Background—: Diabetes mellitus impairs endothelial cell (EC) function and postischemic reparative neovascularization by molecular mechanisms that are not fully understood. microRNAs negatively regulate the expression of target genes mainly by interaction in their 3′ untranslated region. Methods and Results—: We found that microRNA-503 (miR-503) expression in ECs is upregulated in culture conditions mimicking diabetes mellitus (high D-glucose) and ischemia-associated starvation (low growth factors). Under normal culture conditions, lentivirus-mediated miR-503–forced expression inhibited EC proliferation, migration, and network formation on Matrigel (comparisons versus lentivirus.GFP control). Conversely, blocking miR-503 activity by either adenovirus-mediated transfer of a miR-503 decoy ( Ad.decoymiR-503 ) or by antimiR-503 (antisense oligonucleotide) improved the functional capacities of ECs cultured under high D-glucose/low growth factors. We identified CCNE1 and cdc25A as direct miR-503 targets which are downregulated by high glucose/low growth factors in ECs. Next, we obtained evidence that miR-503 expression is increased in ischemic limb muscles of streptozotocin-diabetic mice and in ECs enriched from these muscles. Moreover, Ad.decoymiR-503 delivery to the ischemic adductor of diabetic mice corrected diabetes mellitus–induced impairment of postischemic angiogenesis and blood flow recovery. We finally investigated miR-503 and target gene expression in muscular specimens from the amputated ischemic legs of diabetic patients. As controls, calf biopsies of nondiabetic and nonischemic patients undergoing saphenous vein stripping were used. In diabetic muscles, miR-503 expression was remarkably higher, and it inversely correlated with cdc25 protein expression. Plasma miR-503 levels were also elevated in the diabetic individuals. Conclusions—: Our data suggest miR-503 as a possible therapeutic target in diabetic patients with critical limb ischemia.

Long noncoding RNAs (lncRNAs) are non-protein coding transcripts regulating a variety of physiological and pathological functions. However, their implication in heart failure is still largely unknown. The aim of this study is to identify and characterize lncRNAs deregulated in patients affected by ischemic heart failure. LncRNAs were profiled and validated in left ventricle biopsies of 18 patients affected by non end-stage dilated ischemic cardiomyopathy and 17 matched controls. Further validations were performed in left ventricle samples derived from explanted hearts of end-stage heart failure patients and in a mouse model of cardiac hypertrophy, obtained by transverse aortic constriction. Peripheral blood mononuclear cells of heart failure patients were also analyzed. LncRNA distribution in the heart was assessed by in situ hybridization. Function of the deregulated lncRNA was explored analyzing the expression of the neighbor mRNAs and by gene ontology analysis of the correlating coding transcripts. Fourteen lncRNAs were significantly modulated in non end-stage heart failure patients, identifying a heart failure lncRNA signature. Nine of these lncRNAs (CDKN2B-AS1/ANRIL, EGOT, H19, HOTAIR, LOC285194/TUSC7, RMRP, RNY5, SOX2-OT and SRA1) were also confirmed in end-stage failing hearts. Intriguingly, among the conserved lncRNAs, h19, rmrp and hotair were also induced in a mouse model of heart hypertrophy. CDKN2B-AS1/ANRIL, HOTAIR and LOC285194/TUSC7 showed similar modulation in peripheral blood mononuclear cells and heart tissue, suggesting a potential role as disease biomarkers. Interestingly, RMRP displayed a ubiquitous nuclear distribution, while H19 RNA was more abundant in blood vessels and was both cytoplasmic and nuclear. Gene ontology analysis of the mRNAs displaying a significant correlation in expression with heart failure lncRNAs identified numerous pathways and functions involved in heart failure progression. These data strongly suggest lncRNA implication in the molecular mechanisms underpinning HF.

In order to understand the role of microRNAs (miRNAs) in vascular physiopathology, we took advantage of deep-sequencing techniques to accurately and comprehensively profile the entire miRNA population expressed by endothelial cells exposed to hypoxia. SOLiD sequencing of small RNAs derived from human umbilical vein endothelial cells (HUVECs) exposed to 1% O₂or normoxia for 24 h yielded more than 22 million reads per library. A customized bioinformatic pipeline identified more than 400 annotated microRNA/microRNA* species with a broad abundance range: miR-21 and miR-126 totaled almost 40% of all miRNAs. A complex repertoire of isomiRs was found, displaying also 5′ variations, potentially affecting target recognition. High-stringency bioinformatic analysis identified microRNA candidates, whose predicted pre-miRNAs folded into a stable hairpin. Validation of a subset by qPCR identified 18 high-confidence novel miRNAs as detectable in independent HUVEC cultures and associated to the RISC complex. The expression of two novel miRNAs was significantly down-modulated by hypoxia, while miR-210 was significantly induced. Gene ontology analysis of their predicted targets revealed a significant association to hypoxia-inducible factor signaling, cardiovascular diseases, and cancer. Overexpression of the novel miRNAs in hypoxic endothelial cells affected cell growth and confirmed the biological relevance of their down-modulation. In conclusion, deep-sequencing accurately profiled known, variant, and novel microRNAs expressed by endothelial cells in normoxia and hypoxia.

Long noncoding RNAs (lncRNAs) are non-protein coding RNAs regulating gene expression. Although for some lncRNAs a relevant role in hypoxic endothelium has been shown, the regulation and function of lncRNAs is still largely unknown in the vascular physio-pathology. Taking advantage of next-generation sequencing techniques, transcriptomic changes induced by endothelial cell exposure to hypoxia were investigated. Paired-end sequencing of polyadenylated RNA derived from human umbilical vein endothelial cells (HUVECs) exposed to 1% O₂ or normoxia was performed. Bioinformatics analysis identified ≈2000 differentially expressed genes, including 122 lncRNAs. Extensive validation was performed by both microarray and qPCR. Among the validated lncRNAs, H19, MIR210HG, MEG9, MALAT1 and MIR22HG were also induced in a mouse model of hindlimb ischemia. To test the functional relevance of lncRNAs in endothelial cells, knockdown of H19 expression was performed. H19 inhibition decreased HUVEC growth, inducing their accumulation in G1 phase of the cell cycle; accordingly, p21 (CDKN1A) expression was increased. Additionally, H19 knockdown also diminished HUVEC ability to form capillary like structures when plated on matrigel. In conclusion, a high-confidence signature of lncRNAs modulated by hypoxia in HUVEC was identified and a significant impact of H19 lncRNA was shown.

The communication between vascular endothelial cells (ECs) and pericytes in the microvasculature is fundamental for vascular growth and homeostasis; however, these processes are disrupted by diabetes. Here we show that modulation of p75^NTRexpression in ECs exposed to high glucose activates transcription of miR-503, which negatively affects pericyte function. p75^NTRactivates NF-κB to bind the miR-503 promoter and upregulate miR-503 expression in ECs. NF-κB further induces activation of Rho kinase and shedding of endothelial microparticles carrying miR-503, which transfer miR-503 from ECs to vascular pericytes. The integrin-mediated uptake of miR-503 in the recipient pericytes reduces expression ofEFNB2andVEGFA, resulting in impaired migration and proliferation. We confirm operation of the above mechanisms in mouse models of diabetes, in which EC-derived miR-503 reduces pericyte coverage of capillaries, increased permeability and impaired post-ischaemic angiogenesis in limb muscles. Collectively, our data demonstrate that miR-503 regulates pericyte–endothelial crosstalk in microvascular diabetic complications.

MicroRNAs (miRNAs) are noncoding RNAs that act as negative regulators of gene expression. Interestingly, specific alterations of miRNA expression have been found in failing hearts of different etiologies. The aim of this study was to identify the miRNA expression pattern of peripheral blood mononuclear cells (PBMCs) derived from chronic heart failure (CHF) patients affected by ischemic (ICM) and nonischemic dilated (NIDCM) cardiomyopathy. The expression profile of 257 miRNAs was assessed in 7 NIDCM patients, 8 ICM patients, and 9 control subjects by quantitative real-time PCR. Significantly modulated miRNAs were validated by using an independent set of 34 CHF patients (NIDCM = 19, ICM = 15) and 19 control subjects. Three miRNAs (miR-107, -139, and -142-5p) were downmodulated in both NIDCM and ICM patients versus control subjects. Other miRNAs were deregulated in only one of the CHF classes analyzed compared with control subjects: miR-142-3p and -29b were increased in NIDCM patients, while miR-125b and -497 were decreased in ICM patients. Bioinformatic analysis of miRNA predicted targets and of gene expression modifications associated with CHF in PBMCs indicated a significant impact of the miRNA signature on the transcriptome. Furthermore, miRNAs of both the NIDCM and the ICM signature shared predicted targets among CHF-modulated genes, suggesting potential additive or synergistic effects. The present study identified miRNAs specifically modulated in the PBMCs of NIDCM and ICM patients. Intriguingly, most of these miRNAs were previously reported as deregulated in human and/or mouse failing hearts. The identified miRNAs might have a potential diagnostic and/or prognostic use in CHF.