Unveiling clinical applications of bacterial extracellular vesicles as natural nanomaterials in disease diagnosis and therapeutics

Immunogenicity and vaccine efficacy of Actinobacillus pleuropneumoniae-derived extracellular vesicles as a novel vaccine candidate

Actinobacillus pleuropneumoniae (APP) is a significant pathogen in the swine industry, leading to substantial economic losses and highlighting the need for effective vaccines. This study evaluates the potential of APP-derived extracellular vesicles (APP-EVs) as a vaccine candidate compared to the commercial Coglapix vaccine. APP-EVs, isolated using tangential flow filtration (TFF) and cushioned ultracentrifugation, exhibited an average size of 105 nm and a zeta potential of -17.4 mV. These EVs demonstrated stability under external stressors, such as pH changes and enzymatic exposure and were found to contain 86 major metabolites. Additionally, APP-EVs induced dendritic cell (DC) maturation in a Toll-like receptor 4 (TLR4)-dependent manner without cytotoxicity. APP-EVs predominantly elicited Th1-mediated IgG responses in immunized mice without significant liver and kidney toxicity. Contrarily, unlike Coglapix, which induced stronger Th2-mediated responses and notable toxicity. In addition, APP-EVs triggered APP-specific Th1, Th17, and cytotoxic T lymphocyte (CTL) responses and promoted the activation of multifunctional T-cells. Notably, APP-EV immunization enhanced macrophage phagocytosis and improved survival rates in mice challenged with APP infection compared to those treated with Coglapix. These findings suggest that APP-EVs are promising vaccine candidates, capable of inducing potent APP-specific T-cell responses, particularly Th1, Th17, CTL, and multifunctional T-cells, thereby enhancing the protective immune response against APP infection.

Engineered extracellular vesicles as imaging biomarkers and therapeutic applications for urological diseases

With the ever-increasing burden of urological diseases, the need for developing novel imaging biomarkers and therapeutics to manage these disorders has never been greater. Extracellular vesicles (EVs) are natural membranous nanoparticles and widely applied in both diagnostics and therapeutics for many diseases. A growing body of research has demonstrated that EVs can be engineered to enhance their efficiency, specificity, and safety. We systematically examine the strategies for achieving targeted delivery of EVs as well as the techniques for engineering them in this review, with a particular emphasis on cargo loading and transportation. Additionally, this review highlights and summarizes the wide range of imaging biomarkers and therapeutic applications of engineered EVs in the context of urological diseases, emphasizing the potential applications in urological malignancy and kidney diseases.

Comprehensive method for isolation and functional characterization of bacterial vesicles from human biological samples

Bacterial vesicles (BVs) are membrane-bound extracellular vesicles (EV) released from bacteria. They are known to play crucial role in bacterial communication, host-pathogen interactions, transfer of virulence factors, contribute to immune modulation and are the key players in microbial pathogenesis and survival in the host. Despite their significance, isolation and investigating BVs from human samples remains challenging, necessitating an easy, reliable and reproducible protocol. BVs have been limited due to methodological difficulties in isolating them from host-derived EVs, and the existing knowledge primarily relies on bacteria cultured under controlled laboratory conditions. This study presents a method, where we can identify the enriched BVs and characterizing them from plasma and stool samples of healthy individuals. Blood and fecal samples were collected, processed to density gradient ultracentrifugation to isolate and enrich BVs. Morphological characterization was performed using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA). Further, molecular markers OmpA (BV marker) was used to differentiate from host EVs (Alix as marker) using Western blot. Further the BV fraction was analyzed for LPS and LTA using ELISA. To understand functional relevance, BVs proteomics was performed from BV enriched plasma and stool using mass spectrometry from healthy individuals. The enriched BVs were also co-cultured with healthy peripheral blood mononuclear cells, labelled with Pkh26 dye and analysed at different time points for mRNA expression of candidate genes involved in immune regulation by qRT-PCR. Both TEM and NTA confirmed the presence of BVs, with sizes ranging from 25 nm to 250 nm. The western blot analysis revealed the fractions 6-9 are enriched with host EVs with the presence of Alix and fractions 10-13 contains BVs with the presence of OmpA. Interestingly, the proteomic analysis identified 439 proteins associated with plasma-derived BVs and 327 in stool-derived BVs, with 300 common to both. The Gene ontology and KEGG pathway analysis revealed the majority of proteins associated were immune regulation, cell activation, binding, and catalytic activity. Next, the functional assays indicated BVs were uptaken by PBMCs within 10 mins and it upregulated Toll-like receptor 2 (TLR-2) expression within 30 min. Hence, study establishes a reliable method to identify enriched BV population from human samples. Revealed the proteins associated with BVs in healthy individuals and their role in immune regulation. These findings may provide a platform to investigate BVs potential for diagnostic and therapeutic applications in various diseases.

Extracellular Vesicles: A Review of Their Therapeutic Potentials, Sources, Biodistribution, and Administration Routes

Extracellular vesicles (EVs) participate in intercellular communication and play an essential role in physiological and pathological processes. In recent years, EVs have garnered significant attention as cell-free therapeutic alternatives, vectors for drug and gene delivery, biomarkers for disease diagnosis and prognosis, vaccine development, and nutraceuticals. The biodistribution of EVs critically influences their efficacy and toxicity. Therefore, this review aims to discuss the main factors influencing the biodistribution of unmodified EVs, highlighting their distribution patterns, advantages, limitations, and applications under different routes of administration. In addition, we provide a comprehensive discussion of the currently available sources of EVs and summarize the current status of the therapeutic potentials of EVs. By optimizing administration routes and selecting appropriate EV sources, we aim to offer valuable insights to enhance the delivery efficiency and therapeutic efficacy of EVs to target tissues.

Engineered extracellular vesicles: an emerging nanomedicine therapeutic platform

The intercellular communication role of extracellular vesicles has been widely proved in various organisms. Compelling evidence has illustrated the involvement of these vesicles in both physiological and pathological processes. Various studies indicate that extracellular vesicles surpass conventional synthetic drug carriers, owing to their abundance in organisms, enhanced targeting ability and low immunogenicity. Therefore, extracellular vesicles have been deemed to be potential drug carriers for the treatment of various diseases, and related studies have increased rapidly. Here, we intend to provide a comprehensive and in-depth review of recent advances in the sources, delivery function, extraction and cargo-loading technologies of extracellular vesicles, as well as their clinical potential in constructing emerging nanomedicine therapeutic platforms. In particular, microfluidic-based isolation and drug-loading technologies, as well as the treatment of various diseases, are highlighted. We also make comparisons between extracellular vesicles and other conventional drug carriers and discuss the challenges in developing drug delivery platforms for clinical translation.

Pathogenic and therapeutic roles of extracellular vesicles in sepsis

Sepsis is a systemic injury resulting in vascular dysfunction, which can lead to multiple organ dysfunction, even shock and death. Extracellular vesicles (EVs) released by mammalian cells and bacteria have been shown to play important roles in intercellular communication and progression of various diseases. In past decades, the functional role of EVs in sepsis and its complications has been well explored. EVs are one of the paracrine components of cells. By delivering bioactive materials, EVs can promote immune responses, particularly the development of inflammation. In addition, EVs can serve as beneficial tools for delivering therapeutic cargos. In this review, we discuss the dual role of EVs in the progression and treatment of sepsis, exploring their intricate involvement in both inflammation and tissue repair processes. Specifically, the remarkable role of engineered strategies based on EVs in the treatment of sepsis is highlighted. The engineering EVs-mediated drug delivery and release strategies offer broad prospects for the effective treatment of sepsis. EVs-based approaches provide a novel avenue for diagnosing sepsis and offer opportunities for more precise intervention.

Review on bacterial outer membrane vesicles: structure, vesicle formation, separation and biotechnological applications

Outer membrane vesicles (OMVs), shed by Gram-negative bacteria, are spherical nanostructures that play a pivotal role in bacterial communication and host-pathogen interactions. Comprising an outer membrane envelope and encapsulating a variety of bioactive molecules from their progenitor bacteria, OMVs facilitate material and informational exchange. This review delves into the recent advancements in OMV research, providing a comprehensive overview of their structure, biogenesis, and mechanisms of vesicle formation. It also explores their role in pathogenicity and the techniques for their enrichment and isolation. Furthermore, the review highlights the burgeoning applications of OMVs in the field of biomedicine, emphasizing their potential as diagnostic tools, vaccine candidates, and drug delivery vectors.

Engineering therapeutical extracellular vesicles for clinical translation

Cell-based therapies are revolutionizing medicine by replacing or modifying dysfunctional cells with healthy cells or engineered derivatives, offering disease reversal and cure. One promising approach is using cell-derived extracellular vesicles (EVs), which offer therapeutic benefits similar to cell transplants without the biosafety risks. Although EV applications face challenges like limited production, inadequate therapeutic loading, and poor targeting efficiency, recent advances in bioengineering have enhanced their effectiveness. Herein, we summarize technological breakthroughs in EV bioengineering over the past 5 years, highlighting their improved therapeutic functionalities and potential clinical prospects. We also discuss biomanufacturing processes, regulation, and safety considerations for bioengineered EV therapies, emphasizing the significance of establishing robust frameworks to ensure translation capability, safety, and therapeutic effectiveness for successful clinical adoption.

Extracellular vesicle production by oral bacteria related to dental caries and periodontal disease: role in microbe-host and interspecies interactions

Extracellular vesicles (EVs) are cell membrane-derived structures between 20-400 nm in size. In bacteria, EVs play a crucial role in molecule secretion, cell wall biogenesis, cell-cell communication, biofilm development, and host-pathogen interactions. Despite these increasing reports of bacterial-derived vesicles, there remains a limited number of studies that summarize oral bacterial EVs, their cargo, and their main biological functions. Therefore, the aim of this review is to present the latest research on oral bacteria-derived EVs and how they can modulate various physiological and pathological processes in the oral cavity, including the pathogenesis of highly relevant diseases such as dental caries and periodontitis and their systemic complications. Overall, caries-associated bacteria (such as Streptococcus mutans) as well as periodontal pathogens (including the red complex pathogens Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola) have all been shown to produce EVs that carry an array of virulent factors and molecules involved in biofilm and immune modulation, bacterial adhesion, and extracellular matrix degradation. As bacterial EV production is strongly impacted by genotypic and environmental variations, the inhibition of EV genesis and secretion remains a key potential future approach against oral diseases.

Impact of probiotics-derived extracellular vesicles on livestock gut barrier function

Probiotic extracellular vesicles (pEVs) are biologically active nanoparticle structures that can regulate the intestinal tract through direct or indirect mechanisms. They enhance the intestinal barrier function in livestock and poultry and help alleviate intestinal diseases. The specific effects of pEVs depend on their internal functional components, including nucleic acids, proteins, lipids, and other substances. This paper presents a narrative review of the impact of pEVs on the intestinal barrier across various segments of the intestinal tract, exploring their mechanisms of action while highlighting the limitations of current research. Investigating the mechanisms through which probiotics operate via pEVs could deepen our understanding and provide a theoretical foundation for their application in livestock production.

Potential therapeutic application and mechanism of gut microbiota-derived extracellular vesicles in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a prevalent endocrine and metabolic disorder affecting women of reproductive age. The syndrome is characterized by androgen excess, ovarian dysfunction, insulin resistance (IR) and obesity, with an elevated risk of developing long-term complications, including cardiovascular disease and type 2 diabetes mellitus (T2D). The gut microbiota plays a role in the pathogenesis of PCOS by influencing the host's endocrine, metabolic and inflammatory state, as well as the gut-brain axis. Gut microbiota-derived extracellular vesicles (GMEVs) are lipid bilayer nanoparticles secreted by the gut microbiota and contain a variety of components, including proteins, lipids and nucleic acids. They serve as signaling molecules, facilitating bacterial-bacterial and bacterial-host communications. Bacterial extracellular vesicles (BEVs) affect host cells through the delivery of bioactive substances and physical interaction through membrane components, thereby participating in the regulation of metabolic, immune, and other cellular processes. Furthermore, BEVs, which are distinguished by low toxicity, high biocompatibility and stability, and the capacity to cross biological barriers, present a promising avenue for the development of novel drug delivery systems. The isolation and characterization of BEVs also facilitate the investigation of disease-specific biomarkers. Consequently, BEVs have immense potential for a range of medical research applications, including disease diagnosis and treatment. This article discusses the potential therapeutic effects and mechanisms of GMEVs in the treatment of PCOS.

Nanoparticles and bone microenvironment: a comprehensive review for malignant bone tumor diagnosis and treatment

Malignant bone tumors, which are difficult to treat with current clinical strategies, originate from bone tissues and can be classified into primary and secondary types. Due to the specificity of the bone microenvironment, the results of traditional means of treating bone tumors are often unsatisfactory, so there is an urgent need to develop new treatments for malignant bone tumors. Recently, nanoparticle-based approaches have shown great potential in diagnosis and treatment. Nanoparticles (NPs) have gained significant attention due to their versatility, making them highly suitable for applications in bone tissue engineering, advanced imaging techniques, and targeted drug delivery. For diagnosis, NPs enhance imaging contrast and sensitivity by integrating targeting ligands, which significantly improve the specific recognition and localization of tumor cells for early detection. For treatment, NPs enable targeted drug delivery, increasing drug accumulation at tumor sites while reducing systemic toxicity. In conclusion, understanding bone microenvironment and using the unique properties of NPs holds great promise in improving disease management, enhancing treatment outcomes, and ultimately improving the quality of life for patients with malignant bone tumors. Further research and development will undoubtedly contribute to the advancement of personalized medicine in the field of bone oncology.

Applications of plant-derived extracellular vesicles in medicine

Plant-derived extracellular vesicles (EVs) are promising therapeutic agents owing to their natural abundance, accessibility, and unique biological properties. This review provides a comprehensive exploration of the therapeutic potential of plant-derived EVs and emphasizes their anti-inflammatory, antimicrobial, and tumor-inhibitory effects. Here, we discussed the advancements in isolation and purification techniques, such as ultracentrifugation and size-exclusion chromatography, which are critical for maintaining the functional integrity of these nanovesicles. Next, we investigated the diverse administration routes of EVs and carefully weighed their respective advantages and challenges related to bioavailability and patient compliance. Moreover, we elucidated the multifaceted mechanisms of action of plant-derived EVs, including their roles in anti-inflammation, antioxidation, antitumor activity, and modulation of gut microbiota. We also discussed the impact of EVs on specific diseases such as cancer and inflammatory bowel disease, highlighting the importance of addressing current challenges related to production scalability, regulatory compliance, and immunogenicity. Finally, we proposed future research directions for optimizing EV extraction and developing targeted delivery systems. Through these efforts, we envision the seamless integration of plant-derived EVs into mainstream medicine, offering safe and potent therapeutic alternatives across various medical disciplines.

Role of probiotic extracellular vesicles in inter-kingdom communication and current technical limitations in advancing their therapeutic utility

Diverse functions of probiotic extracellular vesicles (EVs) have been extensively studied over the past decade, proposing their role in inter-kingdom communication. Studies have explored their therapeutic role in pathophysiological processes ranging from cancer, immunoregulation, and ulcerative colitis to stress-induced depression. These studies have highlighted the significant and novel potential of probiotic EVs for therapeutic applications, offering immense promise in addressing several unmet clinical needs. Additionally, probiotic EVs are being explored as vehicles for targeted delivery approaches. However, the realization of clinical utility of probiotic EVs is hindered by several knowledge gaps, pitfalls, limitations, and challenges, which impede their wider acceptance by the scientific community. Among these, limited knowledge of EV biogenesis, markers and regulators in bacteria, variations in cargo due to culture conditions or EV isolation method, and lack of proper understanding of gut uptake and demonstration of in vivo effect are some important issues. This review aims to summarize the diverse roles of probiotic EVs in health and disease conditions. More importantly, it discusses the significant knowledge gaps and limitations that stand in the way of the therapeutic utility of probiotic EVs. Furthermore, the importance of addressing these gaps and limitations with technical advances such as rigorous omics has been discussed.

Bacterial surface derived extracellular vesicles: A ground‐breaking approach in cancer therapy

Conventional cancer therapies are often limited by inherent and acquired drug resistance, non‐specific toxicity, and suboptimal drug delivery. Bacterial extracellular vesicles (BEVs), including outer membrane vesicles and membrane vesicles, present a novel therapeutic strategy for cancer treatment. BEVs were found in both Gram‐negative and Gram‐positive bacteria. This article provides a classified investigation of the therapeutic potential of BEVs in cancer treatment. We discuss the molecular mechanisms underlying their observed anti‐tumor effects, including the induction of apoptosis in cancer cells, suppression of angiogenesis within the tumor microenvironment, and stimulation of both innate and adaptive anti‐tumor immune responses. Moreover, BEVs being biocompatible opens avenue for targeted drug delivery systems, potentially improving the therapeutic index of conventional chemotherapeutics. Challenges to clinical translation, such as BEV heterogeneity and potential immunogenicity, are addressed. We also explore future directions for research and development, comprehensively highlighting how BEVs transform the landscape of precision oncology and cancer treatment, eventually improving patient outcomes.