Plasma 6ß-hydroxycortisol to cortisol ratio as a less invasive cytochrome P450 3A phenotyping method.

AIM: A less invasive evaluation method of cytochrome P450 3A (CYP3A) activity provides an important tool for personalized medicine. We aimed to clarify the usefulness of the plasma 6ß-hydroxycortisol to cortisol concentration (6ß-OHF/F) ratio as a minimally invasive CYP3A phenotyping method. METHODS: Plasma 6ß-OHF and cortisol concentrations were measured via liquid chromatography/tandem mass spectrometry. The plasma 6ß-OHF/F ratio was compared with 6ß-hydroxylation clearance of endogenous cortisol (CLm(6ß); which we previously developed as an index of CYP3A activity) before, during and after oral contraceptive administration in 3 healthy women. The plasma 6ß-OHF/F ratio was observed during oral clarithromycin administration. The plasma 6ß-OHF/F ratio was also measured in 39 healthy participants. RESULTS: The plasma 6ß-OHF/F ratio in 3 healthy women on Day 21 of starting oral contraceptive administration decreased by 39, 49 and 61% compared with Day 0. These values were similar to CLm(6ß) values (43, 54 and 59%, respectively). Plasma 6ß-OHF/F ratio and CLm(6ß) exhibited a good correlation (r = .9053). The 6ß-OHF/F ratio decreased from 0.00921 to 0.00577 only 3 h following clarithromycin administration. The plasma 6ß-OHF/F ratio ranged 0.00565-0.01556 in 39 healthy participants. CONCLUSION: Based on its close relationship with CLm(6ß) and its decrease upon inhibition by clarithromycin, the plasma 6ß-OHF/F ratio serves as an index of CYP3A activity. Using this minimally invasive index, we can identify patients with extremely low CYP3A activity before treatment initiation and optimize the initial drug dose, thereby mitigating the risk of severe adverse reactions.

Calculation of Human Melatonin Partial Metabolic Clearance in Healthy Adult Volunteers for Investigation of a Novel in Vivo CYP1A2 Phenotyping Method: A Pilot Study.

The method of administering caffeine as a probe to evaluate the phenotypic activity of the CYP1A2, has not yet been applied clinically. In contrast, if endogenous melatonin (MEL) metabolism can be used to assess CYP1A2 activity, it could be a simple method that does not require substance administration. The study aim was to calculate the MEL partial metabolic clearance (CLm(MEL)) from plasma MEL and its urinary metabolites and to test the potential of this approach as a novel CYP1A2 phenotyping method. Nine subjects were included in the study; 3 had 6 blood and 4 urine samples collected between 10:00 and 18:00 (collectively, the intraday sample). Nine subjects had 3 blood samples and 2-h urine samples collected between 10:00 and 12:00 once a week for 3 weeks (interday sample). The CLm(MEL) was calculated from the plasma area under the curve (AUC) of MEL (AUCMEL) and urinary MEL metabolites excretion (X6MEL). Among the intraday samples, the AUCMEL ranged from 6.45-13.17 pmol·h/L and X6MEL ranged from 0.204-0.899 nmol/2 h, showing a decrease in concentration over time. In contrast, the CLm(MEL) ranged from 30.52-69.57 L/h (within-individual percent relative standard deviation: 9.2-20.1%), showing no time-dependent variation. Large interindividual variability was observed in AUCMEL and X6MEL in the interday sample, but CLm(MEL) showed small interindividual variabilities. The CLm(MEL) was 1.8-fold higher for smokers than for nonsmokers. The results obtained in this study may be valuable in future studies of evaluating novel CYP1A2 phenotyping method.

Conserved lysine residues in decorin binding proteins of Borrelia garinii are critical in adhesion to human brain microvascular endothelial cells.

Lyme borreliosis is a tick-borne disease caused by Borrelia burgdorferi sensu lato spirochetes (Lyme borreliae). When the disease affects the central nervous system, it is referred to as neuroborreliosis. In Europe, neuroborreliosis is most often caused by Borrelia garinii. Although it is known that in the host Lyme borreliae spread from the tick bite site to distant tissues via the blood vasculature, the adherence of Lyme borreliae to human brain microvascular endothelial cells has not been studied before. Decorin binding proteins are adhesins expressed on Lyme borreliae. They mediate the adhesion of Lyme borreliae to decorin and biglycan, and the lysine residues located in the binding site of decorin binding proteins are important to the binding activity. In this study, we show that lysine residues located in the canonical binding site can also be found in decorin binding proteins of Borrelia garinii, and that these lysines contribute to biglycan and decorin binding. Most importantly, we show that the lysine residues are crucial for the binding of Lyme borreliae to decorin and biglycan expressing human brain microvascular endothelial cells, which in turn suggests that they are involved in the pathogenesis of neuroborreliosis.

Human Immortalized Cell-Based Blood-Brain Barrier Spheroid Models Offer an Evaluation Tool for the Brain Penetration Properties of Macromolecules.

Blood-brain barrier (BBB)-permeable middle- or macromolecules (middle/macromolecules) have recently attracted significant attention as new drug delivery carriers into the human brain via receptor-mediated transcytosis (RMT). During the development process of such carriers, it is necessary to thoroughly evaluate their human BBB permeability levels. In such evaluations, our recently established human immortalized cell-based multicellular spheroidal BBB models (hiMCS-BBB models) have shown high potential. However, the specifics of those capabilities have yet to be elucidated. Therefore, in this study, we characterize the ability of the hiMCS-BBB models to evaluate RMT-mediated BBB penetration properties of middle/macromolecules. More specifically, we began by validating transferrin receptor (TfR)-mediated RMT functionalities using transferrin in the hiMCS-BBB models and then examined the BBB permeability levels of MEM189 antibodies (known BBB-permeable anti-TfR antibodies). The obtained results showed that, as with the case of transferrin, temperature-dependent uptake of MEM189 antibodies was observed in the hiMCS-BBB models, and the extent of that uptake increased in a time-dependent manner until reaching a plateau after around 2 h. To further expand the evaluation applicability of the models, we also examined the BBB permeability levels of the recently developed SLS cyclic peptide and observed that peptide uptake was also temperature-dependent. To summarize, our results show that the hiMCS-BBB models possess the ability to evaluate the RMT-mediated BBB-permeable properties of antibodies and peptides and thus have the potential to provide valuable tools for use in the exploration and identification of middle/macromolecules showing excellent BBB permeability levels, thereby contributing powerfully to the development of new drug delivery carriers for transporting drugs into the human brain.

In Vitro-In Vivo Correlation of Blood-Brain Barrier Permeability of Drugs: A Feasibility Study Towards Development of Prediction Methods for Brain Drug Concentration in Humans.

PURPOSE: In vitro human blood-brain barrier (BBB) models in combination with central nervous system-physiologically based pharmacokinetic (CNS-PBPK) modeling, hereafter referred to as the "BBB/PBPK" method, are expected to contribute to prediction of brain drug concentration profiles in humans. As part of our ongoing effort to develop a BBB/PBPK method, we tried to clarify the relationship of in vivo BBB permeability data to those in vitro obtained from a human immortalized cell-based tri-culture BBB model (hiBBB), which we have recently created. METHODS: The hiBBB models were developed and functionally characterized as previously described. The in vitro BBB permeabilities (Pe, × 10-6 cm/s) of seventeen compounds were determined by permeability assays, and in vivo BBB permeabilities (QECF) for eight drugs were estimated by CNS-PBPK modeling. The correlation of the Pe values with the QECF values was analyzed by linear regression analysis. RESULTS: The hiBBB models showed intercellular barrier properties and several BBB transporter functions, which were enough to provide a wide dynamic range of Pe values from 5.7 ± 0.7 (rhodamine 123) to 2580.4 ± 781.9 (rivastigmine). Furthermore, the in vitro Pe values of the eight drugs showed a good correlation (R2 = 0.96) with their in vivo QECF values estimated from human clinical data. CONCLUSION: We show that in vitro human BBB models provide clinically relevant BBB permeability that can be used as input for CNS-PBPK modeling. Therefore, our findings will encourage the development of a BBB/PBPK method as a promising approach for predicting brain drug concentration profiles in humans.

Development and Validation of an LC-MS/MS-Based Method for Quantifying Urinary Endogenous 6-Hydroxymelatonin.

Evaluation of endogenous melatonin (MEL) secretion using its urinary metabolites is useful for the treatment of circadian rhythm sleep disorders. The primary melatonin metabolites excreted in the urine are 6-hydroxymelatonin (6-O-MEL) sulfate (S-O-MEL) and 6-O-MEL glucuronate, which result from sequential MEL metabolism by phases I and II drug metabolizing enzymes. To determine the accurate MEL secretion level, these urinary metabolites should be enzymatically deconjugated and converted into MEL. Furthermore, the use of LC-tandem mass spectrometry (LC-MS/MS) is preferable for the precision of this determination. Therefore, as part of our ongoing efforts to ultimately determine the level of MEL secretion, we herein aimed to develop an LC-MS/MS-based quantification method for 6-O-MEL and optimize deconjugation conditions. We determined the LC-MS/MS conditions of 6-O-MEL measurement and optimized the conditions of enzymatic reactions. The most efficient S-O-MEL deconjugation (102.1%) was achieved with Roche Glucuronidase/Arylsulfatase (from Helix pomatia) at 37 °C, pH-4.0 reaction buffer, and 60 min of reaction time. For human urine samples, the minimum amount of the enzyme required was 5944 units. Under these conditions, the accuracy and precision values of the 6-O-MEL determination (relative errors and standard deviation) were -3.60--0.47% and <6.80%, respectively. Finally, we analyzed the total amount of MEL metabolites excreted in 24-h urine samples; it was 6.70-11.28 µg in three subjects, which is comparable with the values reported till date. Thus, we have established a new method of measuring the total 6-O-MEL in human urine samples using an LC-MS/MS coupled with the prerequisite deconjugation reaction.

Evaluating a Targeted Cancer Therapy Approach Mediated by RNA trans-Splicing In Vitro and in a Xenograft Model for Epidermolysis Bullosa-Associated Skin Cancer.

Conventional anti-cancer therapies based on chemo- and/or radiotherapy represent highly effective means to kill cancer cells but lack tumor specificity and, therefore, result in a wide range of iatrogenic effects. A promising approach to overcome this obstacle is spliceosome-mediated RNA trans-splicing (SMaRT), which can be leveraged to target tumor cells while leaving normal cells unharmed. Notably, a previously established RNA trans-splicing molecule (RTM44) showed efficacy and specificity in exchanging the coding sequence of a cancer target gene (Ct-SLCO1B3) with the suicide gene HSV1-thymidine kinase in a colorectal cancer model, thereby rendering tumor cells sensitive to the prodrug ganciclovir (GCV). In the present work, we expand the application of this approach, using the same RTM44 in aggressive skin cancer arising in the rare genetic skin disease recessive dystrophic epidermolysis bullosa (RDEB). Stable expression of RTM44, but not a splicing-deficient control (NC), in RDEB-SCC cells resulted in expression of the expected fusion product at the mRNA and protein level. Importantly, systemic GCV treatment of mice bearing RTM44-expressing cancer cells resulted in a significant reduction in tumor volume and weight compared with controls. Thus, our results demonstrate the applicability of RTM44-mediated targeting of the cancer gene Ct-SLCO1B3 in a different malignancy.

Ischemic stroke disrupts the endothelial glycocalyx through activation of proHPSE via acrolein exposure.

Infiltration of peripheral immune cells after blood-brain barrier dysfunction causes severe inflammation after a stroke. Although the endothelial glycocalyx, a network of membrane-bound glycoproteins and proteoglycans that covers the lumen of endothelial cells, functions as a barrier to circulating cells, the relationship between stroke severity and glycocalyx dysfunction remains unclear. In this study, glycosaminoglycans, a component of the endothelial glycocalyx, were studied in the context of ischemic stroke using a photochemically induced thrombosis mouse model. Decreased levels of heparan sulfate and chondroitin sulfate and increased activity of hyaluronidase 1 and heparanase (HPSE) were observed in ischemic brain tissues. HPSE expression in cerebral vessels increased after stroke onset and infarct volume greatly decreased after co-administration of N-acetylcysteine + glycosaminoglycan oligosaccharides as compared with N-acetylcysteine administration alone. These results suggest that the endothelial glycocalyx was injured after the onset of stroke. Interestingly, scission activity of proHPSE produced by immortalized endothelial cells and HEK293 cells transfected with hHPSE1 cDNA were activated by acrolein (ACR) exposure. We identified the ACR-modified amino acid residues of proHPSE using nano LC-MS/MS, suggesting that ACR modification of Lys139 (6-kDa linker), Lys107, and Lys161, located in the immediate vicinity of the 6-kDa linker, at least in part is attributed to the activation of proHPSE. Because proHPSE, but not HPSE, localizes outside cells by binding with heparan sulfate proteoglycans, ACR-modified proHPSE represents a promising target to protect the endothelial glycocalyx.

Haploinsufficiency of microglial MyD88 ameliorates Alzheimer's pathology and vascular disorders in APP/PS1-transgenic mice.

Growing evidence indicates that innate immune molecules regulate microglial activation in Alzheimer's disease (AD); however, their effects on amyloid pathology and neurodegeneration remain inconclusive. Here, we conditionally deleted one allele of myd88 gene specifically in microglia in APP/PS1-transgenic mice by 6 months and analyzed AD-associated pathologies by 9 months. We observed that heterozygous deletion of myd88 gene in microglia decreased cerebral amyloid ß (Aß) load and improved cognitive function of AD mice, which was correlated with reduced number of microglia in the brain and inhibited transcription of inflammatory genes, for example, tnf-α and il-1ß, in both brain tissues and individual microglia. To investigate mechanisms underlying the pathological improvement, we observed that haploinsufficiency of MyD88 increased microglial recruitment toward Aß deposits, which might facilitate Aß clearance. Microglia with haploinsufficient expression of MyD88 also increased vasculature in the brain of APP/PS1-transgenic mice, which was associated with up-regulated transcription of osteopontin and insulin-like growth factor genes in microglia. Moreover, MyD88-haploinsufficient microglia elevated protein levels of LRP1 in cerebral capillaries of APP/PS1-transgenic mice. Cell culture experiments further showed that treatments with interleukin-1ß decreased LRP1 expression in pericytes. In summary, haploinsufficiency of MyD88 in microglia at a late disease stage attenuates pro-inflammatory activation and amyloid pathology, prevents the impairment of microvasculature and perhaps also protects LRP1-mediated Aß clearance in the brain of APP/PS1-transgenic mice, all of which improves neuronal function of AD mice.

Development, Characterization and Potential Applications of a Multicellular Spheroidal Human Blood-Brain Barrier Model Integrating Three Conditionally Immortalized Cell Lines.

In vitro blood-brain barrier (BBB) models are essential research tools for use in developing brain-targeted drugs and understanding the physiological and pathophysiological functions of the BBB. To develop BBB models with better functionalities, three-dimensional (3D) culture methods have gained significant attention as a promising approach. In this study, we report on the development of a human conditionally immortalized cell-based multicellular spheroidal BBB (hiMCS-BBB) model. After being seeded into non-attachment culture wells, HASTR/ci35 (astrocytes) and HBPC/ci37 cells (brain pericytes) self-assemble to form a spheroid core that is then covered with an outer monolayer of HBMEC/ci18 cells (brain microvascular endothelial cells). The results of immunocytochemistry showed the protein expression of several cellular junction and BBB-enriched transporter genes in HBMEC/ci18 cells of the spheroid model. The permeability assays showed that the hiMCS-BBB model exhibited barrier functions against the penetration of dextran (5 and 70 kDa) and rhodamine123 (a P-glycoprotein substrate) into the core. On the other hand, facilitation of 2-(N-[7-nitrobenz-2-oxa-1,3-diazol-4-yl]amino)-2-deoxyglucose (2-NBDG; a fluorescent glucose analog) uptake was observed in the hiMCS-BBB model. Furthermore, tumor necrosis factor-alpha treatment elicited an inflammatory response in HBMEC/ci18 cells, thereby suggesting that BBB inflammation can be recapitulated in the hiMCS-BBB model. To summarize, we have developed an hiMCS-BBB model that possesses fundamental BBB properties, which can be expected to provide a useful and highly accessible experimental platform for accelerating various BBB studies.

Interstitial flow regulates in vitro three-dimensional self-organized brain micro-vessels.

Cell culture under medium flow has been shown to favor human brain microvascular endothelial cells function and maturation. Here a three-dimensional in vitro model of the human brain microvasculature, comprising brain microvascular endothelial cells but also astrocytes, pericytes and a collagen type I microfiber - fibrin based matrix, was cultured under continuous medium flow in a pressure driven microphysiological system (10 kPa, in 60-30 s cycles). The cells self-organized in micro-vessels perpendicular to the shear flow. Comparison with static culture showed that the resulting interstitial flow enhanced a more defined micro-vasculature network, with slightly more numerous lumens, and a higher expression of transporters, carriers and tight junction genes and proteins, essential to the blood-brain barrier functions.

JPH203, a newly developed anti-cancer drug, shows a preincubation inhibitory effect on L-type amino acid transporter 1 function.

JPH203 is a novel anti-cancer drug targeting L-type amino acid transporter 1 (LAT1), which plays a primary role in the uptake of essential amino acids in tumor cells. Although a co-incubation inhibitory effect of JPH203 has been shown in a conventional uptake assay, its preincubation inhibitory effects have remained undetermined. Therefore, we aimed to characterize the preincubation inhibitory effects of JPH203 on LAT1 function using leucine uptake assays in LAT1-positive human colon cancer HT-29 cells. Preincubation of the cells with JPH203 (0.3 µM for 120 min) decreased the activity level to 30% of that in dimethylsulfoxide-treated cells. Similarly, in time-dependency analysis, preincubation of HT-29 cells with 10 µM JPH203 for 30, 60, and 120 min decreased the leucine uptake activity (42%, 32%, and 28% of that in control cells, respectively). Furthermore, the IC50 value of the combination of preincubation and co-incubation effects was lower than that of co-incubation inhibition alone (34.2 ± 3.6 nM vs. 99.2 ± 11.0 nM). In conclusion, we revealed that JPH203 has the capability to inhibit LAT1 function through preincubation effects. Moreover, preincubation synergistically enhances the co-incubation inhibitory effects. These findings provide a novel insight into the anti-cancer effects of JPH203 in cancer therapy.

A Human Immortalized Cell-Based Blood-Brain Barrier Triculture Model: Development and Characterization as a Promising Tool for Drug-Brain Permeability Studies.

Brain microvascular endothelial cells (BMEC), together with astrocytes and pericytes, form the blood-brain barrier (BBB) that strictly restricts drug penetration into the brain. Therefore, in central nervous system drug development, the establishment of an in vitro human BBB model for use in studies estimating the in vivo human BBB permeability of drug candidates has long been awaited. The current study developed and characterized a human immortalized cell-based BBB triculture model, termed the "hiBBB" model. To set up the hiBBB model, human immortalized BMEC (HBMEC/ci18) were cocultured with human immortalized astrocytes (HASTR/ci35) and brain pericytes (HBPC/ci37) in a transwell system. The trans-endothelial electrical resistance of the hiBBB model was 134.4 ± 5.5 (Ω × cm2), and the efflux ratios of rhodamine123 and dantrolene were 1.72 ± 0.11 and 1.72 ± 0.45, respectively, suggesting that the hiBBB model possesses essential cellular junction and efflux transporter functions. In BBB permeability assays, the mean value of the permeability coefficients (Pe) of BBB permeable compounds (propranolol, pyrilamine, memantine, and diphenhydramine) was 960 × 10-6 cm/s, which was clearly distinguishable from that of BBB nonpermeable compounds (sodium fluorescein and Lucifer yellow, 18 × 10-6 cm/s). Collectively, this study successfully developed the hiBBB model, which exhibits essential BBB functionality. Taking into consideration the high availability of the immortalized cells used in the hiBBB model, our results are expected to become an initial step toward the establishment of a useful human BBB model to investigate drug penetration into the human brain.

Large-Scale Quantitative Comparison of Plasma Transmembrane Proteins between Two Human Blood-Brain Barrier Model Cell Lines, hCMEC/D3 and HBMEC/ciß.

Transmembrane (TM) proteins localized at the plasma membrane, such as transporters and receptors, play important roles in regulating the selective permeability of the blood-brain barrier (BBB). The purpose of the present study was to clarify the differences in the expression levels of TM proteins in the plasma membrane between two established human BBB model cell lines, hCMEC/D3 and HBMEC/ciß, in order to assist researchers in selecting the most appropriate cell line for particular purposes. We first confirmed that plasma membranes could be enriched sufficiently for a quantitative proteomics study by using the Plasma Membrane Protein Extraction Kit provided by BioVision with a modified protocol. This method was applied to hCMEC/D3 and HBMEC/ciß cells, and fractions were used for untargeted quantitative proteomics based on sequential window acquisition of all theoretical fragment-ion spectra. In the plasma membrane fractions, 345 TM proteins were quantified, among which 135 showed significant expression differences between the two cell lines. In hCMEC/D3 cells, amino acid transporters SNAT1, SNAT2, SNAT5, ASCT1, CAT1, and LAT1; adenosine 5'-triphosphate-binding cassette transporters P-gp and MRP4; and GLUT1 were more highly expressed. The transferrin receptor expression was also 4.56-fold greater in hCMEC/D3 cells. In contrast, HBMEC/ciß cells expressed greater levels of IgG transporter neonatal Fc receptor, as well as tight-junction proteins PECAM1, JAM1, JAM3, and ESAM. Our results suggest that hCMEC/D3 cells have greater efflux transport, amino acid transport, and transferrin receptor-mediated uptake activities, whereas HBMEC/ciß cells have greater IgG-transport activity and tight-junction integrity.

Polyamines stimulate the CHSY1 synthesis through the unfolding of the RNA G-quadruplex at the 5'-untraslated region.

Glycosaminoglycans (GAGs), a group of structurally related acidic polysaccharides, are primarily found as glycan moieties of proteoglycans (PGs). Among these, chondroitin sulfate (CS) and dermatan sulfate, side chains of PGs, are widely distributed in animal kingdom and show structural variations, such as sulfation patterns and degree of epimerization, which are responsible for their physiological functions through interactions with growth factors, chemokines and adhesion molecules. However, structural changes in CS, particularly the ratio of 4-O-sulfation to 6-O-sulfation (4S/6S) and CS chain length that occur during the aging process, are not fully understood. We found that 4S/6S ratio and molecular weight of CS were decreased in polyamine-depleted cells. In addition, decreased levels of chondroitin synthase 1 (CHSY1) and chondroitin 4-O-sulfotransferase 2 proteins were also observed on polyamine depletion. Interestingly, the translation initiation of CHSY1 was suppressed by a highly structured sequence (positions -202 to -117 relative to the initiation codon) containing RNA G-quadruplex (G4) structures in 5'-untranslated region. The formation of the G4s was influenced by the neighboring sequences to the G4s and polyamine stimulation of CHSY1 synthesis disappeared when the formation of the G4s was inhibited by site-directed mutagenesis. These results suggest that the destabilization of G4 structures by polyamines stimulates CHSY1 synthesis and, at least in part, contribute to the maturation of CS chains.

In Vivo Introduction of mRNA Encapsulated in Lipid Nanoparticles to Brain Neuronal Cells and Astrocytes via Intracerebroventricular Administration.

Gene therapy is a promising strategy for curing certain types of brain diseases. Supplementation of therapeutic proteins such as aromatic amino acid decarboxylase (AADC) or nerve growth factor (NGF) have been reported to be successful examples of such treatments. However, there are safety concerns because these systems are based on virus-based gene vectors. A safe and efficient artificial carrier is thus urgently needed as an alternative. In this study, an mRNA based artificial gene carrier was introduced into the mouse brain via intracerebroventricular administration. As a carrier, a lipid nanoparticle (LNP) composed of environmentally sensitive lipid-like materials called an SS-cleavable proton-activated lipid-like material is used. The apolipoprotein E mediated cellular uptake of the lipid nanoparticles is one of the key features for its superior and homogeneous transfection activity compared to commercially available transfection reagents in both in vitro and in vivo situations. Immunostaining of brain specimens suggested that exogenous proteins can be introduced into neuronal cells as well as astrocytes using the mRNA-based gene carrier. This cannot be achieved using DNA-based artificial gene carriers. The findings suggest that a combination of an mRNA and a lipid based delivery system have great promise as a platform for the treatment of brain disorders.

Synthesis of novel benzbromarone derivatives designed to avoid metabolic activation.

We synthesized six novel BBR derivatives that were designed to avoid metabolic activation via ipso-substitution and evaluated for their degree of toxicity and hURAT1 inhibition. It was found that all of the derivatives demonstrate lower cytotoxicity in mouse hepatocytes and lower levels of metabolic activation than BBR, while maintaining their inhibitory activity toward the uric acid transporter. We propose that these derivatives could serve as effective uricosuric agents that have much better safety profiles than BBR.

Differentiated HASTR/ci35 cells: A promising in vitro human astrocyte model for facilitating CNS drug development studies.

Astrocytes have shown longstanding promise as therapeutic targets for various central nervous system diseases. To facilitate drug development targeting astrocytes, we have recently developed a new conditionally immortalized human astrocyte cell line, termed HASTR/ci35 cells. In this study, in order to further increase their chances to contribute to various astrocyte studies, we report on the development of a culture method that improves HASTR/ci35 cell differentiation status and provide several proofs related to their astrocyte characteristics. The culture method is based on the simultaneous elimination of serum effects and immortalization signals. The results of qPCR showed that the culture method significantly enhanced several astrocyte marker gene expression levels. Using the differentiated HASTR/ci35, we examined their response profiles to nucleotide treatment and inflammatory stimuli, along with their membrane fatty acid composition. Consequently, we found that they responded to ADP or UTP treatment with a transient increase of intracellular Ca2+ concentration, and that they could show reactive response to interleukin-1ß treatments. Furthermore, the membrane phospholipids of the cells were enriched with polyunsaturated fatty acids. To summarize, as a unique human astrocyte model carrying the capability of a differentiation induction properties, HASTR/ci35 cells are expected to contribute substantially to astrocyte-oriented drug development studies.

Development of a Caco-2 Cell Line Carrying the Human Intestine-Type CES Expression Profile as a Promising Tool for Ester-Containing Drug Permeability Studies.

Carboxylesterase 2 (CES2), which is a member of the serine hydrolase superfamily, is primarily expressed in the human small intestine, where it plays an important role in the metabolism of ester-containing drugs. Therefore, to facilitate continued progress in ester-containing drug development, it is crucial to evaluate how CES2-mediated hydrolysis influences its intestinal permeability characteristics. Human colon carcinoma Caco-2 cells have long been widely used in drug permeability studies as an enterocyte model. However, they are not suitable for ester-containing drug permeability studies due to the fact that Caco-2 cells express CES1 (which is not expressed in human enterocytes) but do not express CES2. To resolve this problem, we created a new Caco-2 cell line carrying the human small intestine-type CES expression profile. We began by introducing short-hairpin RNA for CES1 mRNA knockdown into Caco-2 cells to generate CES1-decifient Caco-2 cells (Caco-2CES1KD cells). Then, we developed Caco-2CES1KD cells that stably express CES2 (CES2/Caco-2CES1KD cells) and their control Mock/Caco-2CES1KD cells. The results of a series of functional expression experiments confirmed that CES2-specific activity, along with CES2 mRNA and protein expression, were clearly detected in our CES2/Caco-2CES1KD cells. Furthermore, we also confirmed that CES2/Caco-2CES1KD cells retained their tight junction formation property as well as their drug efflux transporter functions. Collectively, based on our results clearly showing that CES2/Caco-2CES1KD cells carry the human intestinal-type CES expression profile, while concomitantly retaining their barrier properties, it can be expected that this cell line will provide a promising in vitro model for ester-containing drug permeability studies.

Development of a New Conditionally Immortalized Human Liver Sinusoidal Endothelial Cells.

Liver sinusoidal endothelial cells (LSECs), which are specialized endothelial cells that line liver sinusoids, have been reported to participate in a variety of liver functions, such as blood macromolecule clearance and factor VIII production. In addition, LSECs play crucial roles in liver regeneration following acute liver injury, as well as the development and progression of liver diseases or drug-induced hepatotoxicity. However, the molecular mechanisms underlying their roles remain mostly unknown. Therefore, in order to contribute to the clarification of those mechanisms, herein we report on the development of a new immortalized human LSEC (HLSEC) line. To produce this cell line, two immortalized genes were introduced into the primary HLSECs, which eventually resulted in the establishment of the HLSEC/conditionally immortalized, clone-J (HLSEC/ciJ). Consistent with the two-immortalized gene expression, HLSEC/ciJ showed excellent proliferation activity. Additionally, the results of gene expression analyses showed that several LSEC (as well as pan-endothelial) marker mRNAs and proteins were clearly expressed in HLSEC/ciJ. Furthermore, we found that adherence junction proteins were localized at the cell border in the HLSEC/ciJ monolayer, and that the cells exhibited a tube-like structure formation property. Taken together, the results obtained thus far indicate that we have successfully immortalized HLSECs, resulting in creation of HLSEC/ciJ, a cell line that possesses infinite proliferation ability while retaining possession of at least some HLSEC features. We believe that the HLSEC/ciJ have the potential to provide a valuable and unlimited alternative source of HLSECs for use in liver/LSEC physiology/pathophysiology, pharmacology, and toxicology studies.