A novel assay for high-throughput screening of anti-Alzheimer's disease drugs to determine their efficacy by real-time monitoring of changes in PC12 cell proliferation

Natural products from Odontonema strictum promote neurite outgrowth in neuronal PC12 cells

The leaves of Odontonema strictum, a tropical plant used for its antihypertensive properties, are rich in nutrients and biologically active phytochemicals, such as β-sitosterol, stigmasterol, umuravumbolide, deacetylumuravumbolide, dideacetylboronolide, deacetylboronolide, verbascoside, and isoverbascoside. In addition, its roots are rich in β-sitosterol, stigmasterol, and the iridoid glycoside β-O-methyl-unedoside. Ingestion of the roots was reported to have a sedative effect in a dog was previously reported on a dog eating the roots of this plant. In the present study, we report for the first time the cell proliferation- and neurite outgrowth-promoting effects in PC12 neuronal cells of the isolated organic compounds and crude extracts from O. strictum. Pituitary adenylate cyclase-activating peptide (PACAP) and quercetin were used as positive controls. At the concentration of 0.2 μg/mL, β-sitosterol was more potent than quercetin and displayed the same activity (>45 μm/cell) as PACAP (100 nM). At a low concentration (0.04 μg/mL), verbascoside and isoverbascoside showed the strongest neurite outgrowth-promoting effect (neurite length of 30 to 35 μm/cell). Our results indicate that phytomedicines made from O. strictum may be useful in preventing neurodegenerative diseases.

Deciphering the multi-functional role of Indian propolis for the management of Alzheimer's disease by integrating LC-MS/MS, network pharmacology, molecular docking, and in-vitro studies

The conventional one-drug-one-disease theory has lost its sheen in multigenic diseases such as Alzheimer's disease (AD). Propolis, a honeybee-derived product has ethnopharmacological evidence of antioxidant, anti-inflammatory, antimicrobial and neuroprotective properties. However, the chemical composition is complex and highly variable geographically. So, to leverage the potential of propolis as an effective treatment modality, it is essential to understand the role of each phytochemical in the AD pathophysiology. Therefore, the present study was aimed at investigating the anti-Alzheimer effect of bioactive in Indian propolis (IP) by combining LC-MS/MS fingerprinting, with network-based analysis and experimental validation. First, phytoconstituents in IP extract were identified using an in-house LC-MS/MS method. The drug likeness and toxicity were assessed, followed by identification of AD targets. The constituent-target-gene network was then constructed along with protein-protein interactions, gene pathway, ontology, and enrichment analysis. LC-MS/MS analysis identified 16 known metabolites with druggable properties except for luteolin-5-methyl ether. The network pharmacology-based analysis revealed that the hit propolis constituents were majorly flavonoids, whereas the main AD-associated targets were MAOB, ESR1, BACE1, AChE, CDK5, GSK3β, and PTGS2. A total of 18 gene pathways were identified to be associated, with the pathways related to AD among the topmost enriched. Molecular docking analysis against top AD targets resulted in suitable binding interactions at the active site of target proteins. Further, the protective role of IP in AD was confirmed with cell-line studies on PC-12, in situ AChE inhibition, and antioxidant assays.

Anti-Amyloid Drug Screening Methods Using Bacterial Inclusion Bodies

Amyloid aggregation is linked to a number of human disorders that range from non-neurological illnesses such as type 2 diabetes to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. The formation of insoluble protein aggregates with amyloid conformation inside bacteria, namely, in bacterial inclusion bodies, offers the possibility to use bacteria as simple models to study amyloid aggregation processes and potential effects of both anti-amyloid drugs and/or pro-aggregative compounds. This chapter describes fast, simple, inexpensive, highly reproducible, and tunable in vitro and in cellulo methods that use bacterial inclusion bodies as preliminary screening tools for anti-amyloid drugs.

The effect of surface modification of TiMg composite on the in-vitro degradation response, cell survival, adhesion, and proliferation

This study is aimed to evaluate the influence of mechanical surface treatment on the degradation response, cell survival, adhesion, and proliferation of a TiMg composite material. Two sets of the TiMg samples with different surface characteristics were studied: i) as-machined samples (TiMg-T) and ii) samples with a mechanically modified surface (TiMg-P). Surface roughness was determined using a confocal microscope. Degradation rates (DR) were evaluated in artificial Plasma, HBSS, and NaCl 0.9%. The cell viability was evaluated using an MTT assay. The initial cell adhesion and spreading were investigated using the direct contact assay. An xCELLigence system was employed to provide real-time cell proliferation. The focal adhesion and cell morphological changes were also examined. The DR of TiMg-P decreased by ⁓5 times compared with that of TiMg-T. Surface of the TiMg-P specimens after 72 h exposure to either HBSS or Plasma was passivated by a layer enriched with bioactive Ca/P species. The cell viability of L929 and Saos-2 after 72 h incubation for TiMg-P was 94.6% and 94.8% compared with 73.8% and 74.3% obtained for TiMg-T, respectively. The direct contact assay showed that the initial adhesion and spreading of the L929 cells incubated with TiMg-P was more pronounced compared with that of TiMg-T. The proliferation rate of Saos-2 cells incubated with TiMg-P was higher when compared with that of TiMg-T, and was almost comparable to that of the DMEM-blank between the 24 and 72 h interval. TiMg-P had a pronounced difference in the number and area of Focal Adhesions (FA) compared with that of TiMg-T. The morphology of cells incubated with TiMg-P was not altered. The results confirmed that the smooth and less strained surface of the TiMg-P samples effectively improved the in-vitro degradation response, cell survival, adhesion, and proliferation.

Analyzing Olfactory Neuron Precursors Non-Invasively Isolated through NADH FLIM as a Potential Tool to Study Oxidative Stress in Alzheimer's Disease

Among all the proposed pathogenic mechanisms to understand the etiology of Alzheimer’s disease (AD), increased oxidative stress seems to be a robust and early disease feature where many of those hypotheses converge. However, despite the significant lines of evidence accumulated, an effective diagnosis and treatment of AD are not yet available. This limitation might be partially explained by the use of cellular and animal models that recapitulate partial aspects of the disease and do not account for the particular biology of patients. As such, cultures of patient-derived cells of peripheral origin may provide a convenient solution for this problem. Peripheral cells of neuronal lineage such as olfactory neuronal precursors (ONPs) can be easily cultured through non-invasive isolation, reproducing AD-related oxidative stress. Interestingly, the autofluorescence of key metabolic cofactors such as reduced nicotinamide adenine dinucleotide (NADH) can be highly correlated with the oxidative state and antioxidant capacity of cells in a non-destructive and label-free manner. In particular, imaging NADH through fluorescence lifetime imaging microscopy (FLIM) has greatly improved the sensitivity in detecting oxidative shifts with minimal intervention to cell physiology. Here, we discuss the translational potential of analyzing patient-derived ONPs non-invasively isolated through NADH FLIM to reveal AD-related oxidative stress. We believe this approach may potentially accelerate the discovery of effective antioxidant therapies and contribute to early diagnosis and personalized monitoring of this devastating disease.

Application of xCELLigence real-time cell analysis to the microplate assay for pertussis toxin induced clustering in CHO cells

The microplate assay with Chinese Hamster Ovary (CHO) cells is currently used as a safety test to monitor the residual pertussis toxin (PT) amount in acellular pertussis antigens prior to vaccine formulation. The assay is based on the findings that the exposure of CHO cells to PT results in a concentration-dependent clustering response which can be used to estimate the amount of PT in a sample preparation. A major challenge with the current CHO cell assay methodology is that scoring of PT-induced clustering is dependent on subjective operator visual assessment using light microscopy. In this work, we have explored the feasibility of replacing the microscopy readout for the CHO cell assay with the xCELLigence Real-Time Cell Analysis system (ACEA BioSciences, a part of Agilent). The xCELLigence equipment is designed to monitor cell adhesion and growth. The electrical impedance generated from cell attachment and proliferation is quantified via gold electrodes at the bottom of the cell culture plate wells, which is then translated into a unitless readout called cell index. Results showed significant decrease in the cell index readouts of CHO cells exposed to PT compared to the cell index of unexposed CHO cells. Similar endpoint concentrations were obtained when the PT reference standard was titrated with either xCELLigence or microscopy. Testing genetically detoxified pertussis samples unspiked or spiked with PT further supported the sensitivity and reproducibility of the xCELLigence assay in comparison with the conventional microscopy assay. In conclusion, the xCELLigence RTCA system offers an alternative automated and higher throughput method for evaluating PT-induced clustering in CHO cells.

In vitro biological activity of Salvia fruticosa Mill. infusion against amyloid β-peptide-induced toxicity and inhibition of GSK-3β, CK-1δ, and BACE-1 enzymes relevant to Alzheimer's disease

Salvia species have been traditionally used to improve cognition and have been proved to be a potential natural treatment for Alzheimer’s disease. Salvia fruticosa Mill. (Turkish sage or Greek sage) demonstrated to have anticholinergic effects in vitro.

The aim of this study was to understand the mechanism underlying the neuroprotective effects of S. fruticosa infusion and its representative compound rosmarinic acid, which was detected by LC-DAD-ESI-MS/MS. The protective effects of the S. fruticosa infusion (SFINF) and its major substance rosmarinic acid (RA) on amyloid beta 1–42 -induced cytotoxicity on SH-SY5Y cells together with p-GSK-3β activation were investigated. Their in vitro inhibitory effects against glycogen synthase kinase 3β, β-secretase, and casein kinase 1δ enzymes were also evaluated.

The results showed that treatment with the all tested concentrations, SFINF significantly decreased Aβ 1–42-induced cytotoxicity and exhibited promising in vitro glycogen synthase kinase 3β inhibitory activity below 10 µg/mL (IC₅₀ 6.52 ± 1.14 µg/mL), in addition to β-secretase inhibition (IC₅₀ 86 ± 2.9 µg/mL) and casein kinase 1δ inhibition (IC₅₀ 121.57 ± 4.00). The SFINF (100 µg/mL and 250 µg/mL) also activated the expression of p-GSK-3β in amyloid beta 1–42 treated SH-SY5Y cells.

The outcomes of this study demonstrated that the S. fruticosa infusion possessed activity to prevent amyloid beta 1–42 -induced neurotoxicity and provided proof that its mechanism may involve regulation of p-GSK-3β protein.

Cyanidin-3-O-glucoside inhibits Aβ40 fibrillogenesis, disintegrates preformed fibrils, and reduces amyloid cytotoxicity

Alzheimer's disease (AD) is mainly caused by the fibrillogenesis of amyloid-β protein (Aβ). Therefore, the development of effective inhibitors against Aβ fibrillogenesis offers great hope for the treatment of AD. Cyanidin-3-O-glucoside (Cy-3G) is a commonly found anthocyanin that is mainly present in fruits, with established neuroprotective effects in situ. However, it remains unknown if Cy-3G can prevent Aβ fibrillogenesis and alleviate the corresponding cytotoxicity. In this study, extensive biochemical, biophysical, biological and computational experiments were combined to address this issue. It was found that Cy-3G significantly inhibits Aβ40 fibrillogenesis and disintegrates mature Aβ fibrils, and its inhibitory capacity is dependent on the Cy-3G concentration. The circular dichroism results showed that Cy-3G and Aβ40 at a molar ratio of 3 : 1 slightly prevents the structural transformation of Aβ40 from its initial random coil to the β-sheet-rich structure. Co-incubation of Aβ40 with Cy-3G significantly reduced the production of intracellular reactive oxygen species induced by Aβ40 fibrillogenesis and thus reduced Aβ40-induced cytotoxicity. Molecular dynamics simulations revealed that Cy-3G disrupted the β-sheet structure of the Aβ40 trimer. Cy-3G was found to mainly interact with the N-terminal region, the central hydrophobic cluster and the β-sheet region II via hydrophobic and electrostatic interactions. The ten hot spot residues D7, Y10, E11, F19, F20, E22, I31, I32, M35 and V40 were also identified. These findings not only enable a comprehensive understanding of the inhibitory effect of Cy-3G on Aβ40 fibrillogenesis, but also allow the identification of a valuable dietary ingredient that possesses great potential to be developed into functional foods to alleviate AD.

Development of a PC12 Cell Based Assay for Screening Catechol-O-methyltransferase Inhibitors

The male rat adrenal pheochromocytoma cell-derived PC12 cell line can synthesize and release catecholamine neurotransmitters, and it has been widely used as a model system in cell biology and toxicology research. Catechol-O-methyltransferase (COMT) is involved in the inactivation of the catecholamine neurotransmitters, and it is particularly important for the regulation of dopamine. In this study, we explored the feasibility of using PC12 cells as an in vitro drug screening platform to compare the activity of multiple COMT inhibitors. Incubation of PC12 cells with tolcapone, a highly potent and selective COMT inhibitor, increased the concentrations of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) while reducing the metabolites 3-methoxytyramine (3-MT) and homovanillic acid (HVA) in the cell culture medium. LIBD-3, a novel, non-nitrocatechol COMT inhibitor, produced similar effects compared to tolcapone. LIBD-4, a less potent inhibitor, exhibited the expected right-shift in functional inhibition in the assay. These results match the known in vivo effects of COMT inhibition in rodents. Together, these data support the continued use of PC12 cells as an in vitro screen that bridges cell-free enzyme assays and more costly in vivo assays.

Bacterial Inclusion Bodies for Anti-Amyloid Drug Discovery: Current and Future Screening Methods

Amyloid aggregation is linked to an increasing number of human disorders from nonneurological pathologies such as type-2 diabetes to neurodegenerative ones such as Alzheimer or Parkinson's diseases. Thirty-six human proteins have shown the capacity to aggregate into pathological amyloid structures. To date, it is widely accepted that amyloid folding/aggregation is a universal process present in eukaryotic and prokaryotic cells. In the last decade, several studies have unequivocally demonstrated that bacterial inclusion bodies - insoluble protein aggregates usually formed during heterologous protein overexpression in bacteria - are mainly composed of overexpressed proteins in amyloid conformation. This fact shows that amyloid-prone proteins display a similar aggregation propensity in humans and bacteria, opening the possibility to use bacteria as simple models to study amyloid aggregation process and the potential effect of both anti-amyloid drugs and pro-aggregative compounds. Under these considerations, several in vitro and in cellulo methods, which exploit the amyloid properties of bacterial inclusion bodies, have been proposed in the last few years. Since these new methods are fast, simple, inexpensive, highly reproducible, and tunable, they have aroused great interest as preliminary screening tools in the search for anti-amyloid (beta-blocker) drugs for conformational diseases. The aim of this mini-review is to compile recently developed methods aimed at tracking amyloid aggregation in bacteria, discussing their advantages and limitations, and the future potential applications of inclusion bodies in anti-amyloid drug discovery.

Low-molecular-weight chondroitin sulfate attenuated injury by inhibiting oxidative stress in amyloid β-treated SH-SY5Y cells

The neurotoxicity of aggregated amyloid β (Aβ) has been implicated as a critical cause in the pathogenesis of Alzheimer's disease. In a previous work, we have shown that low-molecular-weight chondroitin sulfate (LMWCS), a derivative of chondroitin sulfate, protected the SH-SY5Y neuroblastoma cells from Aβ25-35-induced neurotoxicity, decreased intracellular reactive oxygen species level and inhibited the cell apoptosis. However, the underlying mechanism of the antioxidative effect of LMWCS in the SH-SY5Y cells has not been well explored. In the present study, the SH-SY5Y cells were cultured and exposed to 30 μM Aβ25-35 in the absence or presence of LMWCS (50, 100 and 200 μg/ml). Results indicate that incubation of cells with LMWCS before Aβ25-35 exposure increased superoxide dismutase, glutathione peroxidase and Na/K-ATPase activities and decreased the malondialdehyde content. In addition, LMWCS inhibited the imbalance of Bcl-2 and Bax and decreased caspase-3 and caspase-9 expressions. LMWCS antagonizes Aβ25-35-induced neurotoxicity by attenuating oxidative stress, and our results suggest that LMWCS might be used as a potential compound for Alzheimer's disease prevention.

Lycium barbarum polysaccharide encapsulated Poly lactic-co-glycolic acid Nanofibers: cost effective herbal medicine for potential application in peripheral nerve tissue engineering

Nerve regeneration is a serious clinical challenge following peripheral nerve injury. Lycium barbarum polysaccharide (LBP) is the major component of wolfberry extract, which has been shown to be neuroprotective and promising in nerve recovery in many studies. Electrospun nanofibers, especially core-shell structured nanofibers being capable of serving as both drug delivery system and tissue engineering scaffolds, are well known to be suitable scaffolds for regeneration of peripheral nerve applications. In this study, LBP was incorporated into core-shell structured nanofibrous scaffolds via coaxial electrospinning. Alamar blue assays were performed to investigate the proliferation of both PC12 and Schwann cells cultured on the scaffolds. The neuronal differentiation of PC12 cells was evaluated by NF200 expression with immunostaining and morphology changes observed by SEM. The results indicated that the released LBP dramatically enhanced both proliferation and neuronal differentiation of PC12 cells induced by NGF. Additionally, the promotion of Schwann cells myelination and neurite outgrowth of DRG neurons were also observed on LBP loaded scaffolds by LSCM with immunostaining. In summary, LBP, as a drug with neuroprotection, encapsulated into electrospun nanofibers could be a potential candidate as tissue engineered scaffold for peripheral nerve regeneration.

Bushen-Yizhi formula ameliorates cognitive dysfunction through SIRT1/ER stress pathway in SAMP8 mice

The Chinese formula Bushen-Yizhi (BSYZ) has been reported to ameliorate cognitive dysfunction. However the mechanism is still unclear. In this study, we employ an aging model, SAMP8 mice, to explore whether BSYZ could protect dementia through SIRT1/endoplasmic reticulum (ER) stress pathway. Morris water maze and the fearing condition test results show that oral administration of BSYZ (1.46 g/kg/d, 2.92 g/kg/d and 5.84 g/kg/d) and donepezil (3 mg/kg/d) shorten the escape latency, increase the crossing times of the original position of the platform and the time spent in the target quadrant, and increase the freezing time. BSYZ decreases the activity of acetylcholinesterase (AChE), and increases the activity of choline acetyltransferase (ChAT) and the concentration of acetylcholine (Ach) in both hippocampus and cortex. In addition, western blot results (Bcl-2, Bax and Caspase-3) and TUNEL staining show that BSYZ prevents neuron from apoptosis, and elevates the expression of neurotrophic factors, including nerve growth factor (NGF), postsynapticdensity 95 (PSD95) and synaptophysin (SYN), in both hippocampus and cortex. BSYZ also increases the protein expression of SIRT1 and alleviates ER stress-associated proteins (PERK, IRE-1α, eIF-2α, BIP, PDI and CHOP). These results indicate that the neuroprotective mechanism of BSYZ might be related with SIRT1/ER stress pathway.

The Mechanisms of Bushen-Yizhi Formula as a Therapeutic Agent against Alzheimer's Disease

Bushen-Yizhi prescription (BSYZ) has been an effective traditional Chinese medicine (TCM) prescription in treating Alzheimer’s disease (AD) for hundreds of years. However, the underlying mechanisms have not been fully elucidated yet. In this work, a systems pharmacology approach was developed to reveal the underlying molecular mechanisms of BSYZ in treating AD. First, we obtained 329 candidate compounds of BSYZ by in silico ADME/T filter analysis and 138 AD-related targets were predicted by our in-house WEGA algorithm via mapping predicted targets into AD-related proteins. In addition, we elucidated the mechanisms of BSYZ action on AD through multiple network analysis, including compound-target network analysis and target-function network analysis. Furthermore, several modules regulated by BSYZ were incorporated into AD-related pathways to uncover the therapeutic mechanisms of this prescription in AD treatment. Finally, further verification experiments also demonstrated the therapeutic effects of BSYZ on cognitive dysfunction in APP/PS1 mice, which was possibly via regulating amyloid-β metabolism and suppressing neuronal apoptosis. In conclusion, we provide an integrative systems pharmacology approach to illustrate the underlying therapeutic mechanisms of BSYZ formula action on AD.

Protective Role Of Naringenin Against Aβ25-35-Caused Damage via ER and PI3K/Akt-Mediated Pathways

Senile plaque accumulation and neurofibrillary tangles are primary characteristics of Alzheimer's disease. We aimed to assess the protective functions of naringenin against β-amyloid protein fragment 25-35 (Aβ_25-35)-caused nerve damage in differentiated PC12 cells, and study the potential mechanisms. We evaluated cell viability and apoptosis using the 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) test and flow cytometry, respectively. Moreover, we measured protein kinase B (Akt), glycogen synthase kinase-3β (GSK-3β), and caspase-3 activity via western blotting and RT-PCR. We found that naringenin protected cell against Aβ_25-35-caused nerve damage by increasing cell viability, promoting Akt and GSK3β activation, and inhibiting cell apoptosis and caspase-3 activity. However, treatment with the estrogen receptor (ER) antagonist ICI182, 780 or phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 suppressed the effects of naringenin. Our results suggested that naringenin could effectively suppress Aβ_25-35-caused nerve damage in PC12 cells by regulating the ER and PI3K/Akt pathways.

Combined in Vitro Cell-Based/in Silico Screening of Naturally Occurring Flavonoids and Phenolic Compounds as Potential Anti-Alzheimer Drugs

Alzheimer's disease (AD) is the main cause of dementia in people over 65 years. One of the major culprits in AD is the self-aggregation of amyloid-β peptide (Aβ), which has stimulated the search for small molecules able to inhibit Aβ aggregation. In this context, we recently reported a simple, but effective in vitro cell-based assay to evaluate the potential antiaggregation activity of putative Aβ aggregation inhibitors. In this work this assay was used together with docking and molecular dynamics simulations to analyze the anti-Aβ aggregation activity of several naturally occurring flavonoids and phenolic compounds. The results showed that rosmarinic acid, melatonin, and o-vanillin displayed zero or low inhibitory capacity, curcumin was found to have an intermediate inhibitory potency, and apigenin and quercetin showed potent antiaggregation activity. Finally, the suitability of the combined in vitro cell-based/in silico approach to distinguish between active and inactive compounds was further assessed for an additional set of flavonols and dihydroflavonols.

Effects of cell seeding density on real-time monitoring of anti-proliferative effects of transient gene silencing

Background

Real-time cellular analysis systems enable impedance-based label-free and dynamic monitoring of various cellular events such as proliferation. In this study, we describe the effects of initial cell seeding density on the anti-proliferative effects of transient gene silencing monitored via real-time cellular analysis. We monitored the real-time changes in proliferation of Huh7 hepatocellular carcinoma and A7r5 vascular smooth muscle cells with different initial seeding densities following transient receptor potential canonical 1 (TRPC1) silencing using xCELLigence system. Huh7 and A7r5 cells were seeded on E-plate 96 at 10,000, 5000, 1250 and 5000, 2500 cells well⁻¹, respectively, following silencing vector transfection. The inhibitory effects of transient silencing on cell proliferation monitored every 30 min for 72 h.

Results

TRPC1 silencing did not inhibit the proliferation rates of Huh7 cells at 10,000 cells well⁻¹ seeding density. However, a significant anti-proliferative effect was observed at 1250 cells well⁻¹ density at each time point throughout 72 h. Furthermore, significant inhibitory effects on A7r5 proliferation were observed at both 5000 and 2500 cells well⁻¹ for 72 h.

Conclusions

Data suggest that the effects of transient silencing on cell proliferation differ depending on the initial cell seeding density. While high seeding densities mask the significant changes in proliferation, the inhibitory effects of silencing become apparent at lower seeding densities as the entry into log phase is delayed. Using the optimal initial seeding density is crucial when studying the effects of transient gene silencing. In addition, the results suggest that TRPC1 may contribute to proliferation and phenotypic switching of vascular smooth muscle cells.

In vitro acute and developmental neurotoxicity screening: an overview of cellular platforms and high-throughput technical possibilities

Neurotoxicity and developmental neurotoxicity are important issues of chemical hazard assessment. Since the interpretation of animal data and their extrapolation to man is challenging, and the amount of substances with information gaps exceeds present animal testing capacities, there is a big demand for in vitro tests to provide initial information and to prioritize for further evaluation. During the last decade, many in vitro tests emerged. These are based on animal cells, human tumour cell lines, primary cells, immortalized cell lines, embryonic stem cells, or induced pluripotent stem cells. They differ in their read-outs and range from simple viability assays to complex functional endpoints such as neural crest cell migration. Monitoring of toxicological effects on differentiation often requires multiomics approaches, while the acute disturbance of neuronal functions may be analysed by assessing electrophysiological features. Extrapolation from in vitro data to humans requires a deep understanding of the test system biology, of the endpoints used, and of the applicability domains of the tests. Moreover, it is important that these be combined in the right way to assess toxicity. Therefore, knowledge on the advantages and disadvantages of all cellular platforms, endpoints, and analytical methods is essential when establishing in vitro test systems for different aspects of neurotoxicity. The elements of a test, and their evaluation, are discussed here in the context of comprehensive prediction of potential hazardous effects of a compound. We summarize the main cellular characteristics underlying neurotoxicity, present an overview of cellular platforms and read-out combinations assessing distinct parts of acute and developmental neurotoxicology, and highlight especially the use of stem cell-based test systems to close gaps in the available battery of tests.

Ultra rapid in vivo screening for anti-Alzheimer anti-amyloid drugs

More than 46 million people worldwide suffer from Alzheimer’s disease. A large number of potential treatments have been proposed; among these, the inhibition of the aggregation of amyloid β-peptide (Aβ), considered one of the main culprits in Alzheimer’s disease. Limitations in monitoring the aggregation of Aβ in cells and tissues restrict the screening of anti-amyloid drugs to in vitro studies in most cases. We have developed a simple but powerful method to track Aβ aggregation in vivo in real-time, using bacteria as in vivo amyloid reservoir. We use the specific amyloid dye Thioflavin-S (Th-S) to stain bacterial inclusion bodies (IBs), in this case mainly formed of Aβ in amyloid conformation. Th-S binding to amyloids leads to an increment of fluorescence that can be monitored. The quantification of the Th-S fluorescence along the time allows tracking Aβ aggregation and the effect of potential anti-aggregating agents.

Brain Aggregates: An Effective In Vitro Cell Culture System Modeling Neurodegenerative Diseases

Drug discovery for neurodegenerative diseases is particularly challenging because of the discrepancies in drug effects between in vitro and in vivo studies. These discrepancies occur in part because current cell culture systems used for drug screening have many limitations. First, few cell culture systems accurately model human aging or neurodegenerative diseases. Second, drug efficacy may differ between dividing and stationary cells, the latter resembling nondividing neurons in the CNS. Brain aggregates (BrnAggs) derived from embryonic day 15 gestation mouse embryos may represent neuropathogenic processes in prion disease and reflect in vivo drug efficacy. Here, we report a new method for the production of BrnAggs suitable for drug screening and suggest that BrnAggs can model additional neurological diseases such as tauopathies. We also report a functional assay with BrnAggs by measuring electrophysiological activities. Our data suggest that BrnAggs could serve as an effective in vitro cell culture system for drug discovery for neurodegenerative diseases.

Alleviating effects of Bushen-Yizhi formula on ibotenic acid-induced cholinergic impairments in rat

This study explored the curative effect and underlying mechanisms of a traditional Chinese medicine compound prescription, Bushen-Yizhi formula (BSYZ), in ibotenic acid (IBO)-induced rats. Morris water maze and novel object recognition tests showed that BSYZ significantly improved spatial and object memory. Brain immunohistochemistry staining showed that BSYZ significantly up-regulated expression of choline acetyltransferase (ChAT) and nerve growth factor (NGF) in the hippocampus and cortex. The protein tyrosine kinase high-affinity receptor TrkA was slightly increased in the hippocampus and cortex, and significantly enhanced in the nucleus basalis of Meynert (NBM) after BSYZ intervention. The immunoreactivity of the p75 low-affinity receptor in BSYZ-treated rats was significantly strengthened in the cortex. Similar expression trends of nerve growth factor (NGF), TrkA, and p75 mRNA were observed in the hippocampus and cortex. Additionally, BSYZ reversed IBO-induced disorders of acetylcholine (ACh) levels, ChAT, and cholinesterase (ChE) in the cortex, which was consistent with the changes in mRNA levels of ChAT and acetylcholinesterase (AChE). Expression of ChAT and AChE proteins and mRNA in the hippocampus was up-regulated, whereas the apoptosis-relative protein cleaved caspase-3 was decreased after administration of BSYZ. Moreover, changes in cell death were confirmed by histological morphology. Thus, the results indicated that the BSYZ formula could ameliorate memory impairments in IBO-induced rats, and it exerted its therapeutic action probably by modulating cholinergic pathways, NGF signaling, and anti-apoptosis. Overall, it is suggested that the BSYZ formula might be a potential therapeutic approach for the treatment of Alzheimer's disease (AD) and other cholinergic impairment-related diseases.

Novel screening techniques for ion channel targeting drugs

Ion channels are integral membrane proteins that regulate the flux of ions across the cell membrane. They are involved in nearly all physiological processes, and malfunction of ion channels has been linked to many diseases. Until recently, high-throughput screening of ion channels was limited to indirect, e.g. fluorescence-based, readout technologies. In the past years, direct label-free biophysical readout technologies by means of electrophysiology have been developed. Planar patch-clamp electrophysiology provides a direct functional label-free readout of ion channel function in medium to high throughput. Further electrophysiology features, including temperature control and higher-throughput instruments, are continually being developed. Electrophysiological screening in a 384-well format has recently become possible. Advances in chip and microfluidic design, as well as in cell preparation and handling, have allowed challenging cell types to be studied by automated patch clamp. Assays measuring action potentials in stem cell-derived cardiomyocytes, relevant for cardiac safety screening, and neuronal cells, as well as a large number of different ion channels, including fast ligand-gated ion channels, have successfully been established by automated patch clamp. Impedance and multi-electrode array measurements are particularly suitable for studying cardiomyocytes and neuronal cells within their physiological network, and to address more complex physiological questions. This article discusses recent advances in electrophysiological technologies available for screening ion channel function and regulation.

Real-time cell analysis of the inhibitory effect of vitamin K2 on adhesion and proliferation of breast cancer cells

Breast cancer is the most prevalent cancer type worldwide. Continued efforts to improve treatment strategies for patients with breast cancer will be instrumental in reducing the death rates associated with this disease. In particular, the triple-negative breast cancer subtype of breast cancer has no targeted therapy available so it is essential to continue to work on any potential therapies. Vitamin K (VK) is known for its essential role in the clotting cascade. The antitumor properties of VK derivatives have been reported in both hepatocellular carcinoma and glioblastoma. Our hypothesis was that menaquinone-4, the most common form of vitamin K2 (VK2), is an effective anticancer agent against breast cancer cell types. In this study, we used a novel impedance-based live cell monitoring platform (xCELLigence) to determine the effects of VK derivatives on the triple-negative breast cancer cell line, MDA-MB-231, and the HER2+ breast cancer cell line, MDA-MB-453. Cells were treated with varying concentrations of menaquinone-4 (VK2) previously reported to have an antiproliferative effect on human glioblastoma cells. After initial testing, these concentrations were adjusted to 100, 125, and 150 μmol/L. A significant dose-dependent, growth inhibitory effect was found when cells were treated at these concentrations. These effects were seen in both adhesion and proliferation phases and show a dramatic reduction in cell growth. Additional analysis of MDA-MB-231 cells treated with VK2 (100 μmol/L) in combination with a low-glucose nutrient media showed a further decrease in adhesion and viability. This is the first study of its kind showing the real-time effects of VK derivatives on breast cancer cells and suggests that dietary factors may be an important consideration for patients.

Using real-time impedance-based assays to monitor the effects of fibroblast-derived media on the adhesion, proliferation, migration and invasion of colon cancer cells

Increasing our knowledge of the mechanisms regulating cell proliferation, migration and invasion are central to understanding tumour progression and metastasis. The local tumour microenvironment contributes to the transformed phenotype in cancer by providing specific environmental cues that alter the cells behaviour and promotes metastasis. Fibroblasts have a strong association with cancer and in recent times there has been some emphasis in designing novel therapeutic strategies that alter fibroblast behaviour in the tumour microenvironment. Fibroblasts produce growth factors, chemokines and many of the proteins laid down in the ECM (extracellular matrix) that promote angiogenesis, inflammation and tumour progression. In this study, we use a label-free RTCA (real-time cell analysis) platform (xCELLigence) to investigate how media derived from human fibroblasts alters cancer cell behaviour. We used a series of complimentary and novel experimental approaches to show HCT116 cells adhere, proliferate and migrate significantly faster in the presence of media from human fibroblasts. As well as this, we used the xCELLigence CIM-plates system to show that HCT116 cells invade matrigel layers aggressively when migrating towards media derived from human fibroblasts. These data strongly suggest that fibroblasts have the ability to increase the migratory and invasive properties of HCT116 cells. This is the first study that provides real-time data on fibroblast-mediated migration and invasion kinetics of colon cancer cells.