Thrombin Stimulated Platelet-Derived Exosomes Inhibit Platelet-Derived Growth Factor Receptor-Beta Expression in Vascular Smooth Muscle Cells

Abstract

Background/Aims: It is difficult to predict acute thrombotic cardiovascular events in the clinic. Few studies have reported the presence of plasma exosomes containing microRNAs (miRNAs) in cardiovascular events. Therefore, we aimed to investigate the levels of miR-223, miR-339 and miR-21 in plasma exosomes before thrombosis in mouse models of carotid tandem stenosis, as well as the mechanisms underlying the origin and function of these exosomal miRNAs. Methods: Plasma samples were collected from the carotid tandem stenosis and sham control groups of our successfully developed atherothrombosis mouse models before thrombosis. Platelets from healthy volunteers and mice were purified to obtain thrombin stimulated platelet-derived exosomes. Exosomes were isolated via differential ultracentrifugation, and western blotting and transmission electron microscopy were used for their identification. The total RNA was extracted, and quantitative real-time PCR was performed to determine the expression levels of miR-223, miR-339 and miR-21. DAVID Tools were used to analyze the pathways that were enriched among the miRNA target genes. Immuno-fluorescence staining was performed to identify the protein expression levels of platelet-derived exosome target genes in vascular smooth muscle cells (SMCs) in vitro and in vivo. Results: The levels of miR-223, miR-339 and miR-21, which are associated with platelet activation, were elevated in pooled mouse plasma exosomes before thrombosis and enriched in thrombin-stimulated platelet-derived exosomes in vitro. Platelet-derived growth factor receptor-beta (PDGFRβ) was a target of these miRNAs, and PDGFRβ expression in vascular smooth muscle cells (SMCs) was inhibited following incubation with platelet-derived exosomes. Platelet-derived exosomes could also inhibit PDGF-stimulated SMC proliferation. Furthermore, a decrease in PDGFRβ expression was observed in vascular SMCs around thrombotic areas in vivo. Conclusions: Our data indicate that activated platelet-derived exosomes containing miR-223, miR-339 and miR-21 could be transferred into SMCs and inhibit PDGFRβ expression; these exosomal miRNAs may be a biomarker for predicting atherothrombosis.

Exosomes Derived from Human Bone Marrow Mesenchymal Stem Cells Promote Tumor Growth Through Hedgehog Signaling Pathway

“…Exosomes play an important role in cell-to-cell communication. They can be either taken up by neighboring cells or carried to distant sites via biological fluids and may therefore induce the phenotypic modifications in recipient cells [24, 25]. The possible mechanisms by which MSC-derived exosomes affect tumor initiation and progression have been explored.…”

Tumor-Derived Exosomal Long Noncoding RNAs as Promising Diagnostic Biomarkers for Prostate Cancer

“…They are released into the extracellular space upon fusion of multivesicular bodies with the plasma membrane [20, 21] and play important roles as cellular messengers to trigger diverse physiological and pathological responses and achieve cross-talk without direct contact with one another [22]. They have been found in a variety of biological fluids, such as blood [19], urine [23], saliva [24], milk [25] and bronchoalveolar lavage fluid [26] and are secreted by platelet [27], normal [28, 29] and tumor cells [30, 31]. Analyzing exosomes in the peripheral blood can therefore provide important information on the characteristics of parental cancer cells.…”

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“…MicroRNAs (miRNAs) negatively regulate the expression of their target genes at the post-transcriptional level by binding the 3'-untranslated regions (UTRs) of the genes, and participate in a series of physiological and pathological process, such as embryogenesis, cell differentiation, angiogenesis, wound repair and tumorigenesis [8][9][10]. Ji et al [11] first .…”