Simultaneous detection of cancerous exosomal miRNA-21 and PD-L1 with a sensitive dual-cycling nanoprobe

Recent advances of surface plasmon resonance sensors based on metal-organic frameworks

The surface Plasmon resonance (SPR) sensing technique combines rapid response, high sensitivity, non-destructive operation, high specificity, real-time on-site detection, and continuous monitoring advantages. These distinctive features enable its broad application in detecting disease biomarkers, viruses, foodborne contaminants, and hazardous gases. To enhance SPR sensing signals, metal-organic frameworks (MOFs), which emerge as a category of highly porous-organic frameworks, have demonstrated superior performance as SPR sensitive layers due to their features of large specific surface areas, high porosity, regular skeletons, tunable chemical components and functionality, and promising optoelectronic performances. Varieties of MOFs (such as UiO-66, porphyrin-based MOFs, and zeolitic imidazolate frameworks) and MOFs-based composites with improved plasmon-exciton coupling and charge carrier mobility exhibit amplified SPR responses through the integration of diverse effects. This review systematically summarizes the construction principle of MOFs-based SPR sensors and discusses their advancements for the inspection of biomarkers, drug residuals, viruses, and volatile organic gases. Finally, we also analyze the current challenge and provide the perspective about this field, which can inspire readers to a certain extent.

Exponential rolling circle amplification-hybridization chain reaction (EXRCA-HCR) for AgNPs@gel-enhanced fluorescence ultrasensitive detection of miRNA-21

MicroRNA (miRNA) is a common tumor marker, whose abnormal expression is often closely related to the occurrence of various diseases. However, the conventional method for detecting miRNA is qRT-PCR, requiring additional reverse transcription steps, well-trained professionals, and expensive thermal cycling equipment. In this work, we propose a novel isothermal amplification technique (exponential rolling circle amplification-hybridization chain reaction, EXRCA-HCR) for AgNPs@gel-enhanced fluorescence specific and ultrasensitive detection of miRNA-21. This novel technique consists of rolling circle amplification (RCA), exponential isothermal amplification reaction (EXPAR) and hybridization chain reaction (HCR). Combining these three amplification methods, EXRCA-HCR provides a unique cascade amplification strategy, inheriting the advantages of linear amplification and exponential amplification. Under optimal conditions, this novel EXRCA-HCR exhibits a wide fluorescent detection range from 200 fM to 200 nM for miRNA-21, with low detection limit of 21.47 fM. By introducing AgNPs@gel, the fabricated paper-based fluorosensor based on EXRCA-HCR provides a simple and rapid visual detection of miRNA-21. This research puts forward a promising approach for detecting miRNA-21, which can be applied for early diagnosis.

S9.6 Antibody-Mediated Wireless Portable Biosensor with Multiple Affinity Enhancements for Comprehensive Detection of Nucleic Acid in Serum

Creating biosensors capable of facilely and entirely excluding the influence of interfering biomolecules in complex samples holds profound significance for advancing detection technology and diagnostics. Here, we develop a wireless portable biosensor (WPB) that prevents interference from abundant biomolecules in serum through homogeneous hybridization and S9.6 antibody-mediated multivalent capture. By transferring the hybridization environment from a heterogeneous chip surface to a homogeneous solution, the biosensor maintains consistent hybridization efficiency in serum as in buffer. Additionally, the use of S9.6 antibody-mediated multivalent capture ensures nearly unchanged binding affinity in serum compared to buffer. On the basis of the multiple affinity enhancements, S9.6 antibody-mediated WPB can achieve ultrasensitive detection of nucleic acid in 50% human serum. Specifically, a subtle blocker is designed to eliminate the competitive monovalent S9.6 antibody-heteroduplex binding, ensuring the efficiency of multivalent S9.6 antibody-heteroduplex interactions. The blocker also enables single-step detection. Moreover, the sensing platform utilizes interferents in serum as in situ antifouling biomolecules to prevent nonspecific adsorption. As a result, the proposed WPB achieves a similar limit of detection for nucleic acids in human serum (95 aM) and in buffer (86 aM). This approach inspires a new idea for complex interference elimination and usage and exhibits comprehensive detection performance in complex samples with potential future diagnostic applications.

Logic-Measurer: A Multienzyme-Assisted Ultrasensitive Circuit for Logical Detection of Exosomal MicroRNAs

The logic profiling of exosomal microRNAs (miRNAs) offers broad potential applications in the accurate diagnosis and staging of cancer. However, the logical detection of low-abundance exosomal miRNAs in complex clinical samples remains challenging. This study introduces a logic analysis system termed "Measurer" (a multi-enzyme-assisted ultrasensitive circuit) that offers ultrasensitive and versatile method for detecting multiple exosomal miRNAs. The Logic-Measurer comprises three modules: a stem-loop hairpin-enhanced CRISPR/Cas13a, a polymerase-driven primer exchange reaction, and an exonuclease III-mediated fluorescence output. The efficient Logic-Measurer was switched by the faster rate of trans-cleavage activity of Cas13a due to its improved affinity for hairpin RNA structures. The mechanistic model of hairpin-enhanced CRISPR/Cas13a was confirmed by molecular dynamics simulations. The Logic-Measurer accurately detected exosomal miRNA-21 or miRNA-375 down to 2.1 and 4.4 fM, with superior specificity, and enabled in situ detection of miRNA-21 and miRNA-375 in as low as 1.4 × 102 particles/mL exosomes via membrane fusion. In addition, this method demonstrated 87.3 and 82.1% accuracy in the diagnosis and early detection of breast cancer, respectively, among a cohort of 315 individuals. Subsequent subgroup analysis further confirmed the method's ability to accurately differentiate estrogen receptor-positive patients from healthy individuals. Therefore, the Logic-Measurer offers valuable insights into the development of a CRISPR/Cas-based enhanced diagnostic platform and the next generation of diagnostic technology based on enzyme circuits.

A microfluidic-based chemiluminescence biosensor for sensitive multiplex detection of exosomal microRNAs based on hybridization chain reaction

The analysis of microRNAs (miRNAs) in exosomes is of great importance for noninvasive early disease diagnosis. However, current techniques to detect exosomal miRNAs is hampered either by laborious exosome isolation or low abundance of miRNAs in exosomes. Here, we developed a microfluidic chemiluminescence (CL) analysis method for the multiplexed detection of exosomal miR-21 and miR-155. The microfluidic device contained three parts: a snake-shaped channel for fully mixing chemiluminescent reagents, a ship-shaped channel modified with CD63 protein aptamer for capturing exosomes, and another two parallel ship-shaped channels for hybridization chain reaction (HCR) amplification and CL detection. The multiple signal amplification was realized by Y-shaped arrays, HCR amplification, and poly-HRP catalyzed CL reaction. Using this multiple signal amplification method, our microfluidic CL biosensor achieves a limit of detection of miRNAs of 0.49 fM, with a linear range of 1 fM-10 pM, which is better or comparable to previously reported biosensors. What's more, the proposed microfluidic biosensor exhibits great specificity and selectivity to the target miRNA. Moreover, the microfluidic CL strategy exhibited excellent accuracy and could significantly distinguish different cancer subtypes as well as cancer patients and healthy people. These results suggest that this simple, high sensitive, and more accurate analytical strategy by analyzing different types of exosomal miRNAs has the potential applications in cancer diagnosis and stage monitoring.

Influencing immunity: role of extracellular vesicles in tumor immune checkpoint dynamics

Immune checkpoint proteins (ICPs) serve as critical regulators of the immune system, ensuring protection against damage due to overly activated immune responses. However, within the tumor environment, excessive ICP activation weakens antitumor immunity. Despite the development of numerous immune checkpoint blockade (ICB) drugs in recent years, their broad application has been inhibited by uncertainties about their clinical efficacy. A thorough understanding of ICP regulation in the tumor microenvironment is essential for advancing the development of more effective and safer ICB therapies. Extracellular vesicles (EVs), which are pivotal mediators of cell-cell communication, have been extensively studied and found to play key roles in the functionality of ICPs. Nonetheless, a comprehensive review summarizing the current knowledge about the crosstalk between EVs and ICPs in the tumor environment is lacking. In this review, we summarize the interactions between EVs and several widely studied ICPs as well as their potential clinical implications, providing a theoretical basis for further investigation of EV-related ICB therapeutic approaches.

Exosome-based nanoparticles and cancer immunotherapy

Over the past decades, cancer immunotherapy has encountered challenges such as immunogenicity, inefficiency, and cytotoxicity. Consequently, exosome-based cancer immunotherapy has gained rapid traction as a promising alternative. Exosomes, a type of extracellular vesicles (EVs) ranging from 50 to 150 nm, are self-originating and exhibit fewer side effects compared to traditional therapies. Exosome-based immunotherapy encompasses three significant areas: cancer vaccination, co-inhibitory checkpoints, and adoptive T-cell therapy. Each of these fields leverages the inherent advantages of exosomes, demonstrating substantial potential for individualized tumor therapy and precision medicine. This review aims to elucidate the reasons behind the promise of exosome-based nanoparticles as cancer therapies by examining their characteristics and summarizing the latest research advancements in cancer immunotherapy.

In Situ, Fusion-Free, Multiplexed Detection of Small Extracellular Vesicle miRNAs for Cancer Diagnostics

Tumor-derived small extracellular vesicle (sEV) microRNAs (miRNAs) are emerging biomarkers for cancer diagnostics. Conventional sEV miRNA detection methods necessitate the lysis of sEVs, rendering them laborious and time-consuming and potentially leading to damage or loss of miRNAs. Membrane fusion-based in situ detection of sEV miRNAs involves the preparation of probe-loaded vesicles (e.g., liposomes or cellular vesicles), which are typically sophisticated and require specialist equipment. Membrane perforation methods employ chemical treatments that can induce severe miRNA degradation or leaks. Inspired by previous studies that loaded nucleic acids into EVs or cells using hydrophobic tethers for therapeutic applications, herein, we repurposed this strategy by conjugating a hydrophobic tether onto molecular beacons to aid their transportation into sEVs, allowing for in situ detection of miRNAs in a fusion-free and multiplexing manner. This method enables simultaneous detection of multiple miRNA species within serum-derived sEVs for the diagnosis of prostate cancer, breast cancer, and gastric cancer with an accuracy of 83.3%, 81.8%, and 100%, respectively, in a cohort of 66 individuals, indicating that it holds a high application potential in clinical diagnostics.

Enhancing RNA detection and breast cancer subtyping with a universal 3D-hybridization chain reaction system

Breast cancer, a globally prevalent malignancy, is characterized by pronounced heterogeneity. Accurate subtyping requires the simultaneous detection of different biomarkers, which is crucial for personalized treatment strategies. However, existing methodologies are hindered by limited versatility and sensing performance. To overcome these hurdles, this study presents a universal 3D-Hybridization Chain Reaction (3D-HCR) system for RNA detection and subtype-specific diagnosis of breast cancer. The system integrated a universal trigger for HCR, thereby circumventing the need for complex sequence design and enabling the analysis of various RNA targets. Leveraging the spatial-confinement effect offered by DNA nanocarriers, this system exhibited superior amplification efficiency, achieving detection limits of 3.83 pM and 4.96 pM for PD-L1 mRNA and miR-21, respectively. Importantly, the system could differentiate between triple-negative breast cancer and estrogen receptor-positive breast cancer in both living cells and clinical tissues. These findings underscore the potential of the universal 3D-HCR system as a promising tool in clinical diagnostics. With its proven proficiency in breast cancer diagnostics and versatility in RNA analysis, this system holds the promise of broadening the horizons of precision medicine.

Simultaneous detection of membrane protein and mRNA at single extracellular vesicle level by droplet microfluidics for cancer diagnosis

INTRODUCTION

Simultaneous detection of proteins and mRNA within a single extracellular vesicle (EV) enables comprehensive analysis of specific EVs subpopulations, significantly advancing cancer diagnostics. However, developing a sensitive and user-friendly approach for simultaneously detecting multidimensional biomarkers in single EV is still challenging.

OBJECTIVES

To facilitate the analysis of multidimensional biomarkers in EVs and boost its clinical application, we present a versatile droplet digital system facilitating the concurrent detection of membrane proteins and mRNA at the single EV level with high sensitivity and specificity.

METHODS

The antibody-DNA conjugates were firstly prepared for EVs protein biomarkers recognition and signal transformation. Coupling with the assembled triplex droplet digital PCR system, a versatile droplet digital analysis assay for simultaneous detection of membrane protein and mRNA at a single EV level was developed.

RESULTS

Our new droplet digital system displayed high sensitivity and specificity. Additionally, its clinical application was validated in a breast cancer cohort. As expected, this assay has demonstrated superior performance in distinguishing breast cancer from healthy individuals and benign controls through combined detection of EVs protein and mRNA markers compared to any single kind marker detections, especially for patients with breast cancer at early stage (AUC=0.9229).

CONCLUSION

Consequently, this study proposes a promising strategy for accurately identifying and analyzing specific EV subgroups through the co-detection of proteins and mRNA at the single EV level, holding significant potential for future clinical applications.

Recent advances in the applications of DNA frameworks in liquid biopsy: A review

Cancer is one of the serious threats to public life and health. Early diagnosis, real-time monitoring, and individualized treatment are the keys to improve the survival rate and prolong the survival time of cancer patients. Liquid biopsy is a potential technique for cancer early diagnosis due to its non-invasive and continuous monitoring properties. However, most current liquid biopsy techniques lack the ability to detect cancers at the early stage. Therefore, effective detection of a variety of cancers is expected through the combination of various techniques. Recently, DNA frameworks with tailorable functionality and precise addressability have attracted wide spread attention in biomedical applications, especially in detecting cancer biomarkers such as circulating tumor cells (CTCs), exosomes and circulating tumor nucleic acid (ctNA). Encouragingly, DNA frameworks perform outstanding in detecting these cancer markers, but also face some challenges and opportunities. In this review, we first briefly introduced the development of DNA frameworks and its typical structural characteristics and advantages. Then, we mainly focus on the recent progress of DNA frameworks in detecting commonly used cancer markers in liquid-biopsy. We summarize the advantages and applications of DNA frameworks for detecting CTCs, exosomes and ctNA. Furthermore, we provide an outlook on the possible opportunities and challenges for exploiting the structural advantages of DNA frameworks in the field of cancer diagnosis. Finally, we envision the marriage of DNA frameworks with other emerging materials and technologies to develop the next generation of disease diagnostic biosensors.

Exosomal PD-L1 in cancer and other fields: recent advances and perspectives

PD-1/PD-L1 signaling is a key factor of local immunosuppression in the tumor microenvironment. Immune checkpoint inhibitors targeting PD-1/PD-L1 signaling have achieved tremendous success in clinic. However, several types of cancer are particularly refractory to the anti-PD-1/PD-L1 treatment. Recently, a series of studies reported that IFN-γ can stimulate cancer cells to release exosomal PD-L1 (exoPD-L1), which possesses the ability to suppress anticancer immune responses and is associated with anti-PD-1 response. In this review, we introduce the PD-1/PD-L1 signaling, including the so-called 'reverse signaling'. Furthermore, we summarize the immune treatments of cancers and pay more attention to immune checkpoint inhibitors targeting PD-1/PD-L1 signaling. Additionally, we review the action mechanisms and regulation of exoPD-L1. We also introduce the function of exoPD-L1 as biomarkers. Finally, we review the methods for analyzing and quantifying exoPD-L1, the therapeutic strategies targeting exoPD-L1 to enhance immunotherapy and the roles of exoPD-L1 beyond cancer. This comprehensive review delves into recent advances of exoPD-L1 and all these findings suggest that exoPD-L1 plays an important role in both cancer and other fields.

All-in-one detection of breast cancer-derived exosomal miRNA on a pen-based paper chip

Exosomal microRNAs (miRNAs) play a pivotal role in intercellular communication, regulating gene expression in target cells, and hold significant promise as cancer biomarkers for early detection and screening. However, achieving precise and viable detection of exosomal miRNAs remains a challenge. This paper proposes an all-in-one detection strategy for breast cancer-derived exosomal miRNA-21 on a pen-based paper chip (PPC). The PPC is constructed using a modified automatic pen and lateral flow assay (LFA), which results in a cost-effective fabrication process. The user only needs to add the sample and trigger the top of the self-contained PPC after a period of time to complete the entire detection process. To enhance the sensitivity of exosomal miRNA testing, an enzyme-free catalyzed hairpin assembly (CHA) is further introduced, enabling highly sensitive detection of miRNA-21 with a limit of detection (LOD) of 25 fmol. Additionally, the detection of miRNAs in differentially-expressed cells and clinical samples has also been successfully achieved with high specificity. Overall, the proposed PPC provides an effective tool for detecting early cancer, monitoring diseases, and establishing point of care testing (POCT).

An updated landscape on nanotechnology-based drug delivery, immunotherapy, vaccinations, imaging, and biomarker detections for cancers: recent trends and future directions with clinical success

The recent development of nanotechnology-based formulations improved the diagnostics and therapies for various diseases including cancer where lack of specificity, high cytotoxicity with various side effects, poor biocompatibility, and increasing cases of multi-drug resistance are the major limitations of existing chemotherapy. Nanoparticle-based drug delivery enhances the stability and bioavailability of many drugs, thereby increasing tissue penetration and targeted delivery with improved efficacy against the tumour cells. Easy surface functionalization and encapsulation properties allow various antigens and tumour cell lysates to be delivered in the form of nanovaccines with improved immune response. The nanoparticles (NPs) due to their smaller size and associated optical, physical, and mechanical properties have evolved as biosensors with high sensitivity and specificity for the detection of various markers including nucleic acids, protein/antigens, small metabolites, etc. This review gives, initially, a concise update on drug delivery using different nanoscale platforms like liposomes, dendrimers, polymeric & various metallic NPs, hydrogels, microneedles, nanofibres, nanoemulsions, etc. Drug delivery with recent technologies like quantum dots (QDs), carbon nanotubes (CNTs), protein, and upconverting NPs was updated, thereafter. We also summarized the recent progress in vaccination strategy, immunotherapy involving immune checkpoint inhibitors, and biomarker detection for various cancers based on nanoplatforms. At last, we gave a detailed picture of the current nanomedicines in clinical trials and their possible success along with the existing approved ones. In short, this review provides an updated complete landscape of applications of wide NP-based drug delivery, vaccinations, immunotherapy, biomarker detection & imaging for various cancers with a predicted future of nanomedicines that are in clinical trials.

Integrating Reliable Pt-S Bond-Mediated 3D DNA Nanomachine with Magnetic Separation in a Homogeneous Electrochemical Strategy for Exosomal MicroRNA Detection with Low Background and High Sensitivity

Precise and sensitive analysis of exosomal microRNA (miRNA) is of great importance for noninvasive early disease diagnosis, but it remains a great challenge to detect exosomal miRNA in human blood samples because of their small size, high sequence homology, and low abundance. Herein, we integrated reliable Pt-S bond-mediated three-dimensional (3D) DNA nanomachine and magnetic separation in a homogeneous electrochemical strategy for the detection of exosomal miRNA with low background and high sensitivity. The 3D DNA nanomachine was easily prepared via a facile and rapid freezing method, and it was capable of resisting the influence of biothiols, thus endowing it with high stability. Notably, the as-developed magnetic 3D DNA nanomachine not only enabled the detection system to have a low background but also coupled with liposome nanocarriers to synergistically amplify the current signal. Consequently, by ingeniously combining the low background and multiple signal-amplification strategies in homogeneous electrochemical biosensing, highly sensitive detection of exosomal miRNA was successfully achieved. More significantly, with good anti-interference ability, the as-proposed method could effectively discriminate plasma samples from cancer patients and healthy subjects, thus showing a high potential for application in the nondestructive early clinical diagnosis of disease.

Self-powered dual-mode sensing strategy based on graphdiyne and DNA nanoring for sensitive detection of tumor biomarker

MicroRNA-21 (miRNA-21) is currently the only known oncogenic miRNA that is upregulated in almost all malignant tumors and exhibits a broad spectrum of tumor recognition characteristics. It holds significant value in the early diagnosis, malignant degree assessment, and prognostic evaluation of tumors. In this study, a novel dual-mode self-powered sensing platform is developed using Au nanoparticles/graphdiyne as the electrode substrate and combined with DNA nanoring for highly sensitive and specific detection of miRNA-21. The DNA nanoring structure, which is easy to prepare and contains multiple recognition sites, induces significant electrochemical/colorimetric signal responses of the signaling molecule methylene blue. Under optimal conditions, the linear ranges of the electrochemical and colorimetric detection modes of this self-powered sensor are 0.1 fM-100 pM and 0.1 fM-10 nM, respectively, with the detection limits of 35.1 aM and 61.6 aM (S/N=3). This strategy provides a new reference for the sensitive detection of microRNA and has immense potential for application in the screening and detection of clinical nucleic acid diseases.

ExoPD-L1: an assistant for tumor progression and potential diagnostic marker

The proliferation and function of immune cells are often inhibited by the binding of programmed cell-death ligand 1 (PD-L1) to programmed cell-death 1 (PD-1). So far, many studies have shown that this combination poses significant difficulties for cancer treatment. Fortunately, PD-L1/PD-1 blocking therapy has achieved satisfactory results. Exosomes are tiny extracellular vesicle particles with a diameter of 40~160 nm, formed by cells through endocytosis. The exosomes are a natural shelter for many molecules and an important medium for information transmission. The contents of exosomes are composed of DNA, RNA, proteins and lipids etc. They are crucial to antigen presentation, tumor invasion, cell differentiation and migration. In addition to being present on the surface of tumor cells or in soluble form, PD-L1 is carried into the extracellular environment by tumor derived exosomes (TEX). At this time, the exosomes serve as a medium for communication between tumor cells and other cells or tissues and organs. In this review, we will cover the immunosuppressive role of exosomal PD-L1 (ExoPD-L1), ExoPD-L1 regulatory factors and emerging approaches for quantifying and detecting ExoPD-L1. More importantly, we will discuss how targeted ExoPD-L1 and combination therapy can be used to treat cancer more effectively.

Biogenesis, Isolation, and Detection of Exosomes and Their Potential in Therapeutics and Diagnostics

The increasing research and rapid developments in the field of exosomes provide insights into their role and significance in human health. Exosomes derived from various sources, such as mesenchymal stem cells, cardiac cells, and tumor cells, to name a few, can be potential therapeutic agents for the treatment of diseases and could also serve as biomarkers for the early detection of diseases. Cellular components of exosomes, several proteins, lipids, and miRNAs hold promise as novel biomarkers for the detection of various diseases. The structure of exosomes enables them as drug delivery vehicles. Since exosomes exhibit potential therapeutic applications, their efficient isolation from complex biological/clinical samples and precise real-time analysis becomes significant. With the advent of microfluidics, nano-biosensors are being designed to capture exosomes efficiently and rapidly. Herein, we have summarized the history, biogenesis, characteristics, functions, and applications of exosomes, along with the isolation, detection, and quantification techniques. The implications of surface modifications to enhance specificity have been outlined. The review also sheds light on the engineered nanoplatforms being developed for exosome detection and capture.

CRISPR/Cas13a-Based MicroRNA Detection in Tumor-Derived Extracellular Vesicles

MicroRNAs (miRNAs) in extracellular vesicles (EVs) play essential roles in cancer initiation and progression. Quantitative measurements of EV miRNAs are critical for cancer diagnosis and longitudinal monitoring. Traditional PCR-based methods, however, require multi-step procedures and remain as bulk analysis. Here, the authors introduce an amplification-free and extraction-free EV miRNA detection method using a CRISPR/Cas13a sensing system. CRISPR/Cas13a sensing components are encapsulated in liposomes and delivered them into EVs through liposome-EV fusion. This allows for accurately quantify specific miRNA-positive EV counts using 1 × 108  EVs. The authors show that miR-21-5p-positive EV counts are in the range of 2%-10% in ovarian cancer EVs, which is significantly higher than the positive EV counts from the benign cells (<0.65%). The result show an excellent correlation between bulk analysis with the gold-standard method, RT-qPCR. The authors also demonstrate multiplexed protein-miRNA analysis in tumor-derived EVs by capturing EpCAM-positive EVs and quantifying miR-21-5p-positive ones in the subpopulation, which show significantly higher counts in the plasma of cancer patients than healthy controls. The developed EV miRNA sensing system provides the specific miRNA detection method in intact EVs without RNA extraction and opens up the possibility of multiplexed single EV analysis for protein and RNA markers.

Young Sca-1+ bone marrow stem cell-derived exosomes preserve visual function via the miR-150-5p/MEKK3/JNK/c-Jun pathway to reduce M1 microglial polarization

BACKGROUND

Polarization of microglia, the resident retinal immune cells, plays important roles in mediating both injury and repair responses post-retinal ischemia-reperfusion (I/R) injury, which is one of the main pathological mechanisms behind ganglion cell apoptosis. Aging could perturb microglial balances, resulting in lowered post-I/R retinal repair. Young bone marrow (BM) stem cell antigen 1-positive (Sca-1⁺) cells have been demonstrated to have higher reparative capabilities post-I/R retinal injury when transplanted into old mice, where they were able to home and differentiate into retinal microglia.

METHODS

Exosomes were enriched from young Sca-1⁺ or Sca-1^- cells, and injected into the vitreous humor of old mice post-retinal I/R. Bioinformatics analyses, including miRNA sequencing, was used to analyze exosome contents, which was confirmed by RT-qPCR. Western blot was then performed to examine expression levels of inflammatory factors and underlying signaling pathway proteins, while immunofluorescence staining was used to examine the extent of pro-inflammatory M1 microglial polarization. Fluoro-Gold labelling was then utilized to identify viable ganglion cells, while H&E staining was used to examine retinal morphology post-I/R and exosome treatment.

RESULTS

Sca-1⁺ exosome-injected mice yielded better visual functional preservation and lowered inflammatory factors, compared to Sca-1^-, at days 1, 3, and 7 days post-I/R. miRNA sequencing found that Sca-1⁺ exosomes had higher miR-150-5p levels, compared to Sca-1^- exosomes, which was confirmed by RT-qPCR. Mechanistic analysis found that miR-150-5p from Sca-1⁺ exosomes repressed the mitogen-activated protein kinase kinase kinase 3 (MEKK3)/JNK/c-Jun axis, leading to IL-6 and TNF-α downregulation, and subsequently reduced microglial polarization, all of which contributes to reduced ganglion cell apoptosis and preservation of proper retinal morphology.

CONCLUSION

This study elucidates a potential new therapeutic approach for neuroprotection against I/R injury, via delivering miR-150-5p-enriched Sca-1⁺ exosomes, which targets the miR-150-5p/MEKK3/JNK/c-Jun axis, thereby serving as a cell-free remedy for treating retinal I/R injury and preserving visual functioning.

Capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay for sensitive detection of microRNA with high reliability

To achieve sensitive detection of low-content microRNA, photoelectrochemical/electrochromic dual-mode sensor with intrinsically low background signal has been developed, but the two detection modules are usually designed with a series-connected structure, which may cause signal interference and thus affect the detection reliability. To solve the above problems, a decoupled dual-mode bioassay for sensitive miRNA-21 detection with high reliability is constructed in this work, by selecting two capacitors to realize parallel amplification for the two detection modules, supplemented with a 3D DNA nanoring photoelectrode signal amplification strategy. The complete decoupling of the two detection modes, photoelectrochemical and electrochromic, as well as the use of digital multimeter, improves the reliability and accuracy of the sensor, and also frees it from dependence on electrochemical workstation, making detection more intuitive and faster. With simple structure, low cost, good reproducibility, high sensitivity, and easy operation, the capacitor-parallel-amplified decoupled photoelectrochemical/electrochromic dual-mode bioassay has broad application prospect in on-site point-of-care detection of diseases and low-cost clinical diagnosis. The design idea of decoupled dual-mode detector can also be extended to the construction of other dual-mode methods.

Primer exchange reaction-amplified protein-nucleic acid interactions for ultrasensitive and specific microRNA detection

Protein-nucleic acid interactions are not only fundamental to genetic regulation and cellular metabolism, but molecular basis to artificial biosensors. However, such interactions are generally weak and dynamic, making their specific and sensitive quantitative detection challenging. By using primer exchange reaction (PER)-amplified protein-nucleic acid interactions, we here design a universal and ultrasensitive electrochemical sensor to quantify microRNAs (miRNAs) in blood. This PER-miR sensor leverages specific recognition between S9.6 antibodies and miRNA/DNA hybrids to couple with PER-derived multi-enzyme catalysis for ultrasensitive miRNA detection. Surface binding kinetic analysis shows a rational K_d (8.9 nM) between the miRNA/DNA heteroduplex and electrode-attached S9.6 antibody. Based on such a favorable affinity, the programmable PER amplification enables the sensor to detect target miRNAs with sensitivity up to 90.5 aM, three orders of magnitude higher than that without PER in routine design, and with specificity of single-base resolution. Furthermore, the PER-miR sensor allows detecting multiple miRNAs in parallel, measuring target miRNA in lysates across four types of cell lines, and differentiating tumor patients from healthy individuals by directly analyzing the human blood samples (n = 40). These advantages make the sensor a promising tool to enable quantitative sensing of biomolecular interactions and precision diagnostics.

In situ detection of exosomal RNAs for cancer diagnosis

Exosomes are considered as biomarkers reflecting the physiological state of the human body. Studies have revealed that the expression levels of specific exosomal RNAs are closely associated with certain cancers. Thus, detection of exosomal RNA offers a new avenue for liquid biopsy of cancers. Many exosomal RNA detection methods based on various principles have been developed, and most of the methods detect the extracted RNAs after lysing exosomes. Besides complex and time-consuming extraction steps, a major drawback of this approach is the degradation of the extracted RNAs in the absence of plasma membrane and cytosol. In addition, there is considerable loss of RNAs during their extraction. In situ detection of exosomal RNAs can avoid these drawbacks, thus allowing higher diagnostic reliability. In this paper, in situ detection of exosomal RNAs was systematically reviewed from the perspectives of detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, and involved functional materials. Furthermore, the limitations and possible improvements of the current in situ detection methods for exosomal RNAs towards the clinical diagnostic application are discussed. This review aims to provide a valuable reference for the development of in situ exosomal RNA detection strategies for non-invasive diagnosis of cancers. STATEMENT OF SIGNIFICANCE: Certain RNAs have been identified as valuable biomarkers for some cancers, and sensitive detection of cancer-related RNAs is expected to achieve better diagnostic efficacy. Currently, the detection of exosomal RNAs is receiving increasing attention due to their high stability and significant concentration differences between patients and healthy individuals. In situ detection of exosomal RNAs has greater diagnostic reliability due to the avoidance of RNA degradation and loss. However, this mode is still limited by some factors such as detection methods, transport methods of the probe systems, probe structures, signal amplification strategies, etc. This review focuses on the progress of in situ detection of exosomal RNAs and aims to promote the development of this field.

DNA Nanomaterial-Based Optical Probes for Exosomal miRNA Detection

Micro ribonucleic acids (miRNAs) in exosomes have been proven as reliable biomarkers to detect disease progression. In recent years, deoxyribonucleic acid (DNA)-based nanomaterials show great potential in the field of diagnosis due to the programmable sequence, various molecule recognition and predictable assembly/disassembly of DNA. In this review, we focus on the molecular design and detection mechanism of DNA nanomaterials, and the developed DNA nanomaterial-based optical probes for exosomal miRNA detection are summarized and discussed. The rationally-designed DNA sequences endows these probes with low background signal and high sensitivity in exosomal miRNA detection, and the detection mechanisms based on different DNA nanomaterials are detailly introduced. At the end, the challenges and future opportunities of DNA nanomaterial-based optical probes in exosomal miRNA detection are discussed. We envision that DNA nanomaterial-based optical probes will be promising in precise biomedicine.