Target Exosomes Research Articles

Stimuli-responsive DNA microcapsules for homogeneous electrochemiluminescence sensing of tumor exosomes

A homogeneous electrochemiluminescence (ECL) sensing system was designed for highly sensitive detection of tumor exosomes by combining stimuli-responsive DNA microcapsules with target recycling amplification. In this work, CdS quantum dots (QDs) as ECL emitters were sealed in the inner pores of DNA microcapsules with crosslinking DNA shells. In the presence of target exosomes, S4-combined exosomes were formed and then hybridized with the crosslinking base sequences of DNA shells. Thus, DNA microcapsules were effectively unlocked, leading to the release of CdS QDs. The target exosomes-dependent amount of release CdS QDs could be conveniently monitored by ECL technique. With enzymatic recycling binding of target amplification, the proposed homogeneous ECL sensor possessed a wide detection range, high sensitivity and selectivity in complex biological samples.

Horseradish peroxidase-encapsulated DNA nanoflowers: An innovative signal-generation tag for colorimetric biosensor

Herein a versatile colorimetric biosensing platform was designed for sensitive, specific, and rapid screening of cancer-derived exosomes (HepG2 cell-derived) by introducing horseradish peroxidase -encapsulated DNA nanoflowers (HRP-DF) as the biorecognition elements and signal-generation tags. HRP was concurrently associated with the growing ultralong-chain DNA and the magnesium pyrophosphate crystals (Mg2PPi) during the rolling circle amplification (RCA), thereby ultimately leading to the direct fixation of HRP in DFs. For demonstration, a linear DNA circular molecule encoding the complementary sequence of CD63 aptamer (a nucleic acid sequence that can highly bind to exosomes) was used as a starting amplification template to obtain HRP-DF with the high biorecognition ability of exosomes. Upon addition of target exosomes, a sandwiched reaction was carried out between the cholesterol-modified DNA probes-conjugated magnetic bead (MB) and the HRP-DFs, accompanying formation of ternary complexes (MB-exosomes-HRP-DF). After simple magnetic separation, the HRP carried on the ternary complexes (MB-exosomes-HRP-DF) initiated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS, nearly colorless) into green-colored oxidized ABTS in the presence of hydrogen peroxide (H2O2). The obvious color change (from nearly colorless to dark green) of ABTS-H2O2 system can be easily observed with the naked eye and accurately monitored by UV–visible spectrometry, which was also proportional to the concentration of exosomes. Impressively, HRP-DF-based biosensing platform exhibited satisfactory colorimetric responses toward target exosomes within the working range from 5.0 × 103 to 5.0 × 106 particles/μL at a low detection limit of 3.32 × 103 particles/μL. Combined with a one-step sandwich reaction, magnetic separation and HRP-DF-based color-changing, this system had the advantages of acceptable accuracy, strong anti-interference ability and good reproducibility.

Development of a simple, sensitive and selective colorimetric aptasensor for the detection of cancer-derived exosomes

There is a growing need for cancerous exosome detection towards potential non-invasive cancer diagnosis. This study aims to develop a reliable colorimetric aptasensor for sensitive and specific detection of circulating cancer-derived exosomes. In this design, target exosomes were firstly captured by latex beads via aldimine condensation, followed by bio-recognition using a specific CD63 aptamer, which was conjugated to horseradish peroxidase (HRP) through biotin-streptavidin binding. Colorimetric detection was achieved in 10 min via enzymatic catalysis to produce dark coloured polydopamine (PDA) from colourless substrate dopamine (DA) in especially prepared H2O2 reaction solution. The sensitivity was enhanced by in situ deposition of PDA around exosome particles to strengthen the developed colorimetric signal, which could be directly observed by naked eye. Signal quantification was carried out by absorbance measurement. The colour intensity correlates to the CD63 amount and the limit of detection can be as low as 7.7 × 103 particle/mL, improved by 3-5 orders of magnitude from conventional Dot-blot methods. The aptasensor showed specificity to HER2 and integrin αvβ6 positive, cell culture-derived, breast and pancreatic cancer-derived exosomes, respectively, when the correct aptamer sequence was used. Overall, a sensitive and selective colorimetric aptasensor was successfully developed for detecting cancer-derived exosomes facilitated by HRP-accelerated DA polymerization and in situ PDA deposition. This versatile aptasensor holds great potential for future development of point-of-care detection kits for cancer diagnosis in a clinical setting.

Facile fluorescent aptasensor using aggregation-induced emission luminogens for exosomal proteins profiling towards liquid biopsy

Surface protein patterns of tumor-derived exosomes could be promising noninvasive diagnostic biomarkers for liquid biopsy. However, a convenient and cost-effective platform for exosomal protein profiling is still lacking. Herein, a facile fluorescent aptasensor is developed to assess exosomal tumor-associated proteins, combining aptamers, aggregation-induced emission luminogens (AIEgens), and graphene oxide (GO) as recognition elements, fluorescent dye, and the quencher, respectively. Specifically, numberous TPE-TAs could bind one aptamer and form aggregates rapidly, resulting in an amplified fluorescence signal. In the absence of tumor-derived exosomes, GO absorbs the TPE-TAs/aptamer complex, allowing fluorescence quenching. When the target exosomes are introduced, the aptamer preferentially binds with its target. Thus the TPE-TAs/aptamer complexes detach from GO surface, followed by the appearance of a “turn-on” fluorescent signal. Under the optimized conditions, the linear range of target exosomes is estimated to be 4.07 × 105 to 1.83 × 107 particles/μL (0.68–30.4 pM) with a detection limit of 3.43 × 105 particles/μL (0.57 pM). This strategy demonstrated great performance in differentiating prostate cancer from healthy individuals (AUC: 0.9790). Furthermore, by profiling three tumor-associated protein markers including epidermal growth factor receptor (EGFR), epithelial cell adhesion molecule (EpCAM), and human epidermal growth factor receptor 2 (HER2) on exosomes in a breast tumor cohort, this sensing platform diagnoses breast tumors with high efficiency (AUC: 0.9845) and exhibits a high sensitivity of 97.37% for distinguishing malignant breast cancers, where the stage I cases were detected with 92.31% sensitivity. Therefore, this aptasensor provides a promising strategy to profile tumor-derived exosomal proteins for early diagnosis in liquid biopsy.

Identification of programmed death ligand-1 positive exosomes in breast cancer based on DNA amplification-responsive metal-organic frameworks

Cancer-derived exosomes have recently emerged as potent candidates for diagnosis and prognosis of breast cancer. As an example, programmed death ligand-1 positive (PD-L1+) exosomes are found to be correlated with the progression and immunotherapy response of breast cancer, and therefore show great potential in liquid biopsy. Herein, we propose an electrochemical biosensing method for accurate identification of PD-L1+ exosomes by using DNA amplification-responsive metal-organic frameworks, PVP@HRP@ZIF-8. Specially, PD-L1+ exosomes are captured by anti-CD63 functionalized magnetic beads and bound with anti-PD-L1-linked capture probe. Then, in situ hyperbranched rolling circle amplification, a typical DNA amplification reaction, is conducted using the surface-attached capture probes as primers, which lows environmental pH. As a result, disassembly of PVP@HRP@ZIF-8 takes place, leading to the release of enzymes, which can arouse amplified electrochemical responses for the identification of target exosomes. Experimental results reveal that the biosensing method displays a linear range for PD-L1+ exosomes identification from 1 × 103 to 1 × 1010 particles/mL and the detection limit reaches 334 particles/mL. What is more, by using the method, elevated level of circulating PD-L1+ exosomes is found in the undiluted serum samples from patients with breast cancer, particularly for metastatic breast cancer, revealing a positive correlation of the PD-L1+ exosome level with the tumor staging and disease progression of breast cancer. Therefore, the biosensing method may be valuable for not only exosome identification but also providing reference information for diagnosis and real-time monitoring of breast cancer in the future.

Paper-based ITP technology: An application to specific cancer-derived exosome detection and analysis

Exosomes derived from cancer cells/tissues have great potential for early cancer diagnostic use, but their clinical potential has not been fully explored because of a lack of cost-effective multiplex approaches capable of effectively isolating and identifying specific exosome populations and analyzing their content biomarkers. This study was aimed at overcoming the technical barrier by developing a paper-based isotachophoresis (ITP) technology capable of 1) rapid isolation and identification of exosomes from both malignant and healthy cells and 2) multiplex detection of selected exosomal protein biomarkers of the target exosomes. The technology integrates the focusing power of ITP and the multiplex capability of paper-based lateral flow to achieve on-board separation of target exosomes from large extracellular vesicles, followed by electrokinetic enrichment of the targets, leading to an ultrasensitive platform for comprehensive exosome analysis. For a proof of concept, the technology platform was tested with human serum samples spiked with exosomes derived from healthy human serum and a prostate cancer cell line. Under an anionic ITP condition, the device showed superior performance in simultaneous detection of the cancer exosomes and normal exosomes at concentrations as low as 1.2-2.0 × 106 exosomes/mL, which is equivalent to 2.0-3.0 × 10-18 M. The observed limit of detection was more than 30-fold better than that of enhanced ELISA. More importantly, in a subsequent step the technology was capable of the rapid profiling of a selected protein biomarker panel associated with the target exosomes. The results represent a significant step toward translating the detection of tumor-derived exosomes to a medical use at a point of care.

SUN-100 Exosome-packaged sonic hedgehog in cardiomyocyte plays a central role in type 2 cardiorenal syndrome

Cardiorenal syndrome type 2 (CRS2) is characterized by chronic abnormalities in cardiac function causing progressive chronic kidney disease (CKD). However, the mediators connecting heart and kidney remains largely unknown. In this study, we provide evidence supporting that exosomes containing Shh generated by injured cardiomyocyte plays a vital role in mediating cardiorenal connection in mouse model of transverse aortic constriction (TAC). Four weeks after TAC, mice were randomized into three groups: 1) sham control; 2) TAC mice; 3) TAC mice injected daily with cyclopamine (CPN), a specific inhibitor of hedgehog signaling. At 8 weeks after TAC, all animals were sacrificed. Urine, blood, heart and kidney tissues were collected for analysis. Another set of mice were randomized into three groups after 4 weeks of TAC: 1) sham control mice injected with pcDNA3 plasmid; 2) TAC mice injected with pcDNA3 plasmid; 3) TAC mice injected with shRab27a plasmid, a small GTPases implicated in regulating exosome biogenesis and secretion. These mice were injected with pcDNA3 or shRab27a plasmids once a week for three weeks beginning at 4 weeks after TAC. At 8 weeks after TAC, all animals were sacrificed. Urine, blood, heart and kidney tissues were collected for analysis. Exosomes were isolated from TAC mice serum and CRS2 patients’ serum, and incubated with normal rat kidney interstitial fibroblast (NRK-49F) cells. At 8 weeks after TAC, cardiac hypertrophy and fibrosis were prominent, as evidenced by increased expression of β-myosin heavy chain, α-actin and fibronectin. Echocardiography also revealed an impaired cardiac function in TAC mice. These cardiac lesions were accompanied by an upregulation of Shh and increased production of exosomes in cardiac tissue. Electron microscopy confirmed abundant exosomes derived from the injured cardiomyocytes in the heart of TAC mice. Blockade of Shh signaling by CPN ameliorated cardiac injury and restored heart function. Moreover, TAC mice also developed kidney injury secondary to chronic heart failure, manifested by proteinuria, kidney fibrosis, podocyte injury, and renal upregulation of Shh. CPN mitigated all these lesions in the kidneys. Notably, serum derived from TAC mice or CRS patients was able to induce renal interstitial fibroblast activation in vitro, indicating the circulating factors as mediators of cardiorenal connection. Furthermore, exosomes isolated from TAC serum was sufficient to cause fibroblast activation and matrix production. Furthermore, blockade of exosome biogenesis and secretion by knockdown of Rab27a expression not only protected against cardiac hypertrophy and fibrosis but also ameliorated renal fibrotic lesions. These studies demonstrate that heart-derived, circulating exosomes are a unique and effective vehicle to deliver Shh into the kidney after TAC. Targeting exosome generation and secretion or inhibition of Shh signaling could be novel therapeutic strategies for protecting both heart and kidney in cardiorenal syndrome.

A multipedal DNA walker for amplified detection of tumor exosomes.

We have fabricated an ultrasensitive exosome biosensor based on a multipedal DNA walker with a core of target exosomes. Specific recognition is achieved by introducing a CD63 aptamer and facile separation is obtained with magnetic Fe3O4@Au nanoparticles. A limit of detection down to 6/μL is obtained with excellent selectivity.

Fabrication of an Aptamer-Coated Liposome Complex for the Detection and Profiling of Exosomes Based on Terminal Deoxynucleotidyl Transferase-Mediated Signal Amplification.

The exosome is a promising biomarker carrying many kinds of membrane proteins with huge heterogeneity, so the sensitive and multiplex analysis of exosomes is very significant for disease diagnosis and exploration of their biological functions. Herein, we propose an efficient method for highly sensitive detection and heterogeneity identification of exosomes based on the design and fabrication of an aptamer-coated liposome complex coupled with terminal deoxynucleotidyl transferase (TdT)-mediated polymerization. Specifically, in the presence of target exosomes, the aptamers immobilized on the surface of 1,2-dioleoyl-3-trimethylammonium-propane liposomes prefer to bind with exosomal membrane proteins due to the high affinity. The resulting aptamer-exosome complex will be accessible to TdT to switch on the polymerization reaction for signal amplification, achieving highly sensitive detection of exosomes. Furthermore, the proposed method can be employed to profile different exosomal membrane proteins by making use of a cluster of corresponding aptamers and obtain a fingerprint map of various cancer cell-derived exosomes. Thus, our approach may provide a highly sensitive and robust strategy for the identification of exosome heterogeneity with advantages of being label-free and having no separation, potentially enabling the precise subpopulation of exosomes with practical value in clinical applications.

Structure-switching aptamer triggering hybridization displacement reaction for label-free detection of exosomes

Exosomes play important roles in intercellular communications, tumor migration and invasion. However, the specific detection of cancer exosomes remains as a big challenge due to its low concentration in biofluids. Therefore, the sensitive and selective detection of cancer cells-derived exosomes has attracted growing attention owing to their potential in diagnostic and prognostic applications. Activatable strategies have received great attention for the detection of low abundant analytes due to their high sensitivity. Herein, based on molecular recognition between DNA aptamer and exosome surface biomarker (protein tyrosine kinase-7), a novel activatable and label-free strategy was designed for highly sensitive and specific sensing of exosomes. In this work, the target exosomes trigger strand replacement reaction to form G-quadruplex, which result in an obvious fluorescence enhancement of N-methylmesoporphyrin IX due to the bonding between G-quadruplex and N-methylmesoporphyrin IX. Under the optimum experimental conditions, the linear range for exosomes was measured to be 5.0 × 105–5.0 × 107 particles/μL and the detection limit (LOD) was calculated to be 3.4 × 105 particles/μL (3σ). This assay possesses high specificity to distinguish exosomes derived from different cell lines, and has successfully been validated in patient and healthy plasma samples. Furthermore, the probe can effectively detect the exosomes in 30% fetal bovine serum, indicating that the biological matrix has a negligible effect on this method. This developed label-free, convenient and highly sensitive biosensor will offer a great opportunity for exosomes quantification in biological study and clinical application.

Microfluidic device for on-chip isolation and detection of circulating exosomes in blood of breast cancer patients.

Tumor-derived circulating exosomes have been recognized as a promising biomarker source for cancer diagnosis via a less invasive procedure. The integration of isolation and detection of exosomes in routine clinical settings is still challenging. In this study, we developed a new microfluidic device for immunomagnetic separation and detection of blood exosomes in situ. The microfluidic device may empower the integration of target exosome analysis via high surface to volume ratios of immunomagnetic beads and highly precise fluid control with the aid of microvalves. The obtained microfluidic device was capable of on-chip isolation and detection of circulating exosomes within 1.5 h. The captured exosomes could be directly visualized with an inverted fluorescence microscope in situ by tetramethylbenzidine-based colorimetric sensing. It was revealed that a statistically significant increase (p < 0.01) in EpCAM-positive exosomes was captured for cancer patients (n = 10) on the device when compared to healthy individuals (n = 10). The device also demonstrated high predicting accuracy for tumor exosomal markers with a sensitivity of 90% and a specificity of >95% using receiver operating characteristic curves. The microfluidic device might provide a new platform to assist cancer diagnosis and molecular classification in an automated and simple fashion.

A catalytic molecule machine-driven biosensing method for amplified electrochemical detection of exosomes

Nowadays, exosomes that carry abundant information have attracted increasing attention as potent biomarkers of liquid biopsy and ideal candidates for early diagnosis and treatment of cancers. In this work, we propose a “principle-of-proof” biosensing method for amplified electrochemical detection of exosomes by using HepG2-derived exosomes as models. Specifically, target exosomes are enriched on anti-CD63-functionalized immunobeads and then recognized by a DNA chain containing CD63 aptamer region, which subsequently initiates a catalytic molecule machine that relies on cascade toehold-mediated strand displacement reaction. Benefiting from high efficiency of the molecule machine, the method shows a linear range from 1 × 105 to 5 × 107 particles/mL and a detection limit of 1.72 × 104 particles/mL toward target exosomes, better than most existing detection methods. Moreover, the method demonstrates a high specificity even in serum samples and suggests a potential use in clinic, which may provide sufficient information for disease diagnosis, especially early detection and prognosis monitoring of tumors.

Using Nanoplasmon-Enhanced Scattering and Low-Magnification Microscope Imaging to Quantify Tumor-Derived Exosomes.

Infected or malignant cells frequently secrete more exosomes, leading to elevated levels of disease-associated exosomes in the circulation. These exosomes have the potential to serve as biomarkers for disease diagnosis and to monitor disease progression and treatment response. However, most exosome analysis procedures require exosome isolation and purification steps, which are usually time-consuming and labor-intensive, and thus of limited utility in clinical settings. This report describes a rapid procedure to analyze specific biomarkers on the outer membrane of exosomes without requiring separate isolation and purification steps. In this method, exosomes are captured on the surface of a slide by exosome-specific antibodies and then hybridized with nanoparticle-conjugated antibody probes specific to a disease. After hybridization, the abundance of the target exosome population is determined by analyzing low-magnification dark-field microscope (LMDFM) images of the bound nanoparticles. This approach can be easily adopted for research and clinical use to analyze membrane-associated exosome biomarkers linked to disease.

IL-25 Regulates Alveolar Macrophage Exosome Release in Response to LPS

Abstract Background Acute lung injury (ALI) is a major component of multiple organ dysfunction syndrome (MODS) following pulmonary and systemic infection. Alveolar macrophages (AMf) are at the center of the pathogenesis of ALI. Emerging evidence has shown that cell-cell interactions in the lungs play an important regulatory role in the development of acute lung inflammation. However, the exact mechanisms remain poorly addressed. In this study, we explore a novel function of lung epithelial cells (LEPC)-derived IL-25 in the regulation of AMf release of exosomes following LPS stimulation. Methods For in vivo experiments, C57BL/6 (WT) and TLR4 knockout (TLR4−/−) mice were treated with LPS (2 mg/kg B.W.) in 0.2 ml saline via intratracheal aerosol administration. Bronchoalveolar lavage fluid was then collected at 0 – 24 h after LPS treatment, and the AMf-derived exosomes were measured. For in vitro studies, LEPC and bone marrow-derived Mf (BMDM) were isolated from WT or TLR4−/− mice, and then cocultured in the Transwell™ system. At 0 – 24 h after the coculture, the BMDM and supernatant were harvested for the measurements of exosomes and cytokines. Results We demonstrate that LPS induces AMf release of exosomes, which are then internalized by neighboring Mf to promote TNF-a expression. Secretion of IL-25 from LEPC downregulates Rab27a and Rab27b expression in Mf, resulting in suppressed exosome release, thereby attenuating exosome-induced TNF-a expression and secretion. Conclusion These findings reveal a previously unidentified pathway of LEPC-Mf cross-talk, which negatively regulates Mf inflammatory responses to LPS. Modulating IL-25 signaling and targeting exosome release may present a new therapeutic strategy for the treatment of ALI.

Reversal of Osteoporotic Activity by Endothelial Cell-Secreted Bone Targeting and Biocompatible Exosomes.

Exosomes, also known as extracellular vesicles, are naturally occurring, biocompatible, and bioacive nanoparticles ranging from 40 to 150 nm in diameter. Bone-secreted exosomes play important roles in bone homeostasis, the interruption of which can lead to diseases such as osteoporosis, rheumatoid arthritis, and osteopetrosis. Though the relationship between vascular and bone homeostasis has been recognized recently, the role of vascular endothelial cell (EC)-secreted exosomes (EC-Exos) in bone homeostasis is not well understood. Herein, we found that EC-Exos show more efficient bone targeting than osteoblast-derived exosomes or bone marrow mesenchymal stem cell-derived exosomes. We also found that EC-Exos can be internalized by bone marrow-derived macrophages (BMMs) to alter their morphology. EC-Exos can inhibit osteoclast activity in vitro and inhibit osteoporosis in an ovariectomized mouse model. Sequencing of exosome miRNA revealed that miR-155 was highly expressed in EC-Exos-treated BMMs. The miR-155 level in EC-Exos was much higher than that in BMMs and ECs, indicating that miR-155 was endogenous cargo of EC-derived vesicles. Blockage of BMMs miR-155 levels reversed the suppression by EC-Exos of osteoclast induction, confirming that exosomal miR-155 may have therapeutic potential against osteoporosis. Taken together, our findings suggest that EC-Exos may be utilized as a bone targeting and nontoxic nanomedicine for the treatment of bone resorption disorders.

A Sensitive Aptasensor Based on a Hemin/G-Quadruplex-Assisted Signal Amplification Strategy for Electrochemical Detection of Gastric Cancer Exosomes.

Emerging evidence indicates that exosomes derived from gastric cancer cells enhance tumor migration and invasion through the modulation of the tumor microenvironment. However, it remains a major problem to detect cancer-specific exosomes due to technical and biological challenges. Most of the methods reported could not achieve efficient detection of tumor-derived exosomes in the background of normal exosomes. Herein, a label-free electrochemical aptasensor is presented for specific detection of gastric cancer exosomes. This platform contains an anti-CD63 antibody modified gold electrode and a gastric cancer exosome specific aptamer. The aptamer is linked to a primer sequence that is complementary to a G-quadruplex circular template. The presence of target exosomes could trigger rolling circle amplification and produce multiple G-quadruplex units. This horseradish peroxidase mimicking DNAzyme could catalyze the reduction of H2 O2 and generate electrochemical signals. This aptasensor exhibits high selectivity and sensitivity toward gastric cancer exosomes with a detection limit of 9.54 × 102 mL-1 and a linear response range from 4.8 × 103 to 4.8 × 106 exosomes per milliliter. Therefore, this electrochemical aptasensor is expected to become a useful tool for the early diagnosis of gastric cancer.

Photoactivatable Prodrug of Doxazolidine Targeting Exosomes.

Natural lipid nanocarriers, exosomes, carry cell-signaling materials such as DNA and RNA for intercellular communications. Exosomes derived from cancer cells contribute to the progression and metastasis of cancer cells by transferring oncogenic signaling molecules to neighboring and remote premetastatic sites. Therefore, applying the unique properties of exosomes for cancer therapy has been expected in science, medicine, and drug discovery fields. Herein, we report that an exosome-targeting prodrug system, designated MARCKS-ED-photodoxaz, could spatiotemporally control the activation of an exquisitely cytotoxic agent, doxazolidine (doxaz), with UV light. The MARCKS-ED peptide enters a cell by forming a complex with the exosomes in situ at its plasma membrane and in the media. MARCKS-ED-photodoxaz releases doxaz under near-UV irradiation to inhibit cell growth with low nanomolar IC50 values. The MARCKS-ED-photodoxaz system targeting exosomes and utilizing photochemistry will potentially provide a new approach for the treatment of cancer, especially for highly progressive and invasive metastatic cancers.

Toward Exosome-Based Neuronal Diagnostic Devices.

Targeting exosome for liquid biopsy has gained significant attention for its diagnostic and therapeutic potential. For detecting neuronal disease diagnosis such as Alzheimer’s disease (AD), the main technique for identifying AD still relies on positron-emission tomography (PET) imaging to detect the presence of amyloid-β (Aβ). While the detection of Aβ in cerebrospinal fluid has also been suggested as a marker for AD, the lack of quantitative measurements has compromised existing assays. In cerebrospinal fluid, in addition to Aβ, T-Tau, and P-Tau, alpha-synuclein has been considered a biomarker of neurodegeneration. This review suggests that and explains how the exosome can be used as a neuronal diagnostic component. To this end, we summarize current progress in exosome preparation/isolation and quantification techniques and comment on the outlooks for neuronal exosome-based diagnostic techniques.

ExoAPP: Exosome-Oriented, Aptamer Nanoprobe-Enabled Surface Proteins Profiling and Detection.

Tumor exosomes that inherit molecular markers from their parent cells are emerging as cellular "surrogates" in cancer diagnostics. Molecular profiling and detection of exosomes offer a noninvasive access to the state of cancer progression, yet are still technically challenging. Here we report an exosome-oriented, aptamer nanoprobe-based profiling (ExoAPP) assay to phenotype surface proteins and quantify cancerous exosomes in a facile mix-and-detect format. Our ExoAPP interfaces graphene oxide (GO) with target-responsive aptamers to profile exosomal markers across five cell types by complementing with enzyme-assisted exosome recycling, revealing a heterogeneous pattern.This assay achieves a detection limit down to 1.6 × 105 particles/mL, lowered by several orders of magnitude over other homogeneous protocols. Such a sensitive ExoAPP assay allows for monitoring epithelial-mesenchymal transition through heterogeneous exosomes without involving cellular internalization that often occurs in GO-based cargo delivery. Using ExoAPP to analyze blood samples from prostate cancer patients, we find that target exosome can be identified by surface PSMA, suggesting their potential in clinical diagnosis.

Exosomes Regulate the Transformation of Cancer Cells in Cancer Stem Cell Homeostasis.

In different biological model systems, exosomes are considered mediators of cell-cell communication between different cell populations. Exosomes, as extracellular vesicles, participate in physiological and pathological processes by transmitting signaling molecules such as proteins, nucleic acids, and lipids. The tumor's microenvironment consists of many types of cells, including cancer stem cells and mesenchymal cells. It is well known that these cells communicate with each other and thereby regulate the progression of the tumor. Recent studies have provided evidence that exosomes mediate the interactions between different types of cells in the tumor microenvironment, providing further insight into how these cells interact through exosome signaling. Cancer stem cells are a small kind of heterogeneous cells that existed in tumor tissues or cancer cell lines. These cells possess a stemness phenotype with a self-renewal ability and multipotential differentiation which was considered the reason for the failure of conventional cancer therapies and tumor recurrence. However, a highly dynamic equilibrium was found between cancer stem cells and cancer cells, and this indicates that cancer stem cells are no more special target and blocking the transformation of cancer stem cells and cancer cells seem to be a more significant therapy strategy. Whether exosomes, as an information transforming carrier between cells, regulated cancer cell transformation in cancer stem cell dynamic equilibrium and targeting exosome signaling attenuated the formation of cancer stem cells and finally cure cancers is worthy of further study.