MicroRNAs in Postischemic Vascular Repair

MicroRNA Expression Analysis of Mice Retinas with Oxygen-Induced Retinopathy by RNA Sequencing

Purpose. To characterize the microRNA (miRNA) expression profiles in the retinas of mice with oxygen-induced retinopathy by RNA sequencing and to ascertain miRNAs associated with retinal neovascularization. Methods. Retina samples were obtained from 3 groups (6 retinas/group) of OIR mice and normal mice at P17. RNA was isolated from 24 retina samples and then detected on an Illumina HiSeq. Twelve retina samples were used for quantitative polymerase chain reaction to validate the RNA sequencing. Bioinformatics analyses were performed. Result. The RNA sequence showed that 565 miRNAs were detected in the retina of OIR mice and 583 miRNAs in the retina of normal control mice. A total of 553 miRNAs were expressed in both groups. Thirty-eight miRNAs showed altered expression in both groups ( $p\le 0.05$ ). Compared with the control group, 2 miRNAs were significantly upregulated in the OIR group, while 36 miRNAs were significantly downregulated. Meanwhile, 2 candidate miRNAs (miR-181a-5p and miR-21a-5p) with significant differences in miRNA expression ( $p<0.01$ ) were selected for validation. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to confirm the relative expression of the two miRNAs. Bioinformatics analyses showed that pathways involved in ischemic retinopathy (such as TGF-β, Ras, Hippo, PI3K-Akt, VEGF, and HIF-1 signaling pathways) were enriched. Conclusions. Our study provided an overall view of miRNA profiling in the OIR retina. These miRNA profiles provide a valuable framework for the potential therapy of retinal angiogenesis.

Comparative evaluation of coronary disease burden: bicuspid valve disease is not atheroprotective

OBJECTIVE

Bicuspid aortic valve (BAV) has been associated with less atherosclerosis as compared with tricuspid aortic valve (TAV) patients. It, however, remains unclear whether this reflects the older age of TAV patients and/or accumulation of atherosclerotic risk factors or that the BAV phenotype is atheroprotective. Therefore, we compared the atherosclerotic disease burden of BAV and TAV patients, with that of the general (age-matched) population.

METHODS

The prevalence of coronary artery disease (CAD) and CAD risk factors in BAV and TAV patients who underwent aortic valve surgery were compared with the Dutch general practitioners registry data. BAV (n=454) and TAV (n=1101) patients were divided into four groups: BAV with aortic valve stenosis (BAV-AoS), BAV with aortic valve regurgitation (BAV-AR), TAV with AoS (TAV-AoS) and TAV with AR (TAV-AR). The atherosclerotic disease burden of each group was compared with that of the corresponding age cohort for the general population.

RESULTS

CAD risk factors hypertension and hypercholesterolaemia were more prevalent in the surgery groups than the age-matched general population (all p<0.001). All BAVs (BAV-AoS and BAV-AR) and TAV-AR had a similar incidence of CAD history as compared to the age-matched general populations (p=0.689, p=0.325 and p=0.617 respectively), whereas TAV-AoS had a higher incidence (21.6% versus 14.9% in the age-matched general population, p<0.001).

CONCLUSIONS

Stenotic TAV disease is part of the atherosclerotic disease spectrum, while regurgitant TAV and all BAVs are not. Although the prevalence of cardiovascular risk factors is higher in all BAV patients, the prevalence of CAD is similar to the general population.

Nutraceutical Targeting of Inflammation-Modulating microRNAs in Severe Forms of COVID-19: A Novel Approach to Prevent the Cytokine Storm

The coronavirus disease 2019 (COVID-19) pandemic has become the number one health problem worldwide. As of August 2020, it has affected more than 18 million humans and caused over 700,000 deaths worldwide. COVID-19 is an infectious disease that can lead to severe acute respiratory syndrome. Under certain circumstances, the viral infection leads to excessive and uncontrolled inflammatory response, which is associated with the massive release of inflammatory cytokines in pulmonary alveolar structures. This phenomenon has been referred to as the “cytokine storm,” and it is closely linked to lung injury, acute respiratory syndrome and mortality. Unfortunately, there is currently no vaccine available to prevent the infection, and no effective treatment is available to reduce the mortality associated with the severe form of the disease. The cytokine storm associate with COVID-19 shows similarities with those observed in other pathologies such as sepsis, acute respiratory distress syndrome, acute lung injury and other viral infection including severe cases of influenza. However, the specific mechanisms that cause and modulate the cytokine storm in the different conditions remain to be determined. micro-RNAs are important regulators of gene expression, including key inflammatory cytokines involved in the massive recruitment of immune cells to the lungs such as IL1β, IL6, and TNFα. In recent years, it has been shown that nutraceutical agents can modulate the expression of miRs involved in the regulation of cytokines in various inflammatory diseases. Here we review the potential role of inflammatory-regulating-miRs in the cytokine storm associated with COVID-19, and propose that nutraceutical agents may represent a supportive therapeutic approach to modulate dysregulated miRs in this condition, providing benefits in severe respiratory diseases.

MicroRNA Expression Profiling of Bone Marrow-Derived Proangiogenic Cells (PACs) in a Mouse Model of Hindlimb Ischemia: Modulation by Classical Cardiovascular Risk Factors

Background

Classical cardiovascular risk factors (CRFs) are associated with impaired angiogenic activities of bone marrow–derived proangiogenic cells (PACs) related to peripheral artery diseases (PADs) and ischemia-induced neovascularization. MicroRNAs (miRs) are key regulators of gene expression, and they are involved in the modulation of PAC function and PAC paracrine activity. However, the effects of CRFs on the modulation of miR expression in PACs are unknown.

Aims and Methods

We used a model of hindlimb ischemia and next-generation sequencing to perform a complete profiling of miRs in PACs isolated from the bone marrow of mice subjected to three models of CRFs: aging, smoking (SMK) and hypercholesterolemia (HC).

Results

Approximately 570 miRs were detected in PACs in the different CRF models. When excluding miRs with a very low expression level (<100 RPM), 40 to 61 miRs were found to be significantly modulated by aging, SMK, or HC. In each CRF condition, we identified downregulated proangiogenic miRs and upregulated antiangiogenic miRs that could contribute to explain PAC dysfunction. Interestingly, several miRs were similarly downregulated (e.g., miR-542-3p, miR-29) or upregulated (e.g., miR-501, miR-92a) in all CRF conditions. In silico approaches including Kyoto Encyclopedia of Genes and Genomes and cluster dendogram analyses identified predictive effects of these miRs on pathways having key roles in the modulation of angiogenesis and PAC function, including vascular endothelial growth factor signaling, extracellular matrix remodeling, PI3K/AKT/MAPK signaling, transforming growth factor beta (TGFb) pathway, p53, and cell cycle progression.

Conclusion

This study describes for the first time the effects of CRFs on the modulation of miR profile in PACs related to PAD and ischemia-induced neovascularization. We found that several angiogenesis-modulating miRs are similarly altered in different CRF conditions. Our findings constitute a solid framework for the identification of miRs that could be targeted in PACs in order to improve their angiogenic function and for the future development of novel therapies to improve neovascularization and reduce tissue damage in patients with severe PAD.

Computerised cognitive training to improve cognition including delirium following coronary artery bypass grafting surgery: protocol for a blinded randomised controlled trial

INTRODUCTION

Coronary artery bypass grafting (CABG) surgery is known to improve vascular function and cardiac-related mortality rates; however, it is associated with high rates of postoperative cognitive decline and delirium. Previous attempts to prevent post-CABG cognitive decline using pharmacological and surgical approaches have been largely unsuccessful. Cognitive prehabilitation and rehabilitation are a viable yet untested option for CABG patients. We aim to investigate the effects of preoperative cognitive training on delirium incidence, and preoperative and postoperative cognitive training on cognitive decline at 4 months post-CABG.

METHODS AND ANALYSIS

This study is a randomised, single-blinded, controlled trial investigating the use of computerised cognitive training (CCT) both pre-CABG and post-CABG (intervention group) compared with usual care (control group) in older adults undergoing CABG in Adelaide, South Australia. Those in the intervention group will complete 1-2 weeks of CCT preoperatively (45-60 min sessions, 3.5 sessions/week) and 12 weeks of CCT postoperatively (commencing 1 month following surgery, 45-60 min sessions, 3 sessions/week). All participants will undergo cognitive testing preoperatively, over their hospital stay including delirium, and postoperatively for up to 1 year. The primary delirium outcome variable will be delirium incidence (presence vs absence); the primary cognitive decline variable will be at 4 months (significant decline vs no significant decline/improvement from baseline). Logistic regression modelling will be used, with age and gender as covariates. Secondary outcomes include cognitive decline from baseline to discharge, and at 6 months and 1 year post-CABG.

ETHICS AND DISSEMINATION

Ethics approval was obtained from the Central Adelaide Local Health Network Human Research Ethics Committee (South Australia, Australia) and the University of South Australia Human Ethics Committee, with original approval obtained on 13 December 2017. It is anticipated that approximately two to four publications and multiple conference presentations (national and international) will result from this research.

TRIAL REGISTRATION NUMBER

This clinical trial is registered with the Australian New Zealand Clinical Trials Registry and relates to the pre-results stage. Registration number: ACTRN12618000799257.

MicroRNA-96 Promotes Vascular Repair in Oxygen-Induced Retinopathy-A Novel Uncovered Vasoprotective Function

Background and Aims

Vascular degeneration is a hallmark in the pathogenesis of oxygen-induced retinopathy (OIR). Dysregulation of microRNAs (miRNAs), key regulators of genes expressions, has been implicated in the regulation of ocular angiogenesis. However, miRNAs specific functions in impaired vascular development during OIR are poorly understood. Herein, we identified miR-96 as one of the most highly expressed miRNAs in the retina and choroid during vascular development and investigated the potential role of miR-96 on microvascular degeneration in a rat OIR model.

Methods and Results

Next generation sequencing (NGS) and qRT-PCR analysis showed that miR-96 maintain high levels of expression during ocular vascular development. Nevertheless, miR-96 was significantly downregulated in the retina and choroid of OIR rats (80% O₂ from P5 to P10) during the phase of microvascular degeneration. Similarly, human retinal microvascular endothelial cells (HRMEC) subjected to hyperoxia (80% O₂) showed a significant downregulation of miR-96 evaluated by qPCR. Interestingly, HRMEC supplemented with miR-96 regulated positively the expression of several key angiogenic factors including VEGF and ANG-2. To explore the angiogenic activity of miR-96 on HRMEC, we performed a gain/loss of function study. In a similar way to hyperoxia exposure, we observed a robust angiogenic impairment (tubulogenesis and migration) on HRMEC transfected with an antagomiR-96. Conversely, overexpression of miR-96 stimulated the angiogenic activity of HRMEC and protected against hyperoxia-induced endothelial dysfunction. Finally, we evaluated the potential vasoprotective function of miR-96 in OIR animals. Rat pups intravitreally supplemented with miR-96 mimic (1 mg/kg) displayed a significant preservation of retinal/choroidal microvessels at P10 compared to controls. This result was consistent with the maintenance of physiologic levels of VEGF and ANG-2 in the OIR retina.

Conclusion

This study demonstrates that miR-96 regulates the expression of angiogenic factors (VEGF/ANG-2) associated to the maintenance of retinal and choroidal microvasculature during physiological and pathological conditions. Intravitreal supplementation of miR-96 mimic could constitute a novel therapeutic strategy to improve vascular repair in OIR and other ischemic retinopathies.

MicroRNA expression profile in retina and choroid in oxygen-induced retinopathy model

Background

Ischemic retinopathies (IRs) are leading causes of visual impairment. They are characterized by an initial phase of microvascular degeneration and a second phase of aberrant pre-retinal neovascularization (NV). microRNAs (miRNAs) regulate gene expression, and a number play a role in normal and pathological NV. But, post-transcriptional modulation of miRNAs in the eye during the development of IRs has not been systematically evaluated.

Aims & methods

Using Next Generation Sequencing (NGS) we profiled miRNA expression in the retina and choroid during vasodegenerative and NV phases of oxygen-induced retinopathy (OIR).

Results

Approximately 20% of total miRNAs exhibited altered expression (up- or down-regulation); 6% of miRNA were found highly expressed in retina and choroid of rats subjected to OIR. During OIR-induced vessel degeneration phase, miR-199a-3p, -199a-5p, -1b, -126a-3p displayed a robust decreased expression (> 85%) in the retina. While in the choroid, miR-152-3p, -142-3p, -148a-3p, -532-3p were upregulated (>200%) and miR-96-5p, -124-3p, -9a-3p, -190b-5p, -181a-1-3p, -9a-5p, -183-5p were downregulated (>70%) compared to controls. During peak pathological NV, miR-30a-5p, -30e-5p and 190b-5p were markedly reduced (>70%), and miR-30e-3p, miR-335, -30b-5p strongly augmented (by up to 300%) in the retina. Whereas in choroid, miR-let-7f-5p, miR-126a-5p and miR-101a-3p were downregulated by (>81%), and miR-125a-5p, let-7e-5p and let-7g-5p were upregulated by (>570%) during NV. Changes in miRNA observed using NGS were validated using qRT-PCR for the 24 most modulated miRNAs. In silico approach to predict miRNA target genes (using algorithms of miRSystem database) identified potential new target genes with pro-inflammatory, apoptotic and angiogenic properties.

Conclusion

The present study is the first comprehensive description of retinal/choroidal miRNAs profiling in OIR (using NGS technology). Our results provide a valuable framework for the characterization and possible therapeutic potential of specific miRNAs involved in ocular IR-triggered inflammation, angiogenesis and degeneration.

Let's talk numbers: a qualitative study of community-dwelling US adults to understand the role of numeracy in the management of heart failure

OBJECTIVE

To examine the perspectives of adults with heart failure (HF) about numerical concepts integral to HF self-care.

SETTING

This qualitative study took place at an urban academic primary care practice.

PARTICIPANTS

Thirty men and women aged 47-89 years with a history of HF were recruited to participate. Eligibility criteria included: a history of HF (≥1 year), seen at the clinic within the last year, and a HF hospitalisation within the last 6 months. Non-English speakers and those with severe cognitive impairment were excluded.

METHODS

In-depth semistructured interviews were conducted. Participants were interviewed about numeracy across three domains of HF self-care: (1) monitoring weight,(2) maintaining a diet low in salt and (3) monitoring blood pressure. Interviews were audio-taped, transcribed verbatim and analysed using grounded theory and word cloud techniques.

RESULTS

Five key themes reflecting participants' attitudes towards numerical concepts pertaining to weight, diet and blood pressure were identified: (1) Communication between healthcare providers and patients is a complex, multistage process; (2) Patients possess a wide range of knowledge and understanding; (3) Social and caregiver support is critical for the application of numerical concepts; (4) Prior health experiences shape outlook towards numerical concepts and instructions and (5) Fear serves as a barrier and a facilitator to carrying out HF self-care tasks that involve numbers. The findings informed a theoretical framework of health numeracy in HF.

CONCLUSION

Effective communication of numerical concepts which pertain to HF self-care is highly variable. Many patients with HF lack basic understanding and numeracy skills required for adequate self-care. As such, patients rely on caregivers who may lack HF training. HF-specific training of caregivers and research that seeks to elucidate the intricacies of the patient-caregiver relationship in the context of health numeracy and HF self-care are warranted.

MicroRNA-148b Targets the TGF-β Pathway to Regulate Angiogenesis and Endothelial-to-Mesenchymal Transition during Skin Wound Healing

Transforming growth factor beta (TGF-β) is crucial for regulation of the endothelial cell (EC) homeostasis. Perturbation of TGF-β signaling leads to pathological conditions in the vasculature, causing cardiovascular disease and fibrotic disorders. The TGF-β pathway is critical in endothelial-to-mesenchymal transition (EndMT), but a gap remains in our understanding of the regulation of TGF-β and related signaling in the endothelium. This study applied a gain- and loss-of function approach and an in vivo model of skin wound healing to demonstrate that miR-148b regulates TGF-β signaling and has a key role in EndMT, targeting TGFB2 and SMAD2. Overexpression of miR-148b increased EC migration, proliferation, and angiogenesis, whereas its inhibition promoted EndMT. Cytokine challenge decreased miR-148b levels in ECs while promoting EndMT through the regulation of SMAD2. Finally, in a mouse model of skin wound healing, delivery of miR-148b mimics promoted wound vascularization and accelerated closure. In contrast, inhibition of miR-148b enhanced EndMT in wounds, resulting in impaired wound closure that was reversed by SMAD2 silencing. Together, these results demonstrate for the first time that miR-148b is a key factor controlling EndMT and vascularization. This opens new avenues for therapeutic application of miR-148b in vascular and tissue repair.

MicroRNA-based therapeutics in cardiovascular disease: screening and delivery to the target

MicroRNAs (miRNAs) are small non-coding RNAs of ∼22 nucleotides, which have increasingly been recognized as potent post-transcriptional regulators of gene expression. MiRNA targeting is defined by the complementarities between positions 2-8 of miRNA 5'-end with generally the 3'-untranslated region of target mRNAs (messenger RNAs). The capacity of miRNAs to simultaneously inhibit many different mRNAs allows for an amplification of biological responses. Hence, miRNAs are extremely attractive targets for therapeutic regulation in several diseases, including cardiovascular. Novel approaches are emerging to identify the miRNA functions in cardiovascular biology processes and to improve miRNA delivery in the heart and vasculature. In the present study, we provide an overview of current studies of miRNA functions in cardiovascular cells by the use of high-content screening. We also discuss the challenge to achieve a safe and targeted delivery of miRNA therapeutics in cardiovascular cells.

Hypoxia in CNS Pathologies: Emerging Role of miRNA-Based Neurotherapeutics and Yoga Based Alternative Therapies

Cellular respiration is a vital process for the existence of life. Any condition that results in deprivation of oxygen (also termed as hypoxia) may eventually lead to deleterious effects on the functioning of tissues. Brain being the highest consumer of oxygen is prone to increased risk of hypoxia-induced neurological insults. This in turn has been associated with many diseases of central nervous system (CNS) such as stroke, Alzheimer's, encephalopathy etc. Although several studies have investigated the pathophysiological mechanisms underlying ischemic/hypoxic CNS diseases, the knowledge about protective therapeutic strategies to ameliorate the affected neuronal cells is meager. This has augmented the need to improve our understanding of the hypoxic and ischemic events occurring in the brain and identify novel and alternate treatment modalities for such insults. MicroRNA (miRNAs), small non-coding RNA molecules, have recently emerged as potential neuroprotective agents as well as targets, under hypoxic conditions. These 18-22 nucleotide long RNA molecules are profusely present in brain and other organs and function as gene regulators by cleaving and silencing the gene expression. In brain, these are known to be involved in neuronal differentiation and plasticity. Therefore, targeting miRNA expression represents a novel therapeutic approach to intercede against hypoxic and ischemic brain injury. In the first part of this review, we will discuss the neurophysiological changes caused as a result of hypoxia, followed by the contribution of hypoxia in the neurodegenerative diseases. Secondly, we will provide recent updates and insights into the roles of miRNA in the regulation of genes in oxygen and glucose deprived brain in association with circadian rhythms and how these can be targeted as neuroprotective agents for CNS injuries. Finally, we will emphasize on alternate breathing or yogic interventions to overcome the hypoxia associated anomalies that could ultimately lead to improvement in cerebral perfusion.

Modulating microRNAs in cardiac surgery patients: Novel therapeutic opportunities?

This review focuses on microRNAs (miRs) in cardiac surgery, where they are emerging as potential targets for therapeutic intervention as well as novel clinical biomarkers. Identification of the up/down-regulation of specific miRs in defined groups of cardiac surgery patients can lead to the development of novel strategies for targeted treatment in order to maximise therapeutic results and minimise acute, delayed or chronic complications. MiRs could also be involved in determining the outcome independently of complications, for example in relation to myocardial perfusion and fibrosis. Because of their relevance in disease, their known sequence and pharmacological properties, miRs are attractive candidates for therapeutic manipulation. Pharmacological inhibition of individual miRs can be achieved by modified antisense oligonucleotides, referred to as antimiRs, while miR replacement can be achieved by miR mimics to increase the level of a specific miR. MiR mimics can restore the function of a lost or down-regulated miR, while antimiRs can inhibit the levels of disease-driving or aberrantly expressed miRs, thus de-repressing the expression of mRNAs targeted by the miR. The main delivery methods for miR therapeutics involve lipid-based vehicles, viral systems, cationic polymers, and intravenous or local injection of an antagomiR. Local delivery is particularly desirable for miR therapeutics and options include the development of devices specific for local delivery, light-induced antimiR, and vesicle-encapsulated miRs serving as therapeutic delivery agents able to improve intracellular uptake. Here, we discuss the potential therapeutic use of miRNAs in the context of cardiac surgery.

miR-126 Regulation of Angiogenesis in Age-Related Macular Degeneration in CNV Mouse Model

miR-126 has recently been implicated in modulating angiogenic factors in vascular development. Understandings its biological significance might enable development of therapeutic interventions for diseases like age-related macular degeneration (AMD). We aimed to determine the role of miR-126 in AMD using a laser-induced choroidal neovascularization (CNV) mouse model. CNV was induced by laser photocoagulation in C57BL/6 mice. The CNV mice were transfected with scrambled miR or miR-126 mimic. The expression of miR-126, vascular endothelial growth factor-A (VEGF-A), Kinase insert domain receptor (KDR) and Sprouty-related EVH1 domain-containing protein 1 (SPRED-1) in ocular tissues were analyzed by qPCR and Western blot. The overexpression effects of miR-126 were also proven on human microvascular endothelial cells (HMECs). miR-126 showed a significant decrease in CNV mice (p < 0.05). Both mRNA and protein levels of VEGF-A, KDR and SPRED-1 were upregulated with CNV; these changes were ameliorated by restoration of miR-126 (p < 0.05). CNV was reduced after miR-126 transfection. Transfection of miR-126 reduced the HMECs 2D-capillary-like tube formation (p < 0.01) and migration (p < 0.01). miR-126 has been shown to be a negative modulator of angiogenesis in the eye. All together these results high lights the therapeutic potential of miR-126 suggests that it may contribute as a putative therapeutic target for AMD in humans.

Regulation of angiogenesis through the efficient delivery of microRNAs into endothelial cells using polyamine-coated carbon nanotubes

MicroRNAs (miRNAs) directly regulate gene expression at a post-transcriptional level and represent an attractive therapeutic target for a wide range of diseases. Here, we report a novel strategy for delivering miRNAs to endothelial cells (ECs) to regulate angiogenesis, using polymer functionalized carbon nanotubes (CNTs). CNTs were coated with two different polymers, polyethyleneimine (PEI) or polyamidoamine dendrimer (PAMAM), followed by conjugation of miR-503 oligonucleotides as recognized regulators of angiogenesis. We demonstrated a reduced toxicity for both polymer-coated CNTs, compared with pristine CNTs or polymers alone. Moreover, polymer-coated CNT stabilized miR-503 oligonucleotides and allowed their efficient delivery to ECs. The functionality of PAMAM-CNT-miR-503 complexes was further demonstrated in ECs through regulation of target genes, cell proliferation and angiogenic sprouting and in a mouse model of angiogenesis. This comprehensive series of experiments demonstrates that the use of polyamine-functionalized CNTs to deliver miRNAs is a novel and effective means to regulate angiogenesis.

Cell Therapy in Ischemic Heart Disease: Interventions That Modulate Cardiac Regeneration

The incidence of severe ischemic heart disease caused by coronary obstruction has progressively increased. Alternative forms of treatment have been studied in an attempt to regenerate myocardial tissue, induce angiogenesis, and improve clinical conditions. In this context, cell therapy has emerged as a promising alternative using cells with regenerative potential, focusing on the release of paracrine and autocrine factors that contribute to cell survival, angiogenesis, and tissue remodeling. Evidence of the safety, feasibility, and potential effectiveness of cell therapy has emerged from several clinical trials using different lineages of adult stem cells. The clinical benefit, however, is not yet well established. In this review, we discuss the therapeutic potential of cell therapy in terms of regenerative and angiogenic capacity after myocardial ischemia. In addition, we addressed nonpharmacological interventions that may influence this therapeutic practice, such as diet and physical training. This review brings together current data on pharmacological and nonpharmacological approaches to improve cell homing and cardiac repair.

Vascular repair strategies in type 2 diabetes: novel insights

Impaired functions of vascular cells are responsible for the majority of complications in patients with type 2 diabetes (T2D). Recently a better understanding of mechanisms contributing to development of vascular dysfunction and the role of systemic inflammatory activation and functional alterations of several secretory organs, of which adipose tissue has more recently been investigated, has been achieved. Notably, the progression of vascular disease within the context of T2D appears to be driven by a multitude of incremental signaling shifts. Hence, successful therapies need to target several mechanisms in parallel, and over a long time period. This review will summarize the latest molecular strategies and translational developments of cardiovascular therapy in patients with T2D.

Concise review: MicroRNAs as modulators of stem cells and angiogenesis

MicroRNAs (miRs) are highly conserved, short noncoding RNA molecules that negatively regulate messenger RNA (mRNA) stability and/or translational efficiency. Since a given miR can control the expression of many mRNAs, their importance in governing gene expression in specific cell types including vascular cells and their progenitor cells has become increasingly clear. Understanding how the expression of miRs themselves is regulated and how miRs exert their influence on post-transcriptional gene control provides novel opportunities to dissect gene regulatory networks in clinically relevant cell types. A multitude of miRs have been identified with key roles in vascular development, homeostasis, function, disease, and regeneration. In this review, we will describe the impact of miRs on angiogenesis and their capacity to modulate the behavior of stem and progenitor cells which may be utilitarian for promoting vascular growth in ischemic tissue. Moreover, we summarize these strategies available for modulating miR expression and function and future therapeutic applications.

miRNAs in post-ischaemic angiogenesis and vascular remodelling

miRNAs are highly conserved non-coding RNA molecules that negatively control gene expression by binding to target mRNAs promoting their degradation. A multitude of miRNAs have been reported to be involved in angiogenesis and vascular remodelling. In the present review, we aim to describe the effect of miRNAs in post-ischaemic repair. First, we describe the miRNAs reported in ischaemic diseases and in angiogenesis. Then we examine their capacity to modulate the behaviour of stem and progenitor cells which could be utilized for vascular repair. And finally we discuss the potential of miRNAs as new clinical biomarkers and therapeutic targets.

Inhibition of 14q32 MicroRNAs miR-329, miR-487b, miR-494, and miR-495 Increases Neovascularization and Blood Flow Recovery After Ischemia

Rationale:

Effective neovascularization is crucial for recovery after cardiovascular events.

Objective:

Because microRNAs regulate expression of up to several hundred target genes, we set out to identify microRNAs that target genes in all pathways of the multifactorial neovascularization process. Using www.targetscan.org , we performed a reverse target prediction analysis on a set of 197 genes involved in neovascularization. We found enrichment of binding sites for 27 microRNAs in a single microRNA gene cluster. Microarray analyses showed upregulation of 14q32 microRNAs during neovascularization in mice after single femoral artery ligation.

Methods and Results:

Gene silencing oligonucleotides (GSOs) were used to inhibit 4 14q32 microRNAs, miR-329, miR-487b, miR-494, and miR-495, 1 day before double femoral artery ligation. Blood flow recovery was followed by laser Doppler perfusion imaging. All 4 GSOs clearly improved blood flow recovery after ischemia. Mice treated with GSO-495 or GSO-329 showed increased perfusion already after 3 days (30% perfusion versus 15% in control), and those treated with GSO-329 showed a full recovery of perfusion after 7 days (versus 60% in control). Increased collateral artery diameters (arteriogenesis) were observed in adductor muscles of GSO-treated mice, as well as increased capillary densities (angiogenesis) in the ischemic soleus muscle. In vitro, treatment with GSOs led to increased sprout formation and increased arterial endothelial cell proliferation, as well as to increased arterial myofibroblast proliferation.

Conclusions:

The 14q32 microRNA gene cluster is highly involved in neovascularization. Inhibition of 14q32 microRNAs miR-329, miR-487b, miR-494, and miR-495 provides a promising tool for future therapeutic neovascularization.

Cardiovascular microRNAs: as modulators and diagnostic biomarkers of diabetic heart disease

Diabetic heart disease (DHD) is the leading cause of morbidity and mortality among the people with diabetes, with approximately 80% of the deaths in diabetics are due to cardiovascular complications. Importantly, heart disease in the diabetics develop at a much earlier stage, although remaining asymptomatic till the later stage of the disease, thereby restricting its early detection and active therapeutic management. Thus, a better understanding of the modulators involved in the pathophysiology of DHD is necessary for the early diagnosis and development of novel therapeutic implications for diabetes-associated cardiovascular complications. microRNAs (miRs) have recently been evolved as key players in the various cardiovascular events through the regulation of cardiac gene expression. Besides their credible involvement in controlling the cellular processes, they are also released in to the circulation in disease states where they serve as potential diagnostic biomarkers for cardiovascular disease. However, their potential role in DHD as modulators as well as diagnostic biomarkers is largely unexplored. In this review, we describe the putative mechanisms of the selected cardiovascular miRs in relation to cardiovascular diseases and discuss their possible involvement in the pathophysiology and early diagnosis of DHD.

B cell translocation gene, a direct target of miR-142-5p, inhibits vascular smooth muscle cell proliferation by down-regulating cell cycle progression

Vascular smooth muscle cell (VSMC) proliferation plays a key role in neointimal hyperplasia and restenosis. Here we report the role of the microRNA miR-142-5p and its downstream target genes on the proliferation of cultured VSMCs. miR-142-5p promoted VSMC proliferation by down-regulating B cell translocation gene 3 (BTG3). We found that BTG3 inhibited the expression of cell cycle regulatory genes and cell growth. As shown by luciferase reporter assay, miR-142-5p bound directly to the 3'-untranslated region of BTG3. Overexpression of miR-142-5p induced expression of cell cycle regulatory genes. Thus, BTG3, a novel, direct target of miR-142-5p, negatively regulates VSMC proliferation.

Online resources for miRNA analysis

OBJECTIVE

This review aims to provide a brief introduction to each major category of available tools and algorithms for microRNA (miRNA) research, as well as to present some of the most widely used or promising representative applications.

METHODS

Only tools offering a fully functional web interface have been included, excluding implementations requiring deployment in local servers or workstations. Furthermore, we have specifically evaluated implementations focusing on Homo sapiens or on mammals used extensively in in vivo research, such as mice and rats.

RESULTS

We present an overview of databases and repositories of miRNA sequences and expression, a commentary on miRNA target prediction algorithms, tools for miRNA functional investigation, and online pipelines for the analysis of high throughput experiments. Examples and case studies are provided at the end of the manuscript, which can hopefully contribute in elucidating the utility of these implementations to basic and applied research.

CONCLUSIONS

Computational tools and algorithms play a significant role in miRNA-related research, supporting equally basic and applied research efforts. However, numerous challenges still remain to be answered by the relevant research community.

MicroRNAs in Cerebral Ischemia

The risk of ischemic stroke increases substantially with age, making it the third leading cause of death and the leading cause of long-term disability in the world. Numerous studies demonstrated that genes, RNAs, and proteins are involved in the occurrence and development of stroke. Current studies found that microRNAs (miRNAs or miRs) are also closely related to the pathological process of stroke. miRNAs are a group of short, noncoding RNA molecules playing important role in posttranscriptional regulation of gene expression and they have emerged as regulators of ischemic preconditioning and ischemic postconditioning. Here we give an overview of the expression and function of miRNAs in the brain, miRNAs as biomarkers during cerebral ischemia, and clinical applications and limitations of miRNAs. Future prospects of miRNAs are also discussed.

The continuing challenges of translational research: clinician-scientists' perspective

Over the last twenty years, revolutionary advances in biomedicine including gene therapy, stem cell research, proteomics, genomics and nanotechnology have highlighted the progressive need to restructure traditional approaches to basic and clinical research in order to facilitate the rapid, efficient integration and translation of these new technologies into novel effective therapeutics. Over the past ten years, funding bodies in the USA and UK such as the National Institutes of Health (NIH) and the Medical Research Council (MRC) have been driving translational research by defining and tackling the hurdles but more still remains to be achieved. This article discusses the ongoing challenges translational researchers face and outlines recent initiatives to tackle these including the new changes to translational funding schemes proposed by the NIH and the MRC and the launch of the "European Advanced Translational Research InfraStructure in Medicine" (EATRIS). It is anticipated that initiatives such as these will not only strengthen translational biomedical research programmes already initiated but should lead to rapid benefits to patients and society.