Emerging Prospects of Exosomes for Cancer Treatment: From Conventional Therapy to Immunotherapy

Exosomes Derived from Bone Marrow-Mesenchymal Stem Cells Attenuates Cisplatin-Induced Ototoxicity in a Mouse Model

Background: Both hypoxia preconditioning and exosomes derived from bone marrow mesenchymal stem cells (BMSC-Exo) have been adopted to alleviate hair-loss-related ototoxicity. Whether hypoxic BMSCs-derived exosomes (hypBMSC-Exo) could alleviate cisplatin-induced ototoxicity is investigated in this study. Methods: Cisplatin intraperitoneally injected C57BL/6 mice were trans-tympanically administered BMSC-Exo or hypBMSC-Exo in the left ear. Myosin 7a staining was utilized to detect mature hair cells. Auditory brainstem response (ABR) was assessed to indicate auditory sensitivity at 8, 16, 24, and 32 kHz. The relative expressions of hypoxia-inducible factor-1α (HIF-1α), superoxide dismutase 1 (SOD1), and SOD2 were determined with RT-PCR and Western blot. The content of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), SOD, and glutathione (GSH) in the middle turns of the cochlea were measured. Results: Up-regulated HIF-1α expression was observed in hypBMSC-Exo compared with BMSC-Exo. Diminished auditory sensitivity and increased hair cell loss was observed in the cisplatin-exposed mice with increased content of H₂O₂ and MDA and decreased content of SOD and GSH, which could be reversed by hypBMSC-Exo or BMSC-Exo administration. It is worth noting that hypBMSC-Exo demonstrated more treatment benefits than BMSC-Exo with up-regulated SOD1 and SOD2 expression in the middle turns of the cochlea tissues. Conclusions: Hypoxic preconditioning may provide a new therapeutic option in regenerative medicine, and hypBMSC-Exo could be utilized to alleviate cisplatin-induced ototoxicity.

Electrochemical nano biosensors for the detection of extracellular vesicles exosomes: From the benchtop to everywhere?

Detection of extracellular vesicles (EVs) exosomes is a challenge to address the need for better diagnostic tests and to create a point-of-care (POC) platform that can detect, monitor and treat health conditions early to allow personalized therapies. A multidisciplinary approach is needed to address these health-related technical issues. Over the past decade, materials scientists and engineers have worked on the same platform to develop flexible, lightweight, miniaturized, and integrated POC devices for exosome detection. Therefore, exosome detection based on various nanomaterials is of particular interest. In this paper, we describe the current state of knowledge on 0D-3D nanostructured materials and present a POC-based technique for exosome detection. Finally, the challenges that need to be solved to expand their clinical application are discussed.

Identification of exosomal circRNA CD226 as a potent driver of nonsmall cell lung cancer through miR-1224-3p/high mobility group AT-hook 2 axis

Circular RNAs (circRNAs) are crucial for the pathogenesis of nonsmall lung cancer (NSCLC). Here, we set out to unravel the precise function of circRNA CD226 (circCD226) in NSCLC pathogenesis. The exosomes from serum specimens were observed by transmission electron microscopy. CircCD226, miR-1224-3p and high mobility group AT-hook 2 (HMGA2) were quantified by qRT-PCR, western blot and immunohistochemistry. Actinomycin D and Ribonuclease (RNase) R treatments and subcellular localization assay were used for circCD226 characterization. Cell viability, proliferation, migration, invasion and sphere formation abilities were gauged by CCK-8, EDU, wound-healing, transwell and sphere formation assays, respectively. Directed relationships among circCD226, miR-1224-3p and HMGA2 were examined by RNA pull-down, dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. The abundance of circCD226 was elevated in serum exosomes, tissues and cells of NSCLC. NSCLC serum exosomes enhanced NSCLC cell proliferation, migration, invasion and stemness. Loss of circCD226 impeded cell proliferation, migration, invasion and stemness in vitro, as well as tumor growth in vivo. Mechanistically, circCD226 sponged miR-1224-3p, and miR-1224-3p targeted HMGA2. CircCD226 involved the posttranscriptional regulation of HMGA2 through miR-1224-3p. Moreover, the miR-1224-3p/HMGA2 axis was identified as a functionally downstream effector of circCD226 in regulating NSCLC cell behaviors. Our study identifies circCD226 as a potential driver in NSCLC development depending on the regulation of miR-1224-3p/HMGA2 axis.

Overcoming the blood-brain barrier: Exosomes as theranostic nanocarriers for precision neuroimaging

Exosomes are cell-derived vesicles with a lipid bilayer membrane that play important roles in intercellular communication. They provide an unprecedented opportunity for the development of drug delivery nanoplatforms due to their low immunogenicity, low toxicity, biocompatibility, stability, and ability to change the functions of recipient cells. In addition, exosomes can penetrate the blood-brain barrier and then target and accumulate in relevant pathological brain regions. However, few studies have focused on the applications of exosomes as nanocarriers for use in precision neuroimaging studies. Thus, this report presents the feasibility of fabricating specific exosome-based diagnostic reagents for the application of personalized/precision radiology in the central nervous system based on important recent fundamental discoveries and technological advances.

Naturally Equipped Urinary Exosomes Coated Poly (2−ethyl−2−oxazoline)−Poly (D, L−lactide) Nanocarriers for the Pre−Clinical Translation of Breast Cancer

Recently, biomimetic nanoparticles for tumor−targeted therapy have attracted intensifying interest. Although exosomes are an excellent biomimetic material, numerous challenges are still hindering its clinical applications, such as low yield, insufficient targeting efficiency, and high cost. In this work, urinary exosomes (UEs) with high expression of CD9 and CD47 were extracted from breast cancer patients by a non−invasive method. Here, a nanotechnology approach is reported for tumor homologous targeting via CD9 and phagocytosis escape via CD47 through UE−coated poly (2−ethyl−2−oxazoline)−poly (D, L−lactide) (PEOz−PLA) nanoparticles (UEPP NPs). The cytotoxic agent doxorubicin (DOX)−loaded UEPP (UEPP−D) NPs with an initial particle size of 61.5 nm showed a burst release under acidic condition mimicking the tumor microenvironment. In vitro experiments revealed that UEPP−D NPs exhibited significantly improved cellular uptake, cytotoxicity, and apoptosis in MCF−7 cell lines as compared to DOX−loaded PEOz−PLA nanoparticles (PP−D NPs) and free DOX. More importantly, anti−phagocytosis and pharmacokinetic studies confirmed that UEPP−D NPs had superior immune escape ability and significantly prolonged the drug’s bloodstream circulation in vivo. Finally, UEPP−D NPs showed a markedly higher antitumor efficacy and lower side−toxicity in MCF−7 tumor bearing nude mice model. Thus, this versatile nano−system with immune escape, homologous targeting, and rapid response release characteristics could be a promising tool for breast cancer treatment.

KRAS mutant-driven SUMOylation controls extracellular vesicle transmission to trigger lymphangiogenesis in pancreatic cancer

Lymph node (LN) metastasis occurs frequently in pancreatic ductal adenocarcinoma (PDAC) and predicts poor prognosis for patients. The KRASG12D mutation confers an aggressive PDAC phenotype that is susceptible to lymphatic dissemination. However, the regulatory mechanism underlying KRASG12D mutation-driven LN metastasis in PDAC remains unclear. Herein, we found that PDAC with the KRASG12D mutation (KRASG12D PDAC) sustained extracellular vesicle-mediated (EV-mediated) transmission of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) in a SUMOylation-dependent manner and promoted lymphangiogenesis and LN metastasis in vitro and in vivo. Mechanistically, hnRNPA1 bound with SUMO2 at the lysine 113 residue via KRASG12D-induced hyperactivation of SUMOylation, which enabled its interaction with TSG101 to enhance hnRNPA1 packaging and transmission via EVs. Subsequently, SUMOylation induced EV-packaged-hnRNPA1 anchoring to the adenylate- and uridylate-rich elements of PROX1 in lymphatic endothelial cells, thus stabilizing PROX1 mRNA. Importantly, impeding SUMOylation of EV-packaged hnRNPA1 dramatically inhibited LN metastasis of KRASG12D PDAC in a genetically engineered KrasG12D/+ Trp53R172H/+ Pdx-1-Cre (KPC) mouse model. Our findings highlight the mechanism by which KRAS mutant-driven SUMOylation triggers EV-packaged hnRNPA1 transmission to promote lymphangiogenesis and LN metastasis, shedding light on the potential application of hnRNPA1 as a therapeutic target in patients with KRASG12D PDAC.

Matrix Metalloproteinase-2-Responsive Surface-Changeable Liposomes Decorated by Multifunctional Peptides to Overcome the Drug Resistance of Triple-Negative Breast Cancer through Enhanced Targeting and Penetrability

Although nanomedicine has demonstrated great potential for combating drug resistance, its suboptimal recognition of malignant cells and limited transport across multiple biological obstacles seriously impede the efficacious accumulation of drugs in tumor lesions, which strikingly limits its application in the clinical therapy of drug-resistant triple-negative breast cancer (TNBC). Hence, a surface-variable drug delivery vehicle based on the modification of liposomes with a multifunctional peptide (named EMC) was fabricated in this work and used for encapsulating doxorubicin and the p-glycoprotein inhibitor tariquidar. This EMC peptide contains an EGFR-targeting bullet that was screened from a "one-bead one-compound" combinatorial library, an MMP-2-cleaved substrate, and a cell-penetrating segment. The EGFR-targeting sequence has been validated to possess excellent specificity and affinity for EGFR at both the cellular and molecular levels and could be unloaded from the EMC peptide by MMP-2 in the tumor microenvironment. This doxorubicin/tariquidar-coloaded and peptide-functionalized liposome (DT-pLip) exhibited superior efficacy in tumor growth inhibition to drug-resistant TNBC both in vitro and in vivo through EGFR targeting, osmotic enhancement in response to MMP-2, controllable release, and inhibited efflux. Consequently, our systematic studies indicated the potential of this liposome-based nanoplatform in the therapy of drug-resistant TNBC through targeting effects and tumor microenvironment-triggered penetration enhancement.

Engineered extracellular vesicles as intelligent nanosystems for next-generation nanomedicine

Extracellular vesicles (EVs), as natural carriers of bioactive cargo, have a unique micro/nanostructure, bioactive composition, and characteristic morphology, as well as fascinating physical, chemical and biochemical features, which have shown promising application in the treatment of a wide range of diseases. However, native EVs have limitations such as lack of or inefficient cell targeting, on-demand delivery, and therapeutic feedback. Recently, EVs have been engineered to contain an intelligent core, enabling them to (i) actively target sites of disease, (ii) respond to endogenous and/or exogenous signals, and (iii) provide treatment feedback for optimal function in the host. These advances pave the way for next-generation nanomedicine and offer promise for a revolution in drug delivery. Here, we summarise recent research on intelligent EVs and discuss the use of "intelligent core" based EV systems for the treatment of disease. We provide a critique about the construction and properties of intelligent EVs, and challenges in their commercialization. We compare the therapeutic potential of intelligent EVs to traditional nanomedicine and highlight key advantages for their clinical application. Collectively, this review aims to provide a new insight into the design of next-generation EV-based theranostic platforms for disease treatment.

Research Progress in Exosome-Based Nanoscale Drug Carriers in Tumor Therapies

Current antitumor treatment methods have several reported limitations, including multidrug resistance and serious adverse reactions. Targeted drug delivery systems are effective alternatives that can help healthcare providers overcome these limitations. Exosomes can serve as a natural nanoscale drug delivery system, with the advantages of high biocompatibility, low immunogenicity, and efficient tumor targetability. In this paper, we discuss the biological characteristics of exosomes, summarize the drug-carrying mechanisms of exosome-based drug delivery systems, and examine the potential role and applicability of exosomes in clinical tumor treatment approaches. This review can be used as a guideline for the future development of exosome-based delivery systems in clinical precision tumor treatment.

Exosomes: Potential Biomarkers and Functions in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC), originating from the mucosal epithelial cells of the oral cavity, pharynx, and larynx, is a lethal malignancy of the head and neck. Patients with advanced and recurrent HNSCC have poor outcomes due to limited therapeutic options. Exosomes have active roles in the pathophysiology of tumors and are suggested as a potential therapeutic target of HNSCC. Exosomes in HNSCC have been intensively studied for disease activity, tumor staging, immunosuppression, and therapeutic monitoring. In this review, the biological mechanisms and the recent clinical application of exosomes are highlighted to reveal the potential of exosomes as biomarkers and therapeutic targets for HNSCC.

Crosstalk of Exosomal Non-Coding RNAs in The Tumor Microenvironment: Novel Frontiers

The tumor microenvironment (TME) is defined as a complex and dynamic tissue entity composed of endothelial, stromal, immune cells, and the blood system. The homeostasis and evolution of the TME are governed by intimate interactions among cellular compartments. The malignant behavior of cancer cells, such as infiltrating growth, proliferation, invasion, and metastasis, is predominantly dependent on the bidirectional communication between tumor cells and the TME. And such dialogue mainly involves the transfer of multifunctional regulatory molecules from tumor cells and/or stromal cells within the TME. Interestingly, increasing evidence has confirmed that exosomes carrying regulatory molecules, proteins, and nucleic acids act as an active link in cellular crosstalk in the TME. Notably, extensive studies have identified non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), that could be encapsulated by exosomes, which regulate the coordinated function within the TME and thus participate in cancer development and progression. In this review, we summarize recent literature around the topic of the functions and mechanisms of exosomal ncRNAs in the TME and highlight their clinical significance.

Exosomes as prognostic biomarkers in pancreatic ductal adenocarcinoma-a systematic review and meta-analysis

Extensive research is focused on the role of liquid biopsy in pancreatic cancer since reliable diagnostic and follow-up biomarkers represent an unmet need for this highly lethal malignancy. We performed a systematic review and meta-analysis on the prognostic value of exosomal biomarkers in pancreatic ductal adenocarcinoma (PDAC). MEDLINE, Embase, Scopus, Web of Science, and CENTRAL were systematically searched on the 18th of January, 2021 for studies reporting on the differences in overall (OS) and progression-free survival (PFS) in PDAC patients with positive vs negative exosomal biomarkers isolated from blood. The random-effects model estimated pooled multivariate-adjusted (AHR) and univariate hazard ratios (UHRs) with 95% confidence intervals (CIs). Eleven studies comprising 634 patients were eligible for meta-analysis. Detection of positive exosomal biomarkers indicated increased risk of mortality (UHR = 2.81, CI:1.31-6,00, I2 = 88.7%, P < 0.001), and progression (UHR = 3.33, CI: 2.33-4.77, I2 = 0, P = 0.879) across various disease stages. Positive exosomal biomarkers identified preoperatively revealed a higher risk of mortality in resectable stages (UHR = 5.55, CI: 3.24-9.49, I2 = 0, P = 0.898). The risk of mortality in unresectable stages was not significantly increased with positive exosomal biomarkers (UHR = 2.51, CI: 0.55-11.43, I2 = 90.3%, P < 0.001). Detectable exosomal micro ribonucleic acids were associated with a decreased OS (UHR = 4.08, CI: 2.16-7.69, I2 = 46.9%, P = 0.152) across various stages. Our results reflect the potential of exosomal biomarkers for prognosis evaluation in PDAC. The associated heterogeneity reflects the variability of study methods and need for their uniformization before transition to clinical use.

Manufacturing Therapeutic Exosomes: from Bench to Industry

Process of manufacturing therapeutics exosome development for commercialization. The development of exosome treatment starts at the bench, and in order to be commercialized, it goes through the manufacturing, characterization, and formulation stages, production under Good Manufacturing Practice (GMP) conditions for clinical use, and close consultation with regulatory authorities. Exosome, a type of nanoparticles also known as small extracellular vesicles are gaining attention as novel therapeutics for various diseases because of their ability to deliver genetic or bioactive molecules to recipient cells. Although many pharmaceutical companies are gradually developing exosome therapeutics, numerous hurdles remain regarding manufacture of clinical-grade exosomes for therapeutic use. In this mini-review, we will discuss the manufacturing challenges of therapeutic exosomes, including cell line development, upstream cell culture, and downstream purification process. In addition, developing proper formulations for exosome storage and, establishing good manufacturing practice facility for producing therapeutic exosomes remains as challenges for developing clinicalgrade exosomes. However, owing to the lack of consensus regarding the guidelines for manufacturing therapeutic exosomes, close communication between regulators and companies is required for the successful development of exosome therapeutics. This review shares the challenges and perspectives regarding the manufacture and quality control of clinical grade exosomes.

Heterometallic nanomaterials: activity modulation, sensing, imaging and therapy

Heterometallic nanomaterials (HMNMs) display superior physicochemical properties and stability to monometallic counterparts, accompanied by wider applications in the fields of catalysis, sensing, imaging, and therapy due to synergistic effects between multi-metals in HMNMs. So far, most reviews have mainly concentrated on introduction of their preparation approaches, morphology control and applications in catalysis, assay of heavy metal ions, and antimicrobial activity. Therefore, it is very important to summarize the latest investigations of activity modulation of HMNMs and their recent applications in sensing, imaging and therapy. Taking the above into consideration, we briefly underline appealing chemical/physical properties of HMNMs chiefly tailored through the sizes, shapes, compositions, structures and surface modification. Then, we particularly emphasize their widespread applications in sensing of targets (e.g. metal ions, small molecules, proteins, nucleic acids, and cancer cells), imaging (frequently involving photoluminescence, fluorescence, Raman, electrochemiluminescence, magnetic resonance, X-ray computed tomography, photoacoustic imaging, etc.), and therapy (e.g. radiotherapy, chemotherapy, photothermal therapy, photodynamic therapy, and chemodynamic therapy). Finally, we present an outlook on their forthcoming directions. This timely review would be of great significance for attracting researchers from different disciplines in developing novel HMNMs.

Exosome Processing and Characterization Approaches for Research and Technology Development

Exosomes are extracellular vesicles that share components of their parent cells and are attractive in biotechnology and biomedical research as potential disease biomarkers as well as therapeutic agents. Crucial to realizing this potential is the ability to manufacture high-quality exosomes; however, unlike biologics such as proteins, exosomes lack standardized Good Manufacturing Practices for their processing and characterization. Furthermore, there is a lack of well-characterized reference exosome materials to aid in selection of methods for exosome isolation, purification, and analysis. This review informs exosome research and technology development by comparing exosome processing and characterization methods and recommending exosome workflows. This review also provides a detailed introduction to exosomes, including their physical and chemical properties, roles in normal biological processes and in disease progression, and summarizes some of the on-going clinical trials.

Spiky Cascade Biocatalysts as Peroxisome-Mimics for Ultrasound-Augmented Tumor Ablation

Ultrasound (US)-augmented tumor ablation with sono-catalysts has emerged as a promising therapeutic modality due to high tissue penetration, nonionizing performance, and low cost of US-based therapies. Developing peroxisome-mimetic cascade biocatalysts for US-augmented synergistic treatment would further effectively reduce the dependence of the microenvironment H₂O₂ and enhance the tumor-localized reactive oxygen species (ROS) generation. Here, we proposed and synthesized a novel spiky cascade biocatalyst as peroxisome-mimics that consist of multiple enzyme-mimics, i.e., glucose oxidase-mimics (Au nanoparticles for producing H₂O₂) and heme-mimetic atomic catalytic centers (Fe-porphyrin for ROS generation), for US-augmented cascade-catalytic tumor therapy. The synthesized spiky cascade biocatalysts exhibit an obvious spiky structure, uniform nanoscale size, independent of endogenous H₂O₂, and efficient US-responsive biocatalytic activities. The enzyme-mimetic biocatalytic experiments show that the spiky cascade biocatalysts can generate abundant ·OH via a cascade chemodynamic path and also ¹O₂ via US excitation. Then, we demonstrate that the spiky cascade biocatalysts show highly efficient ROS production to promote melanoma cell apoptosis under US irradiation without extra H₂O₂. Our in vivo animal data further reveal that the proposed US-assisted chemodynamic cascade therapies can significantly augment the therapy efficacy of malignant melanoma. We suggest that these efficient peroxisome-mimetic cascade-catalytic strategies will be promising for clinical tumor therapies.

Pharmacological Inhibition of Exosome Machinery: An Emerging Prospect in Cancer Therapeutics

Abstract:

Exosomes are nanocarriers that mediate intercellular communication, crucial for normal physiological functions. However, exponentially emerging reports have correlated their dysregulated release with various pathologies, including cancer. In cancer, from stromal remodeling to metastasis, where tumor cells bypass the immune surveillance and show drug resistivity, it has been established to be mediated via tumor-derived exosomes. Owing to their role in cancer pathogenicity, exosome-based strategies offer enormous potential in treatment regimens. These strategies include the use of exosomes as a drug carrier or as an immunotherapeutic agent, which requires advanced nanotechnologies for exosome isolation and characterization. In contrast, pharmacological inhibition of exosome machinery surpasses the requisites of nanotechnology and thus emerges as an essential prospect in cancer therapeutics. In this line, researchers are currently trying to dissect the molecular pathways to reveal the involvement of key regulatory proteins that facilitate the release of tumor-derived exosomes. Subsequently, screening of various molecules in targeting these proteins, with eventual abatement of exosome-induced cancer pathogenicity, is being done. However, their clinical translation requires more extensive studies. Here we comprehensively review the molecular mechanisms regulating exosome release in cancer. Moreover, we give insight into the key findings that highlight the effect of various drugs as exosome blockers, which will add to the route of drug development in cancer management.

Congenital microtia patients: the genetically engineered exosomes released from porous gelatin methacryloyl hydrogel for downstream small RNA profiling, functional modulation of microtia chondrocytes and tissue-engineered ear cartilage regeneration

Background

Mesenchymal stem cells (MSCs) exosomes were previously shown to be effective in articular cartilage repairing. However, whether MSCs exosomes promote mature cartilage formation of microtia chondrocytes and the underlying mechanism of action remains unknown. Additionally, some hurdles, such as the low yield and unsatisfactory therapeutic effects of natural exosomes have emerged when considering the translation of exosomes-therapeutics to clinical practices or industrial production. Herein, we investigated the roles of human adipose-derived stem cells (ADSCs) exosomes in modulating microtia chondrocytes and the underlying mechanism of action. Special attention was also paid to the mass production and functional modification of ADSCs exosomes.

Results

We firstly used porous gelatin methacryloyl (Porous Gelma) hydrogel with pores size of 100 to 200 μm for 3D culture of passage 2, 4 and 6 ADSCs (P2, P4 and P6 ADSCs, respectively), and obtained their corresponding exosomes (Exo 2, Exo 4 and Exo 6, respectively). In vitro results showed Exo 2 outperformed both Exo 4 and Exo 6 in enhancing cell proliferation and attenuating apoptosis. However, both Exo 4 and Exo 6 promoted chondrogenesis more than Exo 2 did. Small RNA sequencing results indicated Exo 4 was similar to Exo 6 in small RNA profiles and consistently upregulated PI3K/AKT/mTOR signaling pathway. Notably, we found hsa-miR-23a-3p was highly expressed in Exo 4 and Exo 6 compared to Exo 2, and they modulated microtia chondrocytes by transferring hsa-miR-23a-3p to suppress PTEN expression, and consequently to activate PI3K/AKT/mTOR signaling pathway. Then, we designed genetically engineered exosomes by directly transfecting agomir-23a-3p into parent P4 ADSCs and isolated hsa-miR-23a-3p-rich exosomes for optimizing favorable effects on cell viability and new cartilage formation. Subsequently, we applied the engineered exosomes to in vitro and in vivo tissue-engineered cartilage culture and consistently found that the engineered exosomes could enhance cell proliferation, attenuate apoptosis and promote cartilage regeneration.

Conclusions

Taken together, the porous Gelma hydrogel could be applied to exosomes mass production, and functional modification could be achieved by selecting P4 ADSCs as parent cells and genetically modifying ADSCs. Our engineered exosomes are a promising candidate for tissue-engineered ear cartilage regeneration.

Graphical Abstract

Integrated therapy platform of exosomal system: hybrid inorganic/organic nanoparticles with exosomes for cancer treatment

Recent studies have found that exosomes or extracellular vehicles (EVs) are associated with cancer metastasis, disease progression, diagnosis, and treatment, leading to a rapidly emerging area of exocrine vesicle research. Relying on the superior targeting function and bio-compatibility of exosomes, researchers have been able to deliver drugs to cancer stem cells deep within tumors in mouse models. Despite significant efforts made in this relatively new field of exosome research, progress has been held back by challenges such as inefficient separation methods, difficulties in characterization/tracking, and a lack of specific biomarkers. Therefore, current researches are devoted to combining nanomaterials with exosomes to improve these shortcomings. Adding inorganic/organic nanoparticles such as artificial liposomes and iron oxide can bring more drug options and various fluorescent or magnetic diagnostic possibilities to the exosome system. Moreover, the applications of exosomes need to be further evaluated under actual physiological conditions. This review article highlights the potential of exosome-biomimetic nanoparticles for their use as drug carriers to improve the efficacy of anticancer therapy.

Strategies for Targeted Delivery of Exosomes to the Brain: Advantages and Challenges

Delivering therapeutics to the central nervous system (CNS) is difficult because of the blood-brain barrier (BBB). Therapeutic delivery across the tight junctions of the BBB can be achieved through various endogenous transportation mechanisms. Receptor-mediated transcytosis (RMT) is one of the most widely investigated and used methods. Drugs can hijack RMT by expressing specific ligands that bind to receptors mediating transcytosis, such as the transferrin receptor (TfR), low-density lipoprotein receptor (LDLR), and insulin receptor (INSR). Cell-penetrating peptides and viral components originating from neurotropic viruses can also be utilized for the efficient BBB crossing of therapeutics. Exosomes, or small extracellular vesicles, have gained attention as natural nanoparticles for treating CNS diseases, owing to their potential for natural BBB crossing and broad surface engineering capability. RMT-mediated transport of exosomes expressing ligands such as LDLR-targeting apolipoprotein B has shown promising results. Although surface-modified exosomes possessing brain targetability have shown enhanced CNS delivery in preclinical studies, the successful development of clinically approved exosome therapeutics for CNS diseases requires the establishment of quantitative and qualitative methods for monitoring exosomal delivery to the brain parenchyma in vivo as well as elucidation of the mechanisms underlying the BBB crossing of surface-modified exosomes.

Exosomes for Regulation of Immune Responses and Immunotherapy

Exosomes are membrane-enveloped nanosized (30–150 nm) extracellular vesicles of endosomal origin produced by almost all cell types and encompass a multitude of functioning biomolecules. Exosomes have been considered crucial players of cell-to-cell communication in physiological and pathological conditions. Accumulating evidence suggests that exosomes can modulate the immune system by delivering a plethora of signals that can either stimulate or suppress immune responses, which have potential applications as immunotherapies for cancer and autoimmune diseases. Here, we discuss the current knowledge about the active biomolecular components of exosomes that contribute to exosomal function in modulating different immune cells and also how these immune cell-derived exosomes play critical roles in immune responses. We further discuss the translational potential of engineered exosomes as immunotherapeutic agents with their advantages over conventional nanocarriers for drug delivery and ongoing clinical trials.

WASF2 Serves as a Potential Biomarker and Therapeutic Target in Ovarian Cancer: A Pan-Cancer Analysis

Background

Wiskott-Aldrich syndrome protein family member 2 (WASF2) has been shown to play an important role in many types of cancer. Therefore, it is worthwhile to further study expression profile of WASF2 in human cancer, which provides new molecular clues about the pathogenesis of ovarian cancer.

Methods

We used a series of bioinformatics methods to comprehensively analyze the relationship between WASF2 and prognosis, tumor microenvironment (TME), immune infiltration, tumor mutational burden (TMB), microsatellite instability (MSI), and tried to find the potential biological processes of WASF2 in ovarian cancer. Biological behaviors of ovarian cancer cells were investigated through CCK8 assay, scratch test and transwell assay. We also compared WASF2 expression between epithelial ovarian cancer tissues and normal ovarian tissues by using immunohistochemical staining.

Results

In the present study, we found that WASF2 was abnormally expressed across the diverse cancer and significantly correlated with overall survival (OS) and progression-free interval (PFI). More importantly, the WASF2 expression level also significantly related to the TME. Our results also showed that the expression of WASF2 was closely related to immune infiltration and immune-related genes. In addition, WASF2 expression was associated with TMB, MSI, and antitumor drugs sensitivity across various cancer types. Functional bioinformatics analysis demonstrated that the WASF2 might be involved in several signaling pathways and biological processes of ovarian cancer. A risk factor model was found to be predictive for OS in ovarian cancer based on the expression of WASF2. Moreover, in vitro experiments, it was demonstrated that the proliferative, migratory and invasive capacity of ovarian cancer cells was significantly inhibited due to WASF2 knockdown. Finally, the immunohistochemistry data confirmed that WASF2 were highly expressed in ovarian cancer.

Conclusions

Our study demonstrated that WASF2 expression was associated with a poor prognosis and may be involved in the development of ovarian cancer, which might be explored as a potential prognostic marker and new targeted treatments.

HACE2-Exosome-Based Nano-Bait for Concurrent SARS-CoV-2 Trapping and Antioxidant Therapy

Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is seriously threatening human health. Following SARS-CoV-2 infection, immune cell infiltration creates an inflammatory and oxidative microenvironment, which can cause pneumonia, severe acute respiratory syndrome, kidney failure, and even death. Clinically, a safe and effective treatment strategy remains to be established. Herein, a nano-bait strategy for inhibition of SARS-CoV-2 infection by redirecting viral attack while simultaneously relieving inflammation is developed. Specifically, the nano-bait was based on the exosome-sheathed polydopamine (PDA@Exosome) nanoparticles, which were generated by exocytosis of the PDA nanoparticles from H293T cells. In this approach, PDA@Exosome inherits from the source cells of H293T cells a surface display of ACE2 through pre-engineered expression. The resulting PDA@Exosome can compete with ACE2-expressing epithelial cells for S protein binding, in either the pre-exposure or post-exposure route. Moreover, relying on the ability of PDA to intercept and deactivate radical species, the PDA@Exosome can significantly attenuate the level of inflammatory cytokines by mediating oxidative stress, a major cause of organ injury. Due to its high trapping, multiple antioxidant ability, and good biocompatibility, the HACE2-exosome based nano-bait is a promising robust antiviral nanotherapeutics for the ongoing COVID-19 pandemic.

Hierarchical magnetic nanoparticles for highly effective capture of small extracellular vesicles

Small extracellular vesicles (EVs) have various functions through the transfer of specific biomolecules. However, it is still challenging to capture small EVs with high sensitivity and specificity. Herein, inspired by the unique burry structure and the strong adhesion ability of pollen grains, we presented a novel Fe₃O₄@MgSiO₃ hierarchical magnetic nanoparticles (HNPs) as nanocarriers for the capture of small EVs. The NPs were generated through the solvothermal method and further modified with branching dendrimers to exhibit a hierarchical morphology. The enlarged surface area facilitated high-efficient capture of small EVs through specific recognition of aptamer probes and the small EVs surface markers. Besides, the magnetic core of the NPs allowed them to be isolated under the action of an external magnetic field, and thus the captured small EVs could be easily separated from plasma. These results indicated that the HNPs could serve as excellent nanocarriers for small EVs capture and related biomedical applications.

Stem cell-derived extracellular vesicle therapy for acute brain insults and neurodegenerative diseases

Stem cell-based therapy is a promising approach for treating a variety of disorders, including acute brain insults and neurodegenerative diseases. Stem cells such as mesenchymal stem cells (MSCs) secrete extracellular vesicles (EVs), circular membrane fragments (30 nm−1 μm) that are shed from the cell surface, carrying several therapeutic molecules such as proteins and microRNAs. Because EV-based therapy is superior to cell therapy in terms of scalable production, biodistribution, and safety profiles, it can be used to treat brain diseases as an alternative to stem cell therapy. This review presents evidences evaluating the role of stem cell-derived EVs in stroke, traumatic brain injury, and degenerative brain diseases, such as Alzheimer’s disease and Parkinson’ disease. In addition, stem cell-derived EVs have better profiles in biocompatibility, immunogenicity, and safety than those of small chemical and macromolecules. The advantages and disadvantages of EVs compared with other strategies are discussed. Even though EVs obtained from native stem cells have potential in the treatment of brain diseases, the successful clinical application is limited by the short half-life, limited targeting, rapid clearance after application, and insufficient payload. We discuss the strategies to enhance the efficacy of EV therapeutics. Finally, EV therapies have yet to be approved by the regulatory authorities. Major issues are discussed together with relevant advances in the clinical application of EV therapeutics.

In-Cell Labeling Coupled to Direct Analysis of Extracellular Vesicles in the Conditioned Medium to Study Extracellular Vesicles Secretion with Minimum Sample Processing and Particle Loss

Extracellular vesicles (EVs) are involved in a multitude of physiological functions and play important roles in health and disease. The largest proportion of studies on EVs is based on the analysis and characterization of EVs secreted in the cell culture medium. These studies remain challenging due to the small size of the EV particles, a lack of universal EV markers, and sample loss or technical artifacts that are often associated with EV labeling for single particle tracking and/or separation techniques. To address these problems, we characterized and validated a method for in-cell EV labeling with fluorescent lipids coupled with direct analysis of lipid-labeled EVs in the conditioned medium by imaging flow cytometry (IFC). This approach significantly reduces sample processing and loss compared to established methods for EV separation and labeling in vitro, resulting in improved detection of quantitative changes in EV secretion and subpopulations compared to protocols that rely on EV separation by size-exclusion chromatography and ultracentrifugation. Our optimized protocol for in-cell EV labeling and analysis of the conditioned medium reduces EV sample processing and loss, and is well-suited for cell biology studies that focus on modulation of EV secretion by cells in culture.

Nucleic Acid Substrate-Independent DNA Polymerization on the Exosome Membrane: A Mechanism Study and Application in Exosome Analysis

As generally acknowledged, terminal deoxynucleotidyl transferase (TdT) can only elongate DNA substrates from their 3'-OH ends. Herein, for the first time, we report that TdT-catalyzed DNA polymerization can directly proceed on the exosome membrane without the mediation of any nucleic acids. We prove that both the glycosyl and phenolic hydroxyl groups on the membrane proteins can initiate the DNA polymerization. Accordingly, we have developed powerful strategies for high-sensitive exosome profiling based on a conventional flow cytometer and an emerging CRISPR/Cas system. By using our strategy, the featured membrane protein distributions of different cancer cell-derived exosomes can be figured out, which can clearly distinguish plasma samples of breast cancer patients from those of healthy people. This work paves new ways for exosome profiling and liquid biopsy and expands the understanding of TdT, holding great significance in developing TdT-based sensing systems as well as establishing protein/nucleic acid hybrid biomaterials.

Exosomes from M1‐polarized macrophages promote apoptosis in lung adenocarcinoma via the miR‐181a‐5p/ETS1/STK16 axis

Serine/threonine kinase 16 (STK16) is crucial in on regulating tumor cell proliferation, apoptosis, and prognosis. Activated M1 macrophages regulate lung adenocarcinoma (LUAD) growth by releasing exosomes. This study aims to investigate the role of STK16 and then focus on the possible mechanisms through which exosomes derived from M1 macrophages play their roles in LUAD cells by targeting STK16. Clinical LUAD samples were used to evaluate the expression of STK16 and its association with prognosis. Exosomes were isolated from M0 and M1 macrophages by ultracentrifugation and were then identified by electron microscopy and western blotting. In vitro gain‐ and loss‐of‐function experiments with LUAD cells were performed to elucidate the functions of miR‐181a‐5p, ETS1, and STK16, and mouse xenograft models were used to verify the function of STK16 in vivo. Western blotting, quantitative real‐time PCR, CCK‐8 assay, cell apoptosis, immunohistochemistry staining, luciferase assay, ChIP assay, and bioinformatics analysis were performed to reveal the underlying mechanisms. High expression of STK16 was observed in LUAD tissues and cells, and higher expression of STK16 was associated with worse prognosis. Silencing STK16 expression inhibited cell proliferation and promoted apoptosis via the AKT1 pathway. Exosomes from M1 macrophages inhibited viability and promoted apoptosis by inhibiting STK16. Moreover, miR‐181a‐5p is the functional molecule in M1 macrophage‐derived exosomes and plays a vital role in inhibiting cell proliferation and promoting apoptosis by targeting ETS1 and STK16. Hence, exosomes derived from M1 macrophages were capable of inhibiting viability and promoting apoptosis in LUAD via the miR‐181a‐5p/ETS1/STK16 axis.

Engineered neutrophil-derived exosome-like vesicles for targeted cancer therapy

Neutrophils are the most abundant innate immune cells in human circulation; however, their derived exosomes have been rarely studied for tumor treatment. Here, we reported that exosomes from neutrophils (N-Ex) induce tumor cell apoptosis by delivering cytotoxic proteins and activating caspase signaling pathway. In addition, we decorated N-Ex with superparamagnetic iron oxide nanoparticles (SPIONs) to achieve higher tumor-targeting therapeutic effect. We further fabricated exosome-like nanovesicles from neutrophils (NNVs) at high yield. Compared with liposome-loaded doxorubicin (DOX) and natural NNVs, DOX-loaded NNVs show an improved inhibition of tumor cell proliferation. Moreover, DOX-loaded, SPION-decorated NNVs selectively accumulate at the tumor sites under an external magnetic field, effectively restraining tumor growth and extensively prolonging the survival rate in mice. Overall, a simple and effective method to engineer N-Ex and NNVs at clinical applicable scale was developed, which enables the efficient and safe drug delivery for targeted and combined tumor therapy.

Targeted Delivery of Exosomes Armed with Anti-Cancer Therapeutics

Among extracellular vesicles, exosomes have gained great attention for their role as therapeutic vehicles for delivering various active pharmaceutical ingredients (APIs). Exosomes “armed” with anti-cancer therapeutics possess great potential for an efficient intracellular delivery of anti-cancer APIs and enhanced targetability to tumor cells. Various technologies are being developed to efficiently incorporate anti-cancer APIs such as genetic materials (miRNA, siRNA, mRNA), chemotherapeutics, and proteins into exosomes and to induce targeted delivery to tumor burden by exosomal surface modification. Exosomes can incorporate the desired therapeutic molecules via direct exogenous methods (e.g., electroporation and sonication) or indirect methods by modifying cells to produce “armed” exosomes. The targeted delivery of “armed” exosomes to tumor burden could be accomplished either by “passive” targeting using the natural tropism of exosomes or by “active” targeting via the surface engineering of exosomal membranes. Although anti-cancer exosome therapeutics demonstrated promising results in preclinical studies, success in clinical trials requires thorough validation in terms of chemistry, manufacturing, and control techniques. While exosomes possess multiple advantages over synthetic nanoparticles, challenges remain in increasing the loading efficiency of anti-cancer agents into exosomes, as well as establishing quantitative and qualitative analytical methods for monitoring the delivery of in vivo administered exosomes and exosome-incorporated anti-cancer agents to the tumor parenchyma.

Recent Advances in Device Engineering and Computational Analysis for Characterization of Cell-Released Cancer Biomarkers

During cancer progression, tumors shed different biomarkers into the bloodstream, including circulating tumor cells (CTCs), extracellular vesicles (EVs), circulating cell-free DNA (cfDNA), and circulating tumor DNA (ctDNA). The analysis of these biomarkers in the blood, known as 'liquid biopsy' (LB), is a promising approach for early cancer detection and treatment monitoring, and more recently, as a means for cancer therapy. Previous reviews have discussed the role of CTCs and ctDNA in cancer progression; however, ctDNA and EVs are rapidly evolving with technological advancements and computational analysis and are the subject of enormous recent studies in cancer biomarkers. In this review, first, we introduce these cell-released cancer biomarkers and briefly discuss their clinical significance in cancer diagnosis and treatment monitoring. Second, we present conventional and novel approaches for the isolation, profiling, and characterization of these markers. We then investigate the mathematical and in silico models that are developed to investigate the function of ctDNA and EVs in cancer progression. We convey our views on what is needed to pave the way to translate the emerging technologies and models into the clinic and make the case that optimized next-generation techniques and models are needed to precisely evaluate the clinical relevance of these LB markers.

The potential role of exosomal circRNAs in the tumor microenvironment: insights into cancer diagnosis and therapy

Exosomes are multifunctional regulators of intercellular communication by carrying various messages under both physiological and pathological status of cancer patients. Accumulating studies have identified the presence of circular RNAs (circRNAs) in exosomes with crucial regulatory roles in diverse pathophysiological processes. Exosomal circRNAs derived from donor cells can modulate crosstalk with recipient cells locally or remotely to enhance cancer development and propagation, and play crucial roles in the tumor microenvironment (TME), leading to significant enhancement of tumor immunity, metabolism, angiogenesis, drug resistance, epithelial mesenchymal transition (EMT), invasion and metastasis. In this review, we describe the advances of exosomal circRNAs and their roles in modulating cancer hallmarks, especially those in the TME. Moreover, clinical application potential of exosomal circRNAs in cancer diagnosis and therapy are highlighted, bridging the gap between basic knowledge and clinical practice.

Brusatol Inhibits Proliferation and Invasion of Glioblastoma by Down-Regulating the Expression of ECM1

Brusatol (Bru), a Chinese herbal extract, has a variety of anti-tumor effects. However, little is known regarding its role and underlying mechanism in glioblastoma cells. Here, we found that Bru could inhibit the proliferation of glioblastoma cells in vivo and in vitro. Besides, it also had an inhibitory effect on human primary glioblastoma cells. RNA-seq analysis indicated that Bru possibly achieved these effects through inhibiting the expression of extracellular matrix protein 1 (ECM1). Down-regulating the expression of ECM1 via transfecting siRNA could weaken the proliferation and invasion of glioblastoma cells and promote the inhibitory effect of Bru treatment. Lentivirus-mediated overexpression of ECM1 could effectively reverse this weakening effect. Our findings indicated that Bru could inhibit the proliferation and invasion of glioblastoma cells by suppressing the expression of ECM1, and Bru might be a novel effective anticancer drug for glioblastoma cells.

Cervical cancer-derived exosomal miR-663b promotes angiogenesis by inhibiting vinculin expression in vascular endothelial cells

BACKGROUND

Angiogenesis provides essential nutrients and oxygen for tumor growth and has become the main mechanism of tumor invasion and metastasis. Exosomes are nanoscale membrane vesicles containing proteins, lipids, mRNA and microRNA (miRNA), which mediate intercellular communication and play an important role in tumor progression. Accumulated evidence indicates that tumor-derived exosomal miRNAs participate in the tumor microenvironment and promote angiogenesis.

METHODS

Bioinformatic target prediction and dual luciferase reporter assays were performed to identify the binding site between miR-663b and the 3'-UTR of vinculin (VCL). VCL overexpression lentivirus and miR-663b overexpression/inhibition lentivirus were used to create a VCL overexpression model and miR-663b overexpression/inhibition model in-vitro. Immunohistochemistry (IHC) assays and western blot assays were used to detect protein expression. Exosome-cell cocultures, wound healing assays, tube formation assays and transwell assays were used to measure the migration and tube formation ability of vascular endothelial cells [human umbilical vein endothelial cells (HUVECs)]. siRNA targeted VCL was used to knockdown VCL.

RESULTS

In the present study, we found that miR-663b was elevated in cervical cancer tissue and exosomes. miR-663b could bind the 3'-UTR of VCL and inhibit its expression. VCL is downregulated in cervical cancer, and decreased VCL has a negative correlation with a high level of miR-663b. Further studies demonstrated that exosomes secreted by cervical cancer cells can deliver miR-663b to HUVECs and inhibit the expression of VCL, thereby promoting angiogenesis and tumor growth.

CONCLUSIONS

miR-663b derived from cancer cell exosomes acts as a driving factor for angiogenesis and a potential target of antiangiogenic therapy in cervical cancer. Our findings illustrated a new signaling pathway, including exosomes, miRNAs and target genes, which provides potential targets for antiangiogenic therapy.

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Immune Cell-Derived Extracellular Vesicles – New Strategies in Cancer Immunotherapy

Immune cell-derived extracellular vesicles (EVs) have increasingly become the focus of research due to their unique characteristics and bioinspired applications. They are lipid bilayer membrane nanosized vesicles harboring a range of immune cell-derived surface receptors and effector molecules from parental cells. Immune cell-derived EVs are important mediators of intercellular communication that regulate specific mechanisms of adaptive and innate immune responses. However, the mechanisms underlying the antitumor effects of EVs are still being explored. Importantly, immune cell-derived EVs have some unique features, including accessibility, storage, ability to pass through blood-brain and blood-tumor barriers, and loading of various effector molecules. Immune cell-derived EVs have been directly applied or engineered as potent antitumor vaccines or for the diagnosis of clinical diseases. More research applications involving genetic engineering, membrane engineering, and cargo delivery strategies have improved the treatment efficacy of EVs. Immune cell-derived EV-based therapies are expected to become a separate technique or to complement immunotherapy, radiotherapy, chemotherapy and other therapeutic modalities. This review aims to provide a comprehensive overview of the characteristics and functions of immune cell-derived EVs derived from adaptive (CD4⁺ T, CD8⁺ T and B cells) and innate immune cells (macrophages, NK cells, DCs, and neutrophils) and discuss emerging therapeutic opportunities and prospects in cancer treatment.

Targeting miR-185-3p Inhibits Head and Neck Squamous Cell Carcinoma by Modulating RAB25

Cancer cell-derived exosomes regulate tumor growth and progression. However, the effects of exosomes and its contents on head and neck squamous cell carcinoma (HNSCC) and its underlying mechanisms remain unclear. Here, we found HNSCC displayed a dysregulation of exosomes biogenesis. miR-185-3p was one of the most upregulated exosome-derived miRNAs in HNSCC. Functional assay showed that RAB25 is a direct downstream target of miR-185-3p. miR-185-3p/RAB25 signaling controlled tumor progression and correlated with disease prognosis. Targeting miR-185-3p/RAB25 significantly inhibited tumor growth and promoted drug response to chemotherapy. To conclude, the findings demonstrate exosomal miR-185-3p promotes tumor growth by mediating RAB25 that could be effectively targeted for HNSCC treatment.

Inhibition of microRNA-30a alleviates vascular remodeling in pulmonary arterial hypertension

The excessive and ectopic pulmonary artery smooth muscle cells (PASMCs) are crucial to the pathogenesis of pulmonary arteriole (PA) remodeling in pulmonary arterial hypertension (PAH). We previously found that microRNA (miR)-30a was significantly increased in acute myocardial infarction (AMI) patients and animals, as well as in cultured cardiomyocytes after hypoxia, suggesting that it might be strongly associated with hypoxia-related diseases. Here, we investigated the role of miR-30a in the PASMC remodeling of PAH. The expression of miR-30a was higher in the serum of PAH patients compared with healthy controls. miR-30a was mainly expressed in PAs and was increased in PASMCs after hypoxia, mediating the downregulation of p53 tumor suppressor protein (P53). Genetic knockout of miR-30a effectively decreased right ventricular (RV) systolic pressure (RVSP), PA, and RV remodeling in the Su5416/hypoxia-induced and monocrotaline (MCT)-induced PAH animals. Additionally, pharmacological inhibition of miR-30a via intratracheal liquid instillation (IT-L) delivery strategy showed high efficiency, which downregulated miR-30a to mitigate disease phenotype in the Su5416/hypoxia-induced PAH animals, and these beneficial effects could be partially reduced by simultaneous P53 inhibition. We demonstrate that inhibition of miR-30a could ameliorate experimental PAH through the miR-30a/P53 signaling pathway, and the IT-L delivery strategy shows good therapeutic outcomes, providing a novel and promising approach for the treatment of PAH.

Recent Advances in AIEgen-Based Photodynamic Therapy and Immunotherapy

Cancer, one of the leading causes of death, has seriously threatened public health. However, there is still a lack of effective treatments. Nowadays, photodynamic therapy (PDT), relying on photosensitizers to trigger the generation of reactive oxygen species (ROS) for killing cancer cells, has been emerging as a noninvasive anti-cancer strategy. To enhance the overall anti-cancer efficacy of PDT, various approaches including molecular design and combination with other therapeutic techniques have been proposed and implemented. Especially, photodynamic immunotherapy that can effectively evoke the body's immune response has attracted much attention. Recently, a class of photosensitizers with aggregation-induced emission (AIE) character have shown unique promises, taking advantage of their profound fluorescence and ROS-generating ability in the aggregation state. Despite the promising results demonstrated by several groups, the associated studies are few and the mechanism of such AIEgen-based photodynamic immunotherapy has not been fully understood. This review discusses the recent advances in the AIEgen-based enhanced PDT with a special focus on the AIE photosensitizers for photodynamic immunotherapy, aiming to inspire more opportunities for in-depth investigation of the working principles in this emerging anti-cancer approach.

Mesenchymal stem/stromal cells in cancer therapy

The multipotent mesenchymal stem/stromal cells (MSCs), initially discovered from bone marrow in 1976, have been identified in nearly all tissues of human body now. The multipotency of MSCs allows them to give rise to osteocytes, chondrocytes, adipocytes, and other lineages. Moreover, armed with the immunomodulation capacity and tumor-homing property, MSCs are of special relevance for cell-based therapies in the treatment of cancer. However, hampered by lack of knowledge about the controversial roles that MSC plays in the crosstalk with tumors, limited progress has been made with regard to translational medicine. Therefore, in this review, we discuss the prospects of MSC-associated anticancer strategies in light of therapeutic mechanisms and signal transduction pathways. In addition, the clinical trials designed to appraise the efficacy and safety of MSC-based anticancer therapies will be assessed according to published data.

The Evolution and Future of Targeted Cancer Therapy: From Nanoparticles, Oncolytic Viruses, and Oncolytic Bacteria to the Treatment of Solid Tumors

While many classes of chemotherapeutic agents exist to treat solid tumors, few can generate a lasting response without substantial off-target toxicity despite significant scientific advancements and investments. In this review, the paths of development for nanoparticles, oncolytic viruses, and oncolytic bacteria over the last 20 years of research towards clinical translation and acceptance as novel cancer therapeutics are compared. Novel nanoparticle, oncolytic virus, and oncolytic bacteria therapies all start with a common goal of accomplishing therapeutic drug activity or delivery to a specific site while avoiding off-target effects, with overlapping methodology between all three modalities. Indeed, the degree of overlap is substantial enough that breakthroughs in one therapeutic could have considerable implications on the progression of the other two. Each oncotherapeutic modality has accomplished clinical translation, successfully overcoming the potential pitfalls promising therapeutics face. However, once studies enter clinical trials, the data all but disappears, leaving pre-clinical researchers largely in the dark. Overall, the creativity, flexibility, and innovation of these modalities for solid tumor treatments are greatly encouraging, and usher in a new age of pharmaceutical development.

Exosomes and Exosomal circRNAs: The Rising Stars in the Progression, Diagnosis and Prognosis of Gastric Cancer

Gastric cancer (GC) is a common malignant tumor affecting human health, with occult onset and poor prognosis. Exosomes are extracellular vesicles secreted by almost all cells, which can reflect the state of source cells or tissues. It is reported that exosomes are involved in almost all processes of GC. Exosomes provided a window to understand changes in cell or tissue states by carrying active components such as circular RNAs (circRNAs). CircRNAs are a naturally occurring class of endogenous noncoding RNAs and abnormal expression during the occurrence and development of GC. Exosomal circRNAs are those circRNAs stably existing in exosomes and having high clinical values as novel potential diagnosis and prognosis biomarkers of GC, which have the characteristics of abnormal expression, tissue specificity and development stage specificity. Herein, we briefly summarize the functions and roles and the current research progress of exosomes and exosomal circRNAs in GC with a focus on the potential application for GC progression, diagnosis and prognosis. We also prospected the clinical application of exosomes and exosomal circRNAs in the future.