A cell-microelectronic sensing technique for profiling cytotoxicity of chemicals

A cell-microelectronic sensing technique is developed for profiling chemical cytotoxicity and is used to study different cytotoxic effects of the same class chemicals using nitrosamines as examples. This technique uses three human cell lines (T24 bladder, HepG2 liver, and A549 lung carcinoma cells) and Chinese hamster ovary (CHO-K1) cells in parallel as the living components of the sensors of a real-time cell electronic sensing (RT-CES) method for dynamic monitoring of chemical toxicity. The RT-CES technique measures changes in the impedance of individual microelectronic wells that is correlated linearly with changes in cell numbers during t log phase of cell growth, thus allowing determination of cytotoxicity. Four nitrosamines, N-nitrosodimethylamine (NDMA), N-nitrosodiphenylamine (NDPhA), N-nitrosopiperidine (NPip), and N-nitrosopyrrolidine (NPyr), were examined and unique cytotoxicity profiles were detected for each nitrosamine. In vitro cytotoxicity values (IC₅₀) for NDPhA (ranging from 0.6 to 1.9 mM) were significantly lower than the IC₅₀ values for the well-known carcinogen NDMA (15-95 mM) in all four cell lines. T24 cells were the most sensitive to nitrosamine exposure among the four cell lines tested (T24 > CHO > A549 > HepG2), suggesting that T24 may serve as a new sensitive model for cytotoxicity screening. Cell staining results confirmed that administration of the IC₅₀ concentration from the RT-CES experiments inhibited cell growth by 50% compared to the controls, indicating that the RT-CES method provides reliable measures of IC₅₀. Staining and cell-cycle analysis confirmed that NDPhA caused cell-cycle arrest at the G0/G1 phase, whereas NDMA did not disrupt the cell cycle but induced cell death, thus explaining the different cytotoxicity profiles detected by the RT-CES method. The parallel cytotoxicity profiling of nitrosamines on the four cell lines by the RT-CES method led to the discovery of the unique cytotoxicity of NDPhA causing cell-cycle arrest. This study demonstrates a new approach to comprehensive testing of chemical toxicity.     

Real-time cell-microelectronic sensing of nanoparticle-induced cytotoxic effects

We report a real-time cell analysis (RTCA) sensing method of 96 electronic microwells for profiling the cytotoxicity of nanoparticles on different cell lines. The method consists of 96 microwells embedded with microelectrodes (96x E-plate) to measure impedance changes of adherent cell lines. When the testing cells change in population, adhesion, and/or morphology, the impedance at the cell–electrode interface changes to provide real-time monitoring of overall cell status. To demonstrate this technique, we used three cell lines as sensing probes: two human lung carcinoma cell lines, A549 and SK-MES-1, and a normal mammalian cell line, CHO-K1. We tested two well-characterized nanoparticles: nano-titanium dioxide (nTiO₂) and nano-silver (nAg). The three cell lines were separately seeded into 96x E-plates and treated with varying concentrations of nanoparticles (0.078–160 μg mL⁻¹). This method provides dynamic cell response profiles and temporal IC₅₀ histograms, showing concentration-, time-, particle-, and cell-dependent cytotoxicity. The 24 h and 48 h IC₅₀ values of nAg obtained using both the RTCA and the neutral red uptake (NRU) assays were in good agreement, validating the RTCA technique. The RTCA assay does not suffer interference from nTiO₂, whereas the NRU assay cannot be used due to severe interference from nTiO₂. A cytostatic response was observed in CHO-K1 cells after 24 h exposure to 40 μg mL⁻¹ nTiO₂, which was correlated with S-phase cell cycle arrest based on cell cycle analysis using flow cytometry. This suggests that the shapes of the response curves provide indicative information, directing further studies into the mode of action of the toxicant. Advantages of the RTCA technique over traditional colorimetric assays for screening the cytotoxicity of nanoparticles include minimizing interference, qualitative and quantitative cytotoxicity data, and the capability of real-time and high-throughput measurements.     

Data-based modeling and prediction of cytotoxicity induced by contaminants in water resources

This paper is concerned with dynamic modeling, prediction and analysis of cell cytotoxicity induced by water contaminants. A real-time cell electronic sensing (RT-CES) system has been used for continuously monitoring dynamic cytotoxicity responses of living cells. Cells are grown onto the surfaces of the microelectronic sensors. Changes in cell number expressed as cell index (CI) have been recorded on-line as time series. The CI data are used to develop dynamic prediction models for cell cytotoxicity process. We consider support vector regression (SVR) algorithm to implement data-based system identification for dynamic modeling and prediction of cytotoxicity. Through several validation studies, multi-step-ahead predictions are calculated and compared with the actual CI obtained from experiments. It is shown that SVR-based dynamic modeling has great potential in predicting the cytotoxicity response of the cells in the presence of toxicant.     

Recognition of chemical compounds in contaminated water using time-dependent multiple dose cellular responses

An early determination of toxicant compounds of water contaminations can gain critical time to protect citizens’ health and save substantial amounts of medical costs. To determine toxins in real time, a multi-dose classification algorithm using cellular state variable identification (CSVID) is developed in this paper. First, the dynamic cytotoxicity response profiles of living cells are measured using a real-time cell electronic sensing (RT-CES) system. Changes in cell number expressed as cell index (CI) are recorded on-line as time series. Then CSVID, which reflects the cell killing, cell lysis and certain cellular pathological changes, is extracted from those dynamic cellular responses. Finally, a support vector machine (SVM) algorithm based on CSVID is employed to classify chemical compounds and determine their analogous cellular response pathway. In order to increase the classification accuracy, a majority vote of the class labels is also proposed. Several validation studies demonstrate that CSVID-based classification algorithm has great potential in distinguishing the cytotoxicity response of the cells in the presence of toxins.     

Comparison of Cytotoxic Changes in ECV304 Cell Through Exposure to DMSO and Sodium Butyrate Using Impedance Spectroscopy

This paper decides an impedance spectroscopy measurement system for real-time monitoring of cellular toxicity. The system is used to compare the impedance response of ECV304 cells to two toxicants, dimethyl sulphoxide (DMSO) and sodium butyrate. The responses at different concentration of toxicants were plotted in 3-D impedance spectra and their correlation coefficients were calculated at four time points. Additionally, Phase contrast microscopy images were used to observe the effect of the two toxicants on the morphology change of the cells. The characteristic information of the spectra compared well with the morphological changes of cells, illustrating that the method is useful for monitoring cytotoxicity effects and cell viability.     

Real-time cell-impedance sensing assay as an alternative to clonogenic assay in evaluating cancer radiotherapy

Intrinsic radiosensitivity of normal and tumour tissues has been shown to be an independent prognostic factor for patients’ response to radiotherapy. This study compares the real-time cell-impedance sensing (RT-CES) assay with the conventional clonogenic assay in terms of in-vitro radiosensitivity. One objective in this study was to predict in-vivo response to gold nanoparticle (GNP) treatment on the basis of in-vitro RT-CES testing results. Four adenocarcinoma cancer cell lines were tested using both the RT-CES and the clonogenic assays. Cell-survival curves were plotted, and the mean SF2 values obtained by these two different assay methods were compared using ANOVA. Radiation sensitivities obtained in-vitro were then compared with the in-vivo results. On the basis of the measurement of cell colonies, the RT-CES assay has similar radiosensitivity to the clonogenic assay, but significantly shortens the testing time from 14–21 days to only 72 h. Intrinsic GNP enhanced radiation sensitivity using tumour volume (mm³) in vivo is comparable with that using RT-CES cell survival assay in vitro. Furthermore, the RT-CES system provides real-time information regarding the state of cell radiosensitivity that may give useful information towards personalizing radiotherapy. The RT-CES assay enables more reliable and time-efficient results in the evaluation of radiosensitivity.     

Synthesis and in vitro antitumor activity of 1,3,4-oxadiazole derivatives based on benzisoselenazolone

A series of novel 1,3,4-oxadiazole derivatives based on benzisoselenazolone has been prepared and tested for antiproliferative activity in vitro against the cells of human cancer cell lines: SSMC-7721 (human liver cancer cell), MCF-7 (human breast cancer cell) and A549 (human lung cancer cell). All the compounds obtained exhibited antiproliferative activity and showed selective cytotoxicity against different cancer cells. Compounds 7d and 7i showed significant antiproliferative activities against MCF-7 cells, with IC50 values of 1.07 and 1.76?μM respectively. Compound 7d were found to be the most potent compound against SSMC-7721 cells, with IC50 values 4.46?μM.     

Cytotoxicity of constituents from Mexican propolis against a panel of six different cancer cell lines

The cytotoxicity of 39 compounds, including eighteen flavonoids (flavanones, 1-10; flavones, 11-17; flavanol, 18), sixteen phenolic acid derivatives (aromatic acids, 19-24; aldehyde, 25; esters, 26-34) and five glycerides (35-39), isolated from Mexican propolis, were evaluated against a panel of six different cancer cell lines; murine colon 26-L5 carcinoma, murine B16-BL6 melanoma, murine Lewis lung carcinoma, human lung A549 adenocarcinoma, human cervix HeLa adenocarcinoma and human HT-1080 fibrosarcoma. A phenylpropanoid-substituted flavanol, (2R,3S)-8-[4-phenylprop-2-en-1-one]-4',7-dihydroxy-3',5-dimethoxyflavan-3-ol (18), showed the most potent cytotoxicity against A549 cells (IC50, 6.2 microM) and HT-1080 cells (IC50, 3.9 microM), stronger than those of the clinically used anticancer drug, 5-fluorouracil (IC50, 7.5 microM and 5.4 microM, respectively). Based on the observed results, the structure-activity relationships are discussed.     

SEM and ECIS Investigation of Cells Cultured on Nanopillar Modified Interdigitated Impedance Electrodes for Analysis of Cell Growth and Cytotoxicity of Potential Anticancer Drugs

Cell‐based biosensors treat living cells as sensing elements and are able to detect the functional information of biologically active analytes. Monitoring cytotoxicity with high sensitivity, rapidity and at low cost is of great interest in the fields of clinical diagnostics, environmental monitoring, food safety and security. This research investigates the behaviour of different cell types on nanostructured architectures. The development of cell‐based assays using bioimpedance devices has the potential of screening anti‐cancer drugs; these have a potential impact for developing new techniques and tools for the analysis of cells in the bio‐pharma industry. Gold impedance electrodes have been successfully fabricated for impedance measurement on cells cultured on the electrode surface which was modified with gold nanopillars with a height of 60 nm and 150 nm diameter in a highly ordered layout thanks to the e‐beam lithography technique. This article investigates the effects on the sensitivity achieved with the ECIS (Electric Cell‐substrate Impedance Spectroscopy) measurements while monitoring the cytotoxicity of two different drugs (Antrodia Camphorata extract and Nicotine) on different cell lines (HeLa, A549 and BALBc 3T3) cultured on the nanostructured devices. The change of morphology of cells growing on the nanostructured electrodes was also investigated through SEM imaging.     

Does cytotoxicity of metallointercalators correlate with cellular uptake or DNA affinity?

The cytotoxicity of the metallointercalators, [Pt(5,6-dimethyl-1,10-phenanthroline)(trans-1R,2R-diaminocyclohexane)](2+) ([56MERR]) and [Pt(5,6-dimethyl-1,10-phenanthroline)(trans-1S,2S-diaminocyclohexane)](2+) ([56MESS]), towards A549 human lung cancer cells was examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC(50) value obtained following exposure of A549 cells to [56MESS] for 4 h was approximately three times smaller than that obtained when [56MERR] was administered under the same conditions, indicating that the former complex displayed greater cytotoxicity. Both IC(50) values were greater than that obtained after exposure of A549 cells to cisplatin, demonstrating that the latter compound was the most cytotoxic of the three examined. Microprobe synchrotron radiation X-ray fluorescence (SR-XRF) analyses of metallointercalator-treated A549 cells showed that platinum became localised in DNA-rich regions of the nucleus. In contrast, when the same cells were treated with cisplatin the metal became distributed throughout the cell. Determination of the maximum concentration of platinum present inside the cells using graphite furnace atomic absorption spectrophotometry (GFAAS) of platinum-treated cells suggested that there was greater uptake of [56MERR] compared to [56MESS] by the A549 cells, and that platinum uptake did not account for the greater toxicity of [56MESS], as assessed by the MTT assay. Electrospray ionization mass spectrometric (ESI-MS) and circular dichroism (CD) spectroscopic studies of solutions containing either [56MERR] or [56MESS], and a duplex hexadecamer molecule, showed the two metallointercalators displayed very similar affinity towards the nucleic acid. Overall these results indicate that the difference in cytotoxicity of the two platinum metallointercalators is probably the result of variations in their interactions with other cellular components.     

On-chip anticancer drug test of regular tumor spheroids formed in microwells by a distributive microchannel network

This paper proposes a new cytotoxicity assay in a microfluidic device with microwells and a distributive microfluidic channel network for the formation of cancer cell spheroids. The assay can generate rapid and uniform cell clusters in microwells and test in situ cytotoxicity of anticancer drugs including sequential drug treatments, long term culture of spheroids and cell viability assays. Inlet ports are connected to the microwells by a hydraulic resistance network. This uniform distribution of cell suspensions results in regular spheroid dimensions. Injected cancer cells were trapped in microwells, and aggregated into tumor spheroids within 3 days. A cytotoxicity test of the spheroids in microwells was subsequently processed in the same device without the extraction of cells. The in situ cytotoxicity assay of tumor spheroids in microwells was comparable with the MTT assay on hanging drop spheroids using a conventional 96-well plate. It was observed that the inhibition rate of the spheroids was less than that in the 2D culture dish and the effect on tumor spheroids was different depending on the anticancer drug. This device could provide a convenient in situ assay tool to assess the cytotoxicity of anticancer drugs on tumor spheroids, offering more information than the conventional 2D culture plate.     

High-throughput quantitative analysis with cell growth kinetic curves for low copy number mutant cells

The mutation rate in cells induced by environmental genotoxic hazards is very low and difficult to detect using traditional cell counting assays. The established genetic toxicity tests currently recognized by regulatory authorities, such as conventional Ames and hypoxanthine guanine phosphoribosyl-transferase (HPRT) assays, are not well suited for higher-throughput screening as they require large amounts of test compounds and are very time consuming. In this study, we developed a novel cell-based assay for quantitative analysis of low numbers of cell copies with HPRT mutation induced by an environmental mutagen. The HPRT gene mutant cells induced by the mutagen were selected by 6-thioguanine (6-TG) and the cell’s kinetic growth curve monitored by a real-time cell electronic sensor (RT-CES) system. When a threshold is set at a certain cell index (CI) level, samples with different initial mutant cell copies take different amounts of time in order for their growth (or CI accumulation) to cross this threshold. The more cells that are initially seeded in the test well, the faster the cell accumulation and therefore the shorter the time required to cross this threshold. Therefore, the culture time period required to cross the threshold of each sample corresponds to the original number of cells in the sample. A mutant cell growth time threshold (MT) value of each sample can be calculated to predict the number of original mutant cells. For mutagenesis determination, the RT-CES assay displayed an equal sensitivity (p?>?0.05) and coefficients of variation values with good correlation to conventional HPRT mutagenic assays. Most importantly, the RT-CES mutation assay has a higher throughput than conventional cellular assays.

Synthesis and cytotoxic evaluation of novel N-methyl-4-phenoxypicolinamide derivatives

A series of N-methyl-4-phenoxypicolinamide derivatives were synthesized and evaluated in vitro for their cytotoxic activity against A549, H460 and HT29 cell lines. Pharmacological data indicated that some of the target compounds possessed marked antiproliferative activity, superior to that of the reference drug sorafenib. As the most promising compound, 8e exhibited potent cytotoxicity with the IC(50) value of 3.6, 1.7 and 3.0 μM against A549, H460 and HT-29 cell lines, respectively.     

Cytotoxicity of new 5-phenyl-4,5-dihydro-1,3,4-thiadiazole analogues

A series of 5-phenyl-4,5-dihydro-1,3,4-thiadiazoles were synthesized and their cytotoxicity was examined against four human cancer cell lines, e.g. lung cancer (A549), ovarian cancer (SK-OV-3), skin cancer (SK-MEL-2), and colon cancer (HCT15). The title compounds were synthesized by condensation of thiosemicarbazide with substituted benzaldehydes, followed by cyclization with acetic anhydrides in good yields. Most of the compounds exhibited significant suppressive activity against the growth of all of the cancer cell lines. The 4-hydroxy analogue of 5-phenyl-4,5-dihydro-1,3,4-thiadiazole (2h) was most active in the inhibition of growth of the SK-MEL-2 cell line, with an IC(50) value of 4.27 μg/ml; followed by compound 2a (IC(50) 5.16 μg/ml). The compounds 2j, 2h, and 2b, bearing 3-methoxy-4-hydroxy-, 4-hydroxy- and 4-methyl substituents in the C-5 phenyl ring respectively, exhibited the highest activity against the SK-OV-3 (IC(50) 7.35 μg/ml), HCT15 (IC(50) 8.25 μg/ml) and A549 (IC(50) 9.40 μg/ml) cell lines, respectively. A structure-activity relationship study revealed that an optimal electron density on the C-5 phenyl ring of 1,3,4-thiadiazoles is crucial for their cytotoxic activity against the human cancer cell lines used in the present study.     

Bioactive phenolic constituents from the seeds of Pharbitis nil

Two new lignans, termed pharsyringaresinol (1) and pharbilignoside (2), a new phenylethanoid glycoside, termed pharbiniloside (3), and 22 known compounds, were isolated from the ethanol extract of the seeds of Pharbitis nil. The structures of the new compounds (1-3) were determined on the basis of spectroscopic analyses, including 2D-NMR and circular dichroism (CD) spectroscopy studies. Among the isolates, compounds 2, 11, 12, and 24 exhibited significant cytotoxicity against human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15) with IC(50) values ranging from 8.07 to 28.30 μM. In addition, compounds 11, 12 and 24 potently inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-activated BV-2 cells, a microglia cells with IC(50) values ranging from 14.7 to 19.9 μM.     

Synthesis and evaluation of novel aza-caged Garcinia xanthones

Inspired by the therapeutic potential of the simplified caged xanthones, we have developed a chemical strategy for synthesizing novel aza-caged Garcinia analogues through a regioselective Claisen/Diels-Alder cascade reaction. The origin of regioselectivity has been explained using the DFT method. We have further evaluated the cell proliferation and IKKβ inhibitory activities of these compounds and studied their binding mode with IKKβ by molecular docking. The results suggested that the aza-caged scaffold provides a suitable modification site and the introduction of a hydrophobic moiety leads to improvement in the cytotoxicity and IKKβ inhibitory activity. The aza-caged compound 6c exhibited an IC(50) value of 2.68, 2.10, 8.02 μM against the HepG2, A549 cells and IKKβ, respectively. Mechanism studies with 6c showed that the aza-caged compounds induce apoptosis and cell cycle S phase arrest in A549 cells.     

Studies on the constituents of Cimicifuga foetida collected in Guizhou Province and their cytotoxic activities

Two new triterpenoids and a chromone glycoside, namely, 24-epi-cimigenol-3-one (1), foetinoside (2), cimifugin-4'-O-[6″-feruloyl]-β-D-glucopyranoside (3), together with 18 known compounds, were isolated from the rhizomes of Cimicifuga foetida L. collected in Guizhou Province, China. All of the compounds were identified by spectroscopic methods, as well as chemical methods. In the in vitro cytotoxicity evaluation of these compounds against 5 human cancer cell lines, cimigenol (8) exerted the most potent cytotoxic activity against SMMC-7721 (7.87?μM) and A-549 (12.16 μM), while cimiacerin B (9) also showed obvious cytotoxicity against the A-549 cell line, with an IC(50) value of 16.77?μM.     

Syntheses and Antiproliferative Activities of Novel Diarylthiosemicarbazide Derivatives

A series of novel N-methylpicolinamide-moiety containing diarylthiosemicarbazide derivatives was prepared and evaluated for their in vitro antiproliferative activity against three cancer cell lines(human alveolar epithelial cell A549, human lung cancer cell H460 and human colorectal cancer cell HT-29) by 3-(4,5-dimethyl)thiazolyl-diphenyltetrazoliumromide(MTT) assay. Six compounds(7b―7g) with halogen substituents exhibited preferable cytotoxicity against one or more cell lines in a low micromolar range. Especially, the most promising compound 7g exhibited remarkable antiproliferative activity with the IC50 values of 2.2, 1.8 and 5.2 μmol/L against A549, H460 and HT-29 cell lines respectively, which is comparable to sorafenib.     

Panduratin A inhibits the growth of A549 cells through induction of apoptosis and inhibition of NF-kappaB translocation

In the present study we investigated the effects of panduratin A, isolated from Boesenbergia rotunda, on proliferation and apoptosis in A549 human non-small cell lung cancer cells. Cell proliferation and induction of apoptosis was determined by the real-time cellular analyzer (RTCA), MTT assay and High Content Screening (HCS). The RTCA assay indicated that panduratin A exhibited cytotoxicity, with an IC?? value of 4.4 μg/mL (10.8 μM). Panduratin A arrested cancer cells labeled with bromodeoxyuridine (BrdU) and phospho-Histone H3 in the mitotic phase. The cytotoxic effects of panduratin A were found to be accompanied by a dose-dependent induction of apoptosis, as assessed by DNA condensation, nuclear morphology and intensity, cell permeability, mitochondrial mass/ potential, F-actin and cytochrome c. In addition, treatment with an apoptosis-inducing concentration of panduratin A resulted in significant inhibition of Nuclear Factor-kappa Beta (NF-κB) translocation from cytoplasm to nuclei activated by tumor necrosis factor-alpha (TNF-α), as illustrated by the HCS assay. Our study provides evidence for cell growth inhibition and induction of apoptosis by panduratin A in the A549 cell line, suggesting its therapeutic potential as an NF-κB inhibitor.     

High-throughput single-cell quantification using simple microwell-based cell docking and programmable time-course live-cell imaging

Extracting single-cell information during cellular responses to external signals in a high-throughput manner is an essential step for quantitative single-cell analyses. Here, we have developed a simple yet robust microfluidic platform for measuring time-course single-cell response on a large scale. Our method combines a simple microwell-based cell docking process inside a patterned microfluidic channel, with programmable time-course live-cell imaging and software-aided fluorescent image processing. The budding yeast, Saccharomyces cerevisiae (S. cerevisiae), cells were individually captured in microwells by multiple sweeping processes, in which a cell-containing solution plug was actively migrating back and forth several times by a finger-pressure induced receding meniscus. To optimize cell docking efficiency while minimizing unnecessary flooding in subsequent steps, circular microwells of various channel dimensions (4-24 μm diameter, 8 μm depth) along with different densities of cell solution (1.5-6.0 × 10(9) cells per mL) were tested. It was found that the microwells of 8 μm diameter and 8 μm depth allowed for an optimal docking efficiency (>90%) without notable flooding issues. For quantitative single-cell analysis, time-course (time interval 15 minute, for 2 hours) fluorescent images of the cells stimulated by mating pheromone were captured using computerized fluorescence microscope and the captured images were processed using a commercially available image processing software. Here, real-time cellular responses of the mating MAPK pathway were monitored at various concentrations (1 nM-100 μM) of mating pheromone at single-cell resolution, revealing that individual cells in the population showed non-uniform signaling response kinetics.