Rethinking of TEER measurement reporting for epithelial cells grown on permeable inserts

Phytochemical analysis, antioxidant activity, and cytotoxic effects of Caulerpa lentillifera extracts inducing cell apoptosis and sub-G/G0-G1 cell cycle arrest in KON oral cancer cells

BACKGROUND

Marine algae have excellent phytoconstituents with notable biological activity and bioactive therapeutic benefits, but the anti-oral cancer activity of Caulerpa lentillifera (C. lentillifera) has not been widely studied. This study aimed to explore the anti-cancer properties of C. lentillifera to gain insights into possible treatment approaches.

METHODS

The three C. lentillifera extracts were prepared using the maceration method with methanol (CLM), ethanol (CLE), and acetone (CLA). The chemical composition of extracts of C. lentillifera was investigated. Its metabolite profiles were selectively further investigated using the LC-QTOF MS/MS technique and their antioxidative activity was evaluated. The cytotoxic effect on KON cells and MRC-5 cells was assessed using the MTT test. Morphological changes and apoptosis were examined through Hoechst 33,258 and AO double staining, while DAPI and FDA double labeling were used to observe the nucleus and cytoplasm. Using a flow cytometer, the percentage of cell cycle arrest was calculated and the fraction of cell death was examined.

RESULTS

The CLA exhibited higher quantities of TPC, TFC, chlorophyll a, and chlorophyll b compared to the CLM and CLE. The LC-QTOF MS/MS analysis revealed ten major phytochemicals in the CLA. The three C. lentillifera extracts exhibited antioxidative activity, with the CLE demonstrating significantly higher antioxidant activity compared to the CLM and CLA. In-vitro, the KON oral cancer cells exhibited sensitivity to CLA, CLE, and CLM in that order. The three extracts induced ROS-mediated cell death as well as disruption of mitochondrial membrane potential, with concentrations at IC40, IC60, and IC80 leading to apoptosis within 24 h. Furthermore, the cell cycle of KON cells was blocked in sub-G and G0-G1 by all three extracts. Notably, the extracts significantly impeded colony growth, migration, and invasion. The increase in cellular uptake was measured using the TEER test.

CONCLUSION

The findings showed that C. lentillifera has several functional metabolites, antioxidative activity, and strong anti-tumor properties. According to these results, C. lentillifera extracts may be utilized to treat oral cancer.

Quercetin triggers cell apoptosis-associated ROS-mediated cell death and induces S and G2/M-phase cell cycle arrest in KON oral cancer cells

BACKGROUND

Plant flavonoids such as quercetin are useful for both the therapeutic and preventive care of a variety of illnesses. Nevertheless, their antitumor efficacy against KON oral cancer is still unknown. Therefore, the aim of this investigation was to examine quercetin's anti-growth, anti-migrative, and anti-invasive characteristics. The cell cycle arrest property and mitochondrial function disruption of quercetin were also investigated. Additionally, the cellular mechanism responsible for inducing apoptosis and the anti-metastasis mechanism were identified.

METHODS

KON cells were treated with quercetin in order to test the anticancer activity of this compound. The MTT colorimetric assay was used to examine the cell viability of the treated cells in comparison to MRC-5 fibroblast cells. After being exposed to the detrimental effects of quercetin, the morphology of the KON cells was examined using DAPI and FDA double staining, as well as Hoechst 33,258 and AO double staining. Annexin V-FITC with a flow cytometer and DCFDA labeling were used to detect apoptosis induction and the ROS production associated with cell death. Quercetin's ability to stop the cell cycle was evaluated via PI staining and the flow cytometer. The examination included anti-proliferative, anti-migration, and anti-invasion activities. Values for the transepithelial electrical resistance, or TEER, were measured. Ultimately, the mechanisms of action of the apoptotic markers and genes implicated in the metastatic process were clarified.

RESULTS

Quercetin treatment reduced the vitality of KON cells and had minimal effect on MRC cells. Following quercetin treatment, the characterization of apoptosis and cell death in KON cells was observed. When quercetin was applied to KON cells, the generation of ROS increased. Furthermore, it was discovered that quercetin increased the percentage of dead cells and cell cycle arrests in the S and G2/M phases. Moreover, quercetin inhibited KON cells' capacity for migration and invasion in addition to their effects on cell stability and structure. As a result of identifying the mechanism responsible for inducing apoptosis and preventing metastasis, quercetin was found to downregulate the expression of BCL-2/BCL-XL while increasing the expression of BAX. TIMP-1 expression was upregulated while MMP-2 and MMP-9 were downregulated. Quercetin's anticancer properties and specific mechanisms of action in relation to KON cells were clarified.

CONCLUSION

Quercetin is greatly cytotoxic in oral cancer cells, triggering cells undergoing apoptosis and ROS-mediated cell death, possessing S and G2/M cell cycle arrest properties, and exhibiting anti-metastatic activities. Finally, this discovery opens up a wide range of possibilities for developing an anti-oral cancer drug and further investigating its effectiveness in vivo and in clinical trials as an alternative cancer treatment.

Minimum information for reporting on the TEER (trans-epithelial/endothelial electrical resistance) assay (MIRTA)

Standard information reporting helps to ensure that assay conditions and data are consistently reported and to facilitate inter-laboratory comparisons. Here, we present recommendations on minimum information for reporting on the TEER (trans-epithelial/endothelial electrical resistance) assay (MIRTA). The TEER assay is extensively used to evaluate the health of an epithelial/endothelial cell culture model and as an indicator of the potential toxicity of a test substance. This publication is the result of an international collaboration─called the RespTox (Respiratory Toxicity) Collaborative─through which twelve laboratories shared their protocols for assessing the barrier function of respiratory epithelial cells using the TEER assay following exposure to substances. The protocols from each laboratory were reviewed to identify general steps for performing the TEER assay, interlaboratory differences between steps, the rationale for differences, whether these differences impact results or cross-laboratory comparisons between TEER measurements. While the MIRTA recommendations are focused on respiratory epithelial cell systems, these recommendations can be adapted for other cell systems that form barriers. The use of these recommendations will support data transparency and reproducibility, reduce challenges in data interpretation, enable cross-laboratory comparisons, help assess study quality, and facilitate the incorporation of the TEER assay into national and international testing guidance.

A novel sodium caseinate lipid-based auto-emulsifying delivery system to increase resveratrol intestinal permeation: Characterization and in vitro assessment

In recent years, nutraceuticals have emerged as a promising strategy for maintaining health and represent a high-growth market in Italy and across Europe. However, the lack of strict regulations regarding formulation requirements and proof of efficacy raises serious concerns about their poor bioavailability and, consequently, their uncertain health benefits. An emblematic example is t-resveratrol (RES), a cardioprotective stilbene polyphenol that undergoes extensive metabolism in the intestine and liver, resulting in a bioavailability of <1 %. This manuscript describes a novel technological matrix developed with the primary goal of improving RES oral bioavailability. This technology can be classified as a lipid-based autoemulsifying drug delivery system (LIBADDS), in which RES is thoroughly solubilized in a hot liquid phase composed of lipids and surfactants, and the mixture is further adsorbed onto a powder composed of polysaccharides and sodium caseinate (NaC), along with inert excipients, and then compressed. In this study, NaC was used for the first time to trigger pancreatin-mediated hydrolysis of an enteric-coated tablet, allowing micellar delivery of RES to the small intestine. The RES-containing tablets were characterized via differential scanning calorimetry (DSC) and X-ray diffraction (PXRD). The digested formulation, with simulated gastric and enteric fluids, was dimensionally assessed via dynamic light scattering (DLS). Finally, calculations of the bioaccessible fraction, dissolution tests, and in vitro permeability experiments using Caco-2 cell monolayers were carried out to preliminarily define the overall efficiency and applicability of this new technology in improving RES intestinal permeability.

Short Caco-2 model for evaluation of drug permeability: A sodium valerate-assisted approach

The human colorectal adenocarcinoma cell line Caco-2, widely used for studying intestinal drug permeability, is typically grown on permeable filter supports and matures in 21 days with frequent media changes. The process is labor-intensive, prone to contamination, and has low throughput, contributing to the overall high utilization cost. Efforts to establish a low-cost, high-throughput, and short-duration model have encountered obstacles, such as weaker tight junctions causing monolayer leaks, incomplete differentiation resulting in low transporter expression, intricate and challenging protocols, and cytotoxicity, limiting the usability. Hence, this study aimed to develop a low-cost, efficient, and short-duration model by addressing the aforementioned concerns by customizing the media and finding a safe differentiation inducer. We generated a new rapid model using sodium valerate, which demonstrated sufficient transporter activity, improved monolayer integrity, and higher levels of differentiation markers than the 21-day model. Furthermore, this model exhibited consistent and reliable results when used to evaluate drug permeability over multiple days of repeated use. This study demonstrates the potential of a sodium valerate-assisted abbreviated model for drug permeability assessment with economic and practical advantages.

Nanoparticles and Airway Epithelial Cells: Exploring the Impacts and Methodologies in Toxicity Assessment

The production of nanoparticles has recently surged due to their varied applications in the biomedical, pharmaceutical, textile, and electronic sectors. However, this rapid increase in nanoparticle manufacturing has raised concerns about environmental pollution, particularly its potential adverse effects on human health. Among the various concerns, inhalation exposure to nanoparticles poses significant risks, especially affecting the respiratory system. Airway epithelial cells play a crucial role as the primary defense against inhaled particulate matter and pathogens. Studies have shown that nanoparticles can disrupt the airway epithelial barrier, triggering inflammatory responses, generating reactive oxygen species, and compromising cell viability. However, our understanding of how different types of nanoparticles specifically impact the airway epithelial barrier remains limited. Both in vitro cell culture and in vivo murine models are commonly utilized to investigate nanoparticle-induced cellular responses and barrier dysfunction. This review discusses the methodologies frequently employed to assess nanoparticle toxicity and barrier disruption. Furthermore, we analyze and compare the distinct effects of various nanoparticle types on the airway epithelial barrier. By elucidating the diverse responses elicited by different nanoparticles, we aim to provide insights that can guide future research endeavors in assessing and mitigating the potential risks associated with nanoparticle exposure.

Combining analytical techniques to assess the translocation of diesel particles across an alveolar tissue barrier in vitro

BACKGROUND

During inhalation, airborne particles such as particulate matter ≤ 2.5 μm (PM2.5), can deposit and accumulate on the alveolar epithelial tissue. In vivo studies have shown that fractions of PM2.5 can cross the alveolar epithelium to blood circulation, reaching secondary organs beyond the lungs. However, approaches to quantify the translocation of particles across the alveolar epithelium in vivo and in vitro are still not well established. In this study, methods to assess the translocation of standard diesel exhaust particles (DEPs) across permeable polyethylene terephthalate (PET) inserts at 0.4, 1, and 3 μm pore sizes were first optimized with transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-VIS), and lock-in thermography (LIT), which were then applied to study the translocation of DEPs across human alveolar epithelial type II (A549) cells. A549 cells that grew on the membrane (pore size: 3 μm) in inserts were exposed to DEPs at different concentrations from 0 to 80 µg.mL- 1 ( 0 to 44 µg.cm- 2) for 24 h. After exposure, the basal fraction was collected and then analyzed by combining qualitative (TEM) and quantitative (UV-VIS and LIT) techniques to assess the translocated fraction of the DEPs across the alveolar epithelium in vitro.

RESULTS

We could detect the translocated fraction of DEPs across the PET membranes with 3 μm pore sizes and without cells by TEM analysis, and determine the percentage of translocation at approximatively 37% by UV-VIS (LOD: 1.92 µg.mL- 1) and 75% by LIT (LOD: 0.20 µg.cm- 2). In the presence of cells, the percentage of DEPs translocation across the alveolar tissue was determined around 1% at 20 and 40 µg.mL- 1 (11 and 22 µg.cm- 2), and no particles were detected at higher and lower concentrations. Interestingly, simultaneous exposure of A549 cells to DEPs and EDTA can increase the translocation of DEPs in the basal fraction.

CONCLUSION

We propose a combination of analytical techniques to assess the translocation of DEPs across lung tissues. Our results reveal a low percentage of translocation of DEPs across alveolar epithelial tissue in vitro and they correspond to in vivo findings. The combination approach can be applied to any traffic-generated particles, thus enabling us to understand their involvement in public health.

Modular tissue-in-a-CUBE platform to model blood-brain barrier (BBB) and brain interaction

With the advent of increasingly sophisticated organoids, there is growing demand for technology to replicate the interactions between multiple tissues or organs. This is challenging to achieve, however, due to the varying culture conditions of the different cell types that make up each tissue. Current methods often require complicated microfluidic setups, but fragile tissue samples tend not to fare well with rough handling. Furthermore, the more complicated the human system to be replicated, the more difficult the model becomes to operate. Here, we present the development of a multi-tissue chip platform that takes advantage of the modularity and convenient handling ability of a CUBE device. We first developed a blood-brain barrier-in-a-CUBE by layering astrocytes, pericytes, and brain microvascular endothelial cells in the CUBE, and confirmed the expression and function of important tight junction and transporter proteins in the blood-brain barrier model. Then, we demonstrated the application of integrating Tissue-in-a-CUBE with a chip in simulating the in vitro testing of the permeability of a drug through the blood-brain barrier to the brain and its effect on treating the glioblastoma brain cancer model. We anticipate that this platform can be adapted for use with organoids to build complex human systems in vitro by the combination of multiple simple CUBE units.