MicroRNA-regulated pathways of flow-stimulated angiogenesis and vascular remodeling in vivo

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Cas9-mediated knockout of Ndrg2 enhances the regenerative potential of dendritic cells for wound healing

Chronic wounds impose a significant healthcare burden to a broad patient population. Cell-based therapies, while having shown benefits for the treatment of chronic wounds, have not yet achieved widespread adoption into clinical practice. We developed a CRISPR/Cas9 approach to precisely edit murine dendritic cells to enhance their therapeutic potential for healing chronic wounds. Using single-cell RNA sequencing of tolerogenic dendritic cells, we identified N-myc downregulated gene 2 (Ndrg2), which marks a specific population of dendritic cell progenitors, as a promising target for CRISPR knockout. Ndrg2-knockout alters the transcriptomic profile of dendritic cells and preserves an immature cell state with a strong pro-angiogenic and regenerative capacity. We then incorporated our CRISPR-based cell engineering within a therapeutic hydrogel for in vivo cell delivery and developed an effective translational approach for dendritic cell-based immunotherapy that accelerated healing of full-thickness wounds in both non-diabetic and diabetic mouse models. These findings could open the door to future clinical trials using safe gene editing in dendritic cells for treating various types of chronic wounds.

Cold water immersion in recovery following a single bout resistance exercise suppresses mechanisms of miRNA nuclear export and maturation

Cold water immersion (CWI) following intense exercise is a common athletic recovery practice. However, CWI impacts muscle adaptations to exercise training, with attenuated muscle hypertrophy and increased angiogenesis. Tissue temperature modulates the abundance of specific miRNA species and thus CWI may affect muscle adaptations via modulating miRNA expression following a bout of exercise. The current study focused on the regulatory mechanisms involved in cleavage and nuclear export of mature miRNA, including DROSHA, EXPORTIN-5, and DICER. Muscle biopsies were obtained from the vastus lateralis of young males (n = 9) at rest and at 2, 4, and 48 h of recovery from an acute bout of resistance exercise, followed by either 10 min of active recovery (ACT) at ambient temperature or CWI at 10°C. The abundance of key miRNA species in the regulation of intracellular anabolic signaling (miR-1 and miR-133a) and angiogenesis (miR-15a and miR-126) were measured, along with several gene targets implicated in satellite cell dynamics (NCAM and PAX7) and angiogenesis (VEGF and SPRED-1). When compared to ACT, CWI suppressed mRNA expression of DROSHA (24 h p = 0.025 and 48 h p = 0.017), EXPORTIN-5 (24 h p = 0.008), and DICER (24 h p = 0.0034). Of the analyzed miRNA species, miR-133a (24 h p < 0.001 and 48 h p = 0.007) and miR-126 (24 h p < 0.001 and 48 h p < 0.001) remained elevated at 24 h post-exercise in the CWI trial only. Potential gene targets of these miRNA, however, did not differ between trials. CWI may therefore impact miRNA abundance in skeletal muscle, although the precise physiological relevance needs further investigation.

Low expression of RBP4 in the vitreous humour of patients with proliferative diabetic retinopathy who underwent Conbercept intravitreal injection

Intravitreal injection of anti-VEGF antibodies has been widely used in the treatment of proliferative diabetic retinopathy (PDR). However, anti-VEGF drugs can exacerbate fibrosis and eventually lead to retinal detachment. To explore proteins closely related to fibrosis, we conducted proteomic analysis of human vitreous humour collected from PDR patients who have or have not intravitreal Conbercept (IVC) injection. Sixteen vitreous humour samples from PDR patients with preoperative IVC and 20 samples from those without preoperative IVC were examined. An immunodepletion kit was used to remove high-abundance vitreous proteins. Conbercept-induced changes were determined using a tandem mass tag-based quantitative proteomic strategy. Enzyme-linked immunosorbent assays were performed to confirm the concentrations of selected proteins and validate the proteomic results. Based on a false discovery rate between 0.05% and -0.05% and a fold-change > 1.5, 97 proteins were altered (49 higher levels and 48 lower levels) in response to IVC. Differentially expressed proteins were found in the extracellular and intracellular regions and were found to be involved in VEGF binding and VEGF-activated receptor activity. Protein-protein interactions indicated associations with fibrosis, neovascularisation and inflammatory signalling pathways. We found the low levels of RBP4 in the vitreous humour of PDR patients with IVC injection, as revealed by ELISA and proteomic profiling. Moreover, RBP4 significantly restored the mitochondrial function of HRMECs induced by AGEs and down regulated the level of glycolysis. Our study is the first to report that RBP4 decreases in the vitreous humour of PDR patients who underwent Conbercept treatment, thereby verifying the role of RBP4 in glucose metabolism. Results provide evidence for the potential mechanism underlying Conbercept-related fibrosis.

Endothelial Cell Differentiation and Hemogenic Specification

Formation of the vasculature is a critical step within the developing embryo and its disruption causes early embryonic lethality. This complex process is driven by a cascade of signaling events that controls differentiation of mesodermal progenitors into primordial endothelial cells and their further specification into distinct subtypes (arterial, venous, hemogenic) that are needed to generate a blood circulatory network. Hemogenic endothelial cells give rise to hematopoietic stem and progenitor cells that generate all blood cells in the body during embryogenesis and postnatally. We focus our discussion on the regulation of endothelial cell differentiation, and subsequent hemogenic specification, and highlight many of the signaling pathways involved in these processes, which are conserved across vertebrates. Gaining a better understanding of the regulation of these processes will yield insights needed to optimize the treatment of vascular and hematopoietic disease and generate human stem cell-derived vascular and hematopoietic cells for tissue engineering and regenerative medicine.

MiR-197-3p affects angiogenesis and inflammation of endothelial cells by targeting CXCR2/COX2 axis

BACKGROUND

Decreased circulating miR-197-3p was found in patients with recurrent deep vein thrombosis (DVT), but the specific role of miR-197-3p needs further exploration.

MATERIALS AND METHODS

Venous blood samples were collected from DVT patients and healthy controls, and peripheral blood mononuclear cells (PBMCs) were isolated to examine the expression patterns of miR-197-3p, CXCR2 and COX2 by qRT-PCR. Human umbilical vein endothelial cells (HUVECs) were further used as a cellular model to investigate the role of the miR-197-3p/CXCR2/COX2 axis in regulating cell viability, angiogenesis, and inflammation, which were determined by MTT assay, Matrigel-based tube formation assay, and enzyme-linked immunosorbent assay, respectively. Dual-luciferase reporter assay was used to examine the interactions between miR-198-3p and CXCR2. Expression of NF-κB p65 was examined by western blot to investigate whether the NF-κB pathway was involved in the regulatory effect of miR-197-3p on DVT.

RESULTS

miR-197-3p was decreased in PBMCs of patients with DVT, while CXCR2 and COX2 were increased compared to the healthy controls. In HUVECs, overexpression of miR-197-3p reduced CXCR2 levels and inhibited cell viability, angiogenesis, and release of inflammatory cytokines including TNF-α, IL-1β, and IL-6, which were reversed by miR-197-3p inhibition. Dual-luciferase reporter assay indicated miR-197-3p directly bound to CXCR2. CXCR2 further upregulated the expression of COX2 and activated the NF-κB pathway, promoting cell viability, angiogenesis and release of inflammatory cytokines in HUVECs. The effect of miR-197-3p inhibition on cell viability, angiogenesis and inflammation of HUVECs could be reversed by CXCR2 silencing.

CONCLUSION

MiR-197-3p affected viability, angiogenesis and inflammation of endothelial cells by targeting CXCR2/COX2 axis in vitro. Our findings provided a novel theoretical basis to investigate more effective therapies for DVT.

Transcriptional and Epigenetic Factors Associated with Early Thrombosis of Femoral Artery Involved in Arteriovenous Fistula

Arteriovenous fistulas (AVFs), created for hemodialysis in end-stage renal disease patients, mature through the outward remodeling of the outflow vein. However, early thrombosis and chronic inflammation are detrimental to the process of AVF maturation and precipitate AVF maturation failure. For the successful remodeling of the outflow vein, blood flow through the fistula is essential, but early arterial thrombosis attenuates this blood flow, and the vessels become thrombosed and stenosed, leading to AVF failure. The altered expression of various proteins involved in maintaining vessel patency or thrombosis is regulated by genes of which the expression is regulated by transcription factors and microRNAs. In this study, using thrombosed and stenosed arteries following AVF creation, we delineated transcription factors and microRNAs associated with differentially expressed genes in bulk RNA sequencing data using upstream and causal network analysis. We observed changes in many transcription factors and microRNAs that are involved in angiogenesis; vascular smooth muscle cell proliferation, migration, and phenotypic changes; endothelial cell function; hypoxia; oxidative stress; vessel remodeling; immune responses; and inflammation. These factors and microRNAs play a critical role in the underlying molecular mechanisms in AVF maturation. We also observed epigenetic factors involved in gene regulation associated with these molecular mechanisms. The results of this study indicate the importance of investigating the transcriptional and epigenetic regulation of AVF maturation and maturation failure and targeting factors precipitating early thrombosis and stenosis.

Post-Transcriptional Regulation of Molecular Determinants during Cardiogenesis

Cardiovascular development is initiated soon after gastrulation as bilateral precardiac mesoderm is progressively symmetrically determined at both sides of the developing embryo. The precardiac mesoderm subsequently fused at the embryonic midline constituting an embryonic linear heart tube. As development progress, the embryonic heart displays the first sign of left-right asymmetric morphology by the invariably rightward looping of the initial heart tube and prospective embryonic ventricular and atrial chambers emerged. As cardiac development progresses, the atrial and ventricular chambers enlarged and distinct left and right compartments emerge as consequence of the formation of the interatrial and interventricular septa, respectively. The last steps of cardiac morphogenesis are represented by the completion of atrial and ventricular septation, resulting in the configuration of a double circuitry with distinct systemic and pulmonary chambers, each of them with distinct inlets and outlets connections. Over the last decade, our understanding of the contribution of multiple growth factor signaling cascades such as Tgf-beta, Bmp and Wnt signaling as well as of transcriptional regulators to cardiac morphogenesis have greatly enlarged. Recently, a novel layer of complexity has emerged with the discovery of non-coding RNAs, particularly microRNAs and lncRNAs. Herein, we provide a state-of-the-art review of the contribution of non-coding RNAs during cardiac development. microRNAs and lncRNAs have been reported to functional modulate all stages of cardiac morphogenesis, spanning from lateral plate mesoderm formation to outflow tract septation, by modulating major growth factor signaling pathways as well as those transcriptional regulators involved in cardiac development.

Appreciating the role of cell shape changes in the mechanobiology of epithelial tissues

The wide range of epithelial cell shapes reveals the complexity and diversity of the intracellular mechanisms that serve to construct their morphology and regulate their functions. Using mechanosensitive steps, epithelial cells can sense a variety of different mechanochemical stimuli and adapt their behavior by reshaping their morphology. These changes of cell shape rely on a structural reorganization in space and time that generates modifications of the tensional state and activates biochemical cascades. Recent studies have started to unveil how the cell shape maintenance is involved in mechanical homeostatic tasks to sustain epithelial tissue folding, identity, and self-renewal. Here, we review relevant works that integrated mechanobiology to elucidate some of the core principles of how cell shape may be conveyed into spatial information to guide collective processes such as epithelial morphogenesis. Among many other parameters, we show that the regulation of the cell shape can be understood as the result of the interplay between two counteracting mechanisms: actomyosin contractility and intercellular adhesions, and that both do not act independently but are functionally integrated to operate on molecular, cellular, and tissue scales. We highlight the role of cadherin-based adhesions in force-sensing and mechanotransduction, and we report recent developments that exploit physics of liquid crystals to connect cell shape changes to orientational order in cell aggregates. Finally, we emphasize that the further intermingling of different disciplines to develop new mechanobiology assays will lead the way toward a unified picture of the contribution of cell shape to the pathophysiological behavior of epithelial tissues.

Flow-Responsive Noncoding RNAs in the Vascular System: Basic Mechanisms for the Clinician

The vascular system is largely exposed to the effect of changing flow conditions. Vascular cells can sense flow and its changes. Flow sensing is of pivotal importance for vascular remodeling. In fact, it influences the development and progression of atherosclerosis, controls its location and has a major influx on the development of local complications. Despite its importance, the research community has traditionally paid scarce attention to studying the association between different flow conditions and vascular biology. More recently, a growing body of evidence has been accumulating, revealing that ncRNAs play a key role in the modulation of several biological processes linking flow-sensing to vascular pathophysiology. This review summarizes the most relevant evidence on ncRNAs that are directly or indirectly responsive to flow conditions to the benefit of the clinician, with a focus on the underpinning mechanisms and their potential application as disease biomarkers.

Expression Profiles of Circular RNA in Aortic Vascular Tissues of Spontaneously Hypertensive Rats

Background: Circular RNAs (circRNAs), as a kind of endogenous non-coding RNA, have been implicated in ischemic heart diseases and vascular diseases. Based on theirs high stability with a closed loop structure, circRNAs function as a sponge and bind specific miRNAs to exert inhibitory effects in heart and vasculature, thereby regulating their target gene and protein expression, via competitive endogenous RNA (ceRNA) mechanism. However, the exact roles and underlying mechanisms of circRNAs in hypertension and related cardiovascular diseases remain largely unknown. Methods and Results: High-throughput RNA sequencing (RNA-seq) was used to analyze the differentially expressed (DE) circRNAs in aortic vascular tissues of spontaneously hypertensive rats (SHR). Compared with the Wistar-Kyoto (WKY) rats, there were marked increases in the levels of systolic blood pressure, diastolic blood pressure and mean blood pressure in SHR under awake conditions via the tail-cuff methodology. Totally, compared with WKY rats, 485 DE circRNAs were found in aortic vascular tissues of SHR with 279 up-regulated circRNAs and 206 down-regulated circRNAs. Furthermore, circRNA-target microRNAs (miRNAs) and the target messenger RNAs (mRNAs) of miRNAs were predicted by the miRanda and Targetscan softwares, respectively. Additionally, real-time RT-PCR analysis verified that downregulation of rno_circRNA_0009197, and upregulation of rno_circRNA_0005818, rno_circRNA_0005304, rno_circRNA_0005506, and rno_circRNA_0009301 were observed in aorta of SHR when compared with that of WKY rats. Then, the potential ceRNA regulatory mechanism was constructed via integrating 5 validated circRNAs, 31 predicted miRNAs, and 266 target mRNAs. More importantly, three hub genes (NOTCH1, FOXO3, and STAT3) were recognized according to PPI network and three promising circRNA-miRNA-mRNA regulatory axes were found in hypertensive rat aorta, including rno_circRNA_0005818/miR-615/NOTCH1, rno_circRNA_0009197/ miR-509-5p/FOXO3, and rno_circRNA_0005818/miR-10b-5p/STAT3, respectively. Conclusions: Our results demonstrated for the first time that circRNAs are expressed aberrantly in aortic vascular tissues of hypertensive rats and may serve as a sponge linking with relevant miRNAs participating in pathogenesis of hypertension and related ischemic heart diseases via the circRNA-miRNA-mRNA ceRNAnetwork mechanism.

Vessel grafts for tissue engineering revisited-Vessel segments show location-specific vascularization patterns in ex vivo ring assay

OBJECTIVE

Transplantation of prefabricated tissue-engineered flaps can be a potential alternative for healing large tissue defects. Providing adequate vascular supply for an engineered tissue construct is one of the key points in establishing successful tissue engineering-based treatment approaches. In tissue engineering-based vascularization techniques like the arteriovenous loop, vascular grafts with high angiogenic potential can help to enhance neovascularization and tissue formation. Therefore, our study aimed to compare the angiogenic potential of vascular grafts from different locations in the rat.

METHODS

The angiogenic activity was investigated by an ex vivo vessel outgrowth ring assay using 1-mm height vascular segments embedded in fibrin for 2 weeks.

RESULTS

Maximum vessel outgrowth was observed on Days 10-12. Upper extremity vessels exhibited stronger outgrowth than lower extremity vessels. Moreover, arterial vessels demonstrated higher angiogenic potential compared with venous vessels.

CONCLUSION

Collectively, our ex vivo findings suggest that upper extremity arterial vessels have a higher angiogenic capacity, which could be used to improve neovascularization and tissue formation in tissue engineering.

Gelatin methacryloyl is a slow degrading material allowing vascularization and long-term usein vivo

In situtissue engineering is an emerging field aiming at the generation of ready-to-use three-dimensional tissues. One solution to supply a proper vascularization of larger tissues to provide oxygen and nutrients is the arteriovenous loop (AVL) model. However, for this model, suitable scaffold materials are needed that are biocompatible/non-immunogenic, slowly degradable, and allow vascularization. Here, we investigate the suitability of the known gelatin methacryloyl (GelMA)-based hydrogel forin-situtissue engineering utilizing the AVL model. Rat AVLs are embedded by two layers of GelMA hydrogel in an inert PTFE chamber and implanted in the groin. Constructs were explanted after 2 or 4 weeks and analyzed. For this purpose, gross morphological, histological, and multiphoton microscopic analysis were performed. Immune response was analyzed based on anti-CD68 and anti-CD163 staining of immune cells. The occurrence of matrix degradation was assayed by anti-MMP3 staining. Vascularization was analyzed by anti-α-smooth muscle actin staining, multiphoton microscopy, as well as expression analysis of 53 angiogenesis-related proteins utilizing a proteome profiler angiogenesis array kit. Here we show that GelMA hydrogels are stable for at least 4 weeks in the rat AVL model. Furthermore, our data indicate that GelMA hydrogels are biocompatible. Finally, we provide evidence that GelMA hydrogels in the AVL model allow connective tissue formation, as well as vascularization, introducing multiphoton microscopy as a new methodology to visualize neovessel formation originating from the AVL. GelMA is a suitable material forin situandin vivoTE in the AVL model.

An Integrative Study of Aortic mRNA/miRNA Longitudinal Changes in Long-Term LVAD Support

Studying the long-term impact of continuous-flow left ventricular assist device (CF-LVAD) offers an opportunity for a complex understanding of the pathophysiology of vascular changes in aortic tissue in response to a nonphysiological blood flow pattern. Our study aimed to analyze aortic mRNA/miRNA expression changes in response to long-term LVAD support. Paired aortic samples obtained at the time of LVAD implantation and at the time of heart transplantation were examined for mRNA/miRNA profiling. The number of differentially expressed genes (Pcorr < 0.05) shared between samples before and after LVAD support was 277. The whole miRNome profile revealed 69 differentially expressed miRNAs (Pcorr < 0.05). Gene ontology (GO) analysis identified that LVAD predominantly influenced genes involved in the extracellular matrix and collagen fibril organization. Integrated mRNA/miRNA analysis revealed that potential targets of miRNAs dysregulated in explanted samples are mainly involved in GO biological process terms related to dendritic spine organization, neuron projection organization, and cell junction assembly and organization. We found differentially expressed genes participating in vascular tissue engineering as a consequence of LVAD duration. Changes in aortic miRNA levels demonstrated an effect on molecular processes involved in angiogenesis.

Expression of Connexin43 Stimulates Endothelial Angiogenesis Independently of Gap Junctional Communication In Vitro

Connexins (Cx) form gap junctions (GJ) and allow for intercellular communication. However, these proteins also modulate gene expression, growth, and cell migration. The downregulation of Cx43 impairs endothelial cell migration and angiogenetic potential. Conversely, endothelial Cx43 expression is upregulated in an in vivo angiogenesis model relying on hemodynamic forces. We studied the effects of Cx43 expression on tube formation and proliferation in HUVECs and examined its dependency on GJ communication. Expectedly, intercellular communication assessed by dye transfer was linked to Cx43 expression levels in HUVECs and was sensitive to a GJ blockade by the Cx43 mimetic peptide Gap27. The proliferation of HUVECs was not affected by Cx43 overexpression using Cx43 cDNA transfection, siRNA-mediated knockdown of Cx43, or the inhibition of GJ compared to the controls (transfection of an empty vector, scrambled siRNA, and the solvent). In contrast, endothelial tube and sprout formation in HUVECs was minimized after Cx43 knockdown and significantly enhanced after Cx43 overexpression. This was not affected by a GJ blockade (Gap27). We conclude that Cx43 expression positively modulates the angiogenic potential of endothelial cells independent of GJ communication. Since proliferation remained unaffected, we suggest that Cx43 protein may modulate endothelial cell migration, thereby supporting angiogenesis. The modulation of Cx43 expression may represent an exploitable principle for angiogenesis induction in clinical therapy.

Circular RNA expression profiles in the plasma of patients with infantile hemangioma determined using microarray analysis

Circular RNAs (circRNAs) are noncoding RNAs that have important roles in tumor progression. Previous studies have examined the circRNAs involved in infantile hemangioma (IH) tumors. The present study compared the circRNA levels in plasma samples from patients with IH and control individuals. The circRNA expression profiles were determined using microarray in three pairs of plasma samples from patients with proliferative IH and healthy control subjects. Expression of the identified differentially expressed circRNAs was verified using reverse transcription-quantitative PCR (RT-qPCR) and a bioinformatics analysis was performed to predict the microRNAs targeted by the validated circRNAs. From the circRNA expression profiles in the plasma of patients with IHs, 128 differentially expressed circRNAs were identified, of which 72 were upregulated and 56 were downregulated. The downregulated expression of three circRNAs [Homo sapiens (hsa)_circRNA_101566, hsa_circRNA_103546 and hsa_circRNA_103573] was verified using RT-qPCR. Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway analyses indicated that all identified networks participated in angiogenesis and tumor formation and progression. It was determined that hsa_circRNA_101566, which is able to regulate the mTOR signaling pathway, may be an important regulatory molecule in IH development and that targeting of hsa_miR_520c is able to indirectly regulate the vascular endothelial growth factor signaling pathway. Further studies are required to clarify these effects and the underlying mechanisms.

Exosome-derived miR-let-7c promotes angiogenesis in multiple myeloma by polarizing M2 macrophages in the bone marrow microenvironment

Angiogenesis is an integral part of the multiple myeloma (MM) microenvironment, and affects tumorigenesis, progression, invasion, and metastasis. Exosomes are essential for cell-cell communication and help in regulating the bone marrow microenvironment. Herein, we investigated macrophage polarization and angiogenesis in MM in vitro via exosome-derived miR-let-7c. We observed that exosomal miR-let-7c secreted by mesenchymal stem cells promoted M2 macrophage polarization, thereby enhancing angiogenesis in the bone marrow microenvironment. Suppressing miR-let-7c expression significantly inhibited vascular endothelial cell function in myeloma. Thus, exosomal miR-let-7c may be a reliable biomarker for early prediction of tumor progression and a promising therapeutic target for MM.

MicroRNA regulation of cholesterol metabolism

MicroRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Since many microRNAs have multiple mRNA targets, they are uniquely positioned to regulate the expression of several molecules and pathways simultaneously. For example, the multiple stages of cholesterol metabolism are heavily influenced by microRNA activity. Understanding the scope of microRNAs that control this pathway is highly relevant to diseases of perturbed cholesterol metabolism, most notably cardiovascular disease (CVD). Atherosclerosis is a common cause of CVD that involves inflammation and the accumulation of cholesterol-laden cells in the arterial wall. However, several different cell types participate in atherosclerosis, and perturbations in cholesterol homeostasis may have unique effects on the specialized functions of these various cell types. Therefore, our review discusses the current knowledge of microRNA-mediated control of cholesterol homeostasis, followed by speculation as to how these microRNA-mRNA target interactions might have distinctive effects on different cell types that participate in atherosclerosis.

The antagonistic effects and mechanisms of microRNA-26a action in hypertensive vascular remodelling

BACKGROUND AND PURPOSE

Hypertensive vascular remodelling is responsible for end-organ damage and is the result of increased extracellular matrix accumulation and excessive vascular smooth muscle cell (VSMC) proliferation. MicroRNA-26a (miR-26a), a non-coding small RNA, is involved in several cardiovascular diseases. We aimed to validate the effect and mechanisms of miR-26a in hypertensive vascular remodelling.

EXPERIMENTAL APPROACH

Male spontaneously hypertensive rats (SHRs) were injected intravenously with recombinant adeno-associated virus-miR-26a. Samples of thoracic aorta were examined histologically with H&E staining. In vitro, angiotensin II (AngII)-induced VSMCs cultured from thoracic aortae of female Sprague-Dawley rats, were transfected with miR-26a mimic or inhibitor. Western blots, qRT-PCR and immunohistological methods were used, along with chromatin-immunoprecipitation and luciferase reporter assays. Specific siRNAs were used to silence Smad production in VSMCs KEY RESULTS: Levels of miR-26a were lower in the thoracic aorta and plasma of SHRs than in WKY rats. Overexpression of miR-26a inhibited extracellular matrix deposition by targeting connective tissue growth factor (CTGF) and decreased VSMC proliferation by regulating the enhancer of zeste homologue 2 (EZH2)/p21 pathway both in vitro and in vivo. AngII-mediated Smad3 activation suppressed miR-26a expression, which in turn promoted Smad3 activation via targeted regulation of Smad4, leading to further down-regulation of miR-26a.

CONCLUSION AND IMPLICATIONS

Our data show that AngII stimulated a Smads/miR-26a positive feedback loop, which further reduced expression of miR-26a, leading to collagen production and VSMC proliferation and consequently vascular remodelling. MiR-26a has an antagonistic effect on hypertensive vascular remodelling and can be a strategy for treating hypertensive vascular remodelling.

MicroRNA-29b/c-3p Indicate Advanced Liver Fibrosis/Cirrhosis in Univentricular Heart Patients With and Without Fontan Palliation

Aim: The present study aims to identify those microRNAs (miRNAs) in patients with univentricular heart (UVH) disease with and without Fontan palliation that may be associated with advanced liver fibrosis/cirrhosis. Materials and Methods: SurePrint™ 8 × 60K Human v21 miRNA arrays were used to determine the miRNA abundance profiles in the blood of 48 UVH patients with and without Fontan palliation and 32 matched healthy controls. The abundance levels of selected miRNAs have been validated by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Results: According to microarray analysis, 50 miRNAs were found to be significantly abundant in UVH patients of which miR-29b-3p and miR-29c-3p were significantly related to the model of end-stage liver disease (MELD)-Albumin and albumin-bilirubin (ALBI) score representing advanced liver fibrosis/cirrhosis. Relative expression levels of both miRNAs were significantly higher in patients with a higher collapsibility index representing venous hepatic congestion, a higher MELD-Albumin or ALBI score and incomplete or no Fontan palliation. In the logistic regression analysis, a MELD-Albumin score ≥ 11 or ALBI score > -2.6 were best predicted by total bilirubin (OR 6.630, P = 0.016), albumin (OR 0.424, P = 0.026), and miR-29c-3p (OR 33.060, P = 0.047). After adjustment to the status of Fontan palliation, however, no statistical significance of these parameters was found thus underlining the importance of palliation status on progression of liver fibrosis/ cirrhosis in UVH patients. Conclusions: In UVH patients with and without Fontan palliation, miR-29b-3p and miR-29c-3p seem to be markers of advanced liver fibrosis/cirrhosis and thus may be used in the risk assessment of these patients.

A multivariable miRNA signature delineates the systemic hemodynamic impact of arteriovenous shunt placement in a pilot study

Arteriovenous (AV) fistulas for hemodialysis can lead to cardiac volume loading and increased serum brain natriuretic peptide (BNP) levels. Whether short-term AV loop placement in patients undergoing microsurgery has an impact on cardiac biomarkers and circulating microRNAs (miRNAs), potentially indicating an increased hemodynamic risk, remains elusive. Fifteen patients underwent AV loop placement with delayed free flap anastomosis for microsurgical reconstructions of lower extremity soft-tissue defects. N-terminal pro-BNP (NT-proBNP), copeptin (CT-proAVP), and miRNA expression profiles were determined in the peripheral blood before and after AV loop placement. MiRNA expression in the blood was correlated with miRNA expression from AV loop vascular tissue. Serum NT-proBNP and copeptin levels exceeded the upper reference limit after AV loop placement, with an especially strong NT-proBNP increase in patients with preexistent cardiac diseases. A miRNA signature of 4 up-regulated (miR-3198, miR-3127-5p, miR-1305, miR-1288-3p) and 2 down-regulated miRNAs (miR30a-5p, miR-145-5p) which are related to cardiovascular physiology, showed a significant systemic deregulation in blood and venous tissue after AV loop placement. AV loop placement causes serum elevations of NT-proBNP, copeptin as well as specific circulating miRNAs, indicating a potentially increased hemodynamic risk for patients with cardiovascular comorbidities, if free flap anastomosis is delayed.

Role of miRNAs in Sigmoid Colon Cancer: A Search for Potential Biomarkers

The aberrant expression of microRNAs in known to play a crucial role in carcinogenesis. Here, we evaluated the miRNA expression profile of sigmoid colon cancer (SCC) compared to adjacent-to-tumor (ADJ) and sigmoid colon healthy (SCH) tissues obtained from colon biopsy extracted from Brazilian patients. Comparisons were performed between each group separately, considering as significant p-values < 0.05 and |Log2(Fold-Change)| > 2. We found 20 differentially expressed miRNAs (DEmiRNAs) in all comparisons, two of which were shared between SCC vs. ADJ and SCC vs. SCH. We used miRTarBase, and miRTargetLink to identify target-genes of the differentially expressed miRNAs, and DAVID and REACTOME databases for gene enrichment analysis. We also used TCGA and GTEx databases to build miRNA-gene regulatory networks and check for the reproducibility in our results. As findings, in addition to previously known miRNAs associated with colorectal cancer, we identified three potential novel biomarkers. We showed that the three types of colon tissue could be clearly distinguished using a panel composed by the 20 DEmiRNAs. Additionally, we found enriched pathways related to the carcinogenic process in which miRNA could be involved, indicating that adjacent-to-tumor tissues may be already altered and cannot be considered as healthy tissues. Overall, we expect that these findings may help in the search for biomarkers to prevent cancer progression or, at least, allow its early detection, however, more studies are needed to confirm our results.

Increased expression of CXCL2 in ACPA-positive rheumatoid arthritis and its role in osteoclastogenesis

Anti-citrullinated protein/peptide antibodies (ACPA) play important roles in the pathogenesis of rheumatoid arthritis (RA). ACPA-positive (ACPA⁺ ) and ACPA-negative (ACPA^- ) RA were suggested to be different disease subsets, with distinct differences in genetic variation and clinical outcomes. The aims of the present study were to compare gene expression profiles in ACPA⁺ and ACPA^- RA, and to identify novel candidate gene signatures that might serve as therapeutic targets. Comprehensive transcriptome analysis of peripheral blood mononuclear cells (PBMCs) from ACPA⁺ and ACPA^- RA patients and healthy controls was performed via RNA sequencing. A validation cohort was used to further investigate differentially expressed genes via polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA). Spearman's correlation test was used to evaluate the correlation of differentially expressed genes and the clinical and laboratory data of the patients. The role of differentially expressed genes in osteoclastogenesis was further investigated. Expression of C-X-C motif chemokine ligand 2 (CXCL2) was significantly increased in ACPA⁺ RA than in ACPA^- RA, which was validated in PBMCs and serum. CXCL2 promoted the migration of CD14⁺ monocytes and increased osteoclastogenesis in RA patients. RAW264.7 macrophages were used to investigate specific mechanisms, and the results suggested that CXCL2 stimulated osteoclastogenesis via extracellular receptor kinase (ERK) mitogen-activated protein kinase (MAPK) and nuclear factor kappa B pathways. In conclusion, CXCL2 was highly expressed in ACPA⁺ RA than in ACPA^- RA. CXCL2 promoted osteoclastogenesis and was related to bone erosion in RA, which suggests that the blockade of CXCL2 might be a novel strategy for the treatment of RA.

Tissue Engineering of Axially Vascularized Soft-Tissue Flaps with a Poly-(ɛ-Caprolactone) Nanofiber-Hydrogel Composite

Objective: To develop a novel approach for tissue engineering of soft-tissue flaps suitable for free microsurgical transfer, using an injectable nanofiber hydrogel composite (NHC) vascularized by an arteriovenous (AV) loop. Approach: A rat AV loop model was used for tissue engineering of vascularized soft-tissue flaps. NHC or collagen-elastin (CE) scaffolds were implanted into isolation chambers together with an AV loop and explanted after 15 days. Saphenous veins were implanted into the scaffolds as controls. Neoangiogenesis, ultrastructure, and protein expression of SYNJ2BP, EPHA2, and FOXC1 were analyzed by immunohistochemistry and compared between the groups. Rheological properties were compared between the two scaffolds and native human adipose tissue. Results: A functional neovascularization was evident in NHC flaps with its amount being comparable with CE flaps. Scanning electron microscopy revealed a strong mononuclear cell infiltration along the nanofibers in NHC flaps and a trend toward higher fiber alignment compared with CE flaps. SYNJ2BP and EPHA2 expression in endothelial cells (ECs) was lower in NHC flaps compared with CE flaps, whereas FOXC1 expression was increased in NHC flaps. Compared with the stiffer CE flaps, the NHC flaps showed similar rheological properties to native human adipose tissue. Innovation: This is the first study to demonstrate the feasibility of tissue engineering of soft-tissue flaps with similar rheological properties as human fat, suitable for microsurgical transfer using an injectable nanofiber hydrogel composite. Conclusions: The injectable NHC scaffold is suitable for tissue engineering of axially vascularized soft-tissue flaps with a solid neovascularization, strong cellular infiltration, and biomechanical properties similar to human fat. Our data indicate that SYNJ2BP, EPHA2, and FOXC1 are involved in AV loop-associated angiogenesis and that the scaffold material has an impact on protein expression in ECs.

Overexpression of miR-181a-5p inhibits retinal neovascularization through endocan and the ERK1/2 signaling pathway

Retinal neovascularization (RNV) is a common pathological feature of angiogenesis‐related retinopathy. Endocan inhibition has previously been reported to suppress RNV in oxygen‐induced retinopathy (OIR); however, its molecular mechanisms remain to be elucidated. Here, we investigated the role and mechanism of endocan in OIR. We established an OIR mouse model and detected aberrant endocan overexpression in OIR mouse retinas. Endocan inhibition through small interfering RNA or a neutralizing antibody inhibited vascular endothelial growth factor‐induced cell survival, cell proliferation, and tube formation in human retinal endothelial cells in vitro and reduced the RNV area in vivo. Using RNA sequencing, a luciferase reporter assay, and bioinformatics analyses, we identified endocan as a microRNA‐181a‐5p target gene. The antiangiogenic effect of miR‐181a‐5p on RNV was verified by intravitreal injection, and we showed that this involved the extracellular signal‐regulated protein kinases 1 and 2 (ERK1/2) signaling pathway. Collectively, our data demonstrate that miR‐181a‐5p/endocan regulates retinal angiogenesis through the ERK1/2 signaling pathway and might represent an attractive therapeutic strategy for RNV.

Insights from circulating microRNAs in cardiovascular entities in turner syndrome patients

Background

Turner syndrome (TS) is a chromosomal disorder, in which a female is partially or entirely missing one of the two X chromosomes, with a prevalence of 1:2500 live female births. The present study aims to identify a circulating microRNA (miRNA) signature for TS patients with and without congenital heart disease (CHD).

Methods

Microarray platform interrogating 2549 miRNAs were used to detect the miRNA abundance levels in the blood of 33 TS patients and 14 age-matched healthy volunteer controls (HVs). The differentially abundant miRNAs between the two groups were further validated by RT-qPCR.

Results

We identified 60 differentially abundant miRNA in the blood of TS patients compared to HVs, from which, 41 and 19 miRNAs showed a higher and a lower abundance levels in TS patients compared to HVs, respectively. RT-qPCR confirmed the significantly higher abundance levels of eight miRNAs namely miR-374b-5p, miR-199a-5p, miR-340-3p, miR-125b-5p, miR-30e-3p, miR-126-3p, miR-5695, and miR-26b-5p in TS patients as compared with the HVs. The abundance level of miR-5695 was higher in TS patients displaying CHD as compared to TS patients without CHD (p = 0.0265; log2-fold change 1.99); whereas, the abundance level of miR-126-3p was lower in TS patients with congenital aortic valve disease (AVD) compared to TS patients without BAV (p = 0.0139, log2-fold change 1.52). The clinical feature statistics revealed that miR-126-3p had a significant correlation with sinotubular junction Z-score (r = 0.42; p = 0.0154).

Conclusion

The identified circulating miRNAs signature for TS patients with manifestations associated with cardiovascular diseases provide new insights into the molecular mechanism of TS that may guide the development of novel diagnostic approaches.

Micro-RNA signatures in monozygotic twins discordant for congenital heart defects

Background

MicroRNAs (miRNAs) are small RNAs regulating gene expression post-transcriptionally. Recent studies demonstrated that miRNAs are involved in the development of congenital heart defects (CHD). In this study, we aimed at identifying the specific patterns of miRNAs in blood of monozygotic twin pairs discordant for CHD and to assess whether miRNAs might be involved in the development or reflect the consequences of CHD.

Methods

miRNA microarray analysis and Real-Time Quantitative PCR (RT-qPCR) were employed to determine the miRNA abundance level from 12 monozygotic twins discordant for CHD and their non-CHD co-twins (n = 12). Enrichment analyses of altered miRNAs were performed using bioinformatics tools.

Results

Compared with non-CHD co-twins, profiling analysis indicated 34 miRNAs with a significant difference in abundance level (p<0.05, fold change ≥ 1.3), of which 11 miRNAs were up-regulated and 23 miRNAs were down-regulated. Seven miRNAs were validated with RT-qPCR including miR-511-3p, miR-1306-5p, miR-421, miR-4707-3p, miR-4732-3p, miR-5189-3p, and miR-890, and the results were consistent with microarray analysis. Five miRNAs namely miR-511-3p, miR-1306-5p, miR-4732-3p, miR-5189-3p, and miR-890 were found to be significantly up-regulated in twins < 10 years old. Bioinformatics analysis showed that the 7 validated miRNAs were involved in phosphatidylinositol signaling, gap junction signaling, and adrenergic signaling in cardiomyocytes.

Conclusions

Our data show deregulated miRNA abundance levels in the peripheral blood of monozygotic twins discordant for CHD, and identify new candidates for further analysis, which may contribute to understanding the development of CHD in the future. Bioinformatics analysis indicated that the target genes of these miRNAs are likely involved in signaling and communication of cardiomyocytes.

miR-27a/b is a posttranscriptional regulator of Gpr126 (Adgrg6)

Gpr126 (Adgrg6), a member of the adhesion G protein-coupled receptor family, has been associated with a variety of human diseases. Yet, despite its clinical importance, the mechanisms regulating Gpr126 expression are poorly understood. Here, we aimed at identifying upstream regulatory mechanisms of Gpr126 expression utilizing the heart as model organ in which Gpr126 regulates trabeculation. Here, we focused on possible regulation of Gpr126 regulation by microRNAs, which have emerged as key players in regulating development, have a critical role in disease progression, and might serve as putative therapeutic targets. In silico analyses identified one conserved binding site in the 3' UTR of Gpr126 for microRNA 27a and 27b (miR-27a/b). In addition, miR-27a/b and Gpr126 expression were differentially expressed during rat heart development. A regulatory role of miR-27a/b in controlling Gpr126 expression was substantiated by reduced Gpr126 mRNA levels upon ectopic expression of miR-27a/b in HEK293T cells and miR-27b in zebrafish embryos. Regulation of Gpr126 expression by direct binding of miR-27a/b to the 3' UTR of Gpr126 was verified by luciferase reporter assays in HEK293T cells. Finally, the modulation of gpr126 expression in zebrafish by injection of either miR-27b or miR-27b inhibitor in single cell-stage embryos resulted in hypo- or hypertrabeculation, respectively. Collectively, the data indicate that Gpr126 expression is regulated by miR-27a/b.

One-Stage versus Two-Stage Arteriovenous Loop Reconstructions: An Experience on 103 Cases from a Single Center

BACKGROUND

The optimal time for flap anastomosis to an arteriovenous loop remains controversial. Whether perforator flaps and axially vascularized muscle or fasciocutaneous flaps lead to comparable outcomes in conjunction with arteriovenous loops has not been investigated.

METHODS

Medical records from 103 patients undergoing arteriovenous loop reconstruction (76 one-stage and 27 two-stage) between 2007 and 2017 were reviewed. Postoperative outcomes were compared between one- and two-stage arteriovenous loop reconstructions and different types of free flaps.

RESULTS

Rates of flap thrombosis, major wound complications, and flap failure did not differ significantly between one- and two-stage arteriovenous loop reconstructions (14.47 percent versus 11.11 percent, p = 1.00; 30.26 percent versus 25.93 percent, p = 0.67; and 10.53 percent versus 7.41 percent, p = 1.00). For two-stage arteriovenous loop reconstructions, the time interval between arteriovenous loop placement and flap anastomosis was a predictor for thrombotic events (OR, 1.31; p < 0.05). Anterolateral thigh flaps in conjunction with arteriovenous loops showed higher failure rates (33.33 percent) compared with all other flaps (6.59 percent) (p < 0.05) and combined latissimus dorsi and parascapular flaps (0 percent) (p < 0.05). Thrombosis rates were higher in anterolateral thigh flaps (33.33 percent) compared with all other flaps (10.99 percent; p = 0.056), and combined latissimus dorsi and parascapular flaps (0 percent; p < 0.05).

CONCLUSIONS

Two-stage arteriovenous loop reconstructions do not lead to increased postoperative complications compared to one-stage arteriovenous loop reconstructions and may be favorable in complicated cases because of shorter operative times. To avoid an increased thrombosis risk, flap anastomosis should not be delayed beyond 10 days in two-stage arteriovenous loop reconstructions. Anterolateral thigh flaps are less suitable for arteriovenous loop reconstructions because of higher complication rates.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.