Platelet miRNAs Research Articles

Platelet-derived microRNAs play a pivotal role in cardiac remodeling after myocardial ischemia and reperfusion

Abstract Background Platelets can infiltrate ischemic myocardium and are increasingly recognized as critical regulators of inflammatory processes during myocardial ischemia and reperfusion (I/R). Platelets contain a broad repertoire of miRNAs, which, under certain conditions such as myocardial ischemia, may be transferred to surrounding cells or released into the microenvironment. Recent studies could demonstrate, that platelets contribute substantially to the circulating miRNA pool holding the potential for so far undiscovered regulatory functions. Purpose The present study aimed to determine the role of platelet-derived miRNAs in myocardial injury and repair following myocardial I/R. Methods and Results Combining an in vivo model of myocardial I/R, multimodal in vivo and ex vivo imaging approaches (LSFM, PET&MRI, speckle-tracking echocardiography), in vitro immune cell migration assays and Next-generation deep sequencing analysis of platelet miRNA expression pattern in mice with a MK/platelet-specific knockout of pre-miRNA processing ribonuclease Dicer, the present study discloses a key role of platelet-derived miRNAs in the tightly regulated cellular processes orchestrating LV remodeling after myocardial I/R following transient LCA ligation. Disruption of the miRNA processing machinery in platelets by deletion of Dicer resulted in increased myocardial inflammation, impaired angiogenesis, and accelerated development of cardiac fibrosis, culminating in an increased infarct size by d7 that persisted through d28 of myocardial ischemia and reperfusion. Worsened cardiac remodeling after myocardial infarction (MI) in mice with a platelet-specific Dicer deletion (Dicer Pf4Δ/PfΔ4) resulted in an increased fibrotic scar formation and distinguishably increased perfusion defect of the apical and anterolateral wall at d28 post-MI. Altogether, these observations culminated in an impaired LV function and hampered long-term cardiac recovery after experimental MI and reperfusion therapy. Treatment with the P2Y12 antagonist ticagrelor completely reversed increased myocardial damage and adverse cardiac remodeling observed in Dicer Pf4Δ/Pf4Δ mice. Conclusions The present study discloses a critical role of platelet-derived miRNA in myocardial inflammation and structural remodeling processes following myocardial ischemia and reperfusion.

Platelet miRNA Expression in Patients with Sticky Platelet Syndrome

Abstract Sticky platelet syndrome (SPS) is a disorder with familial occurrence and autosomal dominant trait characterized by platelet hyperaggregability in response to a low concentration of adenosine diphosphate (ADP) and/or epinephrine (EPI). The etiology of SPS may be associated with platelet microRNAs (miRNAs), which are considered as potential biomarkers of platelet function and antiplatelet therapy. We were monitoring the expression of platelet miRNAs in patients with laboratory diagnosed SPS and healthy controls. We have found a statistically significant increased expression of both miR-423-5p and miR-338-3p as well as a statistically significant decreased expression of miR-425-5p between the group of patients with diagnosed SPS type II and the group of healthy controls, which seems to be an interesting issue for a further research.

Platelet miRNAs: differential expression in coronary artery disease and associations with course of left ventricular systolic function

BackgroundMicroRNAs are paramount in post transcriptional gene regulation. We investigated platelet miRNAs in patients with CAD and examined potential associations with course of left ventricular ejection fraction (LVEF%).Materials and methodsIn a first cohort, 62 MiRNAs were measured in platelets of 100 patients suffering from CAD. Expression profiles of individuals with chronic coronary syndrome (CCS) and MI were compared (CCS n = 67, MI n = 33). Also, associations between miRNA profiles and change in left ventricular ejection fraction (LVEF%) were investigated. In a second cohort of patients suffering from CCS (n = 10), MI (n = 11) or no CAD (n = 13), we measured miRNA expression in platelets, platelet supernatant and serum. This was carried out before and after in vitro platelet activation with CRP.ResultsPlatelet miRNAs 103a-3p and 155-5p demonstrated higher expression in patients with CCS then in individuals with MI. Furthermore, multiple miRNAs were significantly higher expressed in matched controls compared to MI patients. 8 miRNAs showed higher expression in patients with improving LVEF% after a 1-year follow-up. In our second cohort, we found higher concentrations of 6 miRNAs in the platelet supernatant of patients with CCS, MI and no CAD after in vitro platelet activation. Most of these miRNAs showed a higher abundance in serum of MI patients as compared to CCS.ConclusionSeveral miRNAs show higher expression in platelets of CCS compared to MI. After in vitro platelet activation, a release of multiple miRNAs out of the thrombocyte was observed. Furthermore, upregulation of serum miRNAs was found in MI patients when compared to CCS patients and individuals without CAD. Hence, platelets could present a source of upregulated circulating miRNAs in MI and additionally affect course of LVEF%.

Decreased platelet miR-199a-5p level might lead to high on-clopidogrel platelet reactivity in patients with coronary artery disease

Clopidogrel combined with aspirin is widely used in coronary artery disease (CAD) patients, while some patients exhibit high platelet activity when receiving the combined treatment. Current environmental and genetic factors could only explain part of the variability in clopidogrel efficacy. Human platelets harbor abundant miRNAs which might affect clopidogrel efficacy by regulating the expression of key proteins in the clopidogrel antiplatelet signaling pathway. This study aimed to investigate the association between platelet miRNA levels and clopidogrel efficacy. Here we recruited 508 CAD patients who underwent clopidogrel antiplatelet therapy and determined the platelet reactivity index (PRI) to evaluate antiplatelet reactivity responses to clopidogrel. Subsequently, 22 patients with extreme clopidogrel response were selected for platelet small RNA sequencing. Another 41 CAD patients taking clopidogrel were collected to verify the differentially expressed candidate miRNAs. We found the metabolic types of the CYP2C19 enzyme (based on CYP2C19 * 2 and * 3 polymorphisms) could significantly affect the PRI of CAD patients with or without percutaneous coronary intervention (PCI) in Chinese. A total of 43 miRNAs were differentially expressed in the platelets from the 22 extreme clopidogrel response samples, and 109 miRNAs were differentially expressed in the 13 CYP2C19 extensive metabolizers with extreme clopidogrel response. Platelet miR-199a-5p levels were correlated negatively with PRI after clopidogrel therapy. Studies in cultured cells revealed that miR-199a-5p inhibited the expression of VASP, a key effector protein downstream of the P2Y12 receptor. In conclusion, we found the expression of VASP could be inhibited by miR-199a-5p, and decreased platelet miR-199a-5p was associated with high on-clopidogrel platelet reactivity in CAD patients.

Platelet-Derived MicroRNAs Regulate Cardiac Remodeling After Myocardial Ischemia.

Platelets can infiltrate ischemic myocardium and are increasingly recognized as critical regulators of inflammatory processes during myocardial ischemia and reperfusion (I/R). Platelets contain a broad repertoire of microRNAs (miRNAs), which, under certain conditions such as myocardial ischemia, may be transferred to surrounding cells or released into the microenvironment. Recent studies could demonstrate that platelets contribute substantially to the circulating miRNA pool holding the potential for so far undiscovered regulatory functions. The present study aimed to determine the role of platelet-derived miRNAs in myocardial injury and repair following myocardial I/R. In vivo model of myocardial I/R, multimodal in vivo and ex vivo imaging approaches (light-sheet fluorescence microscopy, positron emission tomography and magnetic resonance imaging, speckle-tracking echocardiography) of myocardial inflammation and remodeling, and next-generation deep sequencing analysis of platelet miRNA expression. In mice with a megakaryocyte/platelet-specific knockout of pre-miRNA processing ribonuclease Dicer, the present study discloses a key role of platelet-derived miRNAs in the tightly regulated cellular processes orchestrating left ventricular remodeling after myocardial I/R following transient left coronary artery ligation. Disruption of the miRNA processing machinery in platelets by deletion of Dicer resulted in increased myocardial inflammation, impaired angiogenesis, and accelerated development of cardiac fibrosis, culminating in an increased infarct size by d7 that persisted through d28 of myocardial I/R. Worsened cardiac remodeling after myocardial infarction in mice with a platelet-specific Dicer deletion resulted in an increased fibrotic scar formation and distinguishably increased perfusion defect of the apical and anterolateral wall at day 28 post-myocardial infarction. Altogether, these observations culminated in an impaired left ventricular function and hampered long-term cardiac recovery after experimental myocardial infarction and reperfusion therapy. Treatment with the P2Y12 (P2Y purinoceptor 12) antagonist ticagrelor completely reversed increased myocardial damage and adverse cardiac remodeling observed in DicerPf4∆/Pf4∆ mice. The present study discloses a critical role of platelet-derived miRNA in myocardial inflammation and structural remodeling processes following myocardial I/R.

Retracted: Correlation between Platelet miRNA Expression and Coagulation Function in Children with Severe Pneumonia.

[This retracts the article DOI: 10.1155/2022/2826115.].

Pancreatic Cancer Cells Induce MicroRNA Deregulation in Platelets.

Pancreatic cancer is a pathology with a high mortality rate since it is detected at advanced stages, so the search for early-stage diagnostic biomarkers is essential. Liquid biopsies are currently being explored for this purpose and educated platelets are a good candidate, since they are known to present a bidirectional interaction with tumor cells. In this work, we analyzed the effects of platelets on cancer cells’ viability, as determined by MTT, migration using transwell assays, clonogenicity in soft agar and stemness by dilution assays and stem markers’ expression. We found that the co-culture of platelets and pancreatic cancer cells increased the proliferation and migration capacity of BXCP3 cells, augmented clonogenicity and induced higher levels of Nanog, Sox2 and Oct4 expression. As platelets can provide horizontal transfer of microRNAs, we also determined the differential expression of miRNAs in platelets obtained from a small cohort of pancreatic cancer patients and healthy subjects. We found clear differences in the expression of several miRNAs between platelets of patients with cancer healthy subjects. Moreover, when we analyzed microRNAs from the platelets of the pancreatic juice and blood derived from each of the cancer patients, interestingly we find differences between the blood- and pancreatic juice-derived platelets suggesting the presence of different subpopulations of platelets in cancer patients, which warrant further analysis.

Correlation between Platelet miRNA Expression and Coagulation Function in Children with Severe Pneumonia.

Objective To investigate the relationship between expression levels of platelet miRNAs and severe pneumonia (SP) in children. Methods A randomized controlled trial was conducted in 129 children with SP hospitalized from May 2018 to May 2020. All children joined the study group and were divided into the mild infection group, moderate infection group, and severe infection group according to the diagnostic criteria, 43 cases in each group. Besides, 129 healthy children were selected as the control group. The expression levels of platelet miR-223 and miR-192 were detected by real-time quantitative polymerase chain reaction (qPCR). The prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen (FIB) were detected by the Sysmex CA-1500 System (Sysmex Corporation, Japan). The Pearson analysis was conducted to evaluate the correlation between coagulation function and the levels of miR-223 and miR-192. Results Compared with the control group, miR-223 in the study group was significantly higher and miR-192 was significantly lower (P < 0.05). Compared with the mild infection group, miR-223 was significantly higher and miR-192 was significantly lower in the moderate infection group and severe infection group (P < 0.05). Compared with the control group, PT and APTT were significantly lower and FIB was significantly higher in the study group (P < 0.05). Pearson correlation analysis revealed that miR-223 was positively correlated with PT and APTT (P < 0.05) and negatively correlated with FIB (P < 0.05); miR-192 was negatively correlated with PT and APTT (P < 0.05) and positively correlated with FIB (P < 0.05). Conclusion miR-223 and miR-192 can reflect coagulation function in children with SP, which can provide a certain reference basis for clinical guidance and treatment and prognosis.

Comprehensive Characterization of Platelet-Enriched MicroRNAs as Biomarkers of Platelet Activation.

Dysregulation of platelet function is causally connected to thrombus formation and cardiovascular diseases. Therefore, assessing platelet reactivity is crucial. However, current platelet function tests come with pitfalls, limiting clinical use. Plasma miRNA signatures have been suggested as novel biomarkers for predicting/diagnosing cardiovascular diseases and monitoring antiplatelet therapy. Here, we provide results from a comprehensive study on the feasibility of using circulatory platelet miRNAs as surrogate markers of platelet activation. We performed small RNA-Seq on different blood cell types to confirm known and identify novel platelet-enriched miRNAs and validated a panel of 16 miRNAs using RT-qPCR. To identify the main carrier of these blood-based platelet miRNAs, we enriched and analyzed distinct microvesicle populations. Platelets were stimulated with GPVI and P2Y12 agonists in vitro to monitor the release of the selected miRNAs following activation. Finally, the miRNA panel was also measured in plasma from mice undergoing the Folts intervention (recurrent thrombus formation in the carotid artery). Applying an unbiased bioinformatics-supported workflow to our NGS data, we were able to confirm a panel of previously established miRNA biomarker candidates and identify three new candidates (i.e., miR-199a-3p, miR-151a-5p, and miR-148b-3p). Basal levels of platelet-derived miRNAs in plasma were mainly complexed with proteins, not extracellular vesicles. We show that changes in miRNA levels due to platelet activation are detectable using RT-qPCR. In addition, we highlight limitations of studying the in vitro release of miRNAs from platelets. In vivo thrombosis resulted in significant elevations of platelet-derived miRNA levels in mice. In conclusion, we provide in-depth evidence that activated platelets release miRNAs, resulting in measurable changes in circulatory miRNA levels, rendering them promising biomarker candidates.

Platelet microRNAs inhibit primary tumor growth via broad modulation of tumor cell mRNA expression in ectopic pancreatic cancer in mice.

We investigated the contributions of platelet microRNAs (miRNAs) to the rate of growth and regulation of gene expression in primary ectopic tumors using mouse models. We previously identified an inhibitory role for platelets in solid tumor growth, mediated by tumor infiltration of platelet microvesicles (microparticles) which are enriched in platelet-derived miRNAs. To investigate the specific roles of platelet miRNAs in tumor growth models, we implanted pancreatic ductal adenocarcinoma cells as a bolus into mice with megakaryocyte-/platelet-specific depletion of mature miRNAs. We observed an ~50% increase in the rate of growth of ectopic primary tumors in these mice compared to controls including at early stages, associated with reduced apoptosis in the tumors, in particular in tumor cells associated with platelet microvesicles—which were depleted of platelet-enriched miRNAs—demonstrating a specific role for platelet miRNAs in modulation of primary tumor growth. Differential expression RNA sequencing of tumor cells isolated from advanced primary tumors revealed a broad cohort of mRNAs modulated in the tumor cells as a function of host platelet miRNAs. Altered genes comprised 548 up-regulated transcripts and 43 down-regulated transcripts, mostly mRNAs altogether spanning a variety of growth signaling pathways–notably pathways related to epithelial-mesenchymal transition—in tumor cells from platelet miRNA-deleted mice compared with those from control mice. Tumors in platelet miRNA-depleted mice showed more sarcomatoid growth and more advanced tumor grade, indicating roles for host platelet miRNAs in tumor plasticity. We further validated increased protein expression of selected genes associated with increased cognate mRNAs in the tumors due to platelet miRNA depletion in the host animals, providing proof of principle of widespread effects of platelet miRNAs on tumor cell functional gene expression in primary tumors in vivo. Together, these data demonstrate that platelet-derived miRNAs modulate solid tumor growth in vivo by broad-spectrum restructuring of the tumor cell transcriptome.

Screening Analysis of Platelet miRNA Profile Revealed miR-142-3p as a Potential Biomarker in Modeling the Risk of Acute Coronary Syndrome.

Transcriptome analysis constitutes one of the major methods of elucidation of the genetic basis underlying the pathogenesis of various diseases. The post-transcriptional regulation of gene expression is mainly provided by microRNAs. Their remarkable stability in biological fluids and their high sensitivity to disease alteration indicates their potential role as biomarkers. Given the high mortality and morbidity of cardiovascular diseases, novel predictive biomarkers are sorely needed. Our study focuses for the first time on assessing potential biomarkers of acute coronary syndrome (ACS) based on the microRNA profiles of platelets. The study showed the overexpression of eight platelet microRNAs in ACS (miR-142-3p; miR-107; miR-338-3p, miR-223-3p, miR-21-5p, miR-130b-3p, miR-301a-3p, miR-221-3p) associated with platelet reactivity and functionality. Our results show that the combined model based on miR-142-3p and aspartate transaminase reached 82% sensitivity and 88% specificity in the differentiation of the studied groups. Furthermore, the analyzed miRNAs were shown to cluster into two orthogonal groups, regulated by two different biological factors. Bioinformatic analysis demonstrated that one group of microRNAs may be associated with the physiological processes of platelets, whereas the other group may be linked to platelet–vascular environment interactions. This analysis paves the way towards a better understanding of the role of platelet microRNAs in ACS pathophysiology and better modeling of the risk of ACS.

Bioinformatics analysis of tumor-educated platelet microRNAs in patients with hepatocellular carcinoma.

Background: Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies that seriously threaten global health. The primary reason for its grim prognosis is the lack of sensitive tools for early diagnosis. The purpose of the present study was to apply bioinformatics analysis to explore tumor-educated platelet (TEP) microRNA (miRNA) expression and its potential diagnostic utility in HCC.Methods: Twenty-five HCC patients and 25 healthy controls were included. RNA sequencing was utilized to screen miRNA alterations in platelets derived from HCC patients (n=5) and controls (n=5). Gene set enrichment analysis was performed to analyze the targeted mRNAs of differentially expressed miRNAs by using the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, aiming at main functions and pathways, respectively. We then verified the selected platelet miRNAs in another cohort by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) amplification.Results: A total of 250 differentially expressed miRNAs were identified, among which 111 were down-regulated and 139 were up-regulated. The functional enrichment analysis of differentially expressed miRNAs suggested that their target genes were involved primarily in pathways related to HCC. Expression levels of miR-495-3p and miR-1293 were further validated by qRT-PCR, which yielded results consistent with the sequencing analysis. The area under the receiver operating characteristic (ROC) curve of miR-495-3p and miR-1293 as diagnostic tests for HCC were 0.76 and 0.78, respectively.Conclusion: TEP miRNAs such as miR-495-3p and miR-1293 were differentially expressed in HCC patients, and may be involved in the pathophysiology of HCC.

A dry immersion model of microgravity modulates platelet phenotype, miRNA signature, and circulating plasma protein biomarker profile

Ground based research modalities of microgravity have been proposed as innovative methods to investigate the aetiology of chronic age-related conditions such as cardiovascular disease. Dry Immersion (DI), has been effectively used to interrogate the sequelae of physical inactivity (PI) and microgravity on multiple physiological systems. Herein we look at the causa et effectus of 3-day DI on platelet phenotype, and correlate with both miRomic and circulating biomarker expression. The miRomic profile of platelets is reflective of phenotype, which itself is sensitive and malleable to the exposome, undergoing responsive transitions in order to fulfil platelets role in thrombosis and haemostasis. Heterogeneous platelet subpopulations circulate at any given time, with varying degrees of sensitivity to activation. Employing a DI model, we investigate the effect of acute PI on platelet function in 12 healthy males. 3-day DI resulted in a significant increase in platelet count, plateletcrit, platelet adhesion, aggregation, and a modest elevation of platelet reactivity index (PRI). We identified 15 protein biomarkers and 22 miRNA whose expression levels were altered after DI. A 3-day DI model of microgravity/physical inactivity induced a prothrombotic platelet phenotype with an unique platelet miRNA signature, increased platelet count and plateletcrit. This correlated with a unique circulating protein biomarker signature. Taken together, these findings highlight platelets as sensitive adaptive sentinels and functional biomarkers of epigenetic drift within the cardiovascular compartment.

Expression and clinical significance of platelet miRNA after high tibial osteotomy

To explore effect and significance of lateral closed high tibial osteotomy on recovery of activity of knee joint. From February to December 2018, 78 patients with knee osteoarthritis who were treated by high tibial osteotomy for the first time were selected as the observation group, including 46 males and 32 females, aged from 55 to 73 years old with an average age of (61.78±6.39) years old, the course of disease ranged from 6 to 24 months with an average of (16.52±4.25) months;according to Kellgren-Lawrence (K-L) grading, 36 patients were gradeⅡand 42 patients were grade Ⅲ. Another 20 healthy people were selected as healthy group, including 13 males and 7 females, aged from 56 to 73 years old with an average of (60.89±7.12) years old. The expression of miR-146 in peripheral blood was compared between observation group and healthy group. At the same time, patients in observation group were followed up for 6 months. The patients whose knee joint function returned to normal or improved significantly during the follow-up period were admitted as the effective group, while the patients whose knee joint function did not improve significantly or tended to aggravate were admitted as the ineffective group. The clinical data and the relative expression of serum miR-146 between effective group and ineffective group were analyzed. The relative expression of serum miR-146 in observation group after operation was significantly higher than that in healthy group (P<0.05). The results of six months follow-up showed that 15 patients (19.23%) in ineffective group and 63 patients (80.77%) in effective group. Relative expression of miR-146 and interleukin-6 (IL-6) in ineffective group were higher than that of effective group (P<0.05). ROC curve analysis and maximum Yoden index were used to calculate the truncationvalues of the maximum area under curve (AUC) of serum miR-146 and IL-6, which was 0.859 and 0.702 respectively. The truncation values of miRNA-146 and IL-6 were 0.98 (sensitivity was 86.30%, specificity was 93.20%) and 175.65 (sensitivity was 72.80%, specificity was 69.50%). The expression level of serum miR-146 showed upward trend, which could regulate the differentiation of chondrocyte. The monitoring of miR-146 after operation has reference value for predicting the recovery of bone and joint function after operation.

Platelet miRNA Biosignature Discriminates between Dementia with Lewy Bodies and Alzheimer's Disease.

Dementia with Lewy bodies (DLB) is one of the most common causes of degenerative dementia, after Alzheimer’s disease (AD), and presents pathological and clinical overlap with both AD and Parkinson’s disease (PD). Consequently, only one in three DLB cases is diagnosed correctly. Platelets, previously related to neurodegeneration, contain microRNAs (miRNAs) whose analysis may provide disease biomarkers. Here, we profiled the whole platelet miRNA transcriptome from DLB patients and healthy controls. Differentially expressed miRNAs were further validated in three consecutive studies from 2017 to 2019 enrolling 162 individuals, including DLB, AD, and PD patients, and healthy controls. Results comprised a seven-miRNA biosignature, showing the highest diagnostic potential for the differentiation between DLB and AD. Additionally, compared to controls, two miRNAs were down-regulated in DLB, four miRNAs were up-regulated in AD, and two miRNAs were down-regulated in PD. Predictive target analysis identified three disease-specific clusters of pathways as a result of platelet-miRNA deregulation. Our cross-sectional study assesses the identification of a novel, highly specific and sensitive platelet-associated miRNA-based biosignature, which distinguishes DLB from AD.

Platelet miR-107 Participates in Clopidogrel Resistance after PCI Treatment by Regulating P2Y12

Introduction: High platelet reactivity (HPR) caused by clopidogrel tolerance is an adverse reaction of acute coronary syndrome (ACS) patients who receive clopidogrel antiplatelet therapy after percutaneous coronary intervention (PCI) surgery. Platelet microRNA (miRNA) is related to platelet reactivity. This study explored the mechanism of platelet miRNA in regulating platelet reactivity. Methods: We recruited 50 ACS/PCI patients and divided them into the HPR group (P2Y12 reaction units [PRU] ≥300) and the LPR group (PRU < 170) according to the PRU through the VerifyNow P2Y12 assay. P2Y12-related miRNAs were screened by TargetScan, miRWalk, and Gene Expression Omnibus. The expressions of P2Y12 and miRNAs in the HPR group and the LPR group were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Pearson correlation analysis was used to determine the correlation between P2Y12 and miRNAs. The interactions between P2Y12 and miR-107 were predicted by TargetScan and verified by dual-luciferase reporter assay. The regulation of miR-107 mimic or inhibitor on P2Y12 expression was detected by qRT-PCR and Western blot. Results: There were 22 patients in the LPR group and 28 patients in the HPR group. PY212 was highly expressed in the HPR group compared with the LPR group. We screened the P2Y12-related miRNAs (miR-145-5p, miR-4701-3p, miR-107, and miR-15b-5p), but only miR-107 and miR-15b-5p expressions were downregulated in the HPR group and were negatively correlated with PY212 expression. P2Y12 was the target gene of miR-107. PY212 expression was inhibited by miR-107 overexpression but suppressed by miR-107 silencing. Conclusion: Platelet miR-107 participated in clopidogrel resistance in ACS/PCI patients by regulating P2Y12 expression.

New Insights Into Platelet-enriched miRNAs: Production, Functions, Roles in Tumors, and Potential Targets for Tumor Diagnosis and Treatment.

In view of the increasing number of malignant tumors worldwide and their high mortality, efforts are being made to find effective biomarkers for early detection and effective treatment measures of cancer. In recent years, the roles of platelets in tumors have attracted considerable attention. Although platelets do not have nuclei, they are rich in miRNAs, which are important molecules in platelet regulation of tumors. Platelet miRNA expression in tumor patients is abnormal and tumor-specific. Platelet miRNAs have higher accuracy and specificity than conventional tumor detection markers and circulating miRNAs in tumor diagnosis. Platelets enriched miRNAs are involved in the regulation of tumor proliferation, metastasis, tumor-related immunity, tumor-related thrombosis, and antitumor therapy. To understand the role of platelet miRNAs in tumors, this article reviews the biological functions of miRNAs in platelets and summarizes the regulatory roles of platelet miRNAs in tumors and the potential roles of platelet miRNAs in tumor diagnosis and treatment.

Platelet Activation Is Not Always Associated With Platelet-Related Plasma microRNA Abundance - Results From a Randomized Controlled Trial of Periodontal Patients.

Platelets are involved in a variety of diseases, making their adequate functional assessment is essential. However, due to their easily activatable nature this has some methodological pitfalls. Therefore, the availability of stable, easily measurable surrogate markers would be beneficial. In this regard, some evidence suggests that certain microRNAs (miRNAs) circulating in plasma might be useful. We aimed to corroborate their suitability by analyzing plasma samples obtained in a randomized controlled trial, which assessed the effects of periodontal treatment on platelet function. We hypothesized that miRNA levels mirror changes of platelet activation and -function. Both platelet function and miRNA abundance were quantified using state-of-the-art flow cytometry and qPCR methods. The following miRNAs were quantified: 223-3p, 150-5p, 197-3p, 23a-3p, 126-3p, 24-3p, 21-5p, 27b-3p, 33a-5p, 320a, 191-5p, 28-3p, 451a, 29b-3p, and 1-3p. However, periodontal treatment did not affect the abundance of any investigated miRNAs to a relevant extent. Platelet activation and reactivity indices did neither correlate with any tested miRNA at baseline, nor after the treatment period. In addition, there was no evidence that investigated miRNAs were released by platelets, as suggested previously. In conclusion, our data suggest that in patients suffering from periodontal disease the investigated miRNAs are unlikely to be suitable biomarkers for platelet function. Our data aim to raise awareness that previously determined platelet activation dependent circulating miRNAs are not suitable as platelet biomarkers in all cohorts.

Effects of endothelial progenitor cell therapy on microrna expression profiles in plasma, platelets and platelet-derived microvesicles in atherosclerosis

Background and Aims: The purpose was to investigate the effects of transplantation of endothelial progenitor cells (EPCs) on expressed profiles of miRNAs in plasma, platelets and platelet-derived microvesicles (PMVs) obtained from experimental induced atherosclerosis animal model.

High-efficiency unassisted transfection of platelets with naked double-stranded miRNAs modulates signal-activated translation and platelet function

We sought novel approaches to improve transfection efficiencies of microRNAs (miRNAs) in platelets, and to apply these approaches to investigate the roles of miRNAs in regulating signal-activated protein translation and functional effects. We found that ex vivo human platelets support gymnosis––-internalization of ectopic miRNAs following co-incubation in the absence of conventional transfection reagents or schemes---and subsequently incorporate transfected miRNA into ARGONAUTE2 (AGO2)-based RNA-induced silencing complexes (RISC). Thrombin/fibrinogen stimulation activated translation of miR-223-3p target SEPTIN2, which was suppressed by miR-223-3p transfection in an AGO2/RISC-dependent manner. Thrombin/fibrinogen-induced exosome and microvesicle generation was inhibited by miR-223-3p transfection, and this effect was reversed with a RISC inhibitor. Platelet gymnosis of naked miRNAs appeared to be mediated in part by endocytic pathways including clathrin-dependent and fluid-phase endocytosis and caveolae. These results demonstrate the ability of ex vivo platelets to internalize ectopic miRNAs by unassisted transfection, and utilize them to modulate signal-activated translation and platelet function. Our results identify new roles for miR-223-3p in extracellular vesicle generation in stimulated platelets. High-efficiency gymnotic transfection of miRNAs in ex vivo platelets may be a broadly useful tool for exploring molecular genetic regulation of platelet function.