Metadata integrity in bioinformatics: Bridging the gap between data and knowledge.

In the fast-evolving landscape of biomedical research, the emergence of big data has presented researchers with extraordinary opportunities to explore biological complexities. In biomedical research, big data imply also a big responsibility. This is not only due to genomics data being sensitive information but also due to genomics data being shared and re-analysed among the scientific community. This saves valuable resources and can even help to find new insights in silico. To fully use these opportunities, detailed and correct metadata are imperative. This includes not only the availability of metadata but also their correctness. Metadata integrity serves as a fundamental determinant of research credibility, supporting the reliability and reproducibility of data-driven findings. Ensuring metadata availability, curation, and accuracy are therefore essential for bioinformatic research. Not only must metadata be readily available, but they must also be meticulously curated and ideally error-free. Motivated by an accidental discovery of a critical metadata error in patient data published in two high-impact journals, we aim to raise awareness for the need of correct, complete, and curated metadata. We describe how the metadata error was found, addressed, and present examples for metadata-related challenges in omics research, along with supporting measures, including tools for checking metadata and software to facilitate various steps from data analysis to published research.

Progeria and Aging-Omics Based Comparative Analysis.

Since ancient times aging has also been regarded as a disease, and humankind has always strived to extend the natural lifespan. Analyzing the genes involved in aging and disease allows for finding important indicators and biological markers for pathologies and possible therapeutic targets. An example of the use of omics technologies is the research regarding aging and the rare and fatal premature aging syndrome progeria (Hutchinson-Gilford progeria syndrome, HGPS). In our study, we focused on the in silico analysis of differentially expressed genes (DEGs) in progeria and aging, using a publicly available RNA-Seq dataset (GEO dataset GSE113957) and a variety of bioinformatics tools. Despite the GSE113957 RNA-Seq dataset being well-known and frequently analyzed, the RNA-Seq data shared by Fleischer et al. is far from exhausted and reusing and repurposing the data still reveals new insights. By analyzing the literature citing the use of the dataset and subsequently conducting a comparative analysis comparing the RNA-Seq data analyses of different subsets of the dataset (healthy children, nonagenarians and progeria patients), we identified several genes involved in both natural aging and progeria (KRT8, KRT18, ACKR4, CCL2, UCP2, ADAMTS15, ACTN4P1, WNT16, IGFBP2). Further analyzing these genes and the pathways involved indicated their possible roles in aging, suggesting the need for further in vitro and in vivo research. In this paper, we (1) compare "normal aging" (nonagenarians vs. healthy children) and progeria (HGPS patients vs. healthy children), (2) enlist genes possibly involved in both the natural aging process and progeria, including the first mention of IGFBP2 in progeria, (3) predict miRNAs and interactomes for WNT16 (hsa-mir-181a-5p), UCP2 (hsa-mir-26a-5p and hsa-mir-124-3p), and IGFBP2 (hsa-mir-124-3p, hsa-mir-126-3p, and hsa-mir-27b-3p), (4) demonstrate the compatibility of well-established R packages for RNA-Seq analysis for researchers interested but not yet familiar with this kind of analysis, and (5) present comparative proteomics analyses to show an association between our RNA-Seq data analyses and corresponding changes in protein expression.

Application of the Pluripotent Stem Cells and Genomics in Cardiovascular Research-What We Have Learnt and Not Learnt until Now.

Personalized regenerative medicine and biomedical research have been galvanized and revolutionized by human pluripotent stem cells in combination with recent advances in genomics, artificial intelligence, and genome engineering. More recently, we have witnessed the unprecedented breakthrough life-saving translation of mRNA-based vaccines for COVID-19 to contain the global pandemic and the investment in billions of US dollars in space exploration projects and the blooming space-tourism industry fueled by the latest reusable space vessels. Now, it is time to examine where the translation of pluripotent stem cell research stands currently, which has been touted for more than the last two decades to cure and treat millions of patients with severe debilitating degenerative diseases and tissue injuries. This review attempts to highlight the accomplishments of pluripotent stem cell research together with cutting-edge genomics and genome editing tools and, also, the promises that have still not been transformed into clinical applications, with cardiovascular research as a case example. This review also brings to our attention the scientific and socioeconomic challenges that need to be effectively addressed to see the full potential of pluripotent stem cells at the clinical bedside.

Alveolar Regeneration in COVID-19 Patients: A Network Perspective.

A viral infection involves entry and replication of viral nucleic acid in a host organism, subsequently leading to biochemical and structural alterations in the host cell. In the case of SARS-CoV-2 viral infection, over-activation of the host immune system may lead to lung damage. Albeit the regeneration and fibrotic repair processes being the two protective host responses, prolonged injury may lead to excessive fibrosis, a pathological state that can result in lung collapse. In this review, we discuss regeneration and fibrosis processes in response to SARS-CoV-2 and provide our viewpoint on the triggering of alveolar regeneration in coronavirus disease 2019 (COVID-19) patients.

Angiotensin II blockers improve cardiac coronary flow under hemodynamic pressure overload.

Coronary flow velocity (CFV) is reduced in pathologic cardiac hypertrophy. This functional reduction is linked to adverse cardiac remodeling, hypertension and fibrosis, and angiotensin II (AngII) is a key molecular player. Angiotensin receptor blockers (ARBs) are known to attenuate adverse cardiac remodeling and fibrosis following increased afterload, while the mechanism by which these drugs offer clinical benefits and regulate hemodynamics remains unknown. To establish a direct connection between coronary flow changes and angiotensin-induced hypertension, we used a Doppler echocardiographic method in two distinct disease models. First, we performed serial echocardiography to visualize coronary flow and assess heart function in patients newly diagnosed with hypertension and currently on ARBs or calcium channel blockers (CCBs). CFV improved significantly in the hypertensive patients after 12 weeks of ARB treatment but not in those treated with CCBs. Second, using murine models of pressure overload, including Ang II infusion and aortic banding, we mimicked the clinical conditions of Ang II- and mechanical stress-induced hypertension, respectively. Both Ang II infusion and aortic banding increased the end-systolic pressure-volume relationship and cardiac fibrosis, but interestingly, only Ang II infusion resulted in a significant reduction in CFV and corresponding activation of pressure-sensitive proteins, including connective tissue growth factor, hypoxia-inducible factor 1α and signal transducer and activator of transcription 3. These data support the existence of a molecular and functional link between AngII-induced hemodynamic remodeling and alterations in coronary vasculature, which, in part, can explain the clinical benefit of ARB treatment in hypertensive patients.

MicroRNA-21 regulates right ventricular remodeling secondary to pulmonary arterial pressure overload.

Right ventricular (RV) function is a critical determinant of survival in patients with pulmonary arterial hypertension (PAH). While miR-21 is known to associate with vascular remodeling in small animal models of PAH, its role in RV remodeling in large animal models has not been characterized. Herein, we investigated the role of miR-21 in RV dysfunction using a sheep model of PAH secondary to pulmonary arterial constriction (PAC). RV structural and functional remodeling were examined using ultrasound imaging. Our results showed that post PAC, RV strain significantly decreased at the basal region compared with t the control. Moreover, such dysfunction was accompanied by increases in miR-21 levels. To determine the role of miR-21 in RV remodeling secondary to PAC, we investigated the molecular alteration secondary to phenylephrine induced hypertrophy and miR21 overexpression in vitro using neonatal rat ventricular myocytes (NRVMs). We found that overexpression of miR-21 in the setting of hypertrophic stimulation augmented only the expression of proteins critical for mitosis but not cytokinesis. Strikingly, this molecular alteration was associated with an eccentric cellular hypertrophic phenotype similar to what we observed in vivo PAC animal model in sheep. Importantly, this hypertrophic change was diminished upon suppressing miR-21 in NRVMs. Collectively, our in vitro and in vivo data demonstrate that miR-21 is a critical contributor in the development of RV dysfunction and could represent a novel therapeutic target for PAH associated RV dysfunction.

Integrated Skin Transcriptomics and Serum Multiplex Assays Reveal Novel Mechanisms of Wound Healing in Diabetic Foot Ulcers.

Nonhealing diabetic foot ulcers (DFUs) are characterized by low-grade chronic inflammation, both locally and systemically. We prospectively followed a group of patients who either healed or developed nonhealing chronic DFUs. Serum and forearm skin analysis, both at the protein expression and the transcriptomic level, indicated that increased expression of factors such as interferon-γ (IFN-γ), vascular endothelial growth factor, and soluble vascular cell adhesion molecule-1 were associated with DFU healing. Furthermore, foot skin single-cell RNA sequencing analysis showed multiple fibroblast cell clusters and increased inflammation in the dorsal skin of patients with diabetes mellitus (DM) and DFU specimens compared with control subjects. In addition, in myeloid cell DM and DFU upstream regulator analysis, we observed inhibition of interleukin-13 and IFN-γ and dysregulation of biological processes that included cell movement of monocytes, migration of dendritic cells, and chemotaxis of antigen-presenting cells pointing to an impaired migratory profile of immune cells in DM skin. The SLCO2A1 and CYP1A1 genes, which were upregulated at the forearm of nonhealers, were mainly expressed by the vascular endothelial cell cluster almost exclusively in DFU, indicating a potential important role in wound healing. These results from integrated protein and transcriptome analyses identified individual genes and pathways that can potentially be targeted for enhancing DFU healing.

Preclinical development of a miR-132 inhibitor for heart failure treatment.

Despite proven efficacy of pharmacotherapies targeting primarily global neurohormonal dysregulation, heart failure (HF) is a growing pandemic with increasing burden. Treatments mechanistically focusing at the cardiomyocyte level are lacking. MicroRNAs (miRNA) are transcriptional regulators and essential drivers of disease progression. We previously demonstrated that miR-132 is both necessary and sufficient to drive the pathological cardiomyocytes growth, a hallmark of adverse cardiac remodelling. Therefore, miR-132 may serve as a target for HF therapy. Here we report further mechanistic insight of the mode of action and translational evidence for an optimized, synthetic locked nucleic acid antisense oligonucleotide inhibitor (antimiR-132). We reveal the compound's therapeutic efficacy in various models, including a clinically highly relevant pig model of HF. We demonstrate favourable pharmacokinetics, safety, tolerability, dose-dependent PK/PD relationships and high clinical potential for the antimiR-132 treatment scheme.

Natural Compound Library Screening Identifies New Molecules for the Treatment of Cardiac Fibrosis and Diastolic Dysfunction.

BACKGROUND: Myocardial fibrosis is a hallmark of cardiac remodeling and functionally involved in heart failure development, a leading cause of deaths worldwide. Clinically, no therapeutic strategy is available that specifically attenuates maladaptive responses of cardiac fibroblasts, the effector cells of fibrosis in the heart. Therefore, our aim was to develop novel antifibrotic therapeutics based on naturally derived substance library screens for the treatment of cardiac fibrosis. METHODS: Antifibrotic drug candidates were identified by functional screening of 480 chemically diverse natural compounds in primary human cardiac fibroblasts, subsequent validation, and mechanistic in vitro and in vivo studies. Hits were analyzed for dose-dependent inhibition of proliferation of human cardiac fibroblasts, modulation of apoptosis, and extracellular matrix expression. In vitro findings were confirmed in vivo with an angiotensin II-mediated murine model of cardiac fibrosis in both preventive and therapeutic settings, as well as in the Dahl salt-sensitive rat model. To investigate the mechanism underlying the antifibrotic potential of the lead compounds, treatment-dependent changes in the noncoding RNAome in primary human cardiac fibroblasts were analyzed by RNA deep sequencing. RESULTS: High-throughput natural compound library screening identified 15 substances with antiproliferative effects in human cardiac fibroblasts. Using multiple in vitro fibrosis assays and stringent selection algorithms, we identified the steroid bufalin (from Chinese toad venom) and the alkaloid lycorine (from Amaryllidaceae species) to be effective antifibrotic molecules both in vitro and in vivo, leading to improvement in diastolic function in 2 hypertension-dependent rodent models of cardiac fibrosis. Administration at effective doses did not change plasma damage markers or the morphology of kidney and liver, providing the first toxicological safety data. Using next-generation sequencing, we identified the conserved microRNA 671-5p and downstream the antifibrotic selenoprotein P1 as common effectors of the antifibrotic compounds. CONCLUSIONS: We identified the molecules bufalin and lycorine as drug candidates for therapeutic applications in cardiac fibrosis and diastolic dysfunction.

Topical Application of a Mast Cell Stabilizer Improves Impaired Diabetic Wound Healing.

Impaired wound healing in the diabetic foot is a major problem often leading to amputation. Mast cells have been shown to regulate wound healing in diabetes. We developed an indole-carboxamide type mast cell stabilizer, MCS-01, which proved to be an effective mast cell degranulation inhibitor in vitro and can be delivered topically for prolonged periods through controlled release by specifically designed alginate bandages. In diabetic mice, both pre- and post-wounding, topical MCS-01 application accelerated wound healing comparable to that achieved with systemic mast cell stabilization. Moreover, MCS-01 altered the macrophage phenotype, promoting classically activated polarization. Bulk transcriptome analysis from wounds treated with MCS-01 or placebo showed that MCS-01 significantly modulated the mRNA and microRNA profile of diabetic wounds, stimulated upregulation of pathways linked to acute inflammation and immune cell migration, and activated the NF-κB complex along with other master regulators of inflammation. Single-cell RNA sequencing analysis of 6,154 cells from wounded and unwounded mouse skin revealed that MCS-01 primarily altered the gene expression of mast cells, monocytes, and keratinocytes. Taken together, these findings offer insights into the process of diabetic wound healing and suggest topical mast cell stabilization as a potentially successful treatment for diabetic foot ulceration.

Alteration in ventricular pressure stimulates cardiac repair and remodeling.

The mammalian heart undergoes complex structural and functional remodeling to compensate for stresses such as pressure overload. While studies suggest that, at best, the adult mammalian heart is capable of very limited regeneration arising from the proliferation of existing cardiomyocytes, how myocardial stress affects endogenous cardiac regeneration or repair is unknown. To define the relationship between left ventricular afterload and cardiac repair, we induced left ventricle pressure overload in adult mice by constriction of the ascending aorta (AAC). One week following AAC, we normalized ventricular afterload in a subset of animals through removal of the aortic constriction (de-AAC). Subsequent monitoring of cardiomyocyte cell cycle activity via thymidine analog labeling revealed that an acute increase in ventricular afterload induced cardiomyocyte proliferation. Intriguingly, a release in ventricular overload (de-AAC) further increases cardiomyocyte proliferation. Following both AAC and de-AAC, thymidine analog-positive cardiomyocytes exhibited characteristics of newly generated cardiomyocytes, including single diploid nuclei and reduced cell size as compared to age-matched, sham-operated adult mouse myocytes. Notably, those smaller cardiomyocytes frequently resided alongside one another, consistent with local stimulation of cellular proliferation. Collectively, our data demonstrate that adult cardiomyocyte proliferation can be locally stimulated by an acute increase or decrease of ventricular pressure, and this mode of stimulation can be harnessed to promote cardiac repair.

Noncoding RNAs in Heart Failure.

Heart failure is a major contributor to the healthcare burden and mortality worldwide. Current treatment strategies are able to slow down the transition of healthy heart into the failing one; nevertheless better understanding of the complex genetic regulation of maladaptive remodeling in the failing heart is essential for new drug discovery. Noncoding RNAs are key epigenetic regulators of cardiac gene expression and thus significantly influence cardiac homeostasis and functions.In this chapter we will discuss characteristics of noncoding RNAs, especially miRNAs, long noncoding RNAs, and circular RNAs, and review recent evidences proving their profound involvement during different stages of heart failure progression. Several open questions still prevent the extensive use of noncoding RNA-modulating therapies in clinics; yet they are becoming an attractive target to define novel regulatory mechanisms in the heart. In-depth study of their interaction with gene networks will refine our current view of heart failure and revolutionize the drug development in coming years.

Impairment of Wound Healing in Patients With Type 2 Diabetes Mellitus Influences Circulating MicroRNA Patterns via Inflammatory Cytokines.

OBJECTIVE: MicroRNAs (miRNA/miR) are stably present in body fluids and are increasingly explored as disease biomarkers. Here, we investigated influence of impaired wound healing on the plasma miRNA signature and their functional importance in patients with type 2 diabetes mellitus. APPROACH AND RESULTS: miRNA array profiling identified 41 miRNAs significantly deregulated in diabetic controls when compared with patients with diabetes mellitus-associated peripheral arterial disease and chronic wounds. Quantitative real-time polymerase chain reaction validation confirmed decrease in circulating miR-191 and miR-200b levels in type 2 diabetic versus healthy controls. This was reverted in diabetic subjects with associated peripheral arterial disease and chronic wounds, who also exhibited higher circulating C-reactive protein and proinflammatory cytokine levels compared with diabetic controls. miR-191 and miR-200b were significantly correlated with C-reactive protein or cytokine levels in patients with diabetes mellitus. Indeed, proinflammatory stress increased endothelial- or platelet-derived secretion of miR-191 or miR-200b. In addition, dermal cells took up endothelial-derived miR-191 leading to downregulation of the miR-191 target zonula occludens-1. Altered miR-191 expression influenced angiogenesis and migratory capacities of diabetic dermal endothelial cells or fibroblasts, respectively, partly via its target zonula occludens-1. CONCLUSIONS: This study reports that (1) inflammation underlying nonhealing wounds in patients with type 2 diabetes mellitus influences plasma miRNA concentrations and (2) miR-191 modulates cellular migration and angiogenesis via paracrine regulation of zonula occludens-1 to delay the tissue repair process.

Thrombin receptor protease-activated receptor 4 is a key regulator of exaggerated intimal thickening in diabetes mellitus.

BACKGROUND: Diabetes mellitus predisposes to thrombotic and proliferative vascular remodeling, to which thrombin contributes via activation of protease-activated receptor (PAR) 1. However, the use of PAR-1 inhibitors to suppress remodeling may be limited by severe bleeding. We recently reported upregulation of an additional thrombin receptor, PAR-4, in human vascular smooth muscle cells exposed to high glucose and have now examined PAR-4 as a novel mediator linking hyperglycemia, hypercoagulation, and vascular remodeling in diabetes mellitus. METHODS AND RESULTS: PAR-4 expression was increased in carotid atherectomies and saphenous vein specimens from diabetic versus nondiabetic patients and in aorta and carotid arteries from streptozotocin-diabetic versus nondiabetic C57BL/6 mice. Vascular PAR-1 mRNA was not increased in diabetic mice. Ligated carotid arteries from diabetic mice developed more extensive neointimal hyperplasia and showed greater proliferation than arteries from nondiabetic mice. The augmented remodeling response was absent in diabetic mice deficient in PAR-4. At the cellular level, PAR-4 expression was controlled via the mRNA stabilizing actions of human antigen R, which accounted for the stimulatory actions of high glucose, angiotensin II, and H2O2 on PAR-4 expression, whereas cicaprost via protein kinase A activation counteracted this effect. CONCLUSIONS: PAR-4 appears to play a hitherto unsuspected role in diabetic vasculopathy. The development of PAR-4 inhibitors might serve to limit mainly proliferative processes in restenosis-prone diabetic patients, particularly those patients in whom severe bleeding attributed to selective PAR-1 blockade or complete thrombin inhibition must be avoided or those who do not require anticoagulation.

Diabetes-associated microRNAs in pediatric patients with type 1 diabetes mellitus: a cross-sectional cohort study.

CONTEXT: Circulating microRNAs (miRNAs/miRs) are used as novel biomarkers for diseases. miR-21, miR-126, and miR-210 are known to be deregulated in vivo or in vitro under diabetic conditions. OBJECTIVE: The aim of this study was to investigate the circulating miR-21, miR-126, and miR-210 in plasma and urine from pediatric patients with type 1 diabetes and to link our findings to cardiovascular and diabetic nephropathy risk factors in children with type 1 diabetes. DESIGN: miR-21, miR-126, and miR-210 concentrations were measured with quantitative RT-PCR in plasma and urine samples from 68 pediatric patients with type 1 diabetes and 79 sex- and age-matched controls. SETTING: The study consisted of clinical pediatric patients with type 1 diabetes. PATIENTS OR OTHER PARTICIPANTS: Inclusion criterion for patients was diagnosed type 1 diabetes. Exclusion criteria were febrile illness during the last 3 months; chronic inflammatory or rheumatic disease; hepatitis; HIV; glucocorticoid treatment; liver, renal, or cardiac failure; or hereditary dyslipidemia. Patients were age and sex matched to controls. MAIN OUTCOME MEASURE(S): Main outcome parameters were changes in miR-21, miR-126, and miR-210 concentration in plasma and urine from type 1 diabetic patients compared with corresponding controls. RESULTS: Circulating miRNA levels of miR-21 and miR-210 were significantly up-regulated in the plasma and urine of the type 1 diabetic patients. Urinary miR-126 levels in diabetic patients were significantly lower than in age- and gender-matched controls and negatively correlated between the patient's glycated hemoglobin mean and miR-126 concentration value. In contrast, circulating miR-126 levels in plasma were comparable in both cohorts. For urinary miR-21, we found by an adjusted receiver-operating characteristic-curve analysis with an area under the curve of 0.78. CONCLUSIONS: Type 1 diabetic pediatric patients revealed a significant deregulation of miR-21, miR-126, and miR-210 in plasma and urinary samples, which might indicate an early onset of diabetic-associated diseases.

Cardiac fibroblast-derived microRNA passenger strand-enriched exosomes mediate cardiomyocyte hypertrophy.

In response to stress, the heart undergoes extensive cardiac remodeling that results in cardiac fibrosis and pathological growth of cardiomyocytes (hypertrophy), which contribute to heart failure. Alterations in microRNA (miRNA) levels are associated with dysfunctional gene expression profiles associated with many cardiovascular disease conditions; however, miRNAs have emerged recently as paracrine signaling mediators. Thus, we investigated a potential paracrine miRNA crosstalk between cardiac fibroblasts and cardiomyocytes and found that cardiac fibroblasts secrete miRNA-enriched exosomes. Surprisingly, evaluation of the miRNA content of cardiac fibroblast-derived exosomes revealed a relatively high abundance of many miRNA passenger strands ("star" miRNAs), which normally undergo intracellular degradation. Using confocal imaging and coculture assays, we identified fibroblast exosomal-derived miR-21_3p (miR-21*) as a potent paracrine-acting RNA molecule that induces cardiomyocyte hypertrophy. Proteome profiling identified sorbin and SH3 domain-containing protein 2 (SORBS2) and PDZ and LIM domain 5 (PDLIM5) as miR-21* targets, and silencing SORBS2 or PDLIM5 in cardiomyocytes induced hypertrophy. Pharmacological inhibition of miR-21* in a mouse model of Ang II-induced cardiac hypertrophy attenuated pathology. These findings demonstrate that cardiac fibroblasts secrete star miRNA-enriched exosomes and identify fibroblast-derived miR-21* as a paracrine signaling mediator of cardiomyocyte hypertrophy that has potential as a therapeutic target.

MicroRNAs in the bile of patients with biliary strictures after liver transplantation.

Biliary complications after liver transplantation remain a major cause of morbidity and reduced graft survival. Ischemic-type biliary lesions (ITBLs) are common and difficult to treat. The pathophysiology of ITBLs remains unclear, and diagnostic markers are still missing. The analysis of microRNA (miRNA) profiles is an evolving field in hepatology. Our aim was to identify specific miRNA patterns in the bile of patients with ITBLs after liver transplantation. Liver transplant patients with biliary complications were included in a cross-sectional study. Patients with ITBLs (n = 37), anastomotic strictures (ASs; n = 39), and bile duct stones (BDSs; n = 12) were compared. Patients with ITBLs were categorized by disease severity. The miRNA concentrations in bile were determined with global miRNA profiling and subsequent miRNA-specific polymerase chain reaction-mediated validation. The concentrations of microRNA 517a (miR-517a), miR-892a, and miR-106a* in bile were increased for patients with ITBLs versus patients with ASs or BDSs (P < 0.05). Categorization by ITBL severity showed higher median concentrations in patients with intrahepatic and extrahepatic strictures (P > 0.05). miR-210, miR-337-5p, miR-577, and miR-329 displayed no statistical differences. In conclusion, miR-517a, miR-892a, and miR-106a* are increased in the bile fluid of patients with ITBLs versus patients with ASs or BDSs. An analysis of miRNA profiles may be useful in the diagnosis and management of patients with ITBLs. Future studies are needed to prove the potential prognostic value of these miRNAs.

microRNA therapeutics in cardiovascular disease models.

Cardiovascular diseases are a major cause of human morbidity and mortality, posing a high socioeconomic burden on the health sector worldwide. microRNAs (miRNAs) constitute a new class of unique molecular regulators involved in the pathophysiology of a wide range of disorders. Studies in the past decade have identified miRNA signatures of various cardiovascular disorders and successfully validated miRNA-based therapeutic options in various small and a few large experimental cardiovascular disease models. In these models, researchers manipulate the expression of miRNAs and downstream signaling cascades, aiming to prevent and cure cardiovascular disease. Here, we review and discuss the recent reports on the in vivo use of miRNA animal models and miRNA therapeutic development as well as provide an outlook for clinical applications in the near future.

MicroRNA-mediated epigenetic silencing of sirtuin1 contributes to impaired angiogenic responses.

RATIONALE: Transforming growth factor (TGF)-ß was linked to abnormal vessel function and can mediate impairment of endothelial angiogenic responses. Its effect on microRNAs and downstream targets in this context is not known. OBJECTIVE: To study the role of microRNAs in TGF-ß-mediated angiogenic activity. METHODS AND RESULTS: MicroRNA profiling after TGF-ß treatment of endothelial cells identified miR-30a-3p, along with other members of the miR-30 family, to be strongly silenced. Supplementation of miR-30a-3p restored function in TGF-ß-treated endothelial cells. We identified the epigenetic factor methyl-CpG-binding protein 2 (MeCP2) to be a direct and functional target of miR-30a-3p. Viral overexpression of MeCP2 mimicked the effects of TGF-ß, suggesting that derepression of MeCP2 after TGF-ß treatment may be responsible for impaired angiogenic responses. Silencing of MeCP2 rescued detrimental TGF-ß effects on endothelial cells. Microarray transcriptome analysis of MeCP2-overexpressing endothelial cells identified several deregulated genes important for endothelial cell function including sirtuin1 (Sirt1). In vivo experiments using endothelial cell-specific MeCP2 null or Sirt1 transgenic mice confirmed the involvement of MeCP2/Sirt1 in the regulation of angiogenic functions of endothelial cells. Additional experiments identified that MeCP2 inhibited endothelial angiogenic characteristics partly by epigenetic silencing of Sirt1. CONCLUSIONS: TGF-ß impairs endothelial angiogenic responses partly by downregulating miR-30a-3p and subsequent derepression of MeCP2-mediated epigenetic silencing of Sirt1.

Circulating miR-423_5p fails as a biomarker for systemic ventricular function in adults after atrial repair for transposition of the great arteries.

BACKGROUND: Recently, the microRNA miR-423_5p was identified as a biomarker for left ventricular heart failure. Its role in patients with a systemic right ventricle and reduced ejection fraction after atrial repair for transposition of the great arteries has not been evaluated. METHODS: In 41 patients and 10 age- and sex-matched healthy controls circulating miR-423_5p concentration was measured and correlated to clinical parameters, cardiac functional parameters assessed by magnetic resonance imaging, and cardiopulmonary exercise testing. RESULTS: Levels of circulating miR-423_5p showed no difference between patients and controls. Further, there was no correlation between miR-423_5p and parameters of cardiopulmonary exercise testing or imaging findings. CONCLUSIONS: In patients with a systemic right ventricle and reduced ejection fraction miR-423_5p levels are not elevated. Therefore, circulating miR-423_5p is not a useful biomarker for heart failure in this patient group.