Consideration of dual characters of exosomes in the tumour immune response

Exosomes: Biogenesis, targeting, characterisation and their potential as 'Plug & Play' vaccine platforms

Exosomes are typically characterized as spherical extracellular vesicles less than 150 nm in diameter that have been released into the extracellular environment via fusion of multivesicular bodies (MVBs) to the plasma membrane. Exosomes play a key role in cell-cell communication, vary widely in their composition and potential cargo, and are reportedly involved in processes as diverse as angiogenesis, apoptosis, antigen presentation, inflammation, receptor-mediated endocytosis, cell proliferation, and differentiation, and cell-signaling. Exosomes can also act as biomarkers of health and disease and have enormous potential use as therapeutic agents. Despite this, the understanding of how exosome biogenesis can be utilized to generate exosomes carrying specific targets for particular therapeutic uses, their manufacture, detailed analytical characterization, and methods of application are yet to be fully harnessed. In this review, we describe the current understanding of these areas of exosome biology from a biotechnology and bioprocessing aspect, but also highlight the challenges that remain to be overcome to fully harness the power of exosomes as therapeutic agents, with a particular focus on their use and application as vaccine platforms. This article is protected by copyright. All rights reserved.

Progress of Mesenchymal Stem Cell-Derived Exosomes in Tissue Repair

Mesenchymal stem cells (MSCs) are a kind of adult stem cells with self-replication and multidirectional differentiation, which can differentiate into tissue-specific cells under physiological conditions, maintaining tissue self-renewal and physiological functions. They play a role in the pathological condition by lateral differentiation into tissue-specific cells, replacing damaged tissue cells by playing the role of a regenerative medicine , or repairing damaged tissues through angiogenesis, thereby, regulating immune responses, inflammatory responses, and inhibiting apoptosis. It has become an important seed cell for tissue repair and organ reconstruction, and cell therapy based on MSCs has been widely used clinically. The study found that the probability of stem cells migrating to the damaged area after transplantation or differentiating into damaged cells is very low, so the researchers believe the leading role of stem cell transplantation for tissue repair is paracrine secretion, secreting growth factors, cytokines or other components. Exosomes are biologically active small vesicles secreted by MSCs. Recent studies have shown that they can transfer functional proteins, RNA, microRNAs, and lncRNAs between cells, and greatly reduce the immune response. Under the premise of promoting proliferation and inhibition of apoptosis, they play a repair role in tissue damage, which is caused by a variety of diseases. In this paper, the biological characteristics of exosomes (MSCs-exosomes) derived from mesenchymal stem cells, intercellular transport mechanisms, and their research progress in the field of stem cell therapy are reviewed.

Exosomal non‑coding RNAs: Novel biomarkers with emerging clinical applications in gastric cancer (Review)

Gastric cancer (GC) is one of the most common types of malignant tumor and it demonstrates high mortality rates. The majority of cases of GC are diagnosed at an advanced stage, which seriously endangers the health of the patient. Therefore, discovering a novel diagnostic method for GC is a current priority. Exosomes are 40 to 150-nm-diameter vesicles consisting of a lipid bilayer secreted by a variety of cells that exist in multiple different types of body fluids. Exosomes contain diverse types of active substances, including RNAs, proteins and lipids, and play important roles in tumor cell communication, metastasis and neovascularization, as well as tumor growth. Non-coding RNAs (ncRNAs) do not code proteins, and instead have roles in a variety of genetic mechanisms, such as regulating the structure, expression and stability of RNAs, and modulating the translation and function of proteins. In recent years, exosomal ncRNAs have become a novel focus in research. An increasing number of studies have demonstrated that exosomal ncRNAs can be used in the prediction and treatment of GC. The present review briefly discusses the role of exosomal ncRNAs as a potential biomarker, and summarizes important regulatory genes involved in the development and progression of GC.

Antitumor immunity by small extracellular vesicles collected from activated dendritic cells through effective induction of cellular and humoral immune responses

Dendritic cell-derived small extracellular vesicles (DC-sEVs) are proposed as a novel candidate for tumor antigen-based cancer immunotherapy. In order to improve the DC-sEV-induced antitumor immunity, production of DC-sEVs capable of inducing potent antigen-specific humoral and cellular immune responses is necessary. Here, we collected sEVs from DCs and added ovalbumin (OVA), which was used as model antigen, as well as LPS and IFN-γ, to prepare DC-sEVs with high immune activity. After confirming that the collected sEVs, named activated-DC_OVA-sEVs, contained OVA and possessed immunologically relevant components (MHC class I molecule displaying antigen epitopes and co-stimulatory molecules, as well as sEV marker proteins), we found that activated-DC_OVA-sEV stimulated macrophages and DCs through Toll-like receptor 4 signaling and boosted innate immunity in the tumor microenvironment. Moreover, activated-DC_OVA-sEVs induced potent antigen-specific humoral and cellular immune responses both in vitro and in vivo. Finally, immunization with activated-DC_OVA-sEVs exhibited stronger in vivo antitumor effects in tumor-bearing mice induced by inoculation with OVA-expressing tumor cells.

Surface-structured bacterial cellulose loaded with hUSCs accelerate skin wound healing by promoting angiogenesis in rats

Promotion of wound healing is one of the most important fields in clinical medical research. This study aimed to evaluate the potential use of a new surface-structured bacterial cellulose(S-BC) biomaterial with human urine-derived stem cells (hUSCs) for wound healing. In vitro, EA.hy926 were inoculated on structured/non-structured bacterial cellulose, and the growth of EA.hy926 on bacterial cellulose in medium with/without conditioned medium of the hUSCs were observed to explore the effect of bacterial cellulose's surface structure and hUSCs-CM on vascular endothelial cell growth. In vivo, we covered wound surface with various BC materials and/or injected the hUSCs into the wound site on group BC, group S-BC, group hUSCs, group BC + hUSCs, group S-BC + hUSCs to evaluate the effect of S-BC and hUSCs on wound healing in rat full-thickness skin defect model. In vitro study, surface structure of S-BC could promote the growth and survival of EA.hy926, and the hUSCs-CM could further promote the proliferation of EA.hy926 on S-BC. In vivo study, wound healing rate of the group BC, group S-BC, group hUSCs was significantly accelerated, accompanied by faster re-epithelialization, collagen production and neovascularization than control group. It is note worthy that the effect of S-BC on wound healing was better than BC, the effect of S-BC + hUSCs on wound healing was better than BC + hUSCs. Moreover, the effect of S-BC combined with hUSCs on wound is better than treated with S-BC or hUSCs alone. All the findings suggest that the combination of S-BC and hUSCs could facilitate skin wound healing by promoting angiogenesis. This combination of the role of stem cells and biomaterial surface structures may provide a new way to address clinical wound healing problems.

The Dichotomy of Tumor Exosomes (TEX) in Cancer Immunity: Is It All in the ConTEXt?

Exosomes are virus-sized nanoparticles (30–130 nm) formed intracellularly as intravesicular bodies/intralumenal vesicles within maturing endosomes (“multivesicular bodies”, MVBs). If MVBs fuse with the cell’s plasma membrane, the interior vesicles may be released extracellularly, and are termed “exosomes”. The protein cargo of exosomes consists of cytosolic, membrane, and extracellular proteins, along with membrane-derived lipids, and an extraordinary variety of nucleic acids. As such, exosomes reflect the status and identity of the parent cell, and are considered as tiny cellular surrogates. Because of this closely entwined relationship between exosome content and the source/status of the parental cell, conceivably exosomes could be used as vaccines against various pathologies, as they contain antigens associated with a given disease, e.g., cancer. Tumor-derived exosomes (TEX) have been shown to be potent anticancer vaccines in animal models, driving antigen-specific T and B cell responses, but much recent literature concerning TEX strongly places the vesicles as powerfully immunosuppressive. This dichotomy suggests that the context in which the immune system encounters TEX is critical in determining immune stimulation versus immunosuppression. Here, we review literature on both sides of this immune coin, and suggest that it may be time to revisit the concept of TEX as anticancer vaccines in clinical settings.