Reduction of the therapeutic dose of silencing RNA by packaging it in extracellular vesicles via a pre-microRNA backbone

Lipid Nanovesicle Platforms for Hepatocellular Carcinoma Precision Medicine Therapeutics: Progress and Perspectives

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related mortality globally. HCC is highly heterogenous with diverse etiologies leading to different driver mutations potentiating unique tumor immune microenvironments. Current therapeutic options, including immune checkpoint inhibitors and combinations, have achieved limited objective response rates for the majority of patients. Thus, a precision medicine approach is needed to tailor specific treatment options for molecular subsets of HCC patients. Lipid nanovesicle platforms, either liposome- (synthetic) or extracellular vesicle (natural)-derived present are improved drug delivery vehicles which may be modified to contain specific cargos for targeting specific tumor sites, with a natural affinity for liver with limited toxicity. This mini-review provides updates on the applications of novel lipid nanovesicle-based therapeutics for HCC precision medicine and the challenges associated with translating this therapeutic subclass from preclinical models to the clinic.

Cationized extracellular vesicles for gene delivery

Last decade, extracellular vesicles (EVs) attracted a lot of attention as potent versatile drug delivery vehicles. We reported earlier the development of EV-based delivery systems for therapeutic proteins and small molecule chemotherapeutics. In this work, we first time engineered EVs with multivalent cationic lipids for the delivery of nucleic acids. Stable, small size cationized EVs were loaded with plasmid DNA (pDNA), or mRNA, or siRNA. Nucleic acid loaded EVs were efficiently taken up by target cells as demonstrated by confocal microscopy and delivered their cargo to the nuclei in triple negative breast cancer (TNBC) cells and macrophages. Efficient transfection was achieved by engineered cationized EVs formulations of pDNA- and mRNA in vitro. Furthermore, siRNA loaded into cationized EVs showed significant knockdown of the reporter gene in Luc-expressing cells. Overall, multivalent cationized EVs represent a promising strategy for gene delivery.

Extracellular vesicles versus lipid nanoparticles for the delivery of nucleic acids

Extracellular vesicles (EVs) are increasingly investigated for delivering nucleic acid (NA) therapeutics, leveraging their natural role in transporting NA and protein-based cargo in cell-to-cell signaling. Their synthetic counterparts, lipid nanoparticles (LNPs), have been developed over the past decades as NA carriers, culminating in the approval of several marketed formulations such as patisiran/Onpattro® and the mRNA-1273/BNT162 COVID-19 vaccines. The success of LNPs has sparked efforts to develop innovative technologies to target extrahepatic organs, and to deliver novel therapeutic modalities, such as tools for in vivo gene editing. Fueled by the recent advancements in both fields, this review aims to provide a comprehensive overview of the basic characteristics of EV and LNP-based NA delivery systems, from EV biogenesis to structural properties of LNPs. It addresses the primary challenges encountered in utilizing these nanocarriers from a drug formulation and delivery perspective. Additionally, biodistribution profiles, in vitro and in vivo transfection outcomes, as well as their status in clinical trials are compared. Overall, this review provides insights into promising research avenues and potential dead ends for EV and LNP-based NA delivery systems.

Enhanced Extracellular Vesicle Cargo Loading via microRNA Biogenesis Pathway Modulation

Extracellular vesicles (EVs) are physiological vectors for the intercellular transport of a variety of molecules. Among these, small RNAs, and especially microRNAs (miRNAs), have been identified as prevalent components, and there has thus been a robust investigation of EVs for therapeutic miRNAs delivery. However, intrinsic levels of EV-associated miRNAs are generally too low to enable efficient and effective therapeutic outcomes. We hypothesized that miRNA localization to EVs could be improved by limiting competing interactions that occur throughout the miRNA biogenesis process. Using miR-146a-5p as a model, modulation of transcription, nuclear export, and enzymatic cleavage steps of miRNA biogenesis were tested for impact on EV miRNA loading. Working in HEK293T cells, various alterations in the EV biogenesis pathway were shown to impact miRNA localization to EVs. The system was then applied in induced pluripotent stem cells (iPSCs), a more promising substrate for therapeutic EV production, and EVs were separated and assessed for anti-inflammatory efficacy in vitro and in a murine colitis model, where the preservation of function was validated. Overall, the results highlight necessary considerations when designing a cell culture system for the devoted production of miRNA-loaded EVs.

Exosomal ncRNAs in liquid biopsies for lung cancer

Exosomal non-coding RNAs (ncRNAs) have become essential contributors to advancing and treating lung cancers (LCs). The development of liquid biopsies that utilize exosomal ncRNAs (exo-ncRNAs) offers an encouraging method for diagnosing, predicting, and treating LC. This thorough overview examines the dual function of exo-ncRNAs as both indicators for early diagnosis and avenues for LC treatment. Exosomes are tiny vesicles secreted by various cells, including cancerous cells, enabling connection between cells by delivering ncRNAs. These ncRNAs, which encompass circular RNAs, long ncRNAs, and microRNAs, participate in the modulation of gene expression and cellular functions. In LC, certain exo-ncRNAs are linked to tumour advancement, spread, and treatment resistance, positioning them as promising non-invasive indicators in liquid biopsies. Additionally, targeting these ncRNAs offers potential for innovative treatment approaches, whether by suppressing harmful ncRNAs or reinstating the activity of tumour-suppressing ones. This review emphasizes recent developments in the extraction and analysis of exo-ncRNAs, their practical applications in LC treatment, and the challenges and prospects for translating these discoveries into clinical usage. Through this detailed examination of the current state of the art, we aim to highlight the significant potential of exo-ncRNAs for LC diagnostics and treatments.

Canada's contributions to RNA research: past, present, and future perspectives

The field of RNA research has provided profound insights into the basic mechanisms modulating the function and adaption of biological systems. RNA has also been at the center stage in the development of transformative biotechnological and medical applications, perhaps most notably was the advent of mRNA vaccines that were critical in helping humanity through the Covid-19 pandemic. Unbeknownst to many, Canada boasts a diverse community of RNA scientists, spanning multiple disciplines and locations, whose cutting-edge research has established a rich track record of contributions across various aspects of RNA science over many decades. Through this position paper, we seek to highlight key contributions made by Canadian investigators to the RNA field, via both thematic and historical viewpoints. We also discuss initiatives underway to organize and enhance the impact of the Canadian RNA research community, particularly focusing on the creation of the not-for-profit organization RNA Canada ARN. Considering the strategic importance of RNA research in biology and medicine, and its considerable potential to help address major challenges facing humanity, sustained support of this sector will be critical to help Canadian scientists play key roles in the ongoing RNA revolution and the many benefits this could bring about to Canada.

Current knowledge of hybrid nanoplatforms composed of exosomes and organic/inorganic nanoparticles for disease treatment and cell/tissue imaging

Exosome-nanoparticle hybrid nanoplatforms, can be prepared by combining exosomes with different types of nanoparticles. The main purpose of combining exosomes with nanoparticles is to overcome the limitations of using each of them as drug delivery systems. Using nanoparticles for drug delivery has some limitations, such as high immunogenicity, poor cellular uptake, low biocompatibility, cytotoxicity, low stability, and rapid clearance by immune cells. However, using exosomes as drug delivery systems also has its own drawbacks, such as poor encapsulation efficiency, low production yield, and the inability to load large molecules. These limitations can be addressed by utilizing hybrid nanoplatforms. Additionally, the use of exosomes allows for targeted delivery within the hybrid system. Exosome-inorganic/organic hybrid nanoparticles may be used for both therapy and diagnosis in the future. This may lead to the development of personalized medicine using hybrid nanoparticles. However, there are a few challenges associated with this. Surface modifications, adding functional groups, surface charge adjustments, and preparing nanoparticles with the desired size are crucial to the possibility of preparing exosome-nanoparticle hybrids. Additional challenges for the successful implementation of hybrid platforms in medical treatments and diagnostics include scaling up the manufacturing process and ensuring consistent quality and reproducibility across various batches. This review focuses on various types of exosome-nanoparticle hybrid systems and also discusses the preparation and loading methods for these hybrid nanoplatforms. Furthermore, the potential applications of these hybrid nanocarriers in drug/gene delivery, disease treatment and diagnosis, and cell/tissue imaging are explained.

Polymer-DNA Carriers Co-Deliver Photosensitizer and siRNA for Light-Promoted Gene Transfection and Hypoxia-Relieved Photodynamic Therapy

Photochemical internalization is an efficient strategy relying on photodynamic reactions to promote siRNA endosomal escape for the success of RNA-interference gene regulation, which makes gene-photodynamic combined therapy highly synergistic and efficient. However, it is still desired to explore capable carriers to improve the delivery efficiency of the immiscible siRNA and organic photosensitizers simultaneously. Herein, we employ a micellar nanostructure (PSNA) self-assembled from polymer-DNA molecular chimeras to fulfill this task. PSNA can plentifully load photosensitizers in its hydrophobic core simply by the nanoprecipitation method. Moreover, it can organize siRNA self-assembly by the densely packed DNA shell, which leads to a higher loading capacity than the typical electrostatic condensation method. The experimental results prove that this PSNA carrier can greatly facilitate siRNA escape from the endosome/lysosome and enhance transfection. Accordingly, the PSNA-administrated therapy exhibits a significantly improved anti-tumor efficacy owing to the highly efficient co-delivery capability.

DNAzyme-RCA-based colorimetric and lateral flow dipstick assays for the point-of-care testing of exosomal m5C-miRNA-21

Methylation of microRNAs (miRNAs) is a post-transcriptional modification that affects miRNA activity by altering the specificity of miRNAs to target mRNAs. Abnormal methylation of miRNAs in cancer suggests their potential as a tumor marker. However, the traditional methylated miRNA detection mainly includes mass spectrometry, sequencing and others; complex procedures and reliance on large instruments greatly limit their application in point-of-care testing (POCT). Based on this, we developed DNAzyme-RCA-based gold nanoparticle (AuNP) colorimetric and lateral flow dipstick (LFD) assays to achieve convenient detection of exosomal 5-methylcytosine miRNA-21 (m5C-miRNA-21) for the first time. The two assays achieved specific recognition and linear amplification of m5C-miRNA-21 through the DNAzyme triggered RCA reaction and color output with low background interference through AuNP aggregation induced by base complementary pairing. The lowest concentration of m5C-miRNA-21 visible to the naked eye of the two assays can reach 1 pM and 0.1 pM, respectively. Detection of exosomal m5C-miRNA-21 in clinical blood samples showed that the expression level of m5C-miRNA-21 in colorectal cancer patients was significantly higher than that in healthy individuals. This approach not only demonstrates a new strategy for the detection of colorectal cancer but also provides a reference for the development of novel diagnostic tools for other miRNA methylation-related diseases.

Bioengineering extracellular vesicle cargo for optimal therapeutic efficiency

Extracellular vesicles (EVs) have the innate ability to carry proteins, lipids, and nucleic acids between cells, and thus these vesicles have gained much attention as potential therapeutic delivery vehicles. Many strategies have been explored to enhance the loading of specific cargoes of interest into EVs, which could result in the delivery of more therapeutic to recipient cells, thus enhancing therapeutic efficacy. In this review, we discuss the natural biogenesis of EVs, the mechanism by which proteins and nucleic acids are selected for inclusion in EVs, and novel methods that have been employed to enhance loading of specific cargoes into EVs. As well, we discuss biodistribution of administered EVs in vivo and summarize clinical trials that have attempted to harness the therapeutic potential of EVs.

Before Translating Extracellular Vesicles into Personalized Diagnostics and Therapeutics: What We Could Do

Extracellular vesicle (EV) research is rapidly advancing from fundamental science to translational applications in EV-based personalized therapeutics and diagnostics. Yet, fundamental questions persist regarding EV biology and mechanisms, particularly concerning the heterogeneous interactions between EVs and cells. While we have made strides in understanding virus delivery and intracellular vesicle transport, our comprehension of EV trafficking remains limited. EVs are believed to mediate intercellular communication through cargo transfer, but uncertainties persist regarding the occurrence and quantification of EV-cargo delivery within acceptor cells. This ambiguity is crucial to address, given the significant translational impact of EVs on therapeutics and diagnostics. This perspective article does not seek to provide exhaustive recommendations and guidance on EV-related studies, as these are well-articulated in position papers and statements by the International Society for Extracellular Vesicles (ISEV), including the 'Minimum Information for Studies of Extracellular Vesicles' (MISEV) 2014, MISEV2018, and the recent MISEV2023. Instead, recognizing the multilayered heterogeneity of EVs as both a challenge and an opportunity, this perspective emphasizes novel approaches to facilitate our understanding of diverse EV biology, address uncertainties, and leverage this knowledge to advance EV-based personalized diagnostics and therapeutics. Specifically, this perspective synthesizes current insights, identifies opportunities, and highlights exciting technological advancements in ultrasensitive single EV or "digital" profiling developed within the author's multidisciplinary group. These newly developed technologies address technical gaps in dissecting the molecular contents of EV subsets, contributing to the evolution of EVs as next-generation liquid biopsies for diagnostics and providing better quality control for EV-based therapeutics.

MicroRNA Nano-Shuttles: Engineering Extracellular Vesicles as a Cutting-Edge Biotechnology Platform for Clinical Use in Therapeutics

Extracellular vesicles (EVs) are nano-sized, membranous transporters of various active biomolecules with inflicting phenotypic capabilities, that are naturally secreted by almost all cells with a promising vantage point as a potential leading drug delivery platform. The intrinsic characteristics of their low toxicity, superior structural stability, and cargo loading capacity continue to fuel a multitude of research avenues dedicated to loading EVs with therapeutic and diagnostic cargos (pharmaceutical compounds, nucleic acids, proteins, and nanomaterials) in attempts to generate superior natural nanoscale delivery systems for clinical application in therapeutics. In addition to their well-known role in intercellular communication, EVs harbor microRNAs (miRNAs), which can alter the translational potential of receiving cells and thus act as important mediators in numerous biological and pathological processes. To leverage this potential, EVs can be structurally engineered to shuttle therapeutic miRNAs to diseased recipient cells as a potential targeted 'treatment' or 'therapy'. Herein, this review focuses on the therapeutic potential of EV-coupled miRNAs; summarizing the biogenesis, contents, and function of EVs, as well as providing both a comprehensive discussion of current EV loading techniques and an update on miRNA-engineered EVs as a next-generation platform piloting benchtop studies to propel potential clinical translation on the forefront of nanomedicine.

Genetically engineered loaded extracellular vesicles for drug delivery

The use of extracellular vesicles (EVs) for drug delivery is being widely explored by scientists from several research fields. To fully exploit their therapeutic potential, multiple methods for loading EVs have been developed. Although exogenous methods have been extensively utilized, in recent years the endogenous method has gained significant attention. This approach, based on parental cell genetic engineering, is suitable for loading large therapeutic biomolecules such as proteins and nucleic acids. We review the most commonly used EV loading methods and emphasize the inherent advantages of the endogenous method over the others. We also examine the most recent advances and applications of this innovative approach to inform on the diverse therapeutic opportunities that lie ahead in the field of EV-based therapies.

Regulation of cargo selection in exosome biogenesis and its biomedical applications in cancer

Extracellular vesicles (EVs), including exosomes, are increasingly recognized as potent mediators of intercellular communication due to their capacity to transport a diverse array of bioactive molecules. They assume vital roles in a wide range of physiological and pathological processes and hold significant promise as emerging disease biomarkers, therapeutic agents, and carriers for drug delivery. Exosomes encompass specific groups of membrane proteins, lipids, nucleic acids, cytosolic proteins, and other signaling molecules within their interior. These cargo molecules dictate targeting specificity and functional roles upon reaching recipient cells. Despite our growing understanding of the significance of exosomes in diverse biological processes, the molecular mechanisms governing the selective sorting and packaging of cargo within exosomes have not been fully elucidated. In this review, we summarize current insights into the molecular mechanisms that regulate the sorting of various molecules into exosomes, the resulting biological functions, and potential clinical applications, with a particular emphasis on their relevance in cancer and other diseases. A comprehensive understanding of the loading processes and mechanisms involved in exosome cargo sorting is essential for uncovering the physiological and pathological roles of exosomes, identifying therapeutic targets, and advancing the clinical development of exosome-based therapeutics.

Systems Approaches to Cell Culture-Derived Extracellular Vesicles for Acute Kidney Injury Therapy: Prospects and Challenges

Acute kidney injury (AKI) is a heterogeneous syndrome, comprising diverse etiologies of kidney insults that result in high mortality and morbidity if not well managed. Although great efforts have been made to investigate underlying pathogenic mechanisms of AKI, there are limited therapeutic strategies available. Extracellular vesicles (EV) are membrane-bound vesicles secreted by various cell types, which can serve as cell-free therapy through transfer of bioactive molecules. In this review, we first overview the AKI syndrome and EV biology, with a particular focus on the technical aspects and therapeutic application of cell culture-derived EVs. Second, we illustrate how multi-omic approaches to EV miRNA, protein, and genomic cargo analysis can yield new insights into their mechanisms of action and address unresolved questions in the field. We then summarize major experimental evidence regarding the therapeutic potential of EVs in AKI, which we subdivide into stem cell and non-stem cell-derived EVs. Finally, we highlight the challenges and opportunities related to the clinical translation of animal studies into human patients.

Extracellular Vesicles: A New Star for Gene Drug Delivery

Recently, gene therapy has become a subject of considerable research and has been widely evaluated in various disease models. Though it is considered as a stand-alone agent for COVID-19 vaccination, gene therapy is still suffering from the following drawbacks during its translation from the bench to the bedside: the high sensitivity of exogenous nucleic acids to enzymatic degradation; the severe side effects induced either by exogenous nucleic acids or components in the formulation; and the difficulty to cross the barriers before reaching the therapeutic target. Therefore, for the successful application of gene therapy, a safe and reliable transport vector is urgently needed. Extracellular vesicles (EVs) are the ideal candidate for the delivery of gene drugs owing to their low immunogenicity, good biocompatibility and low toxicity. To better understand the properties of EVs and their advantages as gene drug delivery vehicles, this review covers from the origin of EVs to the methods of EVs generation, as well as the common methods of isolation and purification in research, with their pros and cons discussed. Meanwhile, the engineering of EVs for gene drugs is also highlighted. In addition, this paper also presents the progress in the EVs-mediated delivery of microRNAs, small interfering RNAs, messenger RNAs, plasmids, and antisense oligonucleotides. We believe this review will provide a theoretical basis for the development of gene drugs.

Extracellular vesicles from differentiated stem cells contain novel proangiogenic miRNAs and induce angiogenic responses at low doses

Extracellular vesicles (EVs) released from healthy endothelial cells (ECs) have shown potential for promoting angiogenesis, but their therapeutic efficacy remains poorly understood. We have previously shown that transplantation of a human embryonic stem cell-derived endothelial cell product (hESC-ECP), promotes new vessel formation in acute ischemic disease in mice, likely via paracrine mechanism(s). Here, we demonstrated that EVs from hESC-ECPs (hESC-eEVs) significantly increased EC tube formation and wound closure in vitro at ultralow doses, whereas higher doses were ineffective. More important, EVs isolated from the mesodermal stage of the differentiation (hESC-mEVs) had no effect. Small RNA sequencing revealed that hESC-eEVs have a unique transcriptomic profile and are enriched in known proangiogenic microRNAs (miRNAs, miRs). Moreover, an in silico analysis identified three novel hESC-eEV-miRNAs with potential proangiogenic function. Differential expression analysis suggested that two of those, miR-4496 and miR-4691-5p, are highly enriched in hESC-eEVs. Overexpression of miR-4496 or miR-4691-5p resulted in increased EC tube formation and wound closure in vitro, validating the novel proangiogenic function of these miRNAs. In summary, we demonstrated that hESC-eEVs are potent inducers of EC angiogenic response at ultralow doses and contain a unique EV-associated miRNA repertoire, including miR-4496 and miR-4691-5p, with novel proangiogenic function.

Effective exosomes in breast cancer: focusing on diagnosis and treatment of cancer progression

Breast cancer (BC) is the most prevalent aggressive malignant tumor in women worldwide and develops from breast tissue. Although cutting-edge treatment methods have been used and current mortality rates have decreased, BC control is still not satisfactory. Clarifying the underlying molecular mechanisms will help clinical options. Extracellular vesicles known as exosomes mediate cellular communication by delivering a variety of biomolecules, including proteins, oncogenes, oncomiRs, and even pharmacological substances. These transferable bioactive molecules can alter the transcriptome of target cells and affect signaling pathways that are related to tumors. Numerous studies have linked exosomes to BC biology, including therapeutic resistance and the local microenvironment. Exosomes' roles in tumor treatment resistance, invasion, and BC metastasis are the main topics of discussion in this review.

Intercellular Molecular Transfer Mediated by Extracellular Vesicles in Cancer

Among multiple pathways of intercellular communication operative in multicellular organisms, the trafficking of extracellular vesicles (EVs) and particles (EP) represents a unique mode of cellular information exchange with emerging roles in health and disease, including cancer. A distinctive feature of EV/EP-mediated cell-cell communication is that it involves simultaneous short- or long-range transfer of numerous molecular constituents (cargo) from donor to recipient cells. EV/EP uptake by donor cells elicits signalling or metabolic responses, or else leads to EV-re-emission or degradation. EVs are heterogeneous membranous structures released from cells via increasingly defined mechanisms involving either formation of multivesicular endosomes (exosomes) or budding from the plasma membrane (ectosomes). EPs (exomeres, supermeres) are membraneless complex particles, smaller than EVs and of less defined biogenesis and function. EVs/EPs carry complex assemblies of proteins, lipids and nucleic acids (RNA, DNA), which they shuttle into intercellular milieu, body fluids and recipient cells, via surface contact, fusion and different forms of internalization (endocytosis, micropinocytosis). While the physiological functions of EVs/EPs communication pathways continue to be investigated, their roles in cancer are increasingly well-defined. For example, EVs are involved in the transmission of cancer-specific molecular cargo, including mutant, oncogenic, transforming, or regulatory macromolecules to indolent, or normal cells, sometimes triggering their quasi-transformation-like states, or phenotypic alterations. Conversely, a reciprocal and avid uptake of stromal EVs by cancer cells may be responsible for modulating their oncogenic repertoire, as exemplified by the angiocrine effects of endothelial EVs influencing cancer cell stemness. EV exchanges during cancer progression have also been implicated in the formation of tumour stroma, angiogenesis and non-angiogenic neovascularization processes, immunosuppression, colonization of metastatic organ sites (premetastatic niche), paraneoplastic and systemic pathologies (thrombosis, diabetes, hepatotoxicity). Thus, an EV/EP-mediated horizontal transfer of cellular content emerges as a new dimension in cancer pathogenesis with functional, diagnostic, and therapeutic implications.

Adventitial delivery of miR-145 to treat intimal hyperplasia post vascular injuries through injectable and in-situ self-assembling peptide hydrogels

Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. To develop a vascular adventitial drug delivery system to treat intimal hyperplasia post vascular injuries, we loaded miR-145-5p-agomir (miR-145) into an injectable and in-situ self-assembling RAD peptide hydrogel. In vitro data showed that the miR-145 could be well incorporated into the RAD peptide hydrogels and released in a slow and controlled manner. The released miR-145 could transfect SMCs successfully, and the transfected SMCs exhibited a reduced migration capacity and higher expressions of SMC contractile biomarkers as compared to the non-transfected SMCs. In vivo data showed that the retention of the miR-145 was greatly elongated by the RAD peptide hydrogels. In addition, the application of the miR-145-loaded RAD peptide hydrogels surrounding injured arteries decreased the proliferative SMCs, promoted the regeneration of endothelium, reduced the macrophage infiltration, inhibited the neointimal formation and prevented adverse ECM remodeling via downregulation of KLF4 expression. The RAD peptide hydrogels loaded with miR-145 can successfully inhibit intimal hyperplasia after vascular injuries and thus hold great potential as an innovative extravascular drug delivery approach to treat vascular diseases. STATEMENT OF SIGNIFICANCE: Intimal hyperplasia is a common lesion that can be observed in diverse vascular diseases. Drug-eluting stents and drug-coated balloons, which can release anti-proliferative agents to inhibit smooth muscle cell (SMC) proliferation, are developed to prevent intimal hyperplasia. However, these intervention devices still cannot achieve satisfactory clinical outcomes. In contrast to endovascular drug delivery, vascular adventitial drug delivery is a new strategy. Our work here demonstrates that the RAD peptide hydrogels loaded with miR-145-5p-agomir (miR-145) can successfully reverse intimal hyperplasia after vascular injuries and thus hold great potential as an innovative vascular adventitial drug delivery approach to treat vascular diseases. Our work proposes a possible paradigm shift from endovascular drug delivery to extravascular drug delivery for vascular disorder treatment.

Engineering HEK293T cell line by lentivirus to produce miR34a-loaded exosomes

BACKGROUND

RNA (ribonucleic acid) antisense is developing as a possible treatment option. As an RNA, miR-34a is involved in P53 function and cancer cell apoptosis. Although the therapeutic applications of miRNAs have several limitations, such as structural instability and susceptibility to nucleases. To resolve these issues, this study aims to apply exosomes as a delivery vehicle for miR-34a.

AIMS

This study aims to create a cell factory to generate miR34a-enriched exosomes. The produced nanoparticles act as a delivery system and improve the structural stability of miR34a.

METHODS

First exosome specific sequences were inserted into miR34a. The resulting miR34a oligonucleotide was transduced HEK293T cells genome with a lentiviral system. In the structure of miR34a oligonucleotide, six nucleotides were substituted to increase its packaging rate into exosomes. To maintain the secondary structure, stability, and expression of the miRNA gene, changes to the miR34a oligonucleotide were made using PCR (polymerase chain reaction) Extension. The forward-34a (5-TGGGGAGAGGCAGGACAGG-3) and Reverse-34a primers (5-TCCGAAGTCCTGGCGTCTCC-3) were used for amplification of the miR34a gene from DNA.

RESULTS

The results confirmed that the changes in miR34a oligonucleotide do not affect its secondary structure. The energy level of the manipulated miR34a oligonucleotide was kept the same compared to the original one. Moreover, the loading of miR34a to the exosomes was increased.

CONCLUSION

Our findings revealed that normal HEK293T did not express miR34a. However, lentiviral transduced miR34a oligonucleotide induced the loading of miR34a into the exosome. Moreover, replacing six nucleic acids in the 3' end of miR34a increased the loading of miR34a to exosome.

Cell-free therapy based on extracellular vesicles: a promising therapeutic strategy for peripheral nerve injury

Peripheral nerve injury (PNI) is one of the public health concerns that can result in a loss of sensory or motor function in the areas in which injured and non-injured nerves come together. Up until now, there has been no optimized therapy for complete nerve regeneration after PNI. Exosome-based therapies are an emerging and effective therapeutic strategy for promoting nerve regeneration and functional recovery. Exosomes, as natural extracellular vesicles, contain bioactive molecules for intracellular communications and nervous tissue function, which could overcome the challenges of cell-based therapies. Furthermore, the bioactivity and ability of exosomes to deliver various types of agents, such as proteins and microRNA, have made exosomes a potential approach for neurotherapeutics. However, the type of cell origin, dosage, and targeted delivery of exosomes still pose challenges for the clinical translation of exosome therapeutics. In this review, we have focused on Schwann cell and mesenchymal stem cell (MSC)-derived exosomes in nerve tissue regeneration. Also, we expressed the current understanding of MSC-derived exosomes related to nerve regeneration and provided insights for developing a cell-free MSC therapeutic strategy for nerve injury.

Application of exosome engineering modification in targeted delivery of therapeutic drugs

Cancer is the leading cause of premature death in humans. Scientists have developed several therapeutic drugs for cancer treatment. However, drug delivery faces many problems. First, traditional drugs do not target tumors and are prone to causing significant toxic side effects. Second, suitable drug carriers are essential for improving drug delivery to tumors or circulating cancer cells. Exosomes are natural extracellular vesicles with low immunogenicity and prolonged blood circulation in vivo. These characteristics render exosomes ideal drug carriers. This review highlights the properties of exosomes and mechanisms of exosome biogenesis. It also summarizes the engineering modification methods for enhancing exosome yield, targeting, and drug-loading capacity.

Extracellular vesicle-mediated protein delivery to the liver

Extracellular vesicles (EVs) are nanoscale particles that facilitate intercellular communication. They are regarded as a promising natural drug delivery system for transporting and delivering bioactive macromolecules to target cells. Recently, researchers have engineered EVs with FKBP12/FRB heterodimerization domains that interact with rapamycin to load and deliver exogenous proteins for both in vitro and in vivo applications. In this study, we examined the tissue distribution of EVs using near-infrared fluorescent imaging. We evaluated the effectiveness of EV-mediated delivery of Cre recombinase specifically to hepatocytes in the livers of Ai9 Cre-loxP reporter mice. Intravenous injection resulted in more efficient Cre protein delivery to the liver than intraperitoneal injections. Depleting liver-resident macrophages with clodronate-encapsulated liposome pre-treatment did not enhance EV-mediated Cre delivery to hepatocytes. Moreover, we demonstrated that multiple intravenous injections of Cre-EVs facilitated functional Cre delivery to hepatocytes. To the best of our knowledge, this is the first study to simultaneously investigate the tissue distribution of FKBP12/FRB-engineered EVs and their subsequent intracellular protein delivery in Ai9 Cre-loxP reporter mice. These insights can inform preclinical research and contribute to developing next-generation EV-based platforms for delivering therapeutic proteins or genome editing technologies targeting the liver.

Cardiac progenitor cell-derived extracellular vesicles promote angiogenesis through both associated- and co-isolated proteins

Extracellular vesicles (EVs) are cell-derived lipid bilayer-enclosed particles that play a role in intercellular communication. Cardiac progenitor cell (CPC)-derived EVs have been shown to protect the myocardium against ischemia-reperfusion injury via pro-angiogenic effects. However, the mechanisms underlying CPC-EV-induced angiogenesis remain elusive. Here, we discovered that the ability of CPC-EVs to induce in vitro angiogenesis and to stimulate pro-survival pathways was lost upon EV donor cell exposure to calcium ionophore. Proteomic comparison of active and non-active EV preparations together with phosphoproteomic analysis of activated endothelial cells identified the contribution of candidate protein PAPP-A and the IGF-R signaling pathway in EV-mediated cell activation, which was further validated using in vitro angiogenesis assays. Upon further purification using iodixanol gradient ultracentrifugation, EVs partly lost their activity, suggesting a co-stimulatory role of co-isolated proteins in recipient cell activation. Our increased understanding of the mechanisms of CPC-EV-mediated cell activation will pave the way to more efficient EV-based therapeutics.

A Review of Extracellular Vesicles in COVID-19 Diagnosis, Treatment, and Prevention

The 2019 novel coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing, and has necessitated scientific efforts in disease diagnosis, treatment, and prevention. Interestingly, extracellular vesicles (EVs) have been crucial in these developments. EVs are a collection of various nanovesicles which are delimited by a lipid bilayer. They are enriched in proteins, nucleic acids, lipids, and metabolites, and naturally released from different cells. Their natural material transport properties, inherent long-term recycling ability, excellent biocompatibility, editable targeting, and inheritance of parental cell properties make EVs one of the most promising next-generation drug delivery nanocarriers and active biologics. During the COVID-19 pandemic, many efforts have been made to exploit the payload of natural EVs for the treatment of COVID-19. Furthermore, strategies that use engineered EVs to manufacture vaccines and neutralization traps have produced excellent efficacy in animal experiments and clinical trials. Here, the recent literature on the application of EVs in COVID-19 diagnosis, treatment, damage repair, and prevention is reviewed. And the therapeutic value, application strategies, safety, and biotoxicity in the production and clinical applications of EV agents for COVID-19 treatment, as well as inspiration for using EVs to block and eliminate novel viruses are discussed.

Engineered high-strength biohydrogel as a multifunctional platform to deliver nucleic acid for ameliorating intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is a leading cause of low back pain. The strategy of using functional materials to deliver nucleic acids provides a powerful tool for ameliorating IVDD. However, the immunogenicity of nucleic acid vectors and the poor mechanical properties of functional materials greatly limit their effects. Herein, antagomir-204-3p (AM) shows low immunogenicity and effectively inhibits the apoptosis of nucleus pulposus cells. Moreover, a high-strength biohydrogel based on zinc-oxidized sodium alginate-gelatin (ZOG) is designed as a multifunctional nucleic acid delivery platform. ZOG loaded with AM (ZOGA) exhibits great hygroscopicity, antibacterial activity, biocompatibility, and biodegradability. Moreover, ZOGA can be cross-linked with nucleus pulposus tissue to form a high-strength collagen network that improves the mechanical properties of the intervertebral disc (IVD). In addition, ZOGA provides an advantageous microenvironment for genetic expression in which AM can play an efficient role in maintaining the metabolic balance of the extracellular matrix. The results of the radiological and histological analyses demonstrate that ZOGA restores the height of the IVD, retains moisture in the IVD, and maintains the tissue structure. The ZOGA platform shows the sustained release of nucleic acids and has the potential for application to ameliorate IVDD, opening a path for future studies related to IVD.

Context-specific regulation of extracellular vesicle biogenesis and cargo selection

To coordinate, adapt and respond to biological signals, cells convey specific messages to other cells. An important aspect of cell-cell communication involves secretion of molecules into the extracellular space. How these molecules are selected for secretion has been a fundamental question in the membrane trafficking field for decades. Recently, extracellular vesicles (EVs) have been recognized as key players in intercellular communication, carrying not only membrane proteins and lipids but also RNAs, cytosolic proteins and other signalling molecules to recipient cells. To communicate the right message, it is essential to sort cargoes into EVs in a regulated and context-specific manner. In recent years, a wealth of lipidomic, proteomic and RNA sequencing studies have revealed that EV cargo composition differs depending upon the donor cell type, metabolic cues and disease states. Analyses of distinct cargo 'fingerprints' have uncovered mechanistic linkages between the activation of specific molecular pathways and cargo sorting. In addition, cell biology studies are beginning to reveal novel biogenesis mechanisms regulated by cellular context. Here, we review context-specific mechanisms of EV biogenesis and cargo sorting, focusing on how cell signalling and cell state influence which cellular components are ultimately targeted to EVs.

Small extracellular vesicles: a novel drug delivery system for neurodegenerative disorders

Neurodegenerative diseases (NDs) have a slow onset and are usually detected late during disease. NDs are often difficult to cure due to the presence of the blood-brain barrier (BBB), which makes it difficult to find effective treatments and drugs, causing great stress and financial burden to families and society. Currently, small extracellular vesicles (sEVs) are the most promising drug delivery systems (DDSs) for targeted delivery of molecules to specific sites in the brain as a therapeutic vehicle due to their low toxicity, low immunogenicity, high stability, high delivery efficiency, high biocompatibility and trans-BBB functionality. Here, we review the therapeutic application of sEVs in several NDs, including Alzheimer's disease, Parkinson's disease, and Huntington's disease, discuss the current barriers associated with sEVs and brain-targeted DDS, and suggest future research directions.

Current Strategies for Exosome Cargo Loading and Targeting Delivery

Extracellular vesicles (EVs) such as ectosomes and exosomes have gained attention as promising natural carriers for drug delivery. Exosomes, which range from 30 to 100 nm in diameter, possess a lipid bilayer and are secreted by various cells. Due to their high biocompatibility, stability, and low immunogenicity, exosomes are favored as cargo carriers. The lipid bilayer membrane of exosomes also offers protection against cargo degradation, making them a desirable candidate for drug delivery. However, loading cargo into exosomes remains to be a challenge. Despite various strategies such as incubation, electroporation, sonication, extrusion, freeze-thaw cycling, and transfection that have been developed to facilitate cargo loading, inadequate efficiency still persists. This review offers an overview of current cargo delivery strategies using exosomes and summarizes recent approaches for loading small-molecule, nucleic acid, and protein drugs into exosomes. With insights from these studies, we provide ideas for more efficient and effective delivery of drug molecules by using exosomes.

Exploiting the biogenesis of extracellular vesicles for bioengineering and therapeutic cargo loading

Extracellular vesicles (EVs) are gaining increasing attention for diagnostic and therapeutic applications in various diseases. These natural nanoparticles benefit from favorable safety profiles and unique biodistribution capabilities, rendering them attractive drug-delivery modalities over synthetic analogs. However, the widespread use of EVs is limited by technological shortcomings and biological knowledge gaps that fail to unravel their heterogeneity. An in-depth understanding of their biogenesis is crucial to unlocking their full therapeutic potential. Here, we explore how knowledge about EV biogenesis can be exploited for EV bioengineering to load therapeutic protein or nucleic acid cargos into or onto EVs. We summarize more than 75 articles and discuss their findings on the formation and composition of exosomes and microvesicles, revealing multiple pathways that may be stimulation and/or cargo dependent. Our analysis further identifies key regulators of natural EV cargo loading and we discuss how this knowledge is integrated to develop engineered EV biotherapeutics.

Extracellular vesicle-based delivery of silencing sequences for the treatment of Machado-Joseph disease/spinocerebellar ataxia type 3

Machado-Joseph disease (MJD)/spinocerebellar ataxia type 3 (SCA3) is the most common autosomal dominantly inherited ataxia worldwide. It is caused by an over-repetition of the trinucleotide CAG within the ATXN3 gene, which confers toxic properties to ataxin-3 (ATXN3) species. RNA interference technology has shown promising therapeutic outcomes but still lacks a non-invasive delivery method to the brain. Extracellular vesicles (EVs) emerged as promising delivery vehicles due to their capacity to deliver small nucleic acids, such as microRNAs (miRNAs). miRNAs were found to be enriched into EVs due to specific signal motifs designated as ExoMotifs. In this study, we aimed at investigating whether ExoMotifs would promote the packaging of artificial miRNAs into EVs to be used as non-invasive therapeutic delivery vehicles to treat MJD/SCA3. We found that miRNA-based silencing sequences, associated with ExoMotif GGAG and ribonucleoprotein A2B1 (hnRNPA2B1), retained the capacity to silence mutant ATXN3 (mutATXN3) and were 3-fold enriched into EVs. Bioengineered EVs containing the neuronal targeting peptide RVG on the surface significantly decreased mutATXN3 mRNA in primary cerebellar neurons from MJD YAC 84.2 and in a novel dual-luciferase MJD mouse model upon daily intranasal administration. Altogether, these findings indicate that bioengineered EVs carrying miRNA-based silencing sequences are a promising delivery vehicle for brain therapy.

Interdisciplinary advances reshape the delivery tools for effective NASH treatment

BACKGROUND

Nonalcoholic steatohepatitis (NASH), a severe systemic and inflammatory subtype of nonalcoholic fatty liver disease, eventually develops into cirrhosis and hepatocellular carcinoma with few options for effective treatment. Currently potent small molecules identified in preclinical studies are confronted with adverse effects and long-term ineffectiveness in clinical trials. Nevertheless, highly specific delivery tools designed from interdisciplinary concepts may address the significant challenges by either effectively increasing the concentrations of drugs in target cell types, or selectively manipulating the gene expression in liver to resolve NASH.

SCOPE OF REVIEW

We focus on dissecting the detailed principles of the latest interdisciplinary advances and concepts that direct the design of future delivery tools to enhance the efficacy. Recent advances have indicated that cell and organelle-specific vehicles, non-coding RNA research (e.g. saRNA, hybrid miRNA) improve the specificity, while small extracellular vesicles and coacervates increase the cellular uptake of therapeutics. Moreover, strategies based on interdisciplinary advances drastically elevate drug loading capacity and delivery efficiency and ameliorate NASH and other liver diseases.

MAJOR CONCLUSIONS

The latest concepts and advances in chemistry, biochemistry and machine learning technology provide the framework and strategies for the design of more effective tools to treat NASH, other pivotal liver diseases and metabolic disorders.

Extracellular Vesicles for Therapeutic Nucleic Acid Delivery: Loading Strategies and Challenges

Extracellular vesicles (EVs) are membrane vesicles released into the extracellular milieu by cells of various origins. They contain different biological cargoes, protecting them from degradation by environmental factors. There is an opinion that EVs have a number of advantages over synthetic carriers, creating new opportunities for drug delivery. In this review, we discuss the ability of EVs to function as carriers for therapeutic nucleic acids (tNAs), challenges associated with the use of such carriers in vivo, and various strategies for tNA loading into EVs.

Exosome-Based Carrier for RNA Delivery: Progress and Challenges

In the last few decades, RNA-based drugs have emerged as a promising candidate to specifically target and modulate disease-relevant genes to cure genetic defects. The key to applying RNA therapy in clinical trials is developing safe and effective delivery systems. Exosomes have been exploited as a promising vehicle for drug delivery due to their nanoscale size, high stability, high biocompatibility, and low immunogenicity. We reviewed and summarized the progress in the strategy and application of exosome-mediated RNA therapy. The challenges of exosomes as a carrier for RNA drug delivery are also elucidated in this article. RNA molecules can be loaded into exosomes and then delivered to targeted cells or tissues via various biochemical or physical approaches. So far, exosome-mediated RNA therapy has shown potential in the treatment of cancer, central nervous system disorders, COVID-19, and other diseases. To further exploit the potential of exosomes for RNA delivery, more efforts should be made to overcome both technological and logistic problems.

CAR-T-Derived Extracellular Vesicles: A Promising Development of CAR-T Anti-Tumor Therapy

Extracellular vesicles (EVs) are a heterogenous population of plasma membrane-surrounded particles that are released in the extracellular milieu by almost all types of living cells. EVs are key players in intercellular crosstalk, both locally and systemically, given that they deliver their cargoes (consisting of proteins, lipids, mRNAs, miRNAs, and DNA fragments) to target cells, crossing biological barriers. Those mechanisms further trigger a wide range of biological responses. Interestingly, EV phenotypes and cargoes and, therefore, their functions, stem from their specific parental cells. For these reasons, EVs have been proposed as promising candidates for EV-based, cell-free therapies. One of the new frontiers of cell-based immunotherapy for the fight against refractory neoplastic diseases is represented by genetically engineered chimeric antigen receptor T (CAR-T) lymphocytes, which in recent years have demonstrated their effectiveness by reaching commercialization and clinical application for some neoplastic diseases. CAR-T-derived EVs represent a recent promising development of CAR-T immunotherapy approaches. This crosscutting innovative strategy is designed to exploit the advantages of genetically engineered cell-based immunotherapy together with those of cell-free EVs, which in principle might be safer and more efficient in crossing biological and tumor-associated barriers. In this review, we underlined the potential of CAR-T-derived EVs as therapeutic agents in tumors.

Ionizable lipid nanoparticles deliver mRNA to pancreatic β cells via macrophage-mediated gene transfer

Systemic messenger RNA (mRNA) delivery to organs outside the liver, spleen, and lungs remains challenging. To overcome this issue, we hypothesized that altering nanoparticle chemistry and administration routes may enable mRNA-induced protein expression outside of the reticuloendothelial system. Here, we describe a strategy for delivering mRNA potently and specifically to the pancreas using lipid nanoparticles. Our results show that delivering lipid nanoparticles containing cationic helper lipids by intraperitoneal administration produces robust and specific protein expression in the pancreas. Most resultant protein expression occurred within insulin-producing β cells. Last, we found that pancreatic mRNA delivery was dependent on horizontal gene transfer by peritoneal macrophage exosome secretion, an underappreciated mechanism that influences the delivery of mRNA lipid nanoparticles. We anticipate that this strategy will enable gene therapies for intractable pancreatic diseases such as diabetes and cancer.

CRISPR/Cas9 therapeutics: progress and prospects

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene-editing technology is the ideal tool of the future for treating diseases by permanently correcting deleterious base mutations or disrupting disease-causing genes with great precision and efficiency. A variety of efficient Cas9 variants and derivatives have been developed to cope with the complex genomic changes that occur during diseases. However, strategies to effectively deliver the CRISPR system to diseased cells in vivo are currently lacking, and nonviral vectors with target recognition functions may be the focus of future research. Pathological and physiological changes resulting from disease onset are expected to serve as identifying factors for targeted delivery or targets for gene editing. Diseases are both varied and complex, and the choice of appropriate gene-editing methods and delivery vectors for different diseases is important. Meanwhile, there are still many potential challenges identified when targeting delivery of CRISPR/Cas9 technology for disease treatment. This paper reviews the current developments in three aspects, namely, gene-editing type, delivery vector, and disease characteristics. Additionally, this paper summarizes successful examples of clinical trials and finally describes possible problems associated with current CRISPR applications.

Renal Endothelial Cell-Targeted Extracellular Vesicles Protect the Kidney from Ischemic Injury

Endothelial cell injury plays a critical part in ischemic acute kidney injury (AKI) and participates in the progression of AKI. Targeting renal endothelial cell therapy may ameliorate vascular injury and further improve the prognosis of ischemic AKI. Here, P-selectin as a biomarker of ischemic AKI in endothelial cells is identified and P-selectin binding peptide (PBP)-engineered extracellular vesicles (PBP-EVs) with imaging and therapeutic functions are developed. The results show that PBP-EVs exhibit a selective targeting tendency to injured kidneys, while providing spatiotemporal information for the early diagnosis of AKI by quantifying the expression of P-selectin in the kidneys by molecular imaging. Meanwhile, PBP-EVs reveal superior nephroprotective functions in the promotion of renal repair and inhibition of fibrosis by alleviating inflammatory infiltration, improving reparative angiogenesis, and ameliorating maladaptive repair of the renal parenchyma. In conclusion, PBP-EVs, as an ischemic AKI theranostic system that is designed in this study, provide a spatiotemporal diagnosis in the early stages of AKI to help guide personalized therapy and exhibit superior nephroprotective effects, offering proof-of-concept data to design EV-based theranostic strategies to promote renal recovery and further improve long-term outcomes following AKI.

The exosome: a review of current therapeutic roles and capabilities in human reproduction

Exosomes are nano-vesicles (30-150 nm) which may be useful as therapeutic delivery vehicles and as diagnostic biomarkers. Exosomes are produced naturally within the human body and therefore are not prone to immunogenicity effects which would otherwise destroy unelicited foreign bodies. Clinically, they have been regarded as ideal candidates for applications relating to biomarker developments for the early detection of different diseases. Furthermore, exosomes may be of interest as potential drug delivery vehicles, which may improve factors such as bioavailability of loaded molecular cargo, side effect profiles, off-target effects, and pharmacokinetics of drug molecules. In this review, the therapeutic potential of exosomes and their use as clinical biomarkers for early diagnostics will be explored, alongside exosomes as therapeutic delivery vehicles. This review will evaluate techniques for cargo loading, and the capacity of loaded exosomes to improve various reproductive disease states. It becomes important, therefore, to consider factors such as loading efficiency, loading methods, cell viability, exosomal sources, exosome isolation, and the potential therapeutic benefits of exosomes. Issues related to targeted drug delivery will also be discussed. Finally, the variety of therapeutic cargo and the application of appropriate loading methods is explored, in the context of establishing clinical utility. Exosomes have more recently been widely accpeted as potential tools for disease diagnostics and the targeted delivery of certain therapeutic molecules-and in due time exosomes will be utilised more commonly within the clinical setting. Specifically, exosomal biomarkers can be identified and related to various detrimental conditions which occur during pregnancy. Considering, this review will explore the potential future of exosomes as both diagnostic tools and therapeutic delivery vehicles to treat related conditions, including the challenges which exist towards incorporating exosomes within the clinical environment to benefit patients.

A panel of blood-derived miRNAs with a stable expression pattern as a potential pan-cancer detection signature

Introduction: MicroRNAs have a significant role in the regulation of the transcriptome. Several miRNAs have been proposed as potential biomarkers in different malignancies. However, contradictory results have been reported on the capability of miRNA biomarkers in cancer detection. The human biological clock involves molecular mechanisms that regulate several genes over time. Therefore, the sampling time becomes one of the significant factors in gene expression studies. Method: In the present study, we have tried to find miRNAs with minimum fluctuation in expression levels at different time points that could be more accurate candidates as diagnostic biomarkers. The small RNA-seq raw data of ten healthy individuals across nine-time points were analyzed to identify miRNAs with stable expression. Results: We have found five oscillation patterns. The stable miRNAs were investigated in 779 small-RNA-seq datasets of eleven cancer types. All miRNAs with the highest differential expression were selected for further analysis. The selected miRNAs were explored for functional pathways. The predominantly enriched pathways were miRNA in cancer and the P53-signaling pathway. Finally, we have found seven miRNAs, including miR-142-3p, miR-199a-5p, miR-223-5p, let-7d-5p, miR-148b-3p, miR-340-5p, and miR-421. These miRNAs showed minimum fluctuation in healthy blood and were dysregulated in the blood of eleven cancer types. Conclusion: We have found a signature of seven stable miRNAs which dysregulate in several cancer types and may serve as potential pan-cancer biomarkers.

From Promise to Reality: Bioengineering Strategies to Enhance the Therapeutic Potential of Extracellular Vesicles

Extracellular vesicles (EVs) have been the focus of great attention over the last decade, considering their promising application as next-generation therapeutics. EVs have emerged as relevant mediators of intercellular communication, being associated with multiple physiological processes, but also in the pathogenesis of several diseases. Given their natural ability to shuttle messages between cells, EVs have been explored both as inherent therapeutics in regenerative medicine and as drug delivery vehicles targeting multiple diseases. However, bioengineering strategies are required to harness the full potential of EVs for therapeutic use. For that purpose, a good understanding of EV biology, from their biogenesis to the way they are able to shuttle messages and establish interactions with recipient cells, is needed. Here, we review the current state-of-the-art on EV biology, complemented by representative examples of EVs roles in several pathophysiological processes, as well as the intrinsic therapeutic properties of EVs and paradigmatic strategies to produce and develop engineered EVs as next-generation drug delivery systems.

Functional Intercellular Transmission of miHTT via Extracellular Vesicles: An In Vitro Proof-of-Mechanism Study

Huntington's disease (HD) is a fatal neurodegenerative disorder caused by GAG expansion in exon 1 of the huntingtin (HTT) gene. AAV5-miHTT is an adeno-associated virus serotype 5-based vector expressing an engineered HTT-targeting microRNA (miHTT). Preclinical studies demonstrate the brain-wide spread of AAV5-miHTT following a single intrastriatal injection, which is partly mediated by neuronal transport. miHTT has been previously associated with extracellular vesicles (EVs), but whether EVs mediate the intercellular transmission of miHTT remains unknown. A contactless culture system was used to evaluate the transport of miHTT, either from a donor cell line overexpressing miHTT or AAV5-miHTT transduced neurons. Transfer of miHTT to recipient (HEK-293T, HeLa, and HD patient-derived neurons) cells was observed, which significantly reduced HTT mRNA levels. miHTT was present in EV-enriched fractions isolated from culture media. Immunocytochemical and in situ hybridization experiments showed that the signal for miHTT and EV markers co-localized, confirming the transport of miHTT within EVs. In summary, we provide evidence that an engineered miRNA-miHTT-is loaded into EVs, transported across extracellular space, and taken up by neighboring cells, and importantly, that miHTT is active in recipient cells downregulating HTT expression. This represents an additional mechanism contributing to the widespread biodistribution of AAV5-miHTT.

Manufactured extracellular vesicles as human therapeutics: challenges, advances, and opportunities

Extracellular vesicles (EVs) have evolved across all phyla as an intercellular communication system. There are intrinsic advantages of leveraging this capability to deliver therapeutic cargo to treat disease, which have been demonstrated in numerous in vivo studies. As with other new modalities, the challenge has now shifted from proof of concept to developing reliable and efficient large-scale infrastructure to manufacture consistently pure and potent drug for broad-based patient access. This review focuses on how this challenge has been met with both existing and emerging technology platforms that are making impressive strides in the industrialization of EV manufacturing. In addition, we also highlight the gaps and opportunities that are beginning to be explored and addressed to hasten ushering in the era of therapeutic EVs.

Research progress in membrane fusion-based hybrid exosomes for drug delivery systems

Liposomes are the earliest and most widely used nanoparticles for targeted drug delivery. Exosomes are nanosized membrane-bound particles and important mediators of intercellular communication. Combining liposomes and exosomes using various membrane fusion methods gives rise to a novel potential drug delivery system called membrane fusion-based hybrid exosomes (MFHE). These novel MFHEs not only exhibit potential advantageous features, such as high drug loading rate and targeted cellular uptake via surface modification, but are also endowed with high biocompatibility and low immunogenicity. Here, we provide an overview of MFHEs’ various preparation methods, characterization strategies, and their applications for disease treatment and scientific research.

Current Knowledge on Exosome Biogenesis, Cargo-Sorting Mechanism and Therapeutic Implications

Extracellular vesicles (EVs) are nanoscale membrane vesicles released by donor cells that can be taken up by recipient cells. The study of EVs has the potential to identify unknown cellular and molecular mechanisms in intercellular communication and disease. Exosomes, with an average diameter of ≈100 nanometers, are a subset of EVs. Different molecular families have been shown to be involved in the formation of exosomes and subsequent secretion of exosomes, which largely leads to the complexity of the form, structure and function of exosomes. In addition, because of their low immunogenicity and ability to transfer a variety of bioactive components to recipient cells, exosomes are regarded as effective drug delivery systems. This review summarizes the known mechanisms of exosomes biogenesis, cargo loading, exosomes release and bioengineering, which is of great importance for further exploration into the clinical applications of EVs.

Near-Infrared Responsive Droplet for Digital PCR

Digital PCR (dPCR) surpasses the performance of earlier PCR formats because of highly precise, absolute quantification and other unique merits. A simple thermocycling approach and durable microcarrier are of great value for dPCR advancement and application. Herein, a near-infrared (NIR) controlled thermocycling approach by embedding magnetic graphene oxide (GO) composite into the agarose microcarriers is developed. The core-shell composite is constructed by sequentially encapsulating GO and silica outside the magnetic nanocores. Benefiting from these additives, the resultant composite agarose gains appealing features as light-driven temperature changing, switchable gel-sol phase transforming, biocompatibility, and magnetic traction. By further emulsifying into droplets via the microfluidics method, the influence of typical parameters including material loading amount, laser intensity, and droplet diameter at various ranges is investigated for assembling microcarriers with different responsiveness. Then a paradigm of the NIR program can be easily tailored for PCR thermocycling. Finally, the feasibility of the approach is verified by detecting statistically diluted Klebsiella pneumoniae DNA samples, from 0.1 to 2 copies per drop. It is anticipated that this method has promising prospects for dPCR-based and other temperature-controlled applications.

Stem cell-homing hydrogel-based miR-29b-5p delivery promotes cartilage regeneration by suppressing senescence in an osteoarthritis rat model

Osteoarthritis (OA) is a common joint disease characterized by progressive loss of cartilage and reduction in lubricating synovial fluid, which lacks effective treatments currently. Here, we propose a hydrogel-based miRNA delivery strategy to rejuvenate impaired cartilage by creating a regenerative microenvironment to mitigate chondrocyte senescence that mainly contributes to cartilage breakdown during OA development. An aging-related miRNA, miR-29b-5p, was first found to be markedly down-regulated in OA cartilage, and their up-regulation suppressed the expression of matrix metalloproteinases and senescence-associated genes (P16^INK4a/P21) via ten-eleven-translocation enzyme 1 (TET1). An injectable bioactive self-assembling peptide nanofiber hydrogel was applied to deliver agomir-29b-5p, which was functionalized by conjugating a stem cell-homing peptide SKPPGTSS for endogenous synovial stem cell recruitment simultaneously. Sustained miR-29b-5p delivery and recruitment of synovial stem cells and their subsequent differentiation into chondrocytes led to successful cartilage repair and chondrocyte rejuvenation. This strategy enables miRNA-based therapeutic modality to become a viable alternative for surgery in OA treatment.