外泌体在疾病诊断和药物递送系统中的应用研究进展

外泌体是直径为 30~100 nm 的内吞衍生囊泡,由多种活细胞分泌,含有大量的与其来源和功能密切相关的蛋白质、脂质和 RNA 分子,可以在细胞间传递。已有研究表明癌症患者血液中的外泌体浓度比正常人高,且其中包含癌症标志分子,因此其有潜力成为疾病诊 断的生物标志物。此外,作为一种天然的物质运输载体,外泌体已经被作为一种新型的药物递送系统,用于肿瘤及阿尔茨海默病等疾病的治疗。 对外泌体作为疾病诊断标记物以及药物递送载体的研究进展进行综述。     

外泌体miRNA的生物学功能及其在肺纤维化疾病中的调控作用

外泌体是一种微型纳米级细胞外囊泡,由于能够直接参与细胞间信息的传递和物质的运输,被认为是细胞间通讯、免疫调节、疾病诊断和预后循环生物学标志物的重要载体,其携带的核酸和蛋白质等内含物能够影响受体细胞的生理状态.作为一种内源性非编码微小RNA,microRNA (miRNA)对疾病诊断和治疗有着重要的研究价值,有大量证据表明该类分子对肺部疾病的发病进程起着控制调节作用.本文聚焦于近年来细胞外泌体来源miRNA的生物学特性和功能领域,综述了近年来生物医学研究中的热点分子外泌体miRNA在肺部疾病尤其是肺纤维化中调控功能和机制的研究,因此不仅能为肺纤维化疾病的诊断提供新的标志物分子,并且还能够为肺纤维化的外泌体干预治疗建议新的干预策略.     

外泌体及其miRNA在神经系统常见疾病诊断和治疗中的研究进展

外泌体(exosome)主要来源于细胞内的多囊泡内体,通过多囊泡内体外膜与细胞膜融合分泌到胞外间隙,直径为30～100 nm,可作为潜在的生物标志物以及细胞间传递生物信息的载体。近年来的研究表明,外泌体有助于神经系统疾病的早期诊断。在细胞实验和动物模型中,外泌体能够促进神经再生、抑制神经细胞凋亡。本文对外泌体的分离、鉴定及其在缺血性脑卒中、阿尔茨海默病和帕金森病这3种神经系统常见疾病的诊断和治疗中的应用进行综述。     

神经系统中一种新型的潜在治疗工具——外泌体

外泌体(exosomes)是一种由细胞分泌到胞外空间的纳米囊泡(nanovesicles),在神经系统中参与许多生理病理过程。大量研究表明,在神经系统中,外泌体可以作为细胞通讯的信使,参与复杂的细胞间信息交流。同时,外泌体也可作为诊断疾病的生物标志物及小分子物质传递载体,在治疗神经系统疾病中发挥着至关重要的作用。因此,exosomes有望成为治疗神经系统疾病的重要工具。该综述首先阐述了外泌体的基本特性,包括合成、存储、分离等;其次,讨论了间充质干细胞(mesenchymal stem cells,MSCs)分泌的外泌体在神经退行性疾病的诊断和治疗中的作用;最后,讨论了外泌体作为治疗神经系统疾病的新型工具将面临的挑战。该综述阐明了外泌体这一快速进展领域及其在神经系统疾病中的作用,特别是其治疗应用的最新进展。     

外泌体在宫颈癌形成及其诊疗中的作用

宫颈癌作为女性第2大恶性肿瘤,仍然是全球范围内的公共卫生问题。外泌体是活细胞主动分泌的一种具有脂质双分子层结构的纳米级囊泡,能够携带蛋白质、脂质、DNA和RNA (包括mRNA、miRNA、lncRNA和circRNA)等多种具有生物学活性的物质。作为新型的细胞间通讯分子,外泌体不仅参与细胞间正常的信息传递和物质交换等生物学进程,而且在宫颈癌的发生发展过程中发挥重要作用,例如,可通过调节肿瘤微环境来参与HPV感染、促进肿瘤细胞增殖、促进血管形成、参与免疫逃逸以及参与肿瘤的侵袭和转移。外泌体广泛分布于各种生物体液中,可由不同病变程度的宫颈细胞分泌,在阴道灌洗液和血浆中大量富集,且由于其结构的稳定性,因此有望作为一种新型液体活检标志物用于宫颈癌的早期诊断。此外,外泌体具有免疫原性低、稳定性好和穿透性强等特点,可以克服生物利用度低等多种缺点,增强药物的靶向性和药物效应,并且能够降低非靶向的细胞毒性和免疫原性,因此有潜力作为新一代药物或药物载体用于肿瘤的靶向治疗。本文将针对目前国内外关于外泌体在宫颈癌发生发展过程中的作用以及诊断治疗应用领域的最新研究进展加以综述,为临床宫颈癌的诊断和治疗中一种新型的生物标志物的研究提供依据。     

外泌体及其在神经退行性疾病发生、发展和诊治中的作用

外泌体是一种直径在30～100 nm的细胞外膜性囊泡,由真核生物体内的多种细胞产生,其内含有蛋白质、脂质、核酸以及和起源细胞相关的物质等。外泌体能够携带起源细胞内成分并作用于邻近或远距离的细胞,从而实现生理及疾病状态下不同细胞间的信息交流。近年来,研究表明神经退行性疾病发病相关的错误折叠蛋白(如α-突触核蛋白、tau蛋白、β-淀粉样蛋白等)能够通过外泌体运输,从而促进这些蛋白在细胞间传播并传播至未病变区域,加快疾病进程。本综述着重阐述了外泌体的起源和组成、生物合成、分泌、功能,尤其是在神经退行性疾病发生和发展中的作用。除此之外,还探讨了外泌体作为生物标记物和药物传递载体在神经退行性疾病的诊断与治疗中的作用和前景。     

缺氧条件下中枢神经系统外泌体作用机制

外泌体是来源于细胞内吞噬作用的细胞外囊泡(extracellular vesicles,EVs),其含有特定的蛋白质、脂质、RNA和DNA,能将信号传递给受体细胞,从而介导细胞通讯过程。缺氧作为一种严重的细胞应激,是脑部疾病的重要特征,可以诱导外泌体的释放并影响其内容物。越来越多的证据显示,外泌体携带的生物活性物质可以反映其细胞起源和疾病状态,成为诊断或预测缺氧性疾病的潜在生物标志物。现对外泌体的一般特性和功能、缺氧条件下外泌体的分泌机制以及缺氧胁迫下正常神经细胞(例如神经元和星形胶质细胞)和胶质瘤细胞释放的外泌体的作用机制作一综述。     

新的药物传递系统:外泌体作为药物载体递送*

外泌体(exosomes)是细胞分泌的囊泡,在细胞与细胞之间通信中发挥重要作用。由于其固有的长距离通信能力和出色的生物相容性而具有很大的潜力作为药物递送载体,尤其适合递送蛋白质、核酸、基因治疗剂等治疗药物。许多研究表明外泌体可以有效地将许多不同种类的货物递送至靶细胞,因此,它们常被作为药物载体用于治疗。对外泌体作为药物递送系统中面临的外泌体分离,药物装载和靶向治疗应用的进展与挑战作一介绍,以期更好为外泌体药物递送系统开发提供新思路。     

新的药物传递系统:外泌体作为药物载体递送*

外泌体(exosomes)是细胞分泌的囊泡,在细胞与细胞之间通信中发挥重要作用。由于其固有的长距离通信能力和出色的生物相容性而具有很大的潜力作为药物递送载体,尤其适合递送蛋白质、核酸、基因治疗剂等治疗药物。许多研究表明外泌体可以有效地将许多不同种类的货物递送至靶细胞,因此,它们常被作为药物载体用于治疗。对外泌体作为药物递送系统中面临的外泌体分离,药物装载和靶向治疗应用的进展与挑战作一介绍,以期更好为外泌体药物递送系统开发提供新思路。     

外泌体靶向递药在肿瘤治疗中的进展

外泌体是由细胞分泌、粒径为30~150 nm的纳米囊泡。外泌体具有优越的生物相容性、良好的载药功能以及便于修饰的膜表面,是一种具有潜力的药物递送载体。在肿瘤治疗研究中,可利用具有靶向识别功能的外泌体来降低脱靶效应,减少不良反应,达到增强治疗效果的目的。归纳了用不同修饰方法增强外泌体靶向性的研究进展,总结了近五年来利用外泌体作为特异性药物递送载体靶向治疗肿瘤的相关研究,阐述了外泌体作为新型药物递送载体的优势与不足,为设计具有靶向识别功能的外泌体提供了可行的方向与策略。     

Exosomal circRNAs as novel cancer biomarkers: Challenges and opportunities

Identifying high specificity and sensitivity biomarkers has always been the focus of research in the field of non-invasive cancer diagnosis. Exosomes are extracellular vesicles with a lipid bilayer membrane that can be released by all types of cells, which contain a variety of proteins, lipids, and a variety of non-coding RNAs. Increasing research has shown that the lipid bilayer can effectively protect the nucleic acid in exosomes. In cancers, tumor cell-derived exosomal circRNAs can act on target cells or organs through the transport of exosomes, and then participate in the regulation of tumor development and metastasis. Since exosomes exist in various body fluids and circRNAs in exosomes exhibit high stability, exosomal circRNAs have the potential as biomarkers for early and minimally invasive cancer diagnosis and prognosis judgment. In this review, we summarized circRNAs and their biological roles in cancers, with the emerging value biomarkers in cancer diagnosis, disease judgment, and prognosis observation. In addition, we briefly compared the advantages of exosomal circRNAs as biomarkers and the current obstacles in the exosome isolation technology, shed light to the future development of this technology.     

Detection of exosomal tyrosine receptor kinase B as a potential biomarker in ovarian cancer

Ovarian cancer (OC) is a lethal disease diagnosed at advanced stages due to the lack of specific biomarkers. Tyrosine receptor kinase B (TrkB), which has recently been found to be related to OC progression, represents a promising potential biomarker for OC diagnosis and prognosis. The discovery of circulating exosomes as biomarkers for various diseases led us to explore exosomal TrkB in OC. Our previous study proved that the expression of TrkB was elevated in OC tissues. In this study, we focused on the detection of exosomal TrkB in OC. Exosomes were first gathered from three different OC cell lines’ conditioned medium, serum samples of patients with OC as well as xenograft mice serum by serial centrifugation method. Then, we identified exosomes by transmission electron microscopy, NanoSight analysis, and expression of typical exosomal protein markers. The existence of TrkB in exosomes was measured by Western blot analysis, and the expression was detected by enzyme-linked immunosorbent assay. In this study, we demonstrated that exosomes could derive from OC cell lines, serum from OC xenograft nude mice, and clinical patients. Our study shows that serum exosomal TrkB may be considered a minimally invasive biomarker for OC.     

Exosome release and cargo in Down syndrome

Down syndrome (DS) is a multisystem disorder affecting 1 in 800 births worldwide. Advancing technology, medical treatment, and social intervention have dramatically increased life expectancy, yet there are many etiologies of this disorder that are in need of further research. The advent of the ability to capture extracellular vesicles (EVs) in blood from specific cell types allows for the investigation of novel intracellular processes. Exosomes are one type of EVs that have demonstrated great potential in uncovering new biomarkers of neurodegeneration and disease, and also that appear to be intricately involved in the transsynaptic spread of pathogenic factors underlying Alzheimer's disease and other neurological diseases. Exosomes are nanosized vesicles, generated in endosomal multivesicular bodies (MVBs) and secreted by most cells in the body. Since exosomes are important mediators of intercellular communication and genetic exchange, they have emerged as a major research focus and have revealed novel biological sequelae involved in conditions afflicting the DS population. This review summarizes current knowledge on exosome biology in individuals with DS, both early in life and in aging individuals. Collectively these studies have demonstrated that complex multicellular processes underlying DS etiologies may include abnormal formation and secretion of extracellular vesicles such as exosomes.     

The potential role of exosomes in the diagnosis and therapy of ischemic diseases

In the past, exosomes have been thought of as cellular dust. Today, they are thought to be carriers of real biomarkers and intercellular biological information. The composition of exosomes differs according to their source, and the subsequent information they carry, such as protein, microRNA or mRNA, may also be different. Recent studies have demonstrated that exosomes in ischemic diseases can help to make an early diagnosis, and in cellular experiments and animal models, exosomes promote angiogenesis, restrain cell apoptosis and reduce inflammation, among other actions, to protect ischemic organs. There is evidence that these protective effects are related to microRNAs in exosomes. In this review, we discuss the use of exosomes for early diagnosis of ischemic diseases and recent advances in the therapeutic use of exosomes in cell and mammalian models of ischemic diseases.     

Exosomes as new vesicular lipid transporters involved in cell–cell communication and various pathophysiologies

Exosomes are nanovesicles that have emerged as a new intercellular communication system between an intracellular compartment of a donor cell towards the periphery or an internal compartment of a recipient cell. The bioactivity of exosomes resides not only in their protein and RNA contents but also in their lipidic molecules. Exosomes display original lipids organized in a bilayer membrane and along with the lipid carriers such as fatty acid binding proteins that they contain, exosomes transport bioactive lipids. Exosomes can vectorize lipids such as eicosanoids, fatty acids, and cholesterol, and their lipid composition can be modified by in-vitro manipulation. They also contain lipid related enzymes so that they can constitute an autonomous unit of production of various bioactive lipids. Exosomes can circulate between proximal or distal cells and their fate can be regulated in part by lipidic molecules. Compared to their parental cells, exosomes are enriched in cholesterol and sphingomyelin and their accumulation in cells might modulate recipient cell homeostasis. Exosome release from cells appears to be a general biological process. They have been reported in all biological fluids from which they can be recovered and can be monitors of specific pathophysiological situations. Thus, the lipid content of circulating exosomes could be useful biomarkers of lipid related diseases. Since the first lipid analysis of exosomes ten years ago detailed knowledge of exosomal lipids has accumulated. The role of lipids in exosome fate and bioactivity and how they constitute an additional lipid transport system are considered in this review.     

Advances on liver cell-derived exosomes in liver diseases

Exosomes are extracellular vesicles with diameters ranging from 30 to 150 nm, which contain several donor cell-associated proteins as well as mRNA, miRNA, and lipids and coordinate multiple physiological and pathological functions through horizontal communication between cells. Almost all types of liver cells, such as hepatocytes and Kupffer cells, are exosome-releasing and/or exosome-targeted cells. Exosomes secreted by liver cells play an important role in regulating general physiological functions and also participate in the onset and development of liver diseases, including liver cancer, liver injury, liver fibrosis and viral hepatitis. Liver cell-derived exosomes carry liver cell-specific proteins and miRNAs, which can be used as diagnostic biomarkers and treatment targets of liver disease. This review discusses the functions of exosomes derived from different liver cells and provides novel insights based on the latest developments regarding the roles of exosomes in the diagnosis and treatment of liver diseases.     

Discovery of urinary biomarkers

A myriad of proteins and peptides can be identified in normal human urine. These are derived from a variety of sources including glomerular filtration of blood plasma, cell sloughing, apoptosis, proteolytic cleavage of cell surface glycosylphosphatidylinositol-linked proteins, and secretion of exosomes by epithelial cells. Mass spectrometry-based approaches to urinary protein and peptide profiling can, in principle, reveal changes in excretion rates of specific proteins/peptides that can have predictive value in the clinical arena, e.g. in the early diagnosis of disease, in classification of disease with regard to likely therapeutic responses, in assessment of prognosis, and in monitoring response to therapy. These approaches have potential value, not only in diseases of the kidney and urinary tract but also in systemic diseases that are associated with circulating small protein and peptide markers that can pass the glomerular filter. Most large scale biomarker discovery studies reported thus far have used one of two approaches to identify proteins and peptides whose excretion in urine changes in specific disease states: 1) two-dimensional electrophoresis with mass spectrometric and/or immunochemical identification of proteins and 2) top-down mass spectrometric methods (SELDI-TOF-MS and capillary electrophoresis-MS). These studies have been chiefly in the areas of nephrology, urology, and oncology. We review these applications, focusing on two areas of progress, viz. in bladder cancer and in acute rejection of renal transplants. Progress has been limited so far. However, with the advent of powerful LC-MS/MS methods along with methods for quantifying LC-MS/MS output, there is hope for an accelerated discovery and validation of disease biomarkers in urine.     

Isolation and characterization of RNA-containing exosomes

The field of exosome research is rapidly expanding, with a dramatic increase in publications in recent years. These small vesicles (30-100 nm) of endocytic origin were first proposed to function as a way for reticulocytes to eradicate the transferrin receptor while maturing into erythrocytes, and were later named exosomes. Exosomes are formed by inward budding of late endosomes, producing multivesicular bodies (MVBs), and are released into the environment by fusion of the MVBs with the plasma membrane. Since the first discovery of exosomes, a wide range of cells have been shown to release these vesicles. Exosomes have also been detected in several biological fluids, including plasma, nasal lavage fluid, saliva and breast milk. Furthermore, it has been demonstrated that the content and function of exosomes depends on the originating cell and the conditions under which they are produced. A variety of functions have been demonstrated for exosomes, such as induction of tolerance against allergen, eradication of established tumors in mice, inhibition and activation of natural killer cells, promotion of differentiation into T regulatory cells, stimulation of T cell proliferation and induction of T cell apoptosis. Year 2007 we demonstrated that exosomes released from mast cells contain messenger RNA (mRNA) and microRNA (miRNA), and that the RNA can be shuttled from one cell to another via exosomes. In the recipient cells, the mRNA shuttled by exosomes was shown to be translated into protein, suggesting a regulatory function of the transferred RNA. Further, we have also shown that exosomes derived from cells grown under oxidative stress can induce tolerance against further stress in recipient cells and thus suggest a biological function of the exosomal shuttle RNA. Cell culture media and biological fluids contain a mixture of vesicles and shed fragments. A high quality isolation method for exosomes, followed by characterization and identification of the exosomes and their content, is therefore crucial to distinguish exosomes from other vesicles and particles. Here, we present a method for the isolation of exosomes from both cell culture medium and body fluids. This isolation method is based on repeated centrifugation and filtration steps, followed by a final ultracentrifugation step in which the exosomes are pelleted. Important methods to identify the exosomes and characterize the exosomal morphology and protein content are highlighted, including electron microscopy, flow cytometry and Western blot. The purification of the total exosomal RNA is based on spin column chromatography and the exosomal RNA yield and size distribution is analyzed using a Bioanalyzer.