Genome-wide profiling of miRNA-gene regulatory networks in mouse postnatal heart development-implications for cardiac regeneration.

Background: After birth, mammalian cardiomyocytes substantially lose proliferative capacity with a concomitant switch from glycolytic to oxidative mitochondrial energy metabolism. Micro-RNAs (miRNAs) regulate gene expression and thus control various cellular processes. Their roles in the postnatal loss of cardiac regeneration are however still largely unclear. Here, we aimed to identify miRNA-gene regulatory networks in the neonatal heart to uncover role of miRNAs in regulation of cell cycle and metabolism. Methods and results: We performed global miRNA expression profiling using total RNA extracted from mouse ventricular tissue samples collected on postnatal day 1 (P01), P04, P09, and P23. We used the miRWalk database to predict the potential target genes of differentially expressed miRNAs and our previously published mRNA transcriptomics data to identify verified target genes that showed a concomitant differential expression in the neonatal heart. We then analyzed the biological functions of the identified miRNA-gene regulatory networks using enriched Gene Ontology (GO) and KEGG pathway analyses. Altogether 46 miRNAs were differentially expressed in the distinct stages of neonatal heart development. For twenty miRNAs, up- or downregulation took place within the first 9 postnatal days thus correlating temporally with the loss of cardiac regeneration. Importantly, for several miRNAs, including miR-150-5p, miR-484, and miR-210-3p there are no previous reports about their role in cardiac development or disease. The miRNA-gene regulatory networks of upregulated miRNAs negatively regulated biological processes and KEGG pathways related to cell proliferation, while downregulated miRNAs positively regulated biological processes and KEGG pathways associated with activation of mitochondrial metabolism and developmental hypertrophic growth. Conclusion: This study reports miRNAs and miRNA-gene regulatory networks with no previously described role in cardiac development or disease. These findings may help in elucidating regulatory mechanism of cardiac regeneration and in the development of regenerative therapies.

Human iPSC-derived preclinical models to identify toxicity of tumor-specific T cells with clinical potential.

The balance between safety and efficacy of T cell therapies remains challenging and T cell mediated toxicities have occurred. The stringent selection of tumor-specific targets and careful selection of tumor-specific T cells using T cell toxicity screenings are essential. In vitro screening options against vital organs or specialized cell subsets would be preferably included in preclinical pipelines, but options remain limited. Here, we set up preclinical models with human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes, epicardial cells, and kidney organoids to investigate toxicity risks of tumor-specific T cells more thoroughly. CD8+T cells reactive against PRAME, HA-1H, CD20, or WT1, currently used or planned to be used in phase I/II clinical studies, were included. Using these hiPSC-derived preclinical models, we demonstrated that WT1-specific T cells caused on-target toxicity that correlated with target gene expression. Multiple measures of T cell reactivity demonstrated this toxicity on the level of T cells and hiPSC-derived target cells. In addition, phenotypic analysis illustrated interaction and crosstalk between infiltrated T cells and kidney organoids. In summary, we demonstrated the benefit of hiPSC-derived models in determining toxicity risks of tumor-specific T cells. Furthermore, our data emphasizes the additional value of other measures of T cell reactivity on top of the commonly used cytokine levels.

Correction: Nemade, H.; et al. Cyclooxygenases Inhibitors Efficiently Induce Cardiomyogenesis in Human Pluripotent Stem Cells. Cells 2020, 9, 554.

The authors wish to make the following corrections to this paper [...].

PCSK9 inhibition with alirocumab in pediatric patients with heterozygous familial hypercholesterolemia: The ODYSSEY KIDS study.

BACKGROUND: Heterozygous familial hypercholesterolemia (HeFH) is a genetic disorder characterized by elevated levels of low-density lipoprotein cholesterol (LDL-C). OBJECTIVE: This phase 2 dose-finding study (NCT02890992) evaluated the efficacy, safety, and dose selection of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitor alirocumab in pediatric HeFH patients. METHODS: HeFH patients (n = 42) who were aged 8-17 years, had body weight (BW) ≥25 kg, and had LDL-C ≥130 mg/dL despite optimal statin/other lipid-modifying therapies were enrolled in 4 cohorts according to BW: cohort #1: 30 mg (<50 kg) or 50 mg (≥50 kg) every 2 weeks (Q2W), #2: 40 mg (<50 kg) or 75 mg (≥50 kg) Q2W, #3: 75 mg (<50 kg) or 150 mg (≥50 kg) every 4 weeks (Q4W), #4: 150 mg (<50 kg) or 300 mg (≥50 kg) Q4W. Primary endpoint was LDL-C % change from baseline to week 8. RESULTS: Mean age was 12.4 years and 95% of patients were on a statin. Baseline LDL-C levels were 160.0-188.9 mg/dL and free PCSK9 was 186.4-201.7 ng/mL across the cohorts. At week 8, the higher dose cohorts (2 and 4) demonstrated the greatest reductions in LDL-C (-46% and -45%, respectively). Free PCSK9 levels were lowest at week 8 in cohorts 2 and 4 (42.2 ng/mL and 8.6 ng/mL, respectively). Adverse events were reported in 50-90% of patients across the cohorts, and 2 patients discontinued due to adverse events. CONCLUSIONS: In pediatric HeFH patients, LDL-C reductions were greatest in the higher dose cohorts. Alirocumab was generally well tolerated at all doses.

Cyclooxygenases Inhibitors Efficiently Induce Cardiomyogenesis in Human Pluripotent Stem Cells.

Application of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is limited by the challenges in their efficient differentiation. Recently, the Wingless (Wnt) signaling pathway has emerged as the key regulator of cardiomyogenesis. In this study, we evaluated the effects of cyclooxygenase inhibitors on cardiac differentiation of hPSCs. Cardiac differentiation was performed by adherent monolayer based method using 4 hPSC lines (HES3, H9, IMR90, and ES4SKIN). The efficiency of cardiac differentiation was evaluated by flow cytometry and RT-qPCR. Generated hPSC-CMs were characterised using immunocytochemistry, electrophysiology, electron microscopy, and calcium transient measurements. Our data show that the COX inhibitors Sulindac and Diclofenac in combination with CHIR99021 (GSK-3 inhibitor) efficiently induce cardiac differentiation of hPSCs. In addition, inhibition of COX using siRNAs targeted towards COX-1 and/or COX-2 showed that inhibition of COX-2 alone or COX-1 and COX-2 in combination induce cardiomyogenesis in hPSCs within 12 days. Using IMR90-Wnt reporter line, we showed that inhibition of COX-2 led to downregulation of Wnt signalling activity in hPSCs. In conclusion, this study demonstrates that COX inhibition efficiently induced cardiogenesis via modulation of COX and Wnt pathway and the generated cardiomyocytes express cardiac-specific structural markers as well as exhibit typical calcium transients and action potentials. These cardiomyocytes also responded to cardiotoxicants and can be relevant as an in vitro cardiotoxicity screening model.

Omics-based responses induced by bosentan in human hepatoma HepaRG cell cultures.

Bosentan is well known to induce cholestatic liver toxicity in humans. The present study was set up to characterize the hepatotoxic effects of this drug at the transcriptomic, proteomic, and metabolomic levels. For this purpose, human hepatoma-derived HepaRG cells were exposed to a number of concentrations of bosentan during different periods of time. Bosentan was found to functionally and transcriptionally suppress the bile salt export pump as well as to alter bile acid levels. Pathway analysis of both transcriptomics and proteomics data identified cholestasis as a major toxicological event. Transcriptomics results further showed several gene changes related to the activation of the nuclear farnesoid X receptor. Induction of oxidative stress and inflammation were also observed. Metabolomics analysis indicated changes in the abundance of specific endogenous metabolites related to mitochondrial impairment. The outcome of this study may assist in the further optimization of adverse outcome pathway constructs that mechanistically describe the processes involved in cholestatic liver injury.

Cell death mechanisms of the anti-cancer drug etoposide on human cardiomyocytes isolated from pluripotent stem cells.

Etoposide (ETP) and anthracyclines are applied for wide anti-cancer treatments. However, the ETP-induced cardiotoxicity remains to be a major safety issue and the underlying cardiotoxic mechanisms are not well understood. This study is aiming to unravel the cardiotoxicity profile of ETP in comparison to anthracyclines using physiologically relevant human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). Using xCELLigence real-time cell analyser (RTCA), we found that single high dose of ETP induces irreversible increase in hPSC-CMs beating rate and decrease in beating amplitude. We also identified 58 deregulated genes consisting of 33 upregulated and 25 downregulated genes in hPSC-CMs after ETP treatment. Gene ontology (GO) and pathway analysis showed that most upregulated genes are enriched in GO categories like positive regulation of apoptotic process, regulation of cell death, and mitochondria organization, whereas most downregulated genes were enriched in GO categories like cytoskeletal organization, muscle contraction, and Ca2+ ion homeostasis. Moreover, we also found upregulation in 5 miRNAs (has-miR-486-3p, has-miR-34c-5p, has-miR-4423-3p, has-miR-182-5p, and has-miR-139-5p) which play role in muscle contraction, arginine and proline metabolism, and hypertrophic cardiomyopathy (HCM). Immunostaining and transmission electron microscopy also confirmed the cytoskeletal and mitochondrial damage in hPSC-CMs treated with ETP, as well as noticeable alterations in intracellular calcium handling and mitochondrial membrane potential were also observed. The apoptosis inhibitor, Pifithrin-α, found to protect hPSC-CMs from ETP-induced cardiotoxicity, whereas hPSC-CMs treated with ferroptosis inhibitor, Liproxstatin-1, showed significant recovery in hPSC-CMs functional properties like beating rate and amplitude after ETP treatment. We suggest that the damage to mitochondria is a major contributing factor involved in ETP-induced cardiotoxicity and the activation of the p53-mediated ferroptosis pathway by ETP is likely the critical pathway in ETP-induced cardiotoxicity. We also conclude that the genomic biomarkers identified in this study will significantly contribute to develop and predict potential cardiotoxic effects of novel anti-cancer drugs in vitro.

Functional cardiotoxicity assessment of cosmetic compounds using human-induced pluripotent stem cell-derived cardiomyocytes.

There is a large demand of a human relevant in vitro test system suitable for assessing the cardiotoxic potential of cosmetic ingredients and other chemicals. Using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs), we have already established an in vitro cardiotoxicity assay and identified genomic biomarkers of anthracycline-induced cardiotoxicity in our previous work. Here, five cosmetic ingredients were studied by the new hiPSC-CMs test; kojic acid (KJA), triclosan (TS), triclocarban (TCC), 2,7-naphthalenediol (NPT), and basic red 51 (BR51) based on cytotoxicity as well as ATP assays, beating rate, and genomic biomarkers to determine the lowest observed effect concentration (LOEC) and no observed effect concentration (NOEC). The LOEC for beating rate were 400, 10, 3, >400, and 3 µM for KJA, TS, TCC, NPT, and BR51, respectively. The corresponding concentrations for cytotoxicity or ATP depletion were similar, with the exception of TS and TCC, where the cardiomyocyte-beating assay showed positive results at non-cytotoxic concentrations. Functional analysis also showed that the individual compounds caused different effects on hiPSC-CMs. While exposure to KJA, TS, TCC, and BR51 induced significant arrhythmic beating, NPT slightly decreased cell viability, but did not influence beating. Gene expression studies showed that TS and NPT caused down-regulation of cytoskeletal and cardiac ion homeostasis genes. Moreover, TS and NPT deregulated genomic biomarkers known to be affected also by anthracyclines. The present study demonstrates that hiPSC-CMs can be used to determine LOECs and NOECs in vitro, which can be compared to human blood concentrations to determine margins of exposure. Our in vitro assay, which so far has been tested with several anthracyclines and cosmetics, still requires validation by larger numbers of positive and negative controls, before it can be recommended for routine analysis.

Utility of Low Fidelity Manikins for Learning High Quality Chest Compressions.

OBJECTIVES: Primarily, to measure the adequacy of chest compression depth after training on low fidelity manikins and secondarily to assess the comparative experience of the learners on high fidelity and low fidelity simulators. METHODS: An observational cohort study in which seventy-two first year postgraduate students underwent a Basic Life Support (BLS) workshop conducted by AHA accredited BLS trainers and they were then required to perform on a high fidelity manikin to objectively record the quality of their performance. RESULTS: There were 34 (47.22%) male and 38 (52.77%) female participants. CPR skills, as judged by checklist of sequential actions and visual inspection during the BLS training on low fidelity simulators (LFS) were correctly performed by majority (95.89%) participants. However, none of the participants could achieve the recommended depth for high quality chest compressions. The participants' perception of degree of realism and their practical experience on both the types of manikins were similar. CONCLUSIONS: Low fidelity manikins are useful for training CPR in sequential manner but fail to impart quality of chest compressions as per AHA recommendations.

Efficacy and Safety of Alirocumab Versus Ezetimibe Over 2 Years (from ODYSSEY COMBO II).

The proprotein convertase subtilisin/kexin type 9 inhibitor alirocumab has been shown to substantially reduce low-density lipoprotein cholesterol (LDL-C). Demonstrating whether efficacy and safety are maintained over a long duration of exposure is vital for clinical decision-making. The COMBO II trial compared the efficacy and safety of alirocumab versus ezetimibe over 2 years. A prespecified first analysis was reported at 52 weeks. Here we report the final end-of-study data (on-treatment) and evaluate post hoc the safety profile with longer versus shorter duration of alirocumab exposure. Patients (n = 720) on maximally tolerated statin dose were treated with alirocumab (75/150 mg every 2 weeks) or ezetimibe (10 mg/day). Overall mean adherence for both treatment groups during the first and second year was >97%. At 2 years, LDL-C was reduced by 49% (alirocumab) versus 17% (ezetimibe; p <0.0001), and LDL-C <70 mg/dl was achieved by 73% of alirocumab-treated versus 40% of ezetimibe-treated patients. Overall safety was similar in both treatment groups at 2 years and during the first versus the second year. Local injection-site reactions were reported by 2.5% (alirocumab) versus 0.8% (ezetimibe) during the first year, and 0.2% versus 0.5% during the second year, indicating early occurrence during prolonged alirocumab exposure. Two consecutive calculated LDL-C values <25 mg/dl were observed in 28% of alirocumab-treated patients (vs 0.4% with ezetimibe). Persistent anti-drug antibody responses were observed in 1.3% (6 of 454) of alirocumab-treated versus 0.4% (1 of 231) of ezetimibe-treated patients. Neutralizing antibodies (that inhibit binding in vitro) were observed in 1.5% (7 of 454) of alirocumab-treated patients (0 with ezetimibe), mostly at isolated time points. Alirocumab sustained substantial LDL-C reductions and was well tolerated up to 2 years in the COMBO II trial.

Metabolite signatures of doxorubicin induced toxicity in human induced pluripotent stem cell-derived cardiomyocytes.

Drug-induced off-target cardiotoxicity, particularly following anti-cancer therapy, is a major concern in new drug discovery and development. To ensure patient safety and efficient pharmaceutical drug development, there is an urgent need to develop more predictive cell model systems and distinct toxicity signatures. In this study, we applied our previously proposed repeated exposure toxicity methodology and performed 1H NMR spectroscopy-based extracellular metabolic profiling in culture medium of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) exposed to doxorubicin (DOX), an anti-cancer agent. Single exposure to DOX did not show alteration in the basal level of extracellular metabolites while repeated exposure to DOX caused reduction in the utilization of pyruvate and acetate, and accumulation of formate compared to control culture medium. During drug washout, only pyruvate showed reversible effect and restored its utilization by hiPSC-CMs. On the other hand, formate and acetate showed irreversible effect in response to DOX exposure. DOX repeated exposure increased release of lactate dehydrogenase (LDH) in culture medium suggesting cytotoxicity events, while declined ATP levels in hiPSC-CMs. Our data suggests DOX perturbed mitochondrial metabolism in hiPSC-CMs. Pyruvate, acetate and formate can be used as metabolite signatures of DOX induced cardiotoxicity. Moreover, the hiPSC-CMs model system coupled with metabolomics technology offers a novel and powerful approach to strengthen cardiac safety assessment during new drug discovery and development.

Efficacy and safety of the proprotein convertase subtilisin/kexin type 9 monoclonal antibody alirocumab vs placebo in patients with heterozygous familial hypercholesterolemia.

BACKGROUND: Patients with heterozygous familial hypercholesterolemia (HeFH) are characterized by elevated low-density lipoprotein cholesterol (LDL-C) levels. Long-term effects of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition have not been thoroughly investigated in these patients. OBJECTIVE: We evaluated efficacy and safety of alirocumab, a PCSK9 inhibitor, vs placebo in patients with HeFH. METHODS: In total, 1257 patients with HeFH on maximally tolerated statin ± other lipid-lowering therapies from four 78-week ODYSSEY trials were analyzed. In FH I and II, patients with baseline LDL-C levels ≥70/100 mg/dL (n = 735), depending on documented cardiovascular disease history, received placebo or alirocumab 75 mg every 2 weeks (Q2W; with dose increase to 150 mg Q2W at week 12 if week 8 LDL-C was ≥70 mg/dL). Separately, data were pooled from HIGH FH (baseline LDL-C ≥160 mg/dL) and patients with HeFH from LONG TERM (baseline LDL-C ≥70 mg/dL), where patients received placebo or alirocumab 150 mg Q2W (n = 522). RESULTS: At week 24, alirocumab reduced LDL-C levels by -48.8% (75/150 mg Q2W; placebo: +7.1%) and -55.0% (alirocumab 150 mg Q2W; placebo: +1.3%) (both P < .0001 vs placebo; intention-to-treat analysis). Least-squares mean LDL-C levels of 69.1 to 75.6 mg/dL (alirocumab 75/150 mg/dL Q2W; baseline: 141.3 mg/dL) and 72.2 to 82.3 mg/dL (alirocumab 150 mg Q2W; baseline: 168.4 mg/dL) were achieved at weeks 24 to 78 (on-treatment analysis). Additional beneficial effects were observed in other lipids. Treatment-emergent adverse event rates were similar in the alirocumab (80.5%) and placebo groups (83.0%). CONCLUSIONS: In this large cohort of patients with HeFH, alirocumab significantly reduced LDL-C levels. Alirocumab was generally well tolerated.

Safety of Very Low Low-Density Lipoprotein Cholesterol Levels With Alirocumab: Pooled Data From Randomized Trials.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 monoclonal antibodies can reduce low-density lipoprotein cholesterol (LDL-C) to very low levels when added to background lipid-lowering therapy. OBJECTIVES: The safety of alirocumab was evaluated in patients with at least 2 consecutive LDL-C values <25 or <15 mg/dl in the ODYSSEY program, with follow-up as long as 104 weeks. METHODS: Pooled data from 14 trials were analyzed (double-blind treatment 8 to 104 weeks; n = 3,340 alirocumab, n = 1,894 control [placebo or ezetimibe]; representing 4,029 [alirocumab] and 2,114 [control] double-blind patient-years' exposure). RESULTS: In alirocumab-treated patients, 839 (25.1%) achieved 2 consecutive LDL-C values <25 mg/dl, and 314 (9.4%) achieved <15 mg/dl. Baseline LDL-C was lower (mean 100.3 vs. 134.3 mg/dl) in patients with LDL-C <25 versus ≥25 mg/dl. Similar rates of adverse events occurred in patients achieving LDL-C <25 and <15 mg/dl (72.7% and 71.7%, respectively), compared with 76.6% in those who did not achieve LDL-C <25 mg/dl. Neurological and neurocognitive events were similar among the 3 groups. In a propensity score analysis, the rate of cataracts was higher in patients with LDL-C <25 mg/dl (2.6%) versus ≥25 mg/dl (0.8%; hazard ratio: 3.40; 95% confidence interval: 1.58 to 7.35). However, no difference in cataract incidence was observed between pooled alirocumab and control groups. CONCLUSIONS: LDL-C levels <25 or <15 mg/dl on alirocumab were not associated with an increase in overall treatment-emergent adverse event rates or neurocognitive events, although cataract incidence appeared to be increased in the group achieving LDL-C levels <25 mg/dl. (Pooled analyses of already reported trials; NCT01288443, NCT01288469, NCT01266876, NCT01812707, NCT01507831, NCT01617655, NCT01623115, NCT01709500, NCT01644175, NCT01644188, NCT01730040, NCT01730053, NCT01644474, and NCT01709513).

Safety of Alirocumab (A PCSK9 Monoclonal Antibody) from 14 Randomized Trials.

Previous individual trials of alirocumab (a PCSK9 monoclonal antibody) showed significant low-density lipoprotein cholesterol reductions with overall treatment-emergent adverse event (TEAE) rates comparable with controls. This analysis evaluated safety data from 14 trials (4 phase 2 and 10 phase 3, 8 to 104 weeks; n = 5,234), in 2 pools according to control (placebo/ezetimibe). Overall, 3,340 patients received alirocumab (4,029 patient-years' exposure), 1,276 received placebo, and 618 received ezetimibe. Incidence of deaths, serious TEAEs, discontinuations because of TEAEs, and overall TEAEs were similar between alirocumab and control groups. Alirocumab was associated with a higher incidence of local injection site reactions (7.4% vs 5.3% with placebo; 3.1% vs 2.3% with ezetimibe), pruritus (1.3% vs 0.4% placebo; 0.9% vs 0.5% ezetimibe), and upper respiratory tract infection signs and symptoms (2.1% vs 1.1% placebo; 1.3% vs 0.8% ezetimibe). Incidence of musculoskeletal, neurologic, neurocognitive, ophthalmologic, hepatic events, and TEAEs related to diabetes/diabetes complications was similar between alirocumab and control groups. In a prespecified analysis of phase 3 studies, adjudicated major adverse cardiovascular events (coronary heart disease death, nonfatal myocardial infarction, ischemic stroke, and unstable angina requiring hospitalization) occurred in 1.8% alirocumab versus 2.6% placebo patients (hazard ratio 0.69, 95% confidence interval 0.43 to 1.11) and 2.8% alirocumab versus 1.5% ezetimibe patients (hazard ratio 1.4, 95% confidence interval 0.65 to 3.02). In conclusion, pooled safety data from 14 trials demonstrate that alirocumab is generally well tolerated with a favorable safety profile.

Gene network activity in cultivated primary hepatocytes is highly similar to diseased mammalian liver tissue.

It is well known that isolation and cultivation of primary hepatocytes cause major gene expression alterations. In the present genome-wide, time-resolved study of cultivated human and mouse hepatocytes, we made the observation that expression changes in culture strongly resemble alterations in liver diseases. Hepatocytes of both species were cultivated in collagen sandwich and in monolayer conditions. Genome-wide data were also obtained from human NAFLD, cirrhosis, HCC and hepatitis B virus-infected tissue as well as mouse livers after partial hepatectomy, CCl4 intoxication, obesity, HCC and LPS. A strong similarity between cultivation and disease-induced expression alterations was observed. For example, expression changes in hepatocytes induced by 1-day cultivation and 1-day CCl4 exposure in vivo correlated with R = 0.615 (p < 0.001). Interspecies comparison identified predominantly similar responses in human and mouse hepatocytes but also a set of genes that responded differently. Unsupervised clustering of altered genes identified three main clusters: (1) downregulated genes corresponding to mature liver functions, (2) upregulation of an inflammation/RNA processing cluster and (3) upregulated migration/cell cycle-associated genes. Gene regulatory network analysis highlights overrepresented and deregulated HNF4 and CAR (Cluster 1), Krüppel-like factors MafF and ELK1 (Cluster 2) as well as ETF (Cluster 3) among the interspecies conserved key regulators of expression changes. Interventions ameliorating but not abrogating cultivation-induced responses include removal of non-parenchymal cells, generation of the hepatocytes' own matrix in spheroids, supplementation with bile salts and siRNA-mediated suppression of key transcription factors. In conclusion, this study shows that gene regulatory network alterations of cultivated hepatocytes resemble those of inflammatory liver diseases and should therefore be considered and exploited as disease models.

"Watching the Detectives" report of the general assembly of the EU project DETECTIVE Brussels, 24-25 November 2015.

SEURAT-1 is a joint research initiative between the European Commission and Cosmetics Europe aiming to develop in vitro- and in silico-based methods to replace the in vivo repeated dose systemic toxicity test used for the assessment of human safety. As one of the building blocks of SEURAT-1, the DETECTIVE project focused on a key element on which in vitro toxicity testing relies: the development of robust and reliable, sensitive and specific in vitro biomarkers and surrogate endpoints that can be used for safety assessments of chronically acting toxicants, relevant for humans. The work conducted by the DETECTIVE consortium partners has established a screening pipeline of functional and "-omics" technologies, including high-content and high-throughput screening platforms, to develop and investigate human biomarkers for repeated dose toxicity in cellular in vitro models. Identification and statistical selection of highly predictive biomarkers in a pathway- and evidence-based approach constitute a major step in an integrated approach towards the replacement of animal testing in human safety assessment. To discuss the final outcomes and achievements of the consortium, a meeting was organized in Brussels. This meeting brought together data-producing and supporting consortium partners. The presentations focused on the current state of ongoing and concluding projects and the strategies employed to identify new relevant biomarkers of toxicity. The outcomes and deliverables, including the dissemination of results in data-rich "-omics" databases, were discussed as were the future perspectives of the work completed under the DETECTIVE project. Although some projects were still in progress and required continued data analysis, this report summarizes the presentations, discussions and the outcomes of the project.

MicroRNAs as early toxicity signatures of doxorubicin in human-induced pluripotent stem cell-derived cardiomyocytes.

An in depth investigation at the genomic level is needed to identify early human-relevant cardiotoxicity biomarkers that are induced by drugs and environmental toxicants. The main objective of this study was to investigate the role of microRNAs (miRNAs) as cardiotoxicity biomarkers using human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) that were exposed to doxorubicin (DOX) as a "gold standard" cardiotoxicant. hiPSC-CMs were exposed to 156 nM DOX for 2 days or for 6 days of repeated exposure, followed by drug washout and incubation in drug-free culture medium up to day 14 after the onset of exposure. The induced miRNAs were profiled using miRNA microarrays, and the analysis of the data was performed using the miRWalk 2.0 and DAVID bioinformatics tools. DOX induced early deregulation of 14 miRNAs (10 up-regulated and 4 down-regulated) and persistent up-regulation of 5 miRNAs during drug washout. Computational miRNA gene target predictions suggested that several DOX-responsive miRNAs might regulate the mRNA expression of genes involved in cardiac contractile function. The hiPSC-CMs exposed to DOX in a range from 39 to 156 nM did not show a significant release of the cytotoxicity marker lactate dehydrogenase (LDH) compared to controls. Quantitative real-time PCR analyses confirmed the early deregulation of miR-187-3p, miR-182-5p, miR-486-3p, miR-486-5p, miR-34a-3p, miR-4423-3p, miR-34c-3p, miR-34c-5p and miR-1303, and also the prolonged up-regulation of miR-182-5p, miR-4423-3p and miR-34c-5p. Thus, we identified and validated miRNAs showing differential DOX-responsive expression before the occurrence of cytotoxicity markers such as LDH, and these miRNAs also demonstrated the significant involvement in heart failure in patients and animal models. These results suggest that the DOX-induced deregulated miRNAs in human CMs may be used as early sensitive cardiotoxicity biomarkers for screening potential drugs and environmental cardiotoxicants with a similar mechanism of action.

Identification of genomic biomarkers for anthracycline-induced cardiotoxicity in human iPSC-derived cardiomyocytes: an in vitro repeated exposure toxicity approach for safety assessment.

The currently available techniques for the safety evaluation of candidate drugs are usually cost-intensive and time-consuming and are often insufficient to predict human relevant cardiotoxicity. The purpose of this study was to develop an in vitro repeated exposure toxicity methodology allowing the identification of predictive genomics biomarkers of functional relevance for drug-induced cardiotoxicity in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). The hiPSC-CMs were incubated with 156 nM doxorubicin, which is a well-characterized cardiotoxicant, for 2 or 6 days followed by washout of the test compound and further incubation in compound-free culture medium until day 14 after the onset of exposure. An xCELLigence Real-Time Cell Analyser was used to monitor doxorubicin-induced cytotoxicity while also monitoring functional alterations of cardiomyocytes by counting of the beating frequency of cardiomyocytes. Unlike single exposure, repeated doxorubicin exposure resulted in long-term arrhythmic beating in hiPSC-CMs accompanied by significant cytotoxicity. Global gene expression changes were studied using microarrays and bioinformatics tools. Analysis of the transcriptomic data revealed early expression signatures of genes involved in formation of sarcomeric structures, regulation of ion homeostasis and induction of apoptosis. Eighty-four significantly deregulated genes related to cardiac functions, stress and apoptosis were validated using real-time PCR. The expression of the 84 genes was further studied by real-time PCR in hiPSC-CMs incubated with daunorubicin and mitoxantrone, further anthracycline family members that are also known to induce cardiotoxicity. A panel of 35 genes was deregulated by all three anthracycline family members and can therefore be expected to predict the cardiotoxicity of compounds acting by similar mechanisms as doxorubicin, daunorubicin or mitoxantrone. The identified gene panel can be applied in the safety assessment of novel drug candidates as well as available therapeutics to identify compounds that may cause cardiotoxicity.