Exosomal Small RNA Research Articles

Dynamic expression of smRNA from fecal exosome in disease progression of an inflammatory bowel disorder mouse model

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract affecting over 3 million adults in the United States. Despite being widespread, reliable early diagnostic tests are not available. We examined exosomal small RNA (smRNA), specifically targeting microRNA (miRNA) and piRNA from the stool samples of IBD model mice, interleukin 10 knockout mice (IL-10 KO), as a potential diagnostic marker. Stool samples were specifically chosen because they are readily available, and collection is noninvasive. At the end of the experimental period, the gastrointestinal (GI) tract was collected, and disease severity was scored. Histopathology showed a significant increase in inflammation and proliferation within the proximal and distal large intestines. smRNA profiles were examined upon conventional housing (start-point) which is a determinant factor of spontaneous IBD progression in the IL-10 KO mice, terminal illness (end-point), and 6 weeks before the end-point (mid-point), when the mice were still phenotypically healthy. We found 504 smRNA that were significantly differentially expressed between before symptom onset and terminal sedation. These changes were not detected in wild-type samples. Moreover, clustering analysis of expression changes over the disease progression identified a unique set of smRNAs that primarily target pro-inflammatory or anti-inflammatory genes. The expression of smRNAs that suppresses pro-inflammatory genes was higher at 6 weeks before terminal sedation, suggesting the downregulation of the pro-inflammatory genes advances the terminal illness of the IBD. In summary, our study proposes that fecal exosomal smRNA profiling offers a new opportunity to monitor the inflammatory status of the gut with a capability of detecting its pro-inflammatory (asymptomatic) status. Our next step is to understand the spatiotemporal interplay of these exosomes and the host cells in the gut as well as the complete biochemical makeup of fecal exosomes, such as mRNA, DNA, protein, and lipids. This will lead to an exciting development of reengineered exosomes that can be utilized to treat or even prevent the pro-inflammatory colonic lesion while the host is still clinically asymptomatic.

Differential Expression of Urinary Exosomal Small RNAs in Idiopathic Membranous Nephropathy.

Background Idiopathic membranous nephropathy (IMN) is a major cause of adult nephrotic syndromes, and reliable noninvasive biomarkers for diagnosis and monitoring are urgently needed. In this study, we performed small RNA (sRNA) sequencing to explore sRNA profiles of urinary exosomes derived from IMN patients and healthy controls (CON) to provide clues for identifying novel noninvasive sRNA biomarkers for IMN. Methods Urine samples were collected from five healthy controls and six patients with IMN. High-throughput sequencing was used to screen sRNA expression profiles of urinary exosomes from patients with IMN in two independent cohorts. Results Urinary exosomes were successfully isolated and used to obtain exosomal sRNAs. We screened 131 differentially expressed miRNAs, including 28 specifically expressed miRNAs, then explored the top 10 specifically expressed miRNAs in all IMN individuals. The specifically expressed miRNAs and differentially expressed miRNAs provide potential biomarkers for IMN. Additionally, we discovered numerous sRNAs derived from genomic repetitive sequences, which could represent an exciting new area of research. Conclusion Herein, we revealed significant differences in expression profiles of urinary exosomal miRNAs and repetitive region-derived sRNAs between patients with IMN and healthy controls. The findings could facilitate the development of potential molecular targets for membranous nephropathy.

Circulating exosomal small RNAs are promising non-invasive diagnostic biomarkers for gastric cancer.

Dysregulation of small non‐coding RNA (ncRNA) is associated with various human diseases including cancer. This study aimed to evaluate the circulating exosomal small RNAs including microRNAs (miRNAs) and P‑element‑induced wimpy testis (PIWI)‐interacting RNAs (piRNAs) as sensitive and specific non‐invasive biomarkers for gastric cancer (GC) diagnosis. Serum exosomal small RNA transcriptome was examined using unique molecular identifiers (UMI) small RNA sequencing. Dysregulated miRNAs and piRNAs were verified in 70 GC patients and 60 healthy controls (HC) by reverse transcription quantitative PCR. The expressions of miR‐1307‐3p, piR‐019308, piR‐004918 and piR‐018569 in serum exosomes were significantly increased in GC group as compared to those in HC group. Moreover, GC patients with metastasis had significantly higher expression levels of piR‐004918 and piR‐019308 than GC patients without metastasis. The area under the curve (AUC) for miR‐1307‐3p, piR‐019308, piR‐004918 and piR‐018569 in the GC group was 0.845, 0.820, 0.754 and 0.732, respectively. The combination of carcinoembryonic antigen (CEA) and carbohydrate antigen (CA) 199 can improve the AUC of miR‐1307‐3p to 0.902 and piR‐019308 to 0.914 for GC diagnosis. In conclusion, our findings indicate that serum exosomal piRNAs are promising non‐invasive diagnostic biomarkers for GC patients and potential markers for monitoring metastasis.

A comparison between long non-coding RNA repertoires of exosomes derived from naïve and cytokine-activated human mesenchymal stem cells

Background & Aim Mesenchymal stem cells (MSCs) are being used in the fields of regenerative medicine, especially in the treatment of musculoskeletal disorders, diabetes, autoimmune diseases, neuronal injury, and neurodegeneration. The therapeutic effects of MSCs are largely mediated by paracrine factors including exosomes, which are nanometer-sized membrane-bound vesicles with functions as mediators of cell-cell communication. Interestingly, the therapeutic potential of MSCs could be prompted by pro-inflammatory cytokines stimulation. The alternation of MSC-secreted immunomodulatory factors composition after cytokine treatment strengthen the modulation of exosomal regenerative nature. MSC-derived exosomes bypass the concern of pro-fibrogenic potential and the possibility of tumorigenicity upon in vivo transplantation of MSCs and could represent a novel cell-free therapeutics. However, the composition of exosomes, in particular long non-coding RNAs (lncRNAs), are not comprehensively investigated. In this study, we compared the expression level of long non-coding RNAs in exosomes derived from naive and cytokine-activated human adipose-derived MSCs. Methods, Results & Conclusion Human adipose-derived MSCs were incubated with or without TNF-α and IFN-γ in serum-free medium for 24 hrs, and the condition medium were harvested for exosome isolation and small RNA sequencing. Exosome isolation protocol is as previously described (Wu and Lee, Stem Cell Research & Therapy (2017) 8:117). Small RNAs in exosomes were sequenced by the Illumina HiSeq 2500 System (50SE). Twenty upregulated lncRNAs after cytokine treatment are selected for lncRNA-RNA and lncRNA-protein interaction prediction. Our results provide a reference dataset that can help to identify the therapeutic targets for future translational studies.

Analysis of deep sequencing exosome-microRNA expression profile derivedfrom CP-II reveals potential role of gga-miRNA-451 in inflammation.

Mycoplasma gallisepticum (MG) can cause chronic respiratory disease (CRD) in chickens. While several studies have reported the inflammatory functions of microRNAs during MG infection, the mechanism by which exosomal miRNAs regulate MG‐induced inflammation remains to be elucidated. The expression of exosome‐microRNA derived from MG‐infected chicken type II pneumocytes (CP‐II) was screened, and the target genes and function of differentially expressed miRNAs (DEGs) were predicted. To verify the role of exosomal gga‐miR‐451, Western blot, ELISA and RT‐qPCR were used in this study. The results showed that a total of 722 miRNAs were identified from the two exosomal small RNA (sRNA) libraries, and 30 miRNAs (9 up‐regulated and 21 down‐regulated) were significantly differentially expressed. The target miRNAs were significantly enriched in the treatment group, such as cell cycle, Toll‐like receptor signalling pathway and MAPK signalling pathway. The results have also confirmed that gga‐miR‐451‐absent exosomes derived from MG‐infected CP‐II cells increased inflammatory cytokine production in chicken fibroblast cells (DF‐1), and wild‐type CP‐II cell–derived exosomes displayed protective effects. Collectively, our work suggests that exosomes from MG‐infected CP‐II cells alter the dynamics of the DF‐1 cells, and may contribute to pathology of the MG infection via exosomal gga‐miR‐451 targeting YWHAZ involving in inflammation.

Exosomal Small RNA Sequencing Uncovers Dose-Specific MiRNA Markers for Ionizing Radiation Exposure.

Introduction:Acute exposure to ionizing radiation (IR) is hazardous or even lethal. Accurate estimation of the doses of IR exposure is critical to wisely determining the following treatments. Exosomes are nanoscale vesicles harboring biomolecules and mediate the communications among cells and tissues to influence biological processes. Screening out the microRNAs (miRNAs) contained in exosomes as biomarkers can be useful for estimating the IR exposure doses and exploring the correlation between these miRNAs and the occurrence of disease.Methods:We treated mice with 2.0, 6.5, and 8.0 Gy doses of IR and collected the mice sera at 0, 24, 48, and 72 hours after exposure. Then, the serum exosomes were isolated by ultracentrifuge and the small RNA portion was extracted for sequencing and the following bioinformatics analysis. Qualitative polymerase chain reaction was performed to validate the potential dose-specific markers.Results:Fifty-six miRNAs (31 upregulated, 25 downregulated) were differentially expressed after exposure of the above 3 IR doses and may act as common IR exposure miRNA markers. Bioinformatic analysis also identified several dosage-specific responsive miRNAs. Importantly, IR-induced miR-151-3p and miR-128-3p were significantly and stably increased at 24 hours in different mouse strains with distinct genetic background after exposed to 8.0 Gy of IR.Conclusion:Our study shows that miR-151-3p and miR-128-3p can be used as dose-specific biomarkers of 8.0 Gy IR exposure, which can be used to determine the exposure dose by detecting the amount of the 2 miRNAs in serum exosomes.

The expression of small RNAs in exosomes of follicular fluid altered in human polycystic ovarian syndrome.

Polycystic ovary syndrome (PCOS) can cause reproductive disorders that may affect oocyte quality from punctured follicles in human follicular fluid (HFF). The non-coding RNA family includes micro RNA (miRNA), piwi-interacting RNA (piRNA) and transfer RNA (tRNA); these non-coding RNA transcripts play diverse functions and are implicated in a variety of diseases and health conditions, including infertility. In this study, to explore the role of HFF exosomes in PCOS, we extracted and sequenced RNA from HFF exosomes of PCOS patients and compared the analysis results with those of non-PCOS control group. The HFF exosomes were successfully isolated and characterized in a variety of ways. The sequencing results of the HFF exosomal RNA showed that about 6.6% of valid reads in the PCOS group and 8.6% in the non-PCOS group were successfully mapped to the human RNA database. Using a hierarchical clustering method, we found there were ten small RNA sequences whose expression was significantly different between the PCOS and non-PCOS groups. We chose six of them to predict target genes of interest for further GO analysis, and pathway analysis showed that the target genes are mainly involved in biosynthesis of amino acids, glycine, serine and glycosaminoglycan, as well as threonine metabolism. Therefore, the small RNA sequences contained in HFF EXs may play a key role in the mechanism that drives PCOS pathogenesis, and thereby can act as molecular biomarkers for PCOS diagnosis in the future.

Serum Exosomal MicroRNA, miR-10b-5p, as a Potential Diagnostic Biomarker for Early-Stage Hepatocellular Carcinoma.

Exosomal microRNAs (exo-miRs) have been promising cancer biomarkers. MiRs in hepatocellular carcinoma (HCC) cell-derived exosomes (HEX) were analyzed to identify reliable serum biomarkers for HCC. To detect overexpressed miRs in HEX, extracted exosomal small RNAs from human HCC cell lines and normal hepatocytes were sequenced and analyzed. Clinical significance of the overexpressed miRs in HEX was evaluated using quantitative real-time PCR (qRT-PCR) on serum samples of a validation cohort consisting of 28 healthy individuals, 60 with chronic liver disease, and 90 with HCC. We found 49 significantly overexpressed miRs in HEX compared to a normal hepatocyte. Among them, miR-10b-5p, miR-18a-5p, miR-215-5p, and miR-940 were overexpressed in HCC tissues and also associated with prognosis of HCC in the analysis of a public omics database. qRT-PCR analysis of the four serum exo-miRs in the validation cohort revealed serum exo-miR-10b-5p as a promising biomarker for early-stage HCC with 0.934 area under the curve (AUC) (sensitivity, 90.7%; specificity, 75.0%; cutoff value, 1.8-fold). Overexpression of serum exo-miR-215-5p was found to be significantly associated with poor disease-free survival in patients with HCC. Serum exo-miR-10b-5p is a potential biomarker for early-stage HCC, while serum exo-miR-215-5p can be used as prognostic biomarker for HCC.

Acoustofluidic Salivary Exosome Isolation: A Liquid Biopsy Compatible Approach for Human Papillomavirus–Associated Oropharyngeal Cancer Detection

Previous efforts to evaluate the detection of human papilloma viral (HPV) DNA in whole saliva as a diagnostic measure for HPV-associated oropharyngeal cancer (HPV-OPC) have not shown sufficient clinical performance. We hypothesize that salivary exosomes are packaged with HPV-associated biomarkers, and efficient enrichment of salivary exosomes through isolation can enhance diagnostic and prognostic performance for HPV-OPC. In this study, an acoustofluidic (the fusion of acoustics and microfluidics) platform was developed to perform size-based isolation of salivary exosomes. These data showed that this platform is capable of consistently isolating exosomes from saliva samples, regardless of viscosity variation and collection method. Compared with the current gold standard, differential centrifugation, droplet digital RT-PCR analysis showed that the average yield of salivary exosomal small RNA from the acoustofluidic platform is 15 times higher. With this high-yield exosome isolation platform, we show that HPV16 DNA could be detected in isolated exosomes from the saliva of HPV-associated OPC patients at 80% concordance with tissues/biopsies positive for HPV16. Overall, these data demonstrated that the acoustofluidic platform can achieve high-purity and high-yield salivary exosome isolation for downstream salivary exosome-based liquid biopsy applications. Additionally, HPV16 DNA sequences in HPV-OPC patients are packaged in salivary exosomes and their isolation will enhance the detection of HPV16 DNA.

Integrated exosomal miRNA and transcriptome analysis of brain microvascular endothelial cells in spontaneously hypertensive rats.

Endothelial cells, which regulate arterial stiffness via endothelial-derived substances, are independently and strongly associated with hypertension. However, the exact roles of exosome miRNAs from brain endothelial cells in the development of hypertension are still not fully explored. Here, we investigated the miRNA functions systematically by examining both exosomal small RNA and mRNA of endothelial cells in Wistar Kyoto (WKY) rats versus spontaneously hypertensive rats (SHRs). Our findings revealed that miRNAs, representing ~60-70%, account for the majority of small RNAs. Moreover, we found 159 novel miRNAs in total from the unannotated reads across the diverse samples. Afterwards, 76 differentially expressed miRNAs (37 upregulated, 39 downregulated) and 1709 differentially expressed mRNAs (775 upregulated, 934 downregulated) were identified between SHRs and WKY rats, respectively. Finally, 647 genes targeted by 36 miRNAs came to our attention via identification of the target genes of those abnormal miRNAs. The differentially expressed target genes induced by miRNA changes were mapped to a number of genes involved in various gene functions and pathways. These changes lead to dysregulation of angiogenesis, axonogenesis, neuron-to-neuron synapses, focal adhesion, axon guidance, cell adhesion molecules (CAMs), adherens junction, and ECM-receptor interaction pathways. Together, our study revealed that the miRNAs are changed and contribute to the dysregulated functions and pathways of their target genes and provided more insights into their regulation mechanisms during mammalian hypertension development.

Small RNA Profiles of Serum Exosomes Derived From Individuals With Latent and Active Tuberculosis.

Tuberculosis (TB) has been the leading lethal infectious disease worldwide since 2014, and about one third of the world’s population has a latent TB infection (LTBI). This is largely attributed to the difficulties in diagnosis and treatment of TB and LTBI patients. Exosomes offer a new perspective on investigation of the process of TB infection. In this study, we performed small RNA sequencing to explore small RNA profiles of serum exosomes derived from LTBI and TB patients and healthy controls (HC). Our results revealed distinct miRNA profile of the exosomes in the three groups. We screened 250 differentially expressed miRNAs including 130 specifically expressed miRNAs. Some miRNAs were further validated to be specifically expressed in LTBI (hsa-let-7e-5p, hsa-let-7d-5p, hsa-miR-450a-5p, and hsa-miR-140-5p) and TB samples (hsa-miR-1246, hsa-miR-2110, hsa-miR-370-3P, hsa-miR-28-3p, and hsa-miR-193b-5p). Additionally, we demonstrated four expression panels in LTBI and TB groups, and six expression patterns among the three groups. These specifically expressed miRNAs and differentially expressed miRNAs in different panels and patterns provide potential biomarkers for detection/diagnosis of latent and active TB using exosomal miRNAs. Additionally, we also discovered plenty of small RNAs derived from genomic repetitive sequences, which might play roles in host immune responses along with Mtb infection progresses. Overall, our findings provide important reference and an improved understanding about miRNAs and repetitive region-derived small RNAs in exosomes during the Mtb infectious process, and facilitate the development of potential molecular targets for detection/diagnosis of latent and active tuberculosis.

Presence of Circulating miR-145, miR-155, and miR-382 in Exosomes Isolated from Serum of Breast Cancer Patients and Healthy Donors.

miR-145, miR-155, and miR-382 have been proposed as noninvasive biomarkers to distinguish breast cancer patients from healthy individuals. However, it is unknown if these three miRNAs are secreted by exosomes. Thus, we hypothesized that miR-145, miR-155, and miR-382 in breast cancer patients are present in exosomes. We isolated exosomes from serum of breast cancer patients and healthy donors, then we characterized them according to their shape, size, and exosome markers by scanning electron microscopy, atomic force microscopy, nanoparticle tracking analysis (NTA), and Western blot and determined the exosome concentration in all samples by NTA. Later, exosomal small RNA extraction was done to determine the expression levels of miR-145, miR-155, and miR-382 by qRT-PCR. We observed a round shape of exosomes with a mean size of 119.84 nm in breast cancer patients and 115.4 nm in healthy donors. All exosomes present the proteins CD63, Alix, Tsg, CD9, and CD81 commonly used as markers. Moreover, we found a significantly high concentration of exosomes in breast cancer patients with stages I, III, and IV compared to healthy donors. We detected miR-145, miR-155, and miR-382 in the exosomes isolated from serum of breast cancer patients and healthy donors. Our results show that the exosomes isolated from the serum of breast cancer patients and healthy donors contains miR-145, miR-155, and miR-382 but not in a selective manner in breast cancer patients. Moreover, our data support the association between exosome concentration and the presence of breast cancer, opening the possibility to study how miRNAs packaged into exosomes play a role in BC progression.

Role of exosomal small RNA in prostate cancer metastasis.

Prostate cancer (PCa) is the second most common cancer in men worldwide. When the disease becomes metastatic, limited treatment strategies exist, and metastatic disease prognoses are difficult to predict. Recently, evidence has emerged, which indicates that small RNAs are detectable in patient fluids, and exosomal small RNA ectopic expression is correlated with the development, progression, and metastasis of human PCa; however, the role of small RNAs in PCa is only partially understood. In this review, we discuss the research status regarding circulating exosomal small RNAs and applications using these small RNAs in PCa particularly looking at metastatic disease. Exosomal small RNAs could be used as potential biomarkers for the early diagnosis, micrometastasis detection, and prognosis of PCa.

Malignant canine mammary epithelial cells shed exosomes containing differentially expressed microRNA that regulate oncogenic networks

BackgroundBreast (mammary) cancers in human (BC) and canine (CMT) patients share clinical, pathological, and molecular similarities that suggest dogs may be a useful translational model. Many cancers, including BC, shed exosomes that contain microRNAs (miRs) into the microenvironment and circulation, and these may represent biomarkers of metastasis and tumor phenotype.MethodsThree normal canine mammary epithelial cell (CMEC) cultures and 5 CMT cell lines were grown in serum-free media. Exosomes were isolated from culture media by ultracentrifugation then profiled by transmission electron microscopy, dynamic light scattering, and Western blot. Exosomal small RNA was deep-sequenced on an Illumina HiSeq2500 sequencer and validated by qRT-PCR. In silico bioinformatic analysis was carried out to determine microRNA gene and pathway targets.ResultsCMEC and CMT cell lines shed round, “cup-shaped” exosomes approximately 150–200 nm, and were immunopositive for exosomal marker CD9. Deep-sequencing averaged ~ 15 million reads/sample. Three hundred thirty-eight unique miRs were detected, with 145 having > ±1.5-fold difference between one or more CMT and CMEC samples. Gene ontology analysis revealed that the upregulated miRs in this exosomal population regulate a number of relevant oncogenic networks. Several miRNAs including miR-18a, miR-19a and miR-181a were predicted in silico to target the canine estrogen receptor (ESR1α).ConclusionsCMEC and CMT cells shed exosomes in vitro that contain differentially expressed miRs. CMT exosomal RNA expresses a limited number of miRs that are up-regulated relative to CMEC, and these are predicted to target biologically relevant hormone receptors and oncogenic pathways. These results may inform future studies of circulating exosomes and the utility of miRs as biomarkers of breast cancer in women and dogs.

KSHV oral shedding and plasma viremia result in significant changes in the extracellular tumorigenic miRNA expression profile in individuals infected with the malaria parasite.

Kaposi's sarcoma herpesvirus (KSHV) is the etiological agent of Kaposi’s sarcoma (KS). Both KSHV and HIV infections are endemic in Uganda, where KS is among the most common cancers in HIV-infected individuals. Recent studies examined the use of small RNAs as biomarkers of disease, including microRNAs (miRNAs), with viral and tumor-derived miRNAs being detected in exosomes from individuals with KSHV-associated malignancies. In the current study, the host and viral extracellular mature miRNA expression profiles were analyzed in blood of KS-negative individuals in Uganda, comparing those with or without KSHV detectable from the oropharynx. We observed increased levels of cellular oncogenic miRNAs and decreased levels of tumor-suppressor miRNAs in plasma of infected individuals exhibiting oral KSHV shedding. These changes in host oncomiRs were exacerbated in people co-infected with HIV, and partially reversed after 2 years of anti-retroviral therapy. We also detected KSHV miRNAs in plasma of KSHV infected individuals and determined that their expression levels correlated with KSHV plasma viremia. Deep sequencing revealed an expected profile of small cellular RNAs in plasma, with miRNAs constituting the major RNA biotype. In contrast, the composition of small RNAs in exosomes was highly atypical with high levels of YRNA and low levels of miRNAs. Mass spectrometry analysis of the exosomes revealed eleven different peptides derived from the malaria parasite, Plasmodium falciparum, and small RNA sequencing confirmed widespread plasmodium co-infections in the Ugandan cohorts. Proteome analysis indicated an exosomal protein profile consistent with erythrocyte and keratinocyte origins for the plasma exosomes. A strong correlation was observed between the abundance of Plasmodium proteins and cellular markers of malaria. As Plasmodium falciparum is an endemic pathogen in Uganda, our study shows that co-infection with other pathogens, such as KSHV, can severely impact the small RNA repertoire, complicating the use of exosome miRNAs as biomarkers of disease.

Exosomal small RNA sequencing uncovers the microRNA dose markers for power frequency electromagnetic field exposure

Purpose: The potential health risks caused by power frequency electromagnetic field (PFEMF) have led to increase public health concerns. However, the diagnosis and prognosis remain challenging in determination of exact dose of PFEMF exposure.Materials and methods: Mice were exposed to different magnetic doses of PFEMF for the following isolation of serum exosomes, microRNAs (miRNAs) extraction and small RNA sequencing. After small RNA sequencing, bioinformatic analysis, quantitative real-time PCR (qRT-PCR) validation and serum exosomal miRNA biomarkers were determined.Results: Significantly changed serum exosomal miRNA as biomarkers of 0.1, 0.5, 2.5 mT and common PFEMF exposure were confirmed. Gene ontology (GO) and Kyoto encyclopaedia of genes and genomes (KEGG) pathway analysis of the downstream target genes of the above-identified exosomal miRNA markers indicated that, exosomal miRNA markers were predicted to be involved in critical pathophysiological processes of neural system and cancer- or other disease-related signalling pathways.Conclusions: Aberrantly-expressed serum exosomal miRNAs, including miR-128-3p for 0.1 mT, miR-133a-3p for 0.5 mT, miR-142a-5p for 2.5 mT, miR-218-5p and miR-199a-3p for common PFEMF exposure, suggested a series of informative markers for not only identifying the exact dose of PFEMF exposure, also consolidating the base for future clinical intervention.

Characterization of mouse serum exosomal small RNA content: The origins and their roles in modulating inflammatory response.

In the last decade, although studies on exosomal microRNAs (miRNAs) derived from serum and other body fluids have increased dramatically; the contents and biological significance of serum exosomes under normal conditions remain unclear. In the present study, we profiled the small RNA content of mouse serum exosomes (mSEs) using small RNAseq and found that fragments of transfer RNAs (tRNAs) and miRNAs were the two predominant exosomal RNA species, accounting for approximately 60% and 10% of mapped reads, respectively. Moreover, 466 known and 5 novel miRNAs were identified from two independent experiments, among which the five most abundant miRNAs (miR-486a-5p, miR-22-3p, miR-16-5p, miR-10b-5p and miR-27b-3p) accounted for approximately 60% of all the aligned miRNA sequences. As inferred from the identities of the well known cell- or tissue-specific miRNAs, mSEs were primarily released by RBCs, liver and intestinal cells. Bioinformatics analysis revealed over half of the top 20 miRNAs by abundance were involved in inflammatory responses and further in vitro experiments demonstrated that mSEs potently primed macrophages towards the M2 phenotype. To the best of our knowledge, this is the first study to profile small RNAs from mSEs. In addition to providing a reference for future biomarker studies and extrapolating their origins, our data also suggest the roles of mSEs in maintaining internal homeostasis under normal conditions.

Environmental neurotoxicant manganese regulates exosome-mediated extracellular miRNAs in cell culture model of Parkinson's disease: Relevance to α-synuclein misfolding in metal neurotoxicity

Many chronic neurodegenerative disorders share a common pathogenic mechanism involving the aggregation and deposition of misfolded proteins. Recently, it was shown that these aggregated proteins could be transferred from one cell to another via extracellular nanovesicles called exosomes. Initially thought to be a means of cellular waste removal, exosomes have since been discovered to actively participate in cell-to-cell communication. Importantly, various inflammatory and signaling molecules, as well as small RNAs are selectively packaged in these vesicles. Considering the important role of environmental manganese (Mn) in Parkinson's disease (PD)-like neurological disorders, we characterized the effect of Mn on exosome content and release using an MN9D dopaminergic cell model of PD, which was generated to stably express wild-type human α-synuclein (αSyn). Mn exposure (300μM MnCl2) for 24h induced the release of exosomes into the extracellular media prior to cytotoxicity, as determined by NanoSight particle analysis and electron microscopy. Strikingly, Western blot analysis revealed that Mn treatment in αSyn-expressing cells increases the protein Rab27a, which regulates the release of exosomes from cells. Moreover, next-generation sequencing showed more small RNAs in exosomes isolated from Mn-exposed cells than from control exosomes. Our miRNA profiling analysis led to the discovery of increased expression of certain miRNAs previously shown to regulate key biological pathways, including protein aggregation, autophagy, inflammation and hypoxia. Collectively, our results provide a glimpse of Mn's role in modulating extracellular miRNA content through exosomal release from dopaminergic neuronal cells and thus potentially contributing to progressive neurodegeneration. Further characterization of extracellular miRNAs and their targets will have major impacts on biomarker discovery and translational strategies for environmentally linked neurodegenerative diseases including PD.

Isolation and Identification of miRNAs in exosomes derived from serum of colon cancer patients.

Objective: To isolate exosomes from the serum of colon cancer patients and identify RNAs in the small vesicles.Methods: ExoQuick-TC™ Exosome Precipitation Solution was used for exosome isolation and the shapes of exosomes were observed under a transmission electron microscope. Mass spectrometry was used to identify the classification of miRNAs encapsulated in exosomes, and the expression levels of miRNA-21,-133a, and -181b in exosomes were detected by RT-PCR.Results: Exosomes isolated from serum of colon cancer patients were circular-or oval-shaped and vary in size with a diameter of 40-100 nm. Mass spectrometry shows that the main RNAs in exosomes are small RNAs; the levels of these small RNAs in exosomes are significantly higher compared with fresh serum. There is still a tiny amount of small RNAs in exosome-free serum, but the amounts are significantly lower than that in exosomes. No more RNAs were detected in the repeated freezing and thawing serum, but there were still some RNAs detectable in the exosomes extracted from these serums. MiRNA-21, -133a and -181b can be detected in exosomes, and the level of miRNA-21 is associated with early diagnosis of colon cancer.Conclusion: This study proves that commercial kits for exosome separation are more convenient and time-saving and that mass spectrometry is capable of identifying the miRNAs in exosomes. Compared with direct extraction of miRNAs from the serum, the method of isolating exosomes from the serum firstly and then extracting miRNAs from the exosomes can enhance the stability and integrity of their inner miRNAs. Also, we demonstrate that the exosomal miRNA-21 expression is associated with the early diagnosis of colon cancer.

Exosome-mediated small RNA delivery for gene therapy.

Small RNAs, including small interfering RNAs (siRNA) and microRNAs (miRNA), are emerging as promising therapeutic drugs against a wide array of diseases. The key obstacle for the successful clinical application of small RNAs is to develop a safe delivery system directed at the target tissues only. Current small RNA transfer techniques use viruses or synthetic agents as delivery vehicles. The replacement of these delivery vehicles with a low toxicity and high target-specific approach is essential for making small RNA therapy feasible. Because exosomes have the intrinsic ability to traverse biological barriers and to naturally transport functional small RNAs between cells, they represent a novel and exciting delivery vehicle for the field of small RNA therapy. As therapeutic delivery agents, exosomes will potentially be better tolerated by the immune system because they are natural nanocarriers derived from endogenous cells. Furthermore, exosomes derived from genetically engineered cells can deliver small RNAs to target tissues and cells. Thus, exosome-based delivery of small RNAs may provide an untapped, effective delivery strategy to overcome impediments such as inefficiency, nonspecificity, and immunogenic reactions. In this review, we briefly describe how exosomal small RNAs function in recipient cells. Furthermore, we provide an update and overview of new findings that reveal the potential applications of exosome-based small RNA delivery as therapeutics in clinical settings. WIREs RNA 2016, 7:758-771. doi: 10.1002/wrna.1363 For further resources related to this article, please visit the WIREs website.