assays

This work was aimed at defining the suitable test for evaluating Fe₃O₄ NPs cytotoxicity after short-term exposure in human mesenchymal stem cells (hMSCs) using different viability tests, namely NRU, MTT and TB assays, paralleled by cell morphology analyses for cross checking. MTT and NRU data (culture medium with/without hMSCs plus Fe₃O₄NPs) indicated artificial/false increments in cell viability after Fe₃O₄NPs. These observations did not fit with the morphological analyses showing reduced cell density, loss of monolayer features, and morphological alterations at Fe₃O₄NPs ≥50 μg/ml. Fe₃O₄NPs alone induced a substantial increased absorbance at the wavelength required for MTT and NRU. A significant death (25%) of hMSC at Fe₃O₄NPs ≥10 μg/ml, with a maximum effect (45%) at 300 μg/ml after 24 h, exacerbated after 48 h, was observed when applying TB test. These results paralleled the effects on cell morphology. The optical properties and stability of Fe₃O₄NP suspension (tendency to agglomerate in a specific culture medium) represent factors that limit in vitro result interpretation. These findings suggest the non applicability of the spectrophotometric assays for hMSC culture conditions, while TB is an accurate method for determining cell viability after Fe₃O₄NP exposure in this model. In relation to NPs safety assessment: cell-based assays must be considered on case-by-case basis; selection of relevant cell models is also important for predictive toxicological studies; application of a testing strategy is fundamental for understanding the toxicity pathways driving cellular responses.

In vitro toxicity screening of magnetite nanoparticles by applying mesenchymal stem cells derived from human umbilical cord lining

Despite the growing interest in nanoparticles (NPs), their toxicity has not yet been defined and the development of new strategies and predictive models are required. Human stem cells (SCs) offer a promising and innovative cell-based model. Among SCs, mesenchymal SCs (MSCs) derived from cord lining membrane (CL) may represent a new species-specific tool for establishing efficient platforms for primary screening and toxicity/safety testing of NPs. Superparamagnetic iron oxide NPs, including magnetite (Fe₃ O₄ NPs), have aroused great public health and scientific concerns despite their extensive uses. In this study, CL-MSCs were characterized and applied for in vitro toxicity screening of Fe₃ O₄ NPs. Cytotoxicity, internalization/uptake, differentiation and proliferative capacity were evaluated after exposure to different Fe₃ O₄ NP concentrations. Data were compared with those obtained from bone marrow (BM)-MSCs. We observed, at early passages (P3), that: (1) cytotoxicity occurred at 10 μg/mL in CL-MSCs and 100 μg/mL in BM-MSCs (no differences in toxicity, between CL- and BM-MSCs, were observed at higher dosage, 100-300 μg/mL); (2) cell density decrease and monolayer features loss were affected at ≥50 μg/mL in CL-MSCs only; and (3) NP uptake was concentration-dependent in both MSCs. After 100 μg/mL Fe₃ O₄ NP exposures, the capacity of proliferation was decreased (P5-P9) in CL-MSCs without morphology alteration. Moreover, a progressive decrease of intracellular Fe₃ O₄ NPs was observed over culture time. Antigen surface expression and multilineage differentiation were not influenced. These findings suggest that CL-MSCs could be used as a reliable cell-based model for Fe₃ O₄ NP toxicity screening evaluation and support the use of this approach for improving the confidence degree on the safety of NPs to predict health outcomes.

Gold Nanoparticle-Induced Cell Death and Potential Applications in Nanomedicine

Cell death is crucial to human health and is related to various serious diseases. Therefore, generation of new cell death regulators is urgently needed for disease treatment. Nanoparticles (NPs) are now routinely used in a variety of fields, including consumer products and medicine. Exhibiting stability and ease of decoration, gold nanoparticles (GNPs) could be used in diagnosis and disease treatment. Upon entering the human body, GNPs contact human cells in the blood, targeting organs and the immune system. This property results in the disturbance of cell function and even cell death. Therefore, GNPs may act as powerful cell death regulators. However, at present, we are far from establishing a structure–activity relationship between the physicochemical properties of GNPs and cell death, and predicting GNP-induced cell death. In this review, GNPs’ size, shape, and surface properties are observed to play key roles in regulating various cell death modalities and related signaling pathways. These results could guide the design of GNPs for nanomedicine.

Micro-Computed Tomography Detection of Gold Nanoparticle-Labelled Mesenchymal Stem Cells in the Rat Subretinal Layer

Mesenchymal stem cells are widely used in many pre-clinical and clinical settings. Despite advances in molecular technology; the migration and homing activities of these cells in in vivo systems are not well understood. Labelling mesenchymal stem cells with gold nanoparticles has no cytotoxic effect and may offer suitable indications for stem cell tracking. Here, we report a simple protocol to label mesenchymal stem cells using 80 nm gold nanoparticles. Once the cells and particles were incubated together for 24 h, the labelled products were injected into the rat subretinal layer. Micro-computed tomography was then conducted on the 15th and 30th day post-injection to track the movement of these cells, as visualized by an area of hyperdensity from the coronal section images of the rat head. In addition, we confirmed the cellular uptake of the gold nanoparticles by the mesenchymal stem cells using transmission electron microscopy. As opposed to other methods, the current protocol provides a simple, less labour-intensive and more efficient labelling mechanism for real-time cell tracking. Finally, we discuss the potential manipulations of gold nanoparticles in stem cells for cell replacement and cancer therapy in ocular disorders or diseases.

Labeling mesenchymal cells with DMSA-coated gold and iron oxide nanoparticles: assessment of biocompatibility and potential applications

BACKGROUND

Nanoparticles' unique features have been highly explored in cellular therapies. However, nanoparticles can be cytotoxic. The cytotoxicity can be overcome by coating the nanoparticles with an appropriated surface modification. Nanoparticle coating influences biocompatibility between nanoparticles and cells and may affect some cell properties. Here, we evaluated the biocompatibility of gold and maghemite nanoparticles functionalized with 2,3-dimercaptosuccinic acid (DMSA), Au-DMSA and γ-Fe2O3-DMSA respectively, with human mesenchymal stem cells. Also, we tested these nanoparticles as tracers for mesenchymal stem cells in vivo tracking by computed tomography and as agents for mesenchymal stem cells magnetic targeting.

RESULTS

Significant cell death was not observed in MTT, Trypan Blue and light microscopy analyses. However, ultra-structural alterations as swollen and degenerated mitochondria, high amounts of myelin figures and structures similar to apoptotic bodies were detected in some mesenchymal stem cells. Au-DMSA and γ-Fe2O3-DMSA labeling did not affect mesenchymal stem cells adipogenesis and osteogenesis differentiation, proliferation rates or lymphocyte suppression capability. The uptake measurements indicated that both inorganic nanoparticles were well uptaken by mesenchymal stem cells. However, Au-DMSA could not be detected in microtomograph after being incorporated by mesenchymal stem cells. γ-Fe2O3-DMSA labeled cells were magnetically responsive in vitro and after infused in vivo in an experimental model of lung silicosis.

CONCLUSION

In terms of biocompatibility, the use of γ-Fe2O3-DMSA and Au-DMSA as tracers for mesenchymal stem cells was assured. However, Au-DMSA shown to be not suitable for visualization and tracking of these cells in vivo by standard computed microtomography. Otherwise, γ-Fe2O3-DMSA shows to be a promising agent for mesenchymal stem cells magnetic targeting.

Shape and surface chemistry effects on the cytotoxicity and cellular uptake of metallic nanorods and nanospheres

Metallic nanoparticles (such as gold and silver) have been intensely studied for wound healing applications due to their ability to be easily functionalized, possess antibacterial properties, and their strong potential for targeted drug release. In this study, rod-shaped silver nanorods (AgNRs) and gold nanorods (AuNRs) were fabricated by electron beam physical vapor deposition (EBPVD), and their cytotoxicity toward human skin fibroblasts were assessed and compared to sphere-shaped silver nanospheres (AgNSs) and gold nanospheres (AuNSs). Results showed that the 39.94 nm AgNSs showed the greatest toxicity with fibroblast cells followed by the 61.06 nm AuNSs, ∼556 nm × 47 nm (11.8:1 aspect ratio) AgNRs, and the ∼534 nm × 65 nm (8.2:1 aspect ratio) AuNRs demonstrated the least amount of toxicity. The calculated IC50 (50% inhibitory concentration) value for the AgNRs exposed to fibroblasts was greater after 4 days of exposure (387.3 μg mL(-1)) compared to the AgNSs and AuNSs (4.3 and 23.4 μg mL(-1), respectively), indicating that these spherical metallic nanoparticles displayed a greater toxicity to fibroblast cells. The IC50 value could not be measured for the AuNRs due to an incomplete dose response curve. The reduced cell toxicity with the presently developed rod-shaped nanoparticles suggests that they may be promising materials for use in numerous biomedical applications.

Shape and surface effects on the cytotoxicity of nanoparticles: Gold nanospheres versus gold nanostars

Gold nanoparticles are materials with unique optical properties that have made them very attractive for numerous biomedical applications. With the increasing discovery of techniques to synthesize novel nanoparticles such as star-shaped gold nanoparticles for biomedical applications, the safety and performance of these new nanomaterials must be systematically assessed before use. In this study, gold nanostars (AuNSTs) with multibranched surface structures were synthesized, and their influence on the cytotoxicity of human skin fibroblasts and rat fat pad endothelial cells (RFPECs) were assessed and compared with that of gold nanospheres (AuNSPs) with unbranched surfaces. Results showed that the AuNSPs with diameters of approximately 61.46 nm showed greater toxicity with fibroblast cells and RFPECs compared with the synthesized AuNSTs with diameters of approximately 33.69 nm. The AuNSPs were lethal at concentrations of 40 μg/mL for both cell lines, whereas the AuNSTs were less toxic at higher concentrations (400 μg/mL). The calculated IC50 (50% inhibitory concentration) values of the AuNSPs exposed to fibroblast cells were greater at 1 and 4 days of culture (26.4 and 27.7 μg/mL, respectively) compared with the RFPECs (13.6 and 13.8 μg/mL, respectively), indicating that the AuNSPs have a greater toxicity to endothelial cells. It was proposed that possible factors that could be promoting the reduced toxicity effects of the AuNSTs to fibroblast cells and RFPECs, compared with the AuNSPs may be size, surface chemistry, and shape of the gold nanoparticles. The reduced cell toxicity observed with the AuNSTs suggests that AuNSTs may be a promising material for use in biomedical applications.