Cancer-derived exosomes as a delivery platform of CRISPR/Cas9 confer cancer cell tropism-dependent targeting

Exosomes, a New Star for Targeted Delivery

Exosomes are cell-secreted nanoparticles (generally with a size of 30–150 nm) bearing numerous biological molecules including nucleic acids, proteins and lipids, which are thought to play important roles in intercellular communication. As carriers, exosomes hold promise as advanced platforms for targeted drug/gene delivery, owing to their unique properties, such as innate stability, low immunogenicity and excellent tissue/cell penetration capacity. However, their practical applications can be limited due to insufficient targeting ability or low efficacy in some cases. In order to overcome these existing challenges, various approaches have been applied to engineer cell-derived exosomes for a higher selectivity and effectiveness. This review presents the state-of-the-art designs and applications of advanced exosome-based systems for targeted cargo delivery. By discussing experts’ opinions, we hope this review will inspire the researchers in this field to develop more practical exosomal delivery systems for clinical applications.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for Osteoarthritis Treatment: Extracellular Matrix Protection, Chondrocyte and Osteocyte Physiology, Pain and Inflammation Management

Osteoarthritis (OA) is a common degenerative disease that can lead to persistent pain and motion restriction. In the last decade, stem cells, particularly mesenchymal stem cells (MSCs), have been explored as a potential alternative OA therapy due to their regenerative capacity. Furthermore, it has been shown that trophic factors enveloped in extracellular vesicles (EVs), including exosomes, are a crucial aspect of MSC-based treatment for OA. Evidently, EVs derived from different MSC sources might rescue the OA phenotype by targeting many biological processes associated with cartilage extracellular matrix (ECM) degradation and exerting protective effects on different joint cell types. Despite this advancement, different studies employing EV treatment for OA have revealed reverse outcomes depending on the EV cargo, cell source, and pathological condition. Hence, in this review, we aim to summarize and discuss the possible effects of MSC-derived EVs based on recent findings at different stages of OA development, including effects on cartilage ECM, chondrocyte biology, osteocytes and bone homeostasis, inflammation, and pain management. Additionally, we discuss further strategies and technical advances for manipulating EVs to specifically target OA to bring the therapy closer to clinical use.

Editing SOX Genes by CRISPR-Cas: Current Insights and Future Perspectives

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and its associated proteins (Cas) is an adaptive immune system in archaea and most bacteria. By repurposing these systems for use in eukaryote cells, a substantial revolution has arisen in the genome engineering field. In recent years, CRISPR-Cas technology was rapidly developed and different types of DNA or RNA sequence editors, gene activator or repressor, and epigenome modulators established. The versatility and feasibility of CRISPR-Cas technology has introduced this system as the most suitable tool for discovering and studying the mechanism of specific genes and also for generating appropriate cell and animal models. SOX genes play crucial roles in development processes and stemness. To elucidate the exact roles of SOX factors and their partners in tissue hemostasis and cell regeneration, generating appropriate in vitro and in vivo models is crucial. In line with these premises, CRISPR-Cas technology is a promising tool for studying different family members of SOX transcription factors. In this review, we aim to highlight the importance of CRISPR-Cas and summarize the applications of this novel, promising technology in studying and decoding the function of different members of the SOX gene family.

Characterization of Extracellular Vesicles Labelled with a Lipophilic Dye Using Fluorescence Nanoparticle Tracking Analysis

Research on extracellular vesicles (EVs) has intensified over the past decade, including fluorescent membrane labeling of EVs. An optimal fluorescent method requires the size of EVs to be preserved after labeling. Lipophilic fluorescent dyes, such as CellMask™ Green (CMG), have been widely used for this purpose. Here, we investigated conditions affecting the optimum CMG labeling of EVs derived from human choriocarcinoma cells (JAr) and different biological fluids using fluorescence NTA (fl-NTA). The effect of CMG labeling on the size, concentration and zeta potential (ZP) on JAr EVs purified with different methods were measured along with biological fluid-derived EVs. With the increase of CMG dye concentration, a significant decrease in the mean size of fluorescent nanoparticles (fl-NPs) was observed. The ZP of fl-NPs originating from JAr cells with the lowest and highest dye concentrations showed a significant shift towards more and less negative ZP values, respectively. Differences in the concentration of fl-NPs were observed for JAr EVs purified using size-exclusion chromatography (SEC) alone and SEC in combination with tangential flow filtration. The proportion of CMG labeling of NPs varied across different biological sources. CMG labeling may be a reliable technique for the detection of EVs using fl-NTA.

CRISPR/Cas9 Delivery System Engineering for Genome Editing in Therapeutic Applications

The clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) systems have emerged as a robust and versatile genome editing platform for gene correction, transcriptional regulation, disease modeling, and nucleic acids imaging. However, the insufficient transfection and off-target risks have seriously hampered the potential biomedical applications of CRISPR/Cas9 technology. Herein, we review the recent progress towards CRISPR/Cas9 system delivery based on viral and non-viral vectors. We summarize the CRISPR/Cas9-inspired clinical trials and analyze the CRISPR/Cas9 delivery technology applied in the trials. The rational-designed non-viral vectors for delivering three typical forms of CRISPR/Cas9 system, including plasmid DNA (pDNA), mRNA, and ribonucleoprotein (RNP, Cas9 protein complexed with gRNA) were highlighted in this review. The vector-derived strategies to tackle the off-target concerns were further discussed. Moreover, we consider the challenges and prospects to realize the clinical potential of CRISPR/Cas9-based genome editing.

Genetic interference exerted by Salmonella-delivered CRISPR/Cas9 significantly reduces the pathological burden caused by Marek's disease virus in chickens

Efficient in vivo delivery of a CRISPR/Cas9 plasmid is of paramount importance for effective therapy. Here, we investigated the usability of Salmonella as a plasmid carrier for in vivo therapy against virus-induced cancer using Marek’s disease virus (MDV) as a model for study in chickens. A green fluorescent protein-expressing CRISPR/Cas9 plasmid encoding the virulence gene pp38 was constructed against Marek’s disease virus. Therapeutic plasmids were transformed into Salmonella carrying lon and sifA gene deletions. The animals in 5 groups were intraperitoneally inoculated with phosphate-buffered saline, vector control, or Salmonella before or after MDV infection, or left uninfected as a naïve control. Therapeutic effectiveness was evaluated by observing disease outcomes and the viral copy number in peripheral blood mononuclear cells. The efficacy of plasmid delivery by Salmonella was 13 ± 1.7% in the spleen and 8.0 ± 1.8% in the liver on the 6^th day post-infection. The Salmonella-treated groups showed significant resistance to MDV infection. The maximum effect was observed in the group treated with Salmonella before MDV infection. None of the chickens fully recovered; however, the results suggested that timely delivery of Salmonella could be effective for in vivo CRISPR/Cas9-mediated genetic interference against highly pathogenic MDV. The use of Salmonella in CRISPR systems provides a simpler and more efficient platform for in vivo therapy with CRISPR than the use of conventional in vivo gene delivery methods and warrants further development.

Extracellular Vesicles (Exosomes) as Immunosuppressive Mediating Variables in Tumor and Chronic Inflammatory Microenvironments

Exosomes are extracellular vesicles released by most of the eukaryotic cells. Exosomes’ components include proteins, lipids, microRNA, circular RNA, long noncoding RNA, DNA, etc. Exosomes may carry both pro and anti-inflammatory cargos; however, exosomes are predominantly filled with immunosuppressive cargos such as enzymes and microRNAs in chronic inflammation. Exosomes have surfaced as essential participants in physiological and pathological intercellular communication. Exosomes may prevent or promote the formation of an aggressive tumor and chronic inflammatory microenvironments, thus influencing tumor and chronic inflammatory progression as well as clinical prognosis. Exosomes, which transmit many signals that may either enhance or constrain immunosuppression of lymphoid and myeloid cell populations in tumors, are increasingly becoming recognized as significant mediators of immune regulation in cancer. In this review, we outline the function of exosomes as mediators of immunosuppression in tumor and chronic inflammatory microenvironments, with the aim to improve cancer therapy.

Vascular transplantation with dual-biofunctional ePTFE vascular grafts in a porcine model

Cardiovascular disease (CVD) poses serious health concerns worldwide. The lack of transplantable vascular grafts is an unmet clinical need in the surgical treatment of CVD. Although expanded polytetrafluoroethylene (ePTFE) vascular grafts have been used in clinical practice, a low long-term patency rate in small-diameter transplantation application is still the biggest challenge. Thus, surface modification of ePTFE is sought after. In this study, polydopamine (PDA) was used to improve the hydrophilia and provide immobilization sites in ePTFE. Bivalirudin (BVLD), a direct thrombin inhibitor, was used to enhance the anti-thrombotic activity of ePTFE. The peptides derived from extracellular matrix proteins were used to elevate the bioactivity of ePTFE. The morphology, chemical composition, peptide modified strength, wettability, and hemocompatibility of modified ePTFE vascular grafts were investigated. Then, an endothelial cell proliferation assay was used to evaluate the best co-modification strategy of the ePTFE vascular graft in vitro. Since a large animal could relatively better mimic human physiology, we chose a porcine carotid artery replacement model in the current study. The results showed that the BVLD/REDV co-modified ePTFE vascular grafts had a satisfactory patency rate (66.7%) and a higher endothelial cell coverage ratio (70%) at 12 weeks after implantation. This may offer an opportunity to produce a multi-biofunctional ePTFE vascular graft, thereby yielding a potent product to meet the clinical needs.

Exosomes as Smart Nanoplatforms for Diagnosis and Therapy of Cancer

Exosomes are composed of a lipid bilayer membrane, containing proteins, nucleic acids, DNA, RNA, etc., derived from donor cells. They have a size range of approximately 30-150 nm. The intrinsic characteristics of exosomes, including efficient cellular uptake, low immunogenicity, low toxicity, intrinsic ability to traverse biological barriers, and inherent targeting ability, facilitate their application to the drug delivery system. Here, we review the generation, uptake, separation, and purification methods of exosomes, focusing on their application as carriers in tumor diagnosis and treatment, especially in brain tumors, as well as the patent applications of exosomes in recent years.

What we know on the potential use of exosomes for nanodelivery

Antitumor therapy is taking into consideration the possibility to use natural nanovesicles, called exosomes, as an ideal delivery for both old and new anti-cancer molecules. This with the attempt to improve the efficacy, at the same time reducing the systemic toxicity of physical, chemical, and biological molecules. Exosomes may in fact increase the level of biomimetism, through simulating what really occurs in nature. Although extracellularly released vesicles include both microvesicles (MVs) and exosomes, only exosomes have the size that may be considered suitable for potential use to this purpose, also by analogy with the diffusely used artificial nanoparticles, such as lyposomes. In fact, recent reports have shown that exosomes are able to interact with target cells within an organ or at a distance using different mechanisms. Much is yet to be understood about exosomes, and currently, we are looking at the visible top of an iceberg, with most of what we have to understand on these nanovesicles still under the sea. In fact, we know that exosomes released by normal cells always trigger positive effects, while those released by cells in pathological condition, such as tumors may induce undesired, dangerous, and mostly unknown effects. To date we have many pre-clinical data available and possibly useful to think about a strategic use of exosomes as a delivery nanodevice in cancer treatment. However, this review wants to critically emphasize two important points actually hampering further discussion in the field : (i) the clinical data are virtually absent at the moment ; (ii) the best cellular source of exosomes to be used to deliver drugs is really far to be defined. Facing off these two points may well facilitate the attempt to figure out this very important issue for improving at the best future anti-cancer treatments.

Small extracellular vesicle non-coding RNAs in pancreatic cancer: molecular mechanisms and clinical implications

Pancreatic cancer has the worst prognosis among common tumors which is attributed to its aggressive phenotype, diagnosis at advanced, inoperable stages, and resistance to systemic therapy. Non-coding RNAs (ncRNAs) such as microRNAs, long non-coding RNAs, and circular RNAs have been established as important regulators of gene expression and their deregulation has been implicated in multiple diseases and foremost cancer. In the tumor microenvironment, non-coding RNAs can be distributed among cancer cells, stromal cells, and immune cells via small extracellular vesicles (sEVs), thereby facilitating intercellular communication and influencing major cancer hallmarks such as angiogenesis, evasion of the immune system, and metastatic dissemination. Furthermore, sEV-ncRNAs have shown promising potential as liquid biopsies with diagnostic and prognostic significance. In this review, we summarize the role of sEVs as carriers of ncRNAs and underlying molecular mechanisms in pancreatic cancer. Moreover, we review the potential of sEV-ncRNAs as biomarkers and highlight the suitability of sEVs as delivery vehicles for ncRNA-based cancer therapy.

Nanotechnology-based delivery of CRISPR/Cas9 for cancer treatment

CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9) is a potent technology for gene-editing. Owing to its high specificity and efficiency, CRISPR/Cas9 is extensity used for human diseases treatment, especially for cancer, which involves multiple genetic alterations. Different concepts of cancer treatment by CRISPR/Cas9 are established. However, significant challenges remain for its clinical applications. The greatest challenge for CRISPR/Cas9 therapy is how to safely and efficiently deliver it to target sites in vivo. Nanotechnology has greatly contributed to cancer drug delivery. Here, we present the action mechanisms of CRISPR/Cas9, its application in cancer therapy and especially focus on the nanotechnology-based delivery of CRISPR/Cas9 for cancer gene editing and immunotherapy to pave the way for its clinical translation. We detail the difficult barriers for CRISIR/Cas9 delivery in vivo and discuss the relative solutions for encapsulation, target delivery, controlled release, cellular internalization, and endosomal escape.

Ovarian-Cancer-Associated Extracellular Vesicles: Microenvironmental Regulation and Potential Clinical Applications

Ovarian cancer (OC) is one of the most diagnosed gynecological cancers in women. Due to the lack of effective early stage screening, women are more often diagnosed at an advanced stage; therefore, it is associated with poor patient outcomes. There are a lack of tools to identify patients at the highest risk of developing this cancer. Moreover, early detection strategies, therapeutic approaches, and real-time monitoring of responses to treatment to improve survival and quality of life are also inadequate. Tumor development and progression are dependent upon cell-to-cell communication, allowing cancer cells to re-program cells not only within the surrounding tumor microenvironment, but also at distant sites. Recent studies established that extracellular vesicles (EVs) mediate bi-directional communication between normal and cancerous cells. EVs are highly stable membrane vesicles that are released from a wide range of cells, including healthy and cancer cells. They contain tissue-specific signaling molecules (e.g., proteins and miRNA) and, once released, regulate target cell phenotypes, inducing a pro-tumorigenic and immunosuppressive phenotype to contribute to tumor growth and metastasis as well as proximal and distal cell function. Thus, EVs are a “fingerprint” of their cell of origin and reflect the metabolic status. Additionally, via the capacity to evade the immune system and remain stable over long periods in circulation, EVs can be potent therapeutic agents. This review examines the potential role of EVs in the different aspects of the tumor microenvironment in OC, as well as their application in diagnosis, delivery of therapeutic agents, and disease monitoring.

Exosomes-mediated tumor treatment: One body plays multiple roles

Exosomes are vesicles secreted by a variety of living cells, containing proteins, RNA and other components, which are nanoscale capsules commonly existed in the body. Exosomes play important roles in a variety of physiological and pathological processes by participating in material and information exchange between cells, which can play multiple roles in tumor treatment. On the one hand, exosomes can be used as carriers and biomarkers, participate in the apoptosis signaling pathway and improve chemotherapy resistance, thus playing beneficial roles in tumor treatment. On the other hand, exosomes play unfavorable roles in tumor treatment. Tumor cell exosomes contain PD-L1, which is a nuclear weapon for tumor growth, metastasis, and immunosuppression. In addition, exosomes can not only promote the epithelial-mesenchymal transition process, tumor angiogenesis and chemoresistance, but also participate in the autocrine pathway. In this review, the multiple roles of exosomes and their prospects in the treatment of tumor were reviewed in detail.

Applications and challenges of CRISPR-Cas gene-editing to disease treatment in clinics

Clustered regularly interspaced short palindromic repeats (CRISPR)-associated systems (Cas) are efficient tools for targeting specific genes for laboratory research, agricultural engineering, biotechnology, and human disease treatment. Cas9, by far the most extensively used gene-editing nuclease, has shown great promise for the treatment of hereditary diseases, viral infection, cancers, and so on. Recent reports have revealed that some other types of CRISPR-Cas systems may also have surprising potential to join the fray as gene-editing tools for various applications. Despite the rapid progress in basic research and clinical tests, some underlying problems present continuous, significant challenges, such as editing efficiency, relative difficulty in delivery, off-target effects, immunogenicity, etc. This article summarizes the applications of CRISPR-Cas from bench to bedside and highlights the current obstacles that may limit the usage of CRISPR-Cas systems as gene-editing toolkits in precision medicine and offer some viewpoints that may help to tackle these challenges and facilitate technical development. CRISPR-Cas systems, as a powerful gene-editing approach, will offer great hopes in clinical treatments for many individuals with currently incurable diseases.

Key Points in Remote-Controlled Drug Delivery: From the Carrier Design to Clinical Trials

The increased research activity aiming at improved delivery of pharmaceutical molecules indicates the expansion of the field. An efficient therapeutic delivery approach is based on the optimal choice of drug-carrying vehicle, successful targeting, and payload release enabling the site-specific accumulation of the therapeutic molecules. However, designing the formulation endowed with the targeting properties in vitro does not guarantee its selective delivery in vivo. The various biological barriers that the carrier encounters upon intravascular administration should be adequately addressed in its overall design to reduce the off-target effects and unwanted toxicity in vivo and thereby enhance the therapeutic efficacy of the payload. Here, we discuss the main parameters of remote-controlled drug delivery systems: (i) key principles of the carrier selection; (ii) the most significant physiological barriers and limitations associated with the drug delivery; (iii) major concepts for its targeting and cargo release stimulation by external stimuli in vivo. The clinical translation for drug delivery systems is also described along with the main challenges, key parameters, and examples of successfully translated drug delivery platforms. The essential steps on the way from drug delivery system design to clinical trials are summarized, arranged, and discussed.

Exosomes as Targeted Delivery Platform of CRISPR/Cas9 for Therapeutic Genome Editing

Therapeutic genome editing harnesses the power of genome editing tools to correct erroneous genes associated with disease pathology. To bring the CRISPR/Cas9 tool from the bench to the bedside, a critical hurdle is the safe and efficient delivery of this nucleic acid tool to the desired type of cells in patients. This review discusses the use of natural carriers, extracellular vesicles (EVs), in particular exosomes, to fill the gap. Exosomes are lipid-containing nanovesicle released by various types of cells to mediate cell-cell communications. Their inherent long-distance transportation capability, biocompatibility, and engineerability have made EVs potential vehicles for delivering therapeutic drugs. We summarize the recent progress of harnessing exosomes as delivery vehicles for the CRISPR/Cas system to achieve therapeutic gene editing for disease treatment, with a focus on various strategies to achieve selective delivery to a particular type of cell and efficient packaging of the genome editing tools in the vesicles. Critical issues and possible solutions in the design and engineering of the targeting vehicles are highlighted. Taken together, we demonstrate EV/exosome-mediated packaging of the nucleic acid/protein tools and the cell/tissue-targeted delivery to be a viable way towards the clinical translation of the CRISPR/Cas9 technology.

Extracellular vesicles as a drug delivery system: A systematic review of preclinical studies

During the past decades, extracellular vesicles (EVs) have emerged as an attractive drug delivery system. Here, we assess their pre-clinical applications, in the form of a systematic review. For each study published in the past decade, disease models, animal species, EV donor cell types, active pharmaceutical ingredients (APIs), EV surface modifications, API loading methods, EV size and charge, estimation of EV purity, presence of biodistribution studies and administration routes were quantitatively analyzed in a defined and reproducible way. We have interpreted the trends we observe over the past decade, to define the niches where to apply EVs for drug delivery in the future and to provide a basis for regulatory guidelines.

Exosome-mediated delivery of CRISPR/Cas9 for targeting of oncogenic KrasG12D in pancreatic cancer

This work identifies the use of exosomes to specifically deliver CRISPR/Cas9 to target oncogenic KrasG12D mutation in pancreatic cancer as a nonviral therapeutic strategy.

CRISPR/Cas9 is a promising technology for gene editing. To date, intracellular delivery vehicles for CRISPR/Cas9 are limited by issues of immunogenicity, restricted packaging capacity, and low tolerance. Here, we report an alternative, nonviral delivery system for CRISPR/Cas9 based on engineered exosomes. We show that non-autologous exosomes can encapsulate CRISPR/Cas9 plasmid DNA via commonly available transfection reagents and can be delivered to recipient cancer cells to induce targeted gene deletion. As a proof-of-principle, we demonstrate that exosomes loaded with CRISPR/Cas9 can target the mutant Kras^G12D oncogenic allele in pancreatic cancer cells to suppress proliferation and inhibit tumor growth in syngeneic subcutaneous and orthotopic models of pancreatic cancer. Exosomes may thus be a promising delivery platform for CRISPR/Cas9 gene editing for targeted therapies.

CRISPR: History and perspectives to the future

This review summarizes the information about the history and future of the CRISPR/Cas9 method. Genome editing can be perceived as a group of technologies that allow scientists to change the DNA of an organism. These technologies involve the deletion, insertion, or modification of the genome at a specific site in a DNA sequence. Gene therapy in humans has a perspective to be used to eliminate the gene responsible for a particular genetic disorder. The review focuses on the key elements of this promising method and the possibility of its application in the treatment of cancer and genetic diseases.

Engineered EV-Mimetic Nanoparticles as Therapeutic Delivery Vehicles for High-Grade Serous Ovarian Cancer

Simple Summary

In this review, we begin with the role of natural extracellular vesicles (EVs) in high-grade serous ovarian cancer (HGSOC). Then, we narrow our focus on the advantages of using EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics. Furthermore, we discuss the challenges of the clinical translation of engineering EV mimetic drug delivery systems and the promising directions of further development.

Abstract

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecological malignancy among women. Several obstacles impede the early diagnosis and effective treatment options for ovarian cancer (OC) patients, which most importantly include the development of platinum-drug-resistant strains. Currently, extensive efforts are being put into the development of strategies capable of effectively circumventing the physical and biological barriers present in the peritoneal cavity of metastatic OC patients, representing a late stage of gastrointestinal and gynecological cancer with an extremely poor prognosis. Naturally occurring extracellular vesicles (EVs) have been shown to play a pivotal role in progression of OC and are now being harnessed as a delivery vehicle for cancer chemotherapeutics. However, there are limitations to their clinical application due to current challenges in their preparation techniques. Intriguingly, there is a recent drive towards the use of engineered synthetic EVs for the delivery of chemotherapeutics and RNA interference therapy (RNAi), as they show the promise of overcoming the obstacles in the treatment of OC patients. This review discusses the therapeutic application of EVs in OC and elucidates the potential use of engineered EV-mimetic nanoparticles as a delivery vehicle for RNAi therapy and other chemotherapeutics, which would potentially improve clinical outcomes of OC patients.

CRISPR/Cas9: Principle, Applications, and Delivery through Extracellular Vesicles

The establishment of CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9) technology for eukaryotic gene editing opened up new avenues not only for the analysis of gene function but also for therapeutic interventions. While the original methodology allowed for targeted gene disruption, recent technological advancements yielded a rich assortment of tools to modify genes and gene expression in various ways. Currently, clinical applications of this technology fell short of expectations mainly due to problems with the efficient and safe delivery of CRISPR/Cas9 components to living organisms. The targeted in vivo delivery of therapeutic nucleic acids and proteins remain technically challenging and further limitations emerge, for instance, by unwanted off-target effects, immune reactions, toxicity, or rapid degradation of the transfer vehicles. One approach that might overcome many of these limitations employs extracellular vesicles as intercellular delivery devices. In this review, we first introduce the CRISPR/Cas9 system and its latest advancements, outline major applications, and summarize the current state of the art technology using exosomes or microvesicles for transporting CRISPR/Cas9 constituents into eukaryotic cells.

Exosomes as Naturally Occurring Vehicles for Delivery of Biopharmaceuticals: Insights from Drug Delivery to Clinical Perspectives

Exosomes as nanosized vesicles are emerging as drug delivery systems for therapeutics owing to their natural origin, their ability to mediate intercellular communication, and their potential to encapsulate various biological molecules such as proteins and nucleic acids within the lipid bilayer membrane or in the lumen. Exosomes contain endogenous components (proteins, lipids, RNA) that could be used to deliver cargoes to target cells, offering an opportunity to diagnose and treat various diseases. Owing to their ability to travel safely in extracellular fluid and to transport cargoes to target cells with high efficacy, exosomes offer enhanced delivery of cargoes in vivo. However, several challenges related to the stabilization of the exosomes, the production of sufficient amounts of exosomes with safety and efficacy, the efficient loading of drugs into exosomes, the clearance of exosomes from circulation, and the transition from the bench scale to clinical production may limit their development and clinical use. For the clinical use of exosomes, it is important to understand the molecular mechanisms behind the transport and function of exosome vesicles. This review exploits techniques related to the isolation and characterization of exosomes and their drug delivery potential to enhance the therapeutic outcome and stabilization methods. Further, routes of administration, clinical trials, and regulatory aspects of exosomes will be discussed in this review.

Exosome-based Tumor Therapy: Opportunities and Challenges

BACKGROUND

Exosomes play an important role in transferring information among different cell types, as they transport materials from the cell membrane to the cytoplasm. They are involved not only in normal physiological functions, but also in the occurrence and development of a variety of diseases. Cancer is a major health problem affecting humans. Currently, exosomes are considered novel stars in tumor therapy.

OBJECTIVE

To present a review focusing on the role of exosomes in tumorigenesis and development and the possibility of treating tumors with exosome-targeted therapies or using exosomes as carriers.

METHODS

We reviewed literature related to the biological origin and function of exosomes and exosome-tumor relationship.

RESULTS

Exosomes are closely related to tumor immunity, angiogenesis, pre-metastasis microenvironment, chemoresistance, energy metabolism, etc. Tumor therapy involving the targeting of exosomes involves block the generation, secretion, uptake of exosomes, and elimination of circulating exosomes, and develop antitumor vaccines. Exosome as delivery vehicles can be loaded with chemotherapeutic drugs, therapeutic genes, and other therapeutic drugs to target cells. Prospects and challenges of exosome-based tumor therapy are also discussed.

CONCLUSION

Exosomes are involved in multiple processes during tumor development and should be further studied as novel targets for cancer therapy.

Biodistribution of extracellular vesicles following administration into animals: A systematic review

In recent years, attention has turned to examining the biodistribution of EVs in recipient animals to bridge between knowledge of EV function in vitro and in vivo. We undertook a systematic review of the literature to summarize the biodistribution of EVs following administration into animals. There were time-dependent changes in the biodistribution of small-EVs which were most abundant in the liver. Detection peaked in the liver and kidney in the first hour after administration, while distribution to the lungs and spleen peaked between 2-12 h. Large-EVs were most abundant in the lungs with localization peaking in the first hour following administration and decreased between 2-12 h. In contrast, large-EV localization to the liver increased as the levels in the lungs decreased. There was moderate to low localization of large-EVs to the kidneys while localization to the spleen was typically low. Regardless of the origin or size of the EVs or the recipient species into which the EVs were administered, the biodistribution of the EVs was largely to the liver, lungs, kidneys, and spleen. There was extreme variability in the methodology between studies and we recommend that guidelines should be developed to promote standardization where possible of future EV biodistribution studies.

Nucleic acid delivery with extracellular vesicles

Extracellular vesicles (EVs) are membrane-enclosed particles, heterogeneous in size, shape, contents, biogenesis and structure. They are released by eukaryotic and prokaryotic cells and exert (patho-)physiological roles as mediators for transmitting molecular information from the producer (donor) to a recipient cell. This review focuses on the potential of EVs for delivering nucleic acids, as particularly problematic cargoes with regard to stability/protection and uptake efficacy. It highlights important properties of EVs for nucleic acid delivery and discusses their physiological and pathophysiological roles with regard to various cellular RNA species. It then describes the application of EVs for delivering a broad selection of nucleic acids/oligonucleotides, in particular giving a comprehensive overview of preclinical in vivo studies and the various strategies explored. In this context, different techniques for EV loading are discussed, as well as other important technical aspects related to EV preparation, characterization and in particular, the various approaches of artificial EV modification.

Active Delivery of CRISPR System Using Targetable or Controllable Nanocarriers

Among programmable nuclease-based genome editing tools, the clustered regularly interspaced short palindromic repeats (CRISPR) system with accuracy and the convenient operation is most promising to be applied in gene therapy. The development of effective delivery carriers for the CRISPR system is the major premise to achieve practical applications. Although many nanocarrier-mediated deliveries have been reported to be safer and cheaper over the physical and viral delivery, the accumulation at disease sites or controllability with the spatial or temporal resolution are still desired on nanocarriers to reduce side effects and off-target from the CRISPR system. Therefore, the targetable and controllable nanocarriers to actively deliver the CRISPR system are summarized. The cell or even organ selective nanocarriers are introduced first, followed by the discussion of nanocarriers controlled by biochemical or physical signals. At last, the potential challenges faced by existing nanocarriers are discussed.

A call for the standardised reporting of factors affecting the exogenous loading of extracellular vesicles with therapeutic cargos

Extracellular vesicles (EVs) are complex nanoparticles required for the intercellular transfer of diverse biological cargoes. Unlike synthetic nanoparticles, EVs may provide a natural platform for the enhanced targeting and functional transfer of therapeutics across complex and often impenetrable biological boundaries (e.g. the blood-brain barrier or the matrix of densely organised tumours). Consequently, there is considerable interest in utilising EVs as advanced drug delivery systems for the treatment of a range of challenging pathologies. Within the past decade, efforts have focused on providing standard minimal requirements for conducting basic EV research. However, no standard reporting framework has been established governing the therapeutic loading of EVs for drug delivery applications. The purpose of this review is to critically evaluate progress in the field, providing an initial set of guidelines that can be applied as a benchmark to enhance reproducibility and increase the likelihood of translational outcomes.

Minicircles for a two-step blood biomarker and PET imaging early cancer detection strategy

Early cancer detection can dramatically increase treatment options and survival rates for patients, yet detection of early-stage tumors remains difficult. Here, we demonstrate a two-step strategy to detect and locate cancerous lesions by delivering tumor-activatable minicircle (MC) plasmids encoding a combination of blood-based and imaging reporter genes to tumor cells. We genetically engineered the MCs, under the control of the pan-tumor-specific Survivin promoter, to encode: 1) Gaussia Luciferase (GLuc), a secreted biomarker that can be easily assayed in blood samples; and 2) Herpes Simplex Virus Type 1 Thymidine Kinase mutant (HSV-1 sr39TK), a PET reporter gene that can be used for highly sensitive and quantitative imaging of the tumor location. We evaluated two methods of MC delivery, complexing the MCs with the chemical transfection reagent jetPEI or encapsulating the MCs in extracellular vesicles (EVs) derived from a human cervical cancer HeLa cell line. MCs delivered by EVs or jetPEI yielded significant expression of the reporter genes in cell culture versus MCs delivered without a transfection reagent. Secreted GLuc correlated with HSV-1 sr39TK expression with R² = 0.9676. MC complexation with jetPEI delivered a larger mass of MC for enhanced transfection, which was crucial for in vivo animal studies, where delivery of MCs via jetPEI resulted in GLuc and HSV-1 sr39TK expression at significantly higher levels than controls. To the best of our knowledge, this is the first report of the PET reporter gene HSV-1 sr39TK delivered via a tumor-activatable MC to tumor cells for an early cancer detection strategy. This work explores solutions to endogenous blood-based biomarker and molecular imaging limitations of early cancer detection strategies and elucidates the delivery capabilities and limitations of EVs.

Local oncolytic adenovirotherapy produces an abscopal effect via tumor-derived extracellular vesicles

Extracellular vesicles (EVs) play important roles in various intercellular communication processes. The abscopal effect is an interesting phenomenon in cancer treatment, in which immune activation is generally considered a main factor. We previously developed a telomerase-specific oncolytic adenovirus, Telomelysin (OBP-301), and occasionally observed therapeutic effects on distal tumors after local treatment in immunodeficient mice. Here, we hypothesized that EVs may be involved in the abscopal effect of OBP-301. EVs isolated from the supernatant of HCT116 human colon carcinoma cells treated with OBP-301 were confirmed to contain OBP-301, and showed cytotoxic activity (apoptosis and autophagy) similar to OBP-301. In bilateral subcutaneous HCT116 and CT26 tumor models, intratumoral administration of OBP-301 produced potent antitumor effects on tumors that were not directly treated with OBP-301, involving direct mediation by tumor-derived EVs containing OBP-301. This indicates that immune activation is not the main factor in this abscopal effect. Moreover, tumor-derived EVs exhibited high tumor tropism in orthotopic HCT116 rectal tumors, in which adenovirus E1A and adenovirus type 5 proteins were observed in metastatic liver tumors after localized rectal tumor treatment. In conclusion, local treatment with OBP-301 has the potential to produce abscopal effects via tumor-derived EVs.

Roles of exosomes in cancer chemotherapy resistance, progression, metastasis and immunity, and their clinical applications (Review)

Exosomes are a type of vesicle that are secreted by cells, with a diameter of 40-100 nm, and that appear as a cystic shape under an electron microscope. Exosome cargo includes a variety of biologically active substances such as non-coding RNA, lipids and small molecule proteins. Exosomes can be taken up by neighboring cells upon secretion or by distant cells within the circulatory system, affecting gene expression of the recipient cells. The present review discusses the formation and secretion of exosomes, and how they can remodel the tumor microenvironment, enhancing cancer cell chemotherapy resistance and tumor progression. Exosome-mediated induction of tumor metastasis is also highlighted. More importantly, the review discusses the manner in which exosomes can change the metabolism of cancer cells and the immune system, which may help to devise novel therapeutic approaches for cancer treatment. With the development of nanotechnology, exosomes can also be used as biomarkers and for the delivery of chemical drugs, serving as a tool to diagnose and treat cancer.

Nanoparticle Delivery of CRISPR/Cas9 for Genome Editing

The emerging clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated system (Cas) gene-editing system represents a promising tool for genome manipulation. However, its low intracellular delivery efficiency severely compromises its use and potency for clinical applications. Nanocarriers, such as liposomes, polymers, and inorganic nanoparticles, have shown great potential for gene delivery. The remarkable development of nanoparticles as non-viral carriers for the delivery of the CRISPR/Cas9 system has shown great promise for therapeutic applications. In this review, we briefly summarize the delivery components of the CRISPR/Cas9 system and report on the progress of nano-system development for CRISPR/Cas9 delivery. We also compare the advantages of various nano-delivery systems and their applications to deliver CRISPR/Cas9 for disease treatment. Nano-delivery systems can be modified to fulfill the tasks of targeting cells or tissues. We primarily emphasize the novel exosome-based CRISPR/Cas9 delivery system. Overall, we review the challenges, development trends, and application prospects of nanoparticle-based technology for CRISPR/Cas9 delivery.

Phosphatidylcholine-Engineered Exosomes for Enhanced Tumor Cell Uptake and Intracellular Antitumor Drug Delivery

Exosomes derived from non-tumor cells hold great potential as drug delivery vehicles because of their good biosafety and natural transference of bioactive cargo between cells. However, compared to tumor-derived exosomes, efficient delivery is limited by their weak interactions with tumor cells. It is essential to engineer exosomes that improve tumor cellular internalization efficiency. A simple and effective strategy to enhance tumor cell uptake by engineering the exosome membrane lipids can be established by drawing on the role of lipids in tumor exosomes interacting with tumor cells. Amphiphilic phosphatidylcholine (PC) molecules are inserted into the membrane lipid layer of reticulocyte-derived exosomes (Exos) by simple incubation to construct PC-engineered exosomes (PC-Exos). It is demonstrated that PC-Exos showed significantly enhanced tumor cell internalization and uptake rate compared to native Exos, up to a twofold increase. After therapeutic agent loading, PC-Exos remarkably promotes intracellular drug or RNA accumulation in cancer cells, thus showing enhanced in vitro anti-tumor activity. This work demonstrates the crucial role of engineering exosomal lipids in modulating cancer cellular uptake, which may shed light on the design of high-efficiency exosome-based drug delivery carriers.

Clinical applications for exosomes: Are we there yet?

Exosomes are a subset of extracellular vesicles essential for cell-cell communication in health and disease with the ability to transport nucleic acids, functional proteins and other metabolites. Their clinical use as diagnostic biomarkers and therapeutic carriers has become a major field of research over recent years, generating rapidly expanding scientific interest and financial investment. Their reduced immunogenicity compared to liposomes or viral vectors and their ability to cross major physiological barriers like the blood-brain barrier make them an appealing and innovative option as biomarkers and therapeutic agents. Here, we review the latest clinical developments of exosome biotechnology for diagnostic and therapeutic purposes, including the most recent COVID-19-related exosome-based clinical trials. We present current exosome engineering strategies for optimal clinical safety and efficacy, and assess the technology developed for good manufacturing practice compliant scaling up and storage approaches along with their limitations in pharmaceutical industry.

Role of exosomes in the immune microenvironment of ovarian cancer

Exosomes are excretory vesicles that can deliver a variety of bioactive cargo molecules to the extracellular environment. Accumulating evidence demonstrates exosome participation in intercellular communication, immune response, inflammatory response and they even play an essential role in affecting the tumor immune microenvironment. The role of exosomes in the immune microenvironment of ovarian cancer is mainly divided into suppression and stimulation. On one hand exosomes can stimulate the innate and adaptive immune systems by activating dendritic cells (DCs), natural killer cells and T cells, allowing these immune cells exert an antitumorigenic effect. On the other hand, ovarian cancer-derived exosomes initiate cross-talk with immunosuppressive effector cells, which subsequently cause immune evasion; one of the hallmarks of cancer. Exosomes induce the polarization of macrophages in M2 phenotype and induce apoptosis of lymphocytes and DCs. Exosomes further activate additional immunosuppressive effector cells (myeloid-derived suppressor cells and regulatory T cells) that induce fibroblasts to differentiate into cancer-associated fibroblasts. Exosomes also induce the tumorigenicity of mesenchymal stem cells to exert additional immune suppression. Furthermore, besides mediating the intercellular communication, exosomes carry microRNAs (miRNAs), proteins and lipids to the tumor microenvironment, which collectively promotes ovarian cancer cells to proliferate, invade and tumors to metastasize. Studying proteins, lipids and miRNAs carried by exosomes could potentially be used as an early diagnostic marker of ovarian cancer for designing treatment strategies.

CRISPR/Cas9 based genome editing for targeted transcriptional control in triple-negative breast cancer

Breast cancer (BC) is the most common type of cancer in women at the global level and the highest mortality rate has been observed with triple-negative breast cancer (TNBC). Accumulation of genetic lesions an aberrant gene expression and protein degradation are considered to underlie the onset of tumorigenesis and metastasis. Therefore, the challenge to identify the genes and molecules that could be potentially used as potent biomarkers for personalized medicine against TNBC with minimal or no associated side effects. Discovery of the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated protein 9 (Cas9) arrangement and an increasing repertoire of its new variants has provided a much-needed fillip towards editing TNBC genomes. In this review, we discuss the CRISPR/Cas9 genome editing, CRISPR Technology for diagnosis of (Triple-negative breast cancer) TNBC, Drug Resistance, and potential applications of CRISPR/Cas9 and its variants in deciphering or engineering intricate molecular and epigenetic mechanisms associated with TNBC. Furthermore, we have also explored the TNBC and CRISPR/Cas9 genome editing potential for repairing, genetic modifications in TNBC.

Isolation and characterization of extracellular vesicles for clinical applications in cancer - time for standardization?

Extracellular vesicles (EVs) are nanometer sized lipid enclosed particles released by all cell types into the extracellular space and biological fluids in vivo, and into cell culture media in vitro. An important physiological role of EVs is cell-cell communication. EVs interact with, and deliver, their contents to recipient cells in a functional capacity; this makes EVs desirable vehicles for the delivery of therapeutic cargoes. In addition, as EVs contain proteins, lipids, glycans, and nucleic acids that reflect their cell of origin, their potential utility in disease diagnosis and prognostication is of great interest. The number of published studies analyzing EVs and their contents in the pre-clinical and clinical setting is rapidly expanding. However, there is little standardization as to what techniques should be used to isolate, purify and characterize EVs. Here we provide a comprehensive literature review encompassing the use of EVs as diagnostic and prognostic biomarkers in cancer. We also detail their use as therapeutic delivery vehicles to treat cancer in pre-clinical and clinical settings and assess the EV isolation and characterization strategies currently being employed. Our report details diverse isolation strategies which are often dependent upon multiple factors such as biofluid type, sample volume, and desired purity of EVs. As isolation strategies vary greatly between studies, thorough EV characterization would be of great importance. However, to date, EV characterization in pre-clinical and clinical studies is not consistently or routinely adhered to. Standardization of EV characterization so that all studies image EVs, quantitate protein concentration, identify the presence of EV protein markers and contaminants, and measure EV particle size and concentration is suggested. Additionally, the use of RNase, DNase and protease EV membrane protection control experiments is recommended to ensure that the cargo being investigated is truly EV associated. Overall, diverse methodology for EV isolation is advantageous as it can support different sample types and volumes. Nevertheless, EV characterization is crucial and should be performed in a rigorous manor.

Engineered Extracellular Vesicles for Cancer Therapy

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer. As a result of their natural properties to mediate cell-to-cell communication and their high physiochemical stability and biocompatibility, EVs are considered as excellent delivery vehicles for a variety of therapeutic agents such as nucleic acids and proteins, drugs, and nanomaterials. Increasing studies have shown that EVs can be modified, engineered, or designed to improve their efficiency, specificity, and safety for cancer therapy. Herein, a comprehensive overview of the recent advances in the strategies and methodologies of engineering EVs for scalable production and improved cargo-loading and tumor-targeting is provided. Additionally, the potential applications of engineered EVs in cancer therapy are discussed by presenting prominent examples, and the opportunities and challenges for translating engineered EVs into clinical practice are evaluated.

Delivery of cancer therapies by synthetic and bio-inspired nanovectors

BACKGROUND

As a complement to the clinical development of new anticancer molecules, innovations in therapeutic vectorization aim at solving issues related to tumor specificity and associated toxicities. Nanomedicine is a rapidly evolving field that offers various solutions to increase clinical efficacy and safety. MAIN: Here are presented the recent advances for different types of nanovectors of chemical and biological nature, to identify the best suited for translational research projects. These nanovectors include different types of chemically engineered nanoparticles that now come in many different flavors of 'smart' drug delivery systems. Alternatives with enhanced biocompatibility and a better adaptability to new types of therapeutic molecules are the cell-derived extracellular vesicles and micro-organism-derived oncolytic viruses, virus-like particles and bacterial minicells. In the first part of the review, we describe their main physical, chemical and biological properties and their potential for personalized modifications. The second part focuses on presenting the recent literature on the use of the different families of nanovectors to deliver anticancer molecules for chemotherapy, radiotherapy, nucleic acid-based therapy, modulation of the tumor microenvironment and immunotherapy.

CONCLUSION

This review will help the readers to better appreciate the complexity of available nanovectors and to identify the most fitting "type" for efficient and specific delivery of diverse anticancer therapies.

Multifunctional Applications of Engineered Extracellular Vesicles in the Treatment of Cancer

Extracellular vesicles (EVs) are key players of intercellular communication in the physiological and pathological setting. In cancer, EVs mediate complex signaling mechanisms between cancer cells and the tumor microenvironment (TME), and can influence tumor progression and the response to existing therapies. Importantly, EVs can be loaded with therapeutic agents and modified to display tumor-targeting molecules. In the field of nanomedicine, EVs have been engineered to serve as therapeutic delivery vehicles for several anticancer agents, including antibodies, chemotherapy, compounds, CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats-associated endonuclease 9), and small interfering RNA (siRNA). Notably, the engineered EVs were shown to suppress malignant features of cancer cells, to elicit antitumor immunity, and to decrease tumor angiogenesis. Here, we review the EV-based therapies designed to target cancer cells and to educate components of the TME to drive antitumor responses. These studies illustrate the multifunctional applications of EVs in the development of anticancer therapies and their translational potential for cancer treatment.

Engineered extracellular vesicles as versatile ribonucleoprotein delivery vehicles for efficient and safe CRISPR genome editing

Transient delivery of CRISPR-based genome editing effectors is important to reduce off-target effects and immune responses. Recently extracellular vesicles (EVs) have been explored for Cas9 ribonucleoprotein (RNP) delivery. However, lack of mechanisms to enrich RNPs into EVs limited the efficiency of EVs as a RNP delivery vehicle. Here we describe a mechanism to actively enrich RNPs into EVs. We used the specific interaction between RNA aptamer and aptamer-binding protein (ABP) to enrich RNPs into EVs. We inserted RNA aptamer com into single guide RNA (sgRNA), and fused com-binding ABP Com to both termini of tetraspan protein CD63 that is abundant in exosomes. We found that the Com/com interaction enriched Cas9 and adenine base editor (ABE) RNPs into EVs, via forming a three-component complex including CD63-Com fusion protein, com-modified sgRNA and Cas9 or ABE. The RNP enriched EVs are efficient in genome editing and transiently expressed. The system is capable of delivering RNPs targeting multiple loci for multiplex genome editing. In addition, Cas9 from different species can be used together. The EV-delivered RNPs are active in vivo. The data show that the aptamer and ABP interactions can be utilized to actively enrich RNPs into EVs for improved genome editing efficiency and safety.

Smart Nanocarriers for Targeted Cancer Therapy

Cancer is considered one of the most threatening diseases worldwide. Although many therapeutic approaches have been developed and optimized for ameliorating patient's conditions and life expectancy, however, it frequently remains an incurable pathology. Notably, conventional treatments may reveal inefficient in the presence of metastasis development, multidrug resistance and inability to achieve targeted drug delivery. In the last decades, nanomedicine has gained a prominent role, due to many properties ascribable to nanomaterials. It is worth mentioning their small size, their ability to be loaded with small drugs and bioactive molecules and the possibility to be functionalized for tumor targeting. Natural vehicles have been exploited, such as exosomes, and designed, such as liposomes. Biomimetic nanomaterials have been engineered, by modification with biological membrane coating. Several nanoparticles have already entered clinical trials and some liposomal formulations have been approved for therapeutic applications. In this review, natural and synthetic nanocarriers functionalized for actively targeting cancer cells will be described, focusing on their advantages with respect to conventional treatments. Recent innovations related to biomimetic nanoparticles camouflaged with membranes isolated from different types of cells will be reported, together with their promising applications. Finally, a short overview on the latest advances in carrier-free nanomaterials will be provided.

Recent Advancement and Technical Challenges in Developing Small Extracellular Vesicles for Cancer Drug Delivery

Extracellular vesicles (EVs) are a heterogeneous population of lipid bilayer membrane-enclosed vesicles and act like 'messages in a bottle' in cell-cell communication by transporting their cargoes to recipient cells. Small EVs (sEVs, < 200 nm) are highly researched recently and have been harnessed as novel delivery systems for the treatment of various diseases, including neurodegenerative disorders, cardiovascular diseases, and most importantly cancer primarily because of their non-immunogenicity, tissue penetration and cell-tropism. This review will first provide a comprehensive overview of sEVs regarding the current understanding on their properties, biogenesis, new classification by the ISEV, composition, as well as their roles in cancer development (thereby called "oncosomes"). The primary focus will be given to the current state of sEVs as natural nanocarriers for cancer drug delivery, the technologies and challenges involved in sEV isolation and characterization, therapeutic cargo loading, and surface modification to enhance tumor-targeting. We will also provide examples of sEV products under clinical trials. Furthermore, the current challenges as well as the advance in "sEV mimetics" to address some of the sEVs limitations is briefly discussed. We seek to advance our understanding of sEVs to unlock their full potential as superior drug delivery vehicles in cancer therapy.

Overview and Update on Methods for Cargo Loading into Extracellular Vesicles

The enormous library of pharmaceutical compounds presents endless research avenues. However, several factors limit the therapeutic potential of these drugs, such as drug resistance, stability, off-target toxicity, and inadequate delivery to the site of action. Extracellular vesicles (EVs) are lipid bilayer-delimited particles and are naturally released from cells. Growing evidence shows that EVs have great potential to serve as effective drug carriers. Since EVs can not only transfer biological information, but also effectively deliver hydrophobic drugs into cells, the application of EVs as a novel drug delivery system has attracted considerable scientific interest. Recently, EVs loaded with siRNA, miRNA, mRNA, CRISPR/Cas9, proteins, or therapeutic drugs show improved delivery efficiency and drug effect. In this review, we summarize the methods used for the cargo loading into EVs, including siRNA, miRNA, mRNA, CRISPR/Cas9, proteins, and therapeutic drugs. Furthermore, we also include the recent advance in engineered EVs for drug delivery. Finally, both advantages and challenges of EVs as a new drug delivery system are discussed. Here, we encourage researchers to further develop convenient and reliable loading methods for the potential clinical applications of EVs as drug carriers in the future.

MicroRNA‑592 promotes cell proliferation, migration and invasion in colorectal cancer by directly targeting SPARC

Colorectal cancer (CRC), one of the most common cancer types, causes a large number of cancer-related mortalities annually worldwide. Dysregulated microRNAs (miRNAs/miR) are closely associated with the malignant progression of CRC. Therefore, the present study aimed to investigate the expression and regulatory role of miR-592 in CRC. It was found that miR-592 expression was significantly elevated in CRC tissues and cell lines, and was associated with the prognosis of patients. Cellular phenotype assays demonstrated that miR-592 could promote CRC cell proliferation, migration and invasion. Bioinformatics analysis demonstrated that miR-592 mainly participated in the positive regulation of transcription, as well as the regulation of cell motility. Moreover, miR-592 targets were enriched in several signaling pathways, such as the ‘mTOR’ and ‘FoxO’ signaling pathways. In addition, secreted protein acidic and rich in cysteine (SPARC) was identified as a target of miR-592 in CRC. The present results suggested that miR-592 acts as an oncogene in CRC, in part, by directly inhibiting SPARC expression. Collectively, the present study provides a novel potential therapeutic strategy for CRC.

The Emerging Roles of Exosomes in the Chemoresistance of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common gastrointestinal malignancy with a leading incidence of cancer-related mortality worldwide. Despite the progress of treatment options, there remains low efficacy for patients with intermediate-advanced HCC, due to tumor metastasis, recurrence and chemoresistance. Increasing evidence suggests that exosomes in the tumor microenvironment (TME), along with other extracellular vesicles (EVs) and cytokines, contribute to the drug chemosensitivity of cancer cells. Exosomes, the intercellular communicators in various biological activities, have shown to play important roles in HCC progression. This review summarizes the underlying associations between exosomes and chemoresistance of HCC cells. The exosomes derived from distinct cell types mediate the drug resistance by regulating drug efflux, epithelial-mesenchymal transition (EMT), cancer stem cell (CSC) properties, autophagic phenotypes, as well as the immune response. In summary, TME-related exosomes can be a potential target to reverse chemoresistance and a candidate biomarker of drug efficacy in HCC patients.

Microfluidic-based capture and release of cancer-derived exosomes via peptide-nanowire hybrid interface

Cancer-derived circulating exosomes or nanoscale extracellular vesicles are emerging biomarkers for disease detection and treatment because of their cell-specific constituents and unique intercellular pathways. For efficient exosome isolation from bio-fluids, the design of high-affinity nanointerfaces is of great importance in the development of miniaturized systems for the collection of exosomes. Herein, we report peptide-functionalized nanowires as a biorecognition interface for the capture and release of cancer-derived exosomes within a microfluidic channel. Based on the amino-acid sequence of EWI-2 protein, a partial peptide that bound to the CD9 exosome marker and thus targeted cancer exosomes was screened. Linkage of the exosome-targeting peptide with a ZnO-binding sequence allowed one-step and reagent-free peptide modification of the ZnO nanowire array. As a result of peptide functionalization, the exosome-capturing ability of ZnO nanowires was significantly improved. Furthermore, the captured exosomes could be subsequently released from the nanowires under a neutral salt condition for downstream applications. This engineered surface that enhances the nanowires' efficiency in selective and controllable collection of cancer-derived exosomes provides an alternative foundation for developing microfluidic platforms for exosome-based diagnostics and therapeutics.

Microvesicles mediate sorafenib resistance in liver cancer cells through attenuating p53 and enhancing FOXM1 expression

Drug resistance in cancer, still poses therapeutic challenges and tumor microenvironment plays a critical role in it. Microvesicles (MVs) are effective transporters of the molecular information between cells and regulate the tumor microenvironment. They contribute to the drug resistance by transferring functional molecules between cells. Herein we report the effects of liver cancer cell-secreted MVs on sorafenib resistance in liver cancer cells HepG2 and Huh7 both in vitro and in vivo. In our study, these cancer cell-secreted MVs affected the anti-proliferative effect of sorafenib in a dose- and time-dependent manner and also inhibited the sorafenib induced apoptosis in vitro. Further, in in-vivo xenograft mice models, liver cancer cell-secreted MVs increased the tumor volume even after sorafenib treatment. Further, HGF, also got elevated in liver cancer cell-secreted MVs treatment group and activated Ras protein expression. miR-25 in the cancer cell-secreted MVs was transferred to their host cells HepG2 and Huh7 cells and reversed the sorafenib induced expression of tumor suppressor p53. This in turn induced the expression of FOXM1, a key regulator of cell cycle progression and thus affected the anti-proliferative effect of sorafenib. Therefore, this study reveals that liver cancer cell-derived MVs can mediate sorafenib resistance in the liver cancer cells, suggesting that these MVs may not be utilized as vehicles for anti-cancer drug delivery in liver cancer treatments.

CRISPR-dCas9-Based Artificial Transcription Factors to Improve Efficacy of Cancer Treatment With Drug Repurposing: Proposal for Future Research

Due to the high resistance that cancer has shown to conventional therapies, it is difficult to treat this disease, particularly in advanced stages. In recent decades, treatments have been improved, being more specific according to the characteristics of the tumor, becoming more effective, less toxic, and invasive. Cancer can be treated by the combination of surgery, radiation therapy, and/or drug administration, but therapies based on anticancer drugs are the main cancer treatment. Cancer drug development requires long-time preclinical and clinical studies and is not cost-effective. Drug repurposing is an alternative for cancer therapies development since it is faster, safer, easier, cheaper, and repurposed drugs do not have serious side effects. However, cancer is a complex, heterogeneous, and highly dynamic disease with multiple evolving molecular constituents. This tumor heterogeneity causes several resistance mechanisms in cancer therapies, mainly the target mutation. The CRISPR-dCas9-based artificial transcription factors (ATFs) could be used in cancer therapy due to their possibility to manipulate DNA to modify target genes, activate tumor suppressor genes, silence oncogenes, and tumor resistance mechanisms for targeted therapy. In addition, drug repurposing combined with the use of CRISPR-dCas9-based ATFs could be an alternative cancer treatment to reduce cancer mortality. The aim of this review is to describe the potential of the repurposed drugs combined with CRISPR-dCas9-based ATFs to improve the efficacy of cancer treatment, discussing the possible advantages and disadvantages.

Trends in CRISPR-Cas9 technology application in cancer

The evolution of the CRISPR-Cas9 technology in cancer research has tremendous potential to shape the future of oncology. Although this gene-editing tool's pre-clinical progress is into its nascent stage, there are many unanswered questions regarding health benefits and therapy precision using CRISPR. The application of CRISPR is highly specific, economically sustainable, and is a high throughput technique, but on the other hand, its application involves measured risk of countering the toxic immune response of Cas protein, off-target effects, limitation of delivering the edited cells back into cancer patients. The current chapter highlights the possibilities and perils of the present-day CRISPR engineering in cancer that should highlight CRISPR translation to therapy.