A sensitive sensor cell line for the detection of oxidative stress responses in cultured human keratinocytes

Cumulus Cell Transcriptome after Cumulus-Oocyte Complex Exposure to Nanomolar Cadmium in an In Vitro Animal Model of Prepubertal and Adult Age

Cadmium (Cd), a highly toxic pollutant, impairs oocyte fertilization, through oxidative damage on cumulus cells (CCs). This study analysed the transcriptomic profile of CCs of cumulus-oocyte complexes (COCs) from adult and prepubertal sheep, exposed to Cd nanomolar concentration during in vitro maturation. In both age-groups, CCs of matured oocytes underwent RNA-seq, data analysis and validation. Differentially expressed genes (DEGs) were identified in adult (n = 99 DEGs) and prepubertal (n = 18 DEGs) CCs upon Cd exposure. Transcriptomes of adult CCs clustered separately between Cd-exposed and control samples, whereas prepubertal ones did not as observed by Principal Component Analysis. The transcriptomic signature of Cd-induced CC toxicity was identified by gene annotation and literature search. Genes associated with previous studies on ovarian functions and/or Cd effects were confirmed and new genes were identified, thus implementing the knowledge on their involvement in such processes. Enrichment and validation analysis showed that, in adult CCs, Cd acted as endocrine disruptor on DEGs involved in hormone biosynthesis, cumulus expansion, regulation of cell signalling, growth and differentiation and oocyte maturation, whereas in prepubertal CCs, Cd affected DEGs involved in CC development and viability and CC-oocyte communications. In conclusion, these DEGs could be used as valuable non-invasive biomarkers for oocyte competence.

3D Bioprinting of Prevascularized Full-Thickness Gelatin-Alginate Structures with Embedded Co-Cultures

The use of bioprinting allows the creation of complex three-dimensional cell laden grafts with spatial placements of different cell lines. However, a major challenge is insufficient nutrient transfer, especially with the increased size of the graft causing necrosis and reduced proliferation. A possibility to improve nutrient support is the integration of tubular structures for reducing diffusion paths. In this study the influence of prevascularization in full-thickness grafts on cell growth with a variation of cultivation style and cellular composition was investigated. To perform this, the rheological properties of the used gelatin-alginate hydrogel as well as possibilities to improve growth conditions in the hydrogel were assessed. Prevascularized grafts were manufactured using a pneumatic extrusion-based bioprinter with a coaxial extrusion tool. The prevascularized grafts were statically and dynamically cultured with a monoculture of HepG2 cells. Additionally, a co-culture of HepG2 cells, fibroblasts and HUVEC-TERT2 was created while HUVEC-TERT2s were concentrically placed around the hollow channels. A static culture of prevascularized grafts showed short-term improvements in cell proliferation compared to avascular grafts, while a perfusion-based culture showed improvements in mid-term cultivation times. The cultivation of the co-culture indicated the formation of vascular structures from the hollow channels toward avascular areas. According to these results, the integration of prevascular structures show beneficial effects for the in vitro cultivation of bioprinted grafts for which its impact can be increased in larger grafts.

Temporal transcriptomic alterations of cadmium exposed human iPSC-derived renal proximal tubule-like cells

Cadmium is a well-studied environmental pollutant where the kidney and particularly the proximal tubule cells are especially sensitive as they are exposed to higher concentrations of cadmium than other tissues. Here we investigated the temporal transcriptomic alterations (TempO-Seq) of human induced pluripotent stem cell (iPSC)-derived renal proximal tubule-like (PTL) cells exposed to 5 μM cadmium chloride for 1, 2, 4, 8, 12, 16, 20, 24, 72 and 168 h. There was an early activation (within 4 h) of the metal and oxidative stress responses (metal-responsive transcription factor-1 (MTF1) and nuclear factor erythroid-2-related factor 2 (Nrf2) genes). The Nrf2 response returned to baseline within 24 h. The Activator Protein 1 (AP-1) regulated genes HSPA6 and FOSL-1 followed the Nrf2 time course. While the MTF1 genes also spiked at 4 h, they remained strongly elevated over the entire exposure period. The data and cell culture model utilised will be useful in further research aimed at the refinement of safe human exposure limits for cadmium, other metals and their mixtures.

Bio-indicators in cadmium toxicity: Role of HSP27 and HSP70

Heat shock proteins (HSPs) are a family of proteins that are expressed by cells in reply to stressors. The changes in concentration of HSPs could be utilized as a bio-indicator of oxidative stress caused by heavy metal. Exposure to the different heavy metals may induce or reduce the expression of different HSPs. The exposure to cadmium ion (Cd²⁺) could increase HSP70 and HSP27 over 2- to 10-fold or even more. The in vitro and in vivo models indicate that the HSP70 family is more sensitive to Cd intoxication than other HSPs. The analyses of other HSPs along with HSP70, especially HSP27, could also be useful to obtain more accurate results. In this regard, this review focuses on examining the literature to bold the futuristic uses of HSPs as bio-indicators in the initial assessment of Cd exposure risks in defined environments.

Impact of sesquiterpene lactones on the skin and skin-related cells? A systematic review of in vitro and in vivo evidence

Although anti-inflammatory properties are attributed to sesquiterpene lactones (SL), cutaneous hypersensitivity reactions are proposed as limitations for SL-based therapies. Thus, the impact of SL on the skin and skin-related cells was systematically reviewed. Studies indexed in electronic databases were screened from the PRISMA strategy. The risk of bias in all studies was verified from the SYRCLE's tool. Thirty original studies were recovered and analyzed. Mice and guinea pig, keratinocytes and fibroblasts were predominantly investigated from in vivo and in vitro studies, respectively. In vivo studies indicated that most SL induced contact dermatitis associated with edema, erythema, and inflammatory infiltrate. Conversely, in vitro evidence was consistent with a dose-dependent anti-inflammatory effect of SL in response to reduced cytokines, 5-LOX, and COX-2 levels or activity in keratinocytes, fibroblasts, macrophages and dendritic cells; which are events potentially triggered by downregulation of gene expression and/or inhibition of the NF-κB signaling pathway. In vivo studies presented uncertain to high-risk of bias mainly associated with underreporting of randomization and experimental blinding. The current evidence supports potent cutaneous immunomodulatory properties of SL. Although in vitro and in vivo studies indicate opposite anti- or proinflammatory effects, this contradiction exhibits a dose-dependent component. In addition, the anti-inflammatory pathways activated by SL are better understood from in vitro evidence. However, additional studies are required to elucidating specific anti-inflammatory and proinflammatory mechanisms triggered by SL in vivo. Thus, controlling the sources of bias described in this review can contribute to improving the quality of the evidence in further investigations.

Medaka (Oryzias latipes) Embryo as a Model for the Screening of Compounds That Counteract the Damage Induced by Ultraviolet and High-Energy Visible Light

Continuous overexposure to sunlight increases its harmful effects on the skin. For this reason, there is a growing need to characterize economic models more representative of the negative effects and counteracting responses that irradiation causes on human skin. These models will serve for the screening of protective compounds against damage caused by ultraviolet (UV) and high energy visible light (HEV). Therefore, two common in vitro models employed for sunlight irradiation studies, namely human keratinocyte HaCat culture and reconstructed human epidermis (RHE), were compared with the medaka fish embryo model, traditionally used in other scientific disciplines. Using suberythemal doses of UVA and HEV to determine the level of Reactive Oxygen Species (ROS) generation and thymine dimers formed by UVB, we show that medaka embryo responds with a lower damage level, more comparable to human skin, than the other two models, probably due to the protective mechanisms that work in a complete organism. In the same way, the protective effects of antioxidant compounds have the greatest effect on medaka embryos. Taken together, these findings suggest that medaka embryos would be a good alternative in vitro model for sunlight effect studies, and for the screening of molecules with counteracting capacity against the damage caused by UV and HEV.

Oral cadmium exposure affects skin immune reactivity in rats

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ± 0.02 µg/g and 0.127 ± 0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ± 0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1β) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies.

Protease-mediated Inflammation: An In Vitro Human Keratinocyte-based Screening Tool for Anti-inflammatory Drug Nanocarrier Systems

Background:

Refined encapsulation approaches in dermatotherapy gain increased interest. There is need of reproducible in vitro systems representing disease features to screen drug delivery systems for preclinical assessment. Inflammatory human skin diseases are commonly accompanied by abnormal epidermal differentiation and barrier impairment. Serine proteases (SPs) and their inhibitors play a critical role in such dysfunctional differentiation. SPs also initiate cellular pathways via activation of protease-activated receptors, which contribute to inflammation. Thus, function and activity of SPs should be considered for the design of new therapies of such disorders.

Objectives:

Herein, we established a novel simplified cell culture model, based on SP-mediated inflammation suitable to assess nanocarriers loaded with anti-inflammatory drugs.

Methods:

SP-mediated inflammation and the regulatory effect of free or encapsulated dexamethasone were determined by measuring interleukin-6 and interleukin-8 in culture medium of HaCaT (human adult low calcium temperature)-keratinocytes. Additionally, radical formation was analyzed by electron paramagnetic resonance spectroscopy. Cellular uptake of core-multishell nanocarriers was investigated by fluorescence microscopy. Cytotoxicity of all additives was determined by a viability assay.

Results:

SP-Stimulation of keratinocytes resulted in increased radical production and release of inflammatory cytokines without affecting cell viability. Induced inflammation was successfully downregulated by addition of free or encapsulated dexamethasone.

Conclusion:

SP-addition can be used as inflammatory stimulus in cell culture to mimic effects of aberrant enzymatic activities found in skin of atopic dermatitis patients. The set-up is appropriate as a preliminary test to examine the effectiveness of new molecules or delivery-systems to counteract serine protease-mediated inflammatory processes prior to skin studies.

Development of dual-fluorescence cell-based biosensors for detecting the influence of environmental factors on nanoparticle toxicity

With the expanding use of engineered nanoparticles (NPs), development of a high-throughput, sensitive method for evaluating NP safety is important. In this study, we developed cell-based biosensors to efficiently and conveniently monitor NP toxicity. The biosensor cells were obtained by transiently transfecting human cells with biosensor plasmids containing a mCherry gene regulated by an inducible promoter [an activator protein 1 (AP-1) promoter, an interleukin 8 (IL8) promoter, or a B cell translocation gene 2 (BTG2) promoter], with an enhanced green-fluorescent protein gene driven by the cytomegalovirus promoter as the internal control. After optimizing flow cytometric analysis, these dual-fluorescence cell-based biosensors were capable of accurately and rapidly detecting NP toxicity. We found that the responses of AP-1, BTG2, and IL8 biosensors in assessing the toxicity of silver nanoparticles (Ag NPs) showed good dose-related increases after exposure to Ag NPs and were consistent with data acquired by conventional assays, such as western blot, real-time polymerase chain reaction, and immunofluorescence. Further investigation of the effects of environmental factors on Ag NP toxicity revealed that aging in water, co-exposure with fulvic acid, and irradiation with ultraviolet A light could affect Ag NP-induced biosensor responses. These results indicated that these novel dual-fluorescence biosensors can be applied to accurately and sensitively monitor NP toxicity.

A cell-based biosensor for nanomaterials cytotoxicity assessment in three dimensional cell culture

Nanoparticles (NPs) are widely used in consumer and medicinal products. The high prevalence of nanoparticles in the environment raises concerns regarding their effects on human health, but there is limited knowledge about how NPs interact with cells or tissues. Because the European Union has called for a substantial reduction of animal experiments for scientific purposes (Directive 2010/63), increased efforts are required to develop in vitro models to evaluate potentially hazardous agents. Here, we describe a new cell-based biosensor for the evaluation of NPs cytotoxicity. The new biosensor is based on transgenic human hepatoblastoma cells (HepG2) that express a secreted form of alkaline phosphatase (SEAP) as a reporter protein whose expression is induced upon activation of a stress response pathway controlled by the transcription regulator nuclear factor-κB (NF-κB). The NF-κB_HepG2 sensor cells were cultured in a Matrigel-based three dimensional environment to simulate the in vivo situation. The new biosensor cells offer the advantage of generating fast and reproducible readout at lower concentrations and shorter incubation time than conventional viability assays, avoid possible interaction between nanomaterials and assay compounds, therefore, minimize generation of false positive or negative results and indicate mechanism of toxicity through NF-κB signaling.

Biomimetic receptors and sensors

In biomimetics, living systems are imitated to develop receptors for ions, molecules and bioparticles. The most pertinent idea is self-organization in analogy to evolution in nature, which created the key-lock principle. Today, modern science has been developing host-guest chemistry, a strategy of supramolecular chemistry for designing interactions of analytes with synthetic receptors. This can be realized, e.g., by self-assembled monolayers (SAMs) or molecular imprinting. The strategies are used for solid phase extraction (SPE), but preferably in developing recognition layers of chemical sensors.