Structure-Activity Relationship and Voltage Dependence for the Drug-Drug Interaction between Amiodarone Analogs and MNI-1 at the L-type Cav Channel.

The drug-drug interaction (DDI) between amiodarone (AMIO) and sofosbuvir (SOF), a direct-acting hepatitis-C NS5B nucleotide polymerase inhibitor, has been associated with severe bradyarrhythmia in patients. Recent cryo-EM data has revealed that this DDI occurs at the α-subunit of L-type Cav channels, with AMIO binding at the fenestration site and SOF [or MSD nucleotide inhibitor #1 (MNI-1): analog of SOF] binding at the central cavity of the conductance pathway. In this study, we investigated the DDI between 21 AMIO analogs, including dronedarone (DRON) and MNI-1 (or SOF) in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) and hCav1.2 models. Our findings indicate that among the tested AMIO analogs in hiPSC-CMs at clinically relevant concentrations, only three analogs (AA-9, AA-10, and AA-17) were able to effectively substitute for AMIO in this DDI with 1 µM MNI-1. This highlights the importance of the diethyl amino group of AMIO for interacting with MNI-1. In the hCav1.2 model, desethylamiodarone (AA-12) demonstrated synergy with 90 µM MNI-1, while three other analogs with modifications to the position of the diethyl amino group or removal of iodo groups showed weaker synergy with 90 µM MNI-1. Interestingly, DRON did not exhibit any interaction with 270 µM SOF or 90 µM MNI-1, suggesting that it could safely replace AMIO in patients requiring SOF treatment, other clinically relevant differences considered. Overall, our functional data align with the cryo-EM data, highlighting that this DDI is dependent on the structure of AMIO and cardiomyocyte resting membrane potential. SIGNIFICANCE STATEMENT: Our findings point to specific residues in the AMIO molecule playing a critical role in the DDI between AMIO and MNI-1 (SOF analog), confirming cryo-EM results. Applied at clinically relevant AMIO's concentrations or projected MNI-1's concentrations at the resting potentials mimicking the sinoatrial node, this DDI significantly slowed down or completely inhibited the beating of hiPSC-CMs. Finally, these in vitro results support the safe replacement of AMIO (Cordarone) with DRON (Multaq) for patients requiring SOF treatment, other clinical caveats considered.

Discovery and optimization of heteroaryl piperazines as potent and selective PI3Kδ inhibitors.

A high-throughput screening (HTS) campaign identified a class of heteroaryl piperazines with excellent baseline affinity and selectivity for phosphoinositide 3-kinase δ (PI3Kδ) over closely related isoforms. Rapid evaluation and optimization of structure-activity relationships (SAR) for this class, leveraging the modular nature of this scaffold, facilitated development of this hit class into a series of potent and selective inhibitors of PI3Kδ. This effort culminated in the identification of 29, which displayed excellent potency in enzyme and cell-based assays, as well as favorable pharmacokinetic and off-target profiles.

Developing a Multi-Element Sensor to Non-Destructively Monitor Several Fundamental Parameters Related to Concrete Durability.

A design scheme of multi-element sensor which included electrical resistivity probes, multiple Cl- selective electrodes, and a steel corrosion monitoring system was proposed in this work. Embedding this multi-element sensor in concrete enables the real-time and non-destructive monitoring of internal electrical resistivity, free Cl- (Clf) contents in the concrete pore solution at different depths, and steel corrosion parameters. Based on the monitoring data obtained by the multi-element sensor, the freezing-thawing (F-T) damage degree, the Clf diffusion coefficient, the quantitative relation between F-T damage degree and Clf diffusion coefficient, the initiation period of steel corrosion, and the critical content related to steel corrosion are determined. To conclude, the multi-element sensor provides key durability parameters for the establishment of the Clf diffusion model, the assessment of health condition, and the prediction of service life of concrete under the coexistence of the F-T cycle and Cl-.

Interaction between amiodarone and hepatitis-C virus nucleotide inhibitors in human induced pluripotent stem cell-derived cardiomyocytes and HEK-293 Cav1.2 over-expressing cells.

Several clinical cases of severe bradyarrhythmias have been reported upon co-administration of the Hepatitis-C NS5B Nucleotide Polymerase Inhibitor (HCV-NI) direct-acting antiviral agent, sofosbuvir (SOF), and the Class-III anti-arrhythmic amiodarone (AMIO). We model the cardiac drug-drug interaction (DDI) between AMIO and SOF, and between AMIO and a closely-related SOF analog, MNI-1 (Merck Nucleotide Inhibitor #1), in functional assays of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), to provide mechanistic insights into recently reported clinical cases. AMIO co-applied with SOF or MNI-1 increased beating rate or field potential (FP) rate and decreased impedance (IMP) and Ca(2+) transient amplitudes in hiPSC-CM syncytia. This action resembled that of Ca(2+) channel blockers (CCBs) in the model, but CCBs did not substitute for AMIO in the DDI. AMIO analog dronedarone (DRON) did not substitute for, but competed with AMIO in the DDI. Ryanodine and thapsigargin, decreasing intracellular Ca(2+) stores, and SEA-0400, a Na(+)/Ca(2+) exchanger-1 (NCX1) inhibitor, partially antagonized or suppressed DDI effects. Other agents affecting FP rate only exerted additive or subtractive effects, commensurate with their individual effects. We also describe an interaction between AMIO and MNI-1 on Cav1.2 ion channels in an over-expressing HEK-293 cell line. MNI-1 enhanced Cav1.2 channel inhibition by AMIO, but did not affect inhibition of Cav1.2 by DRON, verapamil, nifedipine, or diltiazem. Our data in hiPSC-CMs indicate that HCV-NI agents such as SOF and MNI-1 interact with key intracellular Ca(2+)-handling mechanisms. Additional study in a Cav1.2 HEK-293 cell-line suggests that HCV-NIs potentiate the inhibitory action of AMIO on L-type Ca(2+) channels.

Human dental pulp stem cells have comparable abilities to umbilical cord mesenchymal stem/stromal cells in regulating inflammation and ameliorating hepatic fibrosis.

Hepatic fibrosis, also called cirrhosis, have wide prevalence worldwide for long yeas. Recently, many treatments for liver cirrhosis made marked progress, especially the umbilical cord-derived mesenchymal stromal cells (UCMSC) therapy. However, limited recourses and potential immune-related issues become the obstacles on UCMSC popularization in clinic. Therefore, we took dental pulp stem cells (DPSCs) into the consideration, since autologous DPSCs can be easily obtained without any ethnic or immune-related issues that heterogenous UCMSCs could encounter. We systematically compared the effects of both cell types and found that DPSCs had similar results to UCMSCs in regulating inflammation and reversing hepatic fibrosis. In our study, co-culturing T cells and PBMSCs showed that DPSCs have the ability to inhibit the proliferation of inflammatory cells and downregulate relevant inflammatory factors. In vitro and in vivo sterility tests confirmed the bio-safety of DPSCs. Moreover, the 1 year-aged mouse model demonstrated that DPSCs successfully reversed hepatic fibrosis. Overall, DPSCs demonstrated comparable effectiveness to UCMSCs in regulating inflammation and reversing hepatic fibrosis, particularly in the aged mouse model that represents middle-aged and elderly humans. Since autologous DPSCs avoid potential immune-related issues that heterogenous UCMSCs could encounter, they may be a better choice for stem cell-related therapies.

Efficacy of MUC1-targeted CAR-NK cells against human tongue squamous cell carcinoma.

Introduction: The clinical efficacy of CAR-NK cells against CD19-expressing blood cancers has been demonstrated, and they have shown potential for treating solid tumors as well. However, the efficacy of CAR-NK cells for treating human oral tongue squamous cell carcinoma (OTSCC) has not been examined. Methods: We assessed MUC1 expression in human OTSCC tissue and a cell line using immunohistochemistry and immunofluorescence. We constructed NK cells that express CAR targeted to MUC1 from pluripotent stem cells (iPSC-derived MUC1-targeted CAR-NK cells) and evaluated their effectiveness against OTSCC in vitro using the xCELLigence Real-Time Cell Analysis system and CCK8 assay, and in vivo by measuring xenograft growth daily in BNDG mice treated with MUC1-targeted CAR-NK cells. As controls, we used iPSC-derived NK cells and NK-free media, which were CAR-free and blank, respectively. Results: MUC1 expression was detected in 79.5% (66/83) of all OTSCC patients and 72.7% (24/33) of stage III and IV. In stage III and IV MUC1 positive OTSCC, 63.6% (21/33) and 48.5% (16/33) patients had a MUC1-positive cancer cell rate of more than 50% and 80%, respectively. The iPSC-derived MUC1-targeted CAR-NK cells exhibited significant cytotoxicity against MUC1-expressing OTSCC cells in vitro, in a time- and dose-dependent manner, and showed a significant inhibitory effect on xenograft growth compared to both the iPSC-derived NK cells and the blank controls. We observed no weight loss, severe hematological toxicity or NK cell-mediated death in the BNDG mice. Conclusion: The MUC1-targeted CAR-NK cells had significant efficacy against human OTSCC, and their promising therapeutic response warrants further clinical trials.

Efficacy of the induced pluripotent stem cell derived and engineered CD276-targeted CAR-NK cells against human esophageal squamous cell carcinoma.

Introduction: Chimeric antigen receptor natural killer (CAR-NK) cells have been found to be successful in treating hematologic malignancies and present potential for usage in solid tumors. Methods: In this study, we created CD276-targeted CAR-expressing NK cells from pluripotent stem cells (iPSC CD276-targeted CAR-NK cells) and evaluated their cytotoxicity against esophageal squamous cell carcinoma (ESCC) using patient-specific organoid (PSO) models comprising of both CD276-positive and CD276-negative adjacent epithelium PSO models (normal control PSO, NC PSO) as well as primary culture of ESCC cell models. In addition, in vitro and in vivo models such as KYSE-150 were also examined. iPSC NK cells and NK-free media were used as the CAR-free and NK-free controls, respectively. Results: The positive CD276 staining was specifically detected on the ESCC membrane in 51.43% (54/105) of the patients of all stages, and in 51.35% (38/74) of stages III and IV. The iPS CD276-targeted CAR-NK cells, comparing with the iPS NK cells and the NK-free medium, exhibited specific and significant cytotoxic activity against CD276-positive ESCC PSO rather than CD276-negative NC PSO, and exhibited significant cytotoxicity against CD276-expressing cultured ESCC cells, as well as against CD276-expressing KYSE-150 in vitro and in BNDG mouse xenograft. Discussion: The efficacy of the iPSC CD276-targeted CAR-NK cells demonstrated by their successful treatment of CD276-expressing ESCC in a multitude of pre-clinical models implied that they hold tremendous therapeutic potential for treating patients with CD276-expressing ESCC.

Investigation on the Electrical Conductivity of Graphene/Cement Composites by Alternating Current Method.

This paper is concerned with an analysis of the electrical conductivity of graphene/cement composites by means of DC (direct current) and AC (alternating current) techniques. Moreover, the micrograph and element composition of composites have been characterized through SEM (scanning electron microscopy) and EDS (energy-dispersive spectrometers) techniques, respectively. Results revealed that a percolation transition region Φ2-Φ1 (Φ2 and Φ1 values are determined as 0.8% and 1.8%, respectively) can be observed in the S-shaped curve. In addition, the logistic model has been recommended to characterize the relationship between the conductivity and the graphene concentration, which ranged from 0.001% to 2.5%. The micrographs obtained by SEM technique clearly indicate a complete conductive network as well as agglomeration of graphene slices when the graphene content reaches the threshold value. Furthermore, graphene slices can be distinguished from the cement hydration products by means of the analysis of element composition obtained through the EDS technique. It is promising to apply the graphene/cement composites as intelligent materials.

Mesothelin-targeted CAR-NK Cells Derived From Induced Pluripotent Stem Cells Have a High Efficacy in Killing Triple-negative Breast Cancer Cells as Shown in Several Preclinical Models.

The emergence of immunotherapy has introduced a promising, novel approach to cancer treatment. While multiple chimeric antigen receptor (CAR) T-cell therapies have demonstrated remarkable clinical efficacy against leukemia, their effect on solid tumors has been limited. One potential option for treating solid tumors is the engineering of natural killer (NK) cells with CARs. Mesothelin (MSLN), a tumor differentiation antigen, is expressed on triple-negative breast cancer (TNBC) cells, making it a potential target for CAR-NK therapy in the treatment of TNBC. We first constructed induced pluripotent stem cells with stable anti-MSLN-CAR expression and subsequently differentiated these cells into mesothelin-targeted CAR-NK (MSLN-NK) cells. We then assessed the effects of MSLN-NK cells on TNBC cells both in vitro (using the MDA-MB-231 cell line), in vivo (in a CDX mouse model), and ex vivo (using patient-specific primary cells and patient-specific organoids), in which MSLN surface expression was confirmed. Our CDX study results indicated that MSLN-NK cells effectively killed MDA-MB-231 (MD231) cells in vitro, reduced tumor growth in the CDX mouse model of TNBC, and lysed patient-specific primary cells and patient-specific organoids derived from the tumor samples of TNBC patients. Our data demonstrated that MSLN-NK cells had high efficacy on killing TNBC cells in in vitro, in vivo, and ex vivo. Therefore, MSLN-NK could be a promising treatment option for TNBC patients.

STAT3 inhibitor BBI608 reduces patient-specific primary cell viability of cervical and endometrial cancer at a clinical-relevant concentration.

PURPOSE: Aberrant activation of STAT3 signal pathway promotes tumor progression in many solid tumor types, including cervical cancer and endometrial cancer. BBI608, the STAT3 inhibitor had been reported in previous studies for restraining cancer stem cells. However, whether BBI608 is available for inhibiting the proliferation of cervical cancer or endometrial cancer remains poorly understood. This study investigated the anti-tumor effect and molecular mechanism of BBI608 on the patient-specific primary cells (PSPC) generated from cervical and endometrial cancer in vitro. METHODS: PSPCs were obtained from four patients via biopsy. The cell viability was analyzed by the CCK8 assay. The PSPCs were treated with various concentrations of BBI608 or/and paclitaxel; and then, western blot was applied to investigate the expression of phosphorylated STAT3 (pSTAT3). RESULTS: The PSPCs cell viability was reduced after treated with BBI608 at a lower concentration. Western blot results showed a reduction trend of pSTAT3 after PSPCs treated with BBI608. Our results demonstrated that BBI608 at the certain concentrations worked well in reducing the cell viability of PSPC from the patients who suffered from cervical cancer and endometrial cancer. CONCLUSIONS: In this study, the patient-specific primary cell (PSPC) was used as the pre-clinical model for investigating the efficiency of BBI608 in reducing cancer cells viability. BBI608, at a clinical-relevant concentration, had valid efficiency in PSPCs from the patients. The dose of drugs treatment and the measured results were more valuable for further guiding clinical trials.

MSCohi-O lenses for long-term retention of mesenchymal stem cells on ocular surface as a therapeutic approach for chronic ocular graft-versus-host disease.

Chronic ocular graft-versus-host disease (oGVHD) is a common complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and can lead to vision loss if not diagnosed and treated promptly. Currently, no approved drugs exist for oGVHD treatment. However, umbilical cord-derived mesenchymal stem cells (UCMSCs) have known immunoregulatory properties and have been employed in clinical trials for immune-mediated diseases. To address oGVHD, the application of UCMSCs to the ocular surface is a logical approach. Intravenous administration of UCMSCs poses risks, necessitating topical and local delivery. Retaining UCMSCs on the ocular surface remains a challenge. To overcome this, we invented mesenchymal stem cell-coating high oxygen-permeable hydrogel lenses combining UCMSCs and machinery to enable the long-term retention of UCMSCs on the ocular surface. Animal model experiments demonstrated that these lenses effectively retained UCMSCs, providing therapeutic benefits by decreasing corneal inflammation and damage, and inhibiting immune rejection and response, all crucial aspects in oGVHD treatment.

BME-free primary patient-specific organoids obtained with a one-day mimicking method to replicate the corresponding tumor for personalized treatment options.

Introduction: In cancer treatment, every minute counts. Due to the unpredictable behavior of cancer cells caused by continuous mutations, each cancer patient has a unique situation and may or may not respond to a specific drug or treatment. The process of finding an effective therapy can be time-consuming, but cancer patients do not have the luxury of time for trial and error. Therefore, a novel technology to fast generate a patient relevant organoid for the therapies selecting is urgently needed. Methods: Utilizing the new organoid technology by specially dissolving the mesenchyme in tumor tissues acquired from cancer patients, we realized the work of creating patient-specific organoids (PSO) within one day. Results: PSO properties reflect those of its respective original in vivo tumor tissue and can be utilized to perform various in vitro drug sensitivity tests to identify the most effective clinical treatment for patients. Additionally, PSO can aid in assessing the efficacy of immune cell therapies. Discussion: Organoid technology has advanced significantly in recent years. However, current cancer organoid methods involve creating 3D tumor tissue from 2D cancer cells or cell clusters, primarily for cancer research purposes aimed at investigating related molecular and cellular mechanisms of tumor development. These methods are research-driven, not tailored towards clinical applications, and cannot provide personalized information for individual patients. PSO filled the gap of clinic-driven and time-saving method for the personalized therapies selecting to the cancer patients.

Prediction of Temperature Distribution in Concrete under Variable Environmental Factors through a Three-Dimensional Heat Transfer Model.

Temperature distribution in concrete is significant to the concrete structure's macro properties and different factors affect the heat transfer in concrete, and therefore influence the temperature distribution. This work established a three-dimensional transient heat transfer model coupled with various environmental factors, using the finite element method for calculating the results and real-measured data for testing accuracy. In addition, a sensitivity evaluation of various factors was conducted. Due to various environmental factors, the results revealed that the prediction of temperature distribution in concrete by the three-dimensional model had great accuracy with an error of less than 4%. A particular hysteresis effect of temperature response in the concrete existed. Considering heat transfer in different spatial directions, the model can predict the temperature change of each spatial point instead of the spatial surface in different depths, proving the shortcomings of a one-dimensional heat transfer model. A greater solar radiation intensity caused a more significant temperature difference on the concrete surface: the surface temperature difference in July was twice as significant as that in December. Wind speed had a cooling effect on the concrete surface, and stronger wind speed accompanied with a stronger cooling effect made the surface temperature closer to the ambient temperature. Material properties had different effects on the temperature distribution of the surface part and internal part: the specific heat capacity determined the speed of the outer layer temperature change while the thermal conductivity determined the speed of the inner layer temperature change.

Development of ProTx-II Analogues as Highly Selective Peptide Blockers of Nav1.7 for the Treatment of Pain.

Inhibitor cystine knot peptides, derived from venom, have evolved to block ion channel function but are often toxic when dosed at pharmacologically relevant levels in vivo. The article describes the design of analogues of ProTx-II that safely display systemic in vivo blocking of Nav1.7, resulting in a latency of response to thermal stimuli in rodents. The new designs achieve a better in vivo profile by improving ion channel selectivity and limiting the ability of the peptides to cause mast cell degranulation. The design rationale, structural modeling, in vitro profiles, and rat tail flick outcomes are disclosed and discussed.

The efficacy of Bifidobacterium quadruple viable tablet in the treatment of diarrhea predominant irritable bowel syndrome: protocol for a randomized, double-blind, placebo-controlled, multicenter trial.

BACKGROUND: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders characterized by recurrent abdominal pain associated with defecation or a change in bowel habits. Leading to significant negative effect on patients' quality of life and huge financial burden to health system, the management of IBS is a great challenge. Probiotics are considered as an effective therapy; however, in a lack of high-quality evidence of efficacy, no strain- and dose-specific probiotics were recommended in clinical guidelines. This study aims to evaluate the efficacy of the Bifidobacterium quadruple viable tablet in the treatment of IBS-D. METHODS/DESIGN: A multicenter randomized controlled trial will be performed in fourteen hospitals. A total of three hundred patients who fulfill the eligibility criteria will be stratified divided into an experimental group and a control group randomly in a ratio of 1:1. The experimental group is treated with the Bifidobacterium quadruple viable tablet while the control group is treated with placebo. All the patients will receive a 4-week treatment and a 2-week follow-up. The primary outcome is the effectiveness in improving abdominal pain and stool consistency; the secondary outcome includes evaluation of overall symptom relief, frequency of defecation, bloating, urgency of defecation, remedial medication, score of IBS-QOL, and changes of microbiota and metabonomics. Physical examination, vital signs, laboratory tests, adverse events, and concomitant medication will be taken into account for intervention safety assessment during the trial. DISCUSSION: This multicenter randomized controlled trial may provide high-quality evidence on the efficacy of the Bifidobacterium quadruple viable tablet for IBS-D on both physical and mental dimensions in China. To fill the gap of previous probiotic intervention studies, in addition, this study will also present safety assessment which will be a significant emphasis. TRIAL REGISTRATION: ChiCTR1800017721 . Registered on 10 August 2018.

Resolving the Reversed Rate Effect of Calcium Channel Blockers on Human-Induced Pluripotent Stem Cell-Derived Cardiomyocytes and the Impact on In Vitro Cardiac Safety Evaluation.

Calcium channel blockers (CCBs), such as diltiazem, nifedipine, and verapamil, cause tachycardia effects on several commercially available human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), when tested in culture media provided by suppliers, rather than bradycardia effects, as seen in vivo. We found that in test conditions where Na+ current of hiPSC-CMs was reduced to certain threshold by either specific Na+ channel blocker tetrodotoxin (TTX), or by voltage-dependent inactivation using elevated extracellular potassium concentrations, CCBs produced bradycardia effects on hiPSC-CMs. However, elevated extracellular potassium concentrations or the presence of TTX did not change other pharmacological responses of hiPSC-CMs, including CCBs' effects on contraction intensity and duration; beating rate change by calcium channel opener FPL64176, HCN blocker ivabradine, and ß-adrenergic agonist isoproterenol; and action potential duration prolongation by hERG channel blocker dofetilide. We concluded that action potentials of hiPSC-CMs, with regards to the CCB phenotype, were Na+ current driven. When Na+ channel availability was reduced to a critical level, their action potentials became Ca2+ current driven, and their responses to CCBs correlated well to those seen in vivo. Importantly, the corrected bradycardia effect of calcium channel block with our defined conditions will provide more reliable results in cardiac safety readouts of test compounds that integrate multiple effects including calcium channel inhibition.

Human-induced pluripotent stem cell-derived cardiomyocytes have limited IKs for repolarization reserve as revealed by specific KCNQ1/KCNE1 blocker.

OBJECTIVE: We investigated if there is IKs, and if there is repolarization reserve by IKs in human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). DESIGN: We used a specific KCNQ1/KCNE1 channel blocker, L-000768673, with an IC50 of 9 nM, and four hERG-specific blockers, astemizole, cisapride, dofetilide, and E-4031 to investigate the issue. RESULTS: L-000768673 concentration-dependently prolonged feature point duration (FPD)-a surrogate signal of action potential duration-from 1 to 30 nM without pacing or paced at 1.2 Hz, resulting from IKs blockade in hiPSC-CMs. At higher concentrations, the effect of L-000768673 on IKs was mitigated by its effect on ICa-L, resulting in shortened FPD, reduced impedance amplitude, and increased beating rate at 1 µM and above, recapitulating the self-limiting properties of L-000768673 on action potentials. All four hERG-specific blockers prolonged FPD as expected. Co-application of L-000768673 at sub-threshold (0.1 and 0.3 nM) and threshold (1 nM) concentrations failed to synergistically enhance the effects of hERG blockers on FPD prolongation, rather it showed additive effects, inconsistent with the repolarization reserve role of IKs in mature human myocytes that enhanced IKr response, implying a difference between hiPSC-CMs used in this study and mature human cardiomyocytes. CONCLUSION: There was IKs current in hiPSC-CMs, and blockade of IKs current caused prolongation of action potential of hiPSC-CMs. However, we could not demonstrate any synergistic effects on action potential duration prolongation of hiPSC-CMs by blocking hERG current and IKs current simultaneously, implying little or no repolarization reserve by IKs current in hiPSC-CMs used in this study.

HiPSC-CMs from different sex and ethnic origin donors exhibit qualitatively different responses to several classes of pharmacological challenges.

We investigated whether human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) created from diverse origins could have qualitatively (not just quantitatively) different responses to pharmacological reagents. Specifically, we challenged six hiPSC-CM syncytia made from a female Caucasian, a female black non-Hispanic, a female white non-Hispanic, a male Caucasian non-Hispanic, a male Asian Indian, and a male-Asian, respectively, with eight different classes of pharmacological reagents (hERG channel blocker cisapride and dofetilide, calcium channel opener FPL64176, ß-adrenergic agonist Isoproterenol, HCN channel blocker Ivabradine, IKs current blocker L-000768673, sodium channel blocker tetrodotoxin, and calcium channel blocker verapamil). We focused our analysis and comparison on qualitative differences (e.g., yes or no), and, found the following: hiPSC-CMs from female donors were uniformly more sensitive to dofetilide or cisapride, whereas those from male donors of all races were less sensitive to the two typical hERG blockers; isoproterenol had no chronotropic effect at all in one line; and two lines reacted to tetrodotoxin at very low concentrations and were more sensitive to external stimulation. We conclude that not all hiPSC-CMs are suitable for drug testing in terms of cardiac safety assessment, and pre-set acceptance criteria need to be established before any hiPSC-CMs can be used in CiPA-style study to evaluate cardiac liabilities of drug candidates.

Assessing Drug-Induced Long QT and Proarrhythmic Risk Using Human Stem-Cell-Derived Cardiomyocytes in a Ca2+ Imaging Assay: Evaluation of 28 CiPA Compounds at Three Test Sites.

The goal of this research consortium including Janssen, MSD, Ncardia, FNCR/LBR, and Health and Environmental Sciences Institute (HESI) was to evaluate the utility of an additional in vitro assay technology to detect potential drug-induced long QT and torsade de pointes (TdP) risk by monitoring cytosolic free Ca2+ transients in human stem-cell-derived cardiomyocytes (hSC-CMs). The potential proarrhythmic risks of the 28 comprehensive in vitro proarrhythmia assay (CiPA) drugs linked to low, intermediate, and high clinical TdP risk were evaluated in a blinded manner using Ca2+-sensitive fluorescent dye assay recorded from a kinetic plate reader system (Hamamatsu FDSS/µCell and FDSS7000) in 2D cultures of 2 commercially available hSC-CM lines (Cor.4U and CDI iCell Cardiomyocytes) at 3 different test sites. The Ca2+ transient assay, performed at the 3 sites using the 2 different hSC-CMs lines, correctly detected potential drug-induced QT prolongation among the 28 CiPA drugs and detected cellular arrhythmias-like/early afterdepolarization in 7 of 8 high TdP-risk drugs (87.5%), 6 of 11 intermediate TdP-risk drugs (54.5%), and 0 of 9 low/no TdP-risk drugs (0%). The results were comparable among the 3 sites and from 2 hSC-CM cell lines. The Ca2+ transient assay can serve as a user-friendly and higher throughput alternative to complement the microelectrode array and voltage-sensing optical action potential recording assays used in the HESI-CiPA study for in vitro assessment of drug-induced long QT and TdP risk.

1-[1-Hexyl-6-(methyloxy)-1H-indazol-3-yl]-2-methyl-1-propanone, a potent and highly selective small molecule blocker of the large-conductance voltage-gated and calcium-dependent K+ channel.

The large-conductance voltage-gated and calcium-dependent K(+) (BK) channels are widely distributed and play important physiological roles. Commonly used BK channel inhibitors are peptide toxins that are isolated from scorpion venoms. A high-affinity, nonpeptide, synthesized BK channel blocker with selectivity against other ion channels has not been reported. We prepared several compounds from a published patent application (Doherty et al., 2004) and identified 1-[1-hexyl-6-(methyloxy)-1H-indazol-3-yl]-2-methyl-1-propanone (HMIMP) as a potent and selective BK channel blocker. The patch-clamp technique was used for characterizing the activity of HMIMP on recombinant human BK channels (alpha subunit, alpha+beta1 and alpha+beta4 subunits). HMIMP blocked all of these channels with an IC(50) of approximately 2 nM. The inhibitory effect of HMIMP was not voltage-dependent, nor did it require opening of BK channels. HMIMP also potently blocked BK channels in freshly isolated detrusor smooth muscle cells and vagal neurons. HMIMP (10 nM) reduced the open probability significantly without affecting single BK-channel current in inside-out patches. HMIMP did not change the time constant of open states but increased the time constants of the closed states. More importantly, HMIMP was highly selective for the BK channel. HMIMP had no effect on human Na(V)1.5 (1 microM), Ca(V)3.2, L-type Ca(2+), human ether-a-go-go-related gene potassium channel, KCNQ1+minK, transient outward K(+) or voltage-dependent K(+) channels (100 nM). HMIMP did not change the action potentials of ventricular myocytes, confirming its lack of effect on cardiac ion channels. In summary, HMIMP is a highly potent and selective BK channel blocker, which can serve as an important tool in the pharmacological study of the BK channel.