Secretion Of Small Extracellular Vesicles Research Articles

Adipose stem cells-derived small extracellular vesicles transport Thrombospondin 1 cargo to promote insulin resistance in gestational diabetes mellitus

BackgroundGestational diabetes mellitus (GDM) is a highly prevalent disease and poses a significant risk to the health of pregnant women. Abdominal adipose tissue (AT) contributes to insulin resistance (IR) associated with GDM. However, the underlying mechanisms remain unclear.MethodsIn this study, we developed a mouse model of GDM by subjecting mice to a high-fat diet. We collected adipose-derived stem cells (ADSCs) from the abdominal and inguinal regions and examined their role in inducing IR in normal tissues through the secretion of small extracellular vesicles (sEVs). The sEVs derived from ADSCs isolated from GDM mice (ADSC/GDM) were found to inhibit cell viability and insulin sensitivity in AML12, a normal mouse liver cell line.ResultsThrough proteomic analysis, we identified high levels of the thrombospondin 1 (Thbs1) protein in the sEVs derived from ADSC/GDM. Subsequent overexpression of Thbs1 protein in AML12 cells demonstrated similar IR as observed with ADSC/GDM-derived sEVs. Mechanistically, the Thbs1 protein within the sEVs interacted with CD36 and transforming growth factor (Tgf) β receptors in AML12 cells, leading to the activation of Tgfβ/Smad2 signaling. Furthermore, the administration of LSKL, an antagonistic peptide targeting Thbs1, suppressed Thbs1 expression in ADSC/GDM-derived sEVs, thereby restoring insulin sensitivity in AML12 cells and GDM mice in vivo.ConclusionsThese findings shed light on the intercellular transmission mechanism through which ADSCs influence hepatic insulin sensitivity and underscore the therapeutic potential of targeting the Thbs1 protein within sEVs.

Oral Microbially-Induced Small Extracellular Vesicles Cross the Blood-Brain Barrier.

Porphyromonas gingivalis (Pg) and its gingipain proteases contribute to Alzheimer's disease (AD) pathogenesis through yet unclear mechanisms. Cellular secretion of small extracellular vesicles or exosomes (EXO) increases with aging as part of the senescence-associated secretory phenotype (SASP). We have shown that EXO isolated from Pg-infected dendritic cells contain gingipains and other Pg antigens and transmit senescence to bystander gingival cells, inducing alveolar bone loss in mice in vivo. Here, EXO were isolated from the gingiva of mice and humans with/without periodontitis (PD) to determine their ability to penetrate the blood-brain barrier (BBB) in vitro and in vivo. PD was induced by Pg oral gavage for 6 weeks in C57B6 mice. EXO isolated from the gingiva or brain of donor Pg-infected (PD EXO) or control animals (Con EXO) were characterized by NTA, Western blot, and TEM. Gingival PD EXO or Con EXO were labeled and injected into the gingiva of uninfected WT mouse model. EXO biodistribution in brains was tracked by an in vivo imaging system (IVIS) and confocal microscopy. The effect of human PD EXO on BBB integrity and permeability was examined using TEER and FITC dextran assays in a human in vitro 3D model of the BBB. Pg antigens (RGP and Mfa-1) were detected in EXO derived from gingival and brain tissues of donor Pg-infected mice. Orally injected PD EXO from donor mice penetrated the brains of recipient uninfected mice and colocalized with hippocampal microglial cells. IL-1β and IL-6 were expressed in human PD EXO and not in Con EXO. Human PD EXO promoted BBB permeability and penetrated the BBB in vitro. This is the first demonstration that microbial-induced EXO in the oral cavity can disseminate, cross the BBB, and may contribute to AD pathogenesis.

The small extracellular vesicle-mediated intercellular transformation of CXCR1Low to CXCR1High tumour cells promotes the progression of head and neck squamous cell carcinoma.

The heterogeneity of tumour cells enables cancers to dynamically adapt to microenvironmental stresses during progression. However, the mechanism underlying the transformation and intercellular communication between heterogeneous tumour cells has remained elusive. Here, we report a "contagion model" that mediates intercellular transformation between heterogeneous tumour cells which facilitates tumour progression. Initially identifying heterogeneous expression of CXCR1, a receptor for interleukin-8, in head and neck squamous cell carcinoma (HNSCC) tumour cells, we found that CXCR1High tumour cells had higher abilities for migration and invasion. Following interleukin-8-mediated activation, CXCR1High cells transformed CXCR1Low cells into CXCR1High cells through the secretion of small extracellular vesicles (sEVs), which increased the proportion of CXCR1High cells and facilitated tumour progression. Mechanistically, we demonstrate that sEVs derived from interleukin-8-activated CXCR1High cells contain high levels of ATP citrate lyase (ACLY), which acetylates NF-κB p65 and facilitates its nuclear translocation to transcribe CXCR1 in CXCR1Low cells. That process could be inhibited by Bempedoic acid, an FDA-approved ACLY-targeted drug. Taken together, our study reveals an sEV-mediated transformation of CXCR1Low to CXCR1High cells that promotes HNSCC progression. This provides a new paradigm to explain the dynamic changes of heterogeneous tumour cells, and identifies Bempedoic acid as a potential drug for HNSCC treatment.

Abstract 1258: A cholesterol metabolite can modulate neutrophil-derived extracellular vesicles to promote breast cancer cell epithelial to mesenchymal transition (EMT) and stemness

Abstract Breast cancer is the second leading cause of cancer-related death in women, with mortality most often due to metastatic recurrence. Elevated cholesterol is associated with poor prognosis, with several potential mechanisms proposed. Work in murine models found that many of the pro-metastatic actions of cholesterol required the enzymatic conversion of cholesterol to 27-hydroxycholesterol (27HC), which functions as a ligand for both the estrogen receptors (ERs) and liver X receptors (LXRs). Importantly, we have found that 27HC promotes metastasis, in part through its actions on neutrophils. When examining mechanisms, we have made the observation that 27HC resulted in increased secretion of small extracellular vesicles (sEVs) from neutrophils. These 27HC-neutrophil-sEVs independently promote metastatic colonization. Since we have found that breast cancer cell lines can take up neutrophil-derived sEVs, we hypothesized that 27HC results in altered cargo within sEVs which leads to functional changes within cancer cells, the ultimate consequence of which being their increased metastatic potential. Using a non-biased small RNA-seq approach we have found that sEVs from 27HC-treated neutrophils had an altered miRNA signature. Bioinformatic analysis revealed several downregulated miRNAs from the let-7 subgroup. Let-7 miRs are known to target several genes associated with the WNT/β-catenin pathway, a pathway strongly implicated in epithelial to mesenchymal transition (EMT) and cancer cell stemness. Strikingly, breast cancer cells treated with sEVs from neutrophils treated with 27HC lost their adherent properties and adopted a mesenchymal and stem-like phenotype. In order to elucidate the mechanism by which these sEVs promote EMT and stemness, we performed comprehensive transcriptomics through time. Weighted gene co-expression network analysis (WGCNA) confirmed these phenotypic shifts, and implicated the WNT/β-catenin pathway, providing support to our hypothesis that the loss of let-7 miRs is the upstream mediator. Collectively, our data suggests that 27HC increases metastasis in part through its effects on neutrophils, by shifting sEVs cargo towards a loss of protective microRNA, resulting in increased EMT and stemness, and thus the ability of cancer cells to migrate, invade and metastasize. Funding: National Cancer Institute (ERN: R01CA234025) Department of Defense (ERN: BCRP Era of Hope Award), and Beckman Institute for Advanced Science and Technology (NK) Citation Format: Natalia J. Krawczynska, Yu Wang, Anasuya Das Gupta, Jenny Drnevich, Julie Ostrander, Erik R. Nelson. A cholesterol metabolite can modulate neutrophil-derived extracellular vesicles to promote breast cancer cell epithelial to mesenchymal transition (EMT) and stemness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1258.

Acute exercise-induced release of innate immune proteins via small extracellular vesicles changes with aerobic fitness and age.

Physical exercise triggers the secretion of small extracellular vesicles (sEVs) into the circulation in humans, enabling signalling crosstalk between tissues. Exercise-derived EVs and their cargo have been proposed to mediate adaptations to exercise; however, our understanding of how exercise-derived EV protein cargo is modulated by factors such as aerobic fitness and age of an individual is currently unknown. Here, we examined the circulating sEV proteome following aerobic exercise in healthy males of different ages and aerobic fitness to understand exercise-induced EV response during the aging process. Twenty-eight healthy men completed a bout of 20-min cycling exercise at 70% estimated VO2peak . Small EVs were isolated from blood samples collected before and immediately after exercise, and then quantified using particle analysis and Western blotting. Small EV proteome was examined using quantitative proteomic analysis. We identified a significant increase in 13 proteins in small plasma EVs following moderate-to-vigorous intensity exercise. We observed distinct changes in sEV proteome after exercise in young, mature, unfit, and fit individuals, highlighting the impact of aerobic fitness and age on sEV protein secretion. Functional enrichment and pathway analysis identified that the majority of the significantly altered sEV proteins are associated with the innate immune system, including proteins known to be damage-associated molecular patterns (DAMPs). Together, our findings suggest that exercise-evoked acute stress can positively challenge the innate immune system through the release of signalling molecules such as DAMPs in sEVs, proposing a novel EV-based mechanism for moderate-to-vigorous intensity exercise in immune surveillance pathways.

Activation of the receptor KIT induces the secretion of exosome‐like small extracellular vesicles

AbstractThe receptor tyrosine kinase (RTK) KIT and its ligand stem cell factor (SCF) are essential for human mast cell (huMC) survival and proliferation. HuMCs expressing oncogenic KIT variants secrete large numbers of extracellular vesicles (EVs). The role KIT plays in regulating EV secretion has not been examined. Here, we investigated the effects of stimulation or inhibition of KIT activity on the secretion of small EVs (sEVs). In huMCs expressing constitutively active KIT, the quantity and quality of secreted sEVs positively correlated with the activity status of KIT. SCF‐mediated stimulation of KIT in huMCs or murine MCs, or of transiently expressed KIT in HeLa cells, enhanced the release of sEVs expressing exosome markers. In contrast, ligand‐mediated stimulation of the RTK EGFR in HeLa cells did not affect sEV secretion. The release of sEVs induced by either constitutively active or ligand‐activated KIT was remarkably decreased when cells were treated with KIT inhibitors, concomitant with reduced exosome markers in sEVs. Similarly, inhibition of oncogenic KIT signalling kinases like PI3K, and MAPK significantly reduced the secretion of sEVs. Thus, activation of KIT and its early signalling cascades stimulate the secretion of exosome‐like sEVs in a regulated fashion, which may have implications for KIT‐driven functions.

Hypoxic tumor cell-derived small extracellular vesicle miR-152-3p promotes cervical cancer radioresistance through KLF15 protein

BackgroundRadiotherapy is widely used in treating cervical cancer patients, however, radioresistance unavoidably occurs and seriously affects the treatment effect. It is well known that hypoxia plays an important role in promoting radioresistance in tumor microenvironment, yet our understanding of the effect of small extracellular vesicles miRNA on cervical cancer radiosensitivity in hypoxic environment is still limited.MethodsSmall extracellular vesicles extracted from hypoxic and normoxic cultured cervical cancer cells were evaluated for their effects on radioresistance. miR-152-3p was found to be a potential effector in hypoxia-derived extracellular vesicles by searching the GEO database. Its downstream substrate was confirmed by double luciferase report, which was KLF15. The role of miR-152-3p and KLF15 in regulating cervical cancer radioresistance was detected by cell activity assays. The findings were confirmed in vivo by animal models. The expression of miR-152-3p was quantified by qRT-PCR and its prognostic significance was evaluated.ResultsHypoxic environment promoted the secretion of small extracellular vesicles, and reduced the apoptosis and DNA damage caused by radiation, accompanied by increased expression of small extracellular vesicles miR-152-3p from hypoxic cervical cancer cells. Furthermore, small extracellular vesicles miR-152-3p promoted Hela xenograft growth and reduced the radiosensitivity vivo. Mechanism studies revealed that KLF15 protein was the downstream target of miR-152-3p in regulating radioresistance.ConclusionOur findings suggest that small extracellular vesicles miR-152-3p affects the therapeutic effect of radiotherapy and holds potential as a biomarker or therapeutic target for cervical cancer prognosis and improving radiotherapy.

Endothelial-derived small extracellular vesicles support B-cell acute lymphoblastic leukemia development.

The bone marrow niche plays an important role in leukemia development. However, the contributions of different niche components to leukemia development and their underlying mechanisms remain largely unclear. Cre/LoxP-based conditional knockout technology was used to delete VPS33B or ANGPTL2 gene in niche cells. Murine B-ALL model was established by overexpressing the N-Myc oncogene in hematopoietic stem progenitor cells. The frequency of leukemia cells and immunophenotypic B220+ CD43+ LICs was detected by flow cytometry. SEVs was isolated by sequential centrifugation and mass spectrometry was performed to analyze the different components of SEVs. Immunoprecipitation and western blot were used to measure the interaction of VPS33B and ANGPTL2. Here, we showed that specific knockout of vascular protein sorting 33b (Vps33b) in endothelial cells (ECs), but not megakaryocytes or mesenchymal stem cells, resulted in a significant decrease in the secretion of small extracellular vesicles (SEVs) and a delay in the development of B-cell lymphoblastic leukemia (B-ALL). Vps33b knockdown endothelial cells contained much lower levels of SEVs that contained angiopoietin-like protein 2 (ANGPTL2) than the control cells. Importantly, conditional knockout of Angptl2 in ECs significantly delayed B-ALL progression. Moreover, C-terminal region of ANGPTL2 (aa247-471) could directly interact with Sec1-like domain 1 of VPS33B (aa1-aa146). We further demonstrated that the point mutations R399H and G402S in ANGPTL2 led to a dramatic decrease in the secretion of ANGPTL2-SEVs. We also showed that wild-type ANGPTL2-containing SEVs, but not mutant ANGPTL2-containing SEVs, significantly enhanced B-ALL development. In summary, our findings indicate that the secretion of ANGPTL2-containing SEVs in ECs sustains the leukemogenic activities of B-ALL cells, which is fine-tuned by the direct interaction of VPS33B and ANGPTL2. These findings reveal that niche-specific SEVs play an important role in B-ALL development.

EPIC-1042 as a potent PTRF/Cavin1-caveolin-1 interaction inhibitor to induce PARP1 autophagic degradation and suppress temozolomide efflux for glioblastoma.

Temozolomide (TMZ) treatment efficacy in glioblastoma is determined by various mechanisms such as TMZ efflux, autophagy, base excision repair (BER) pathway, and the level of O6-methylguanine-DNA methyltransferase (MGMT). Here, we reported a novel small-molecular inhibitor (SMI) EPIC-1042 (C20H28N6) with the potential to decrease TMZ efflux and promote PARP1 degradation via autolysosomes in the early stage. EPIC-1042 was obtained from receptor-based virtual screening. Co-immunoprecipitation and pull-down assays were applied to verify the blocking effect of EPIC-1042. Western blotting, co-immunoprecipitation, and immunofluorescence were used to elucidate the underlying mechanisms of EPIC-1042. In vivo experiments were performed to verify the efficacy of EPIC-1042 in sensitizing glioblastoma cells to TMZ. EPIC-1042 physically interrupted the interaction of PTRF/Cavin1 and caveolin-1, leading to reduced secretion of small extracellular vesicles (sEVs) to decrease TMZ efflux. It also induced PARP1 autophagic degradation via increased p62 expression that more p62 bound to PARP1 and specially promoted PARP1 translocation into autolysosomes for degradation in the early stage. Moreover, EPIC-1042 inhibited autophagy flux at last. The application of EPIC-1042 enhanced TMZ efficacy in glioblastoma in vivo. EPIC-1042 reinforced the effect of TMZ by preventing TMZ efflux, inducing PARP1 degradation via autolysosomes to perturb the BER pathway and recruitment of MGMT, and inhibiting autophagy flux in the later stage. Therefore, this study provided a novel therapeutic strategy using the combination of TMZ with EPIC-1042 for glioblastoma treatment.

Kinesin-mediated transport in the secretion of extracellular vesicles

The secretion of small extracellular vesicles (EVs) plays a crucial role in intercellular communication and cellular homeostasis. However, there are still many unanswered questions regarding the transport processes within the endosomal system that lead to the generation and secretion of small EVs. This review will specifically address the transport of endocytic vesicles throughout the cell and the involvement of motor proteins, particularly kinesins, in the transport of endosomal compartments destined for the secretion of EVs.

Photosensitive small extracellular vesicles regulate the immune microenvironment of triple negative breast cancer

Currently, the treatment of triple-negative breast cancer (TNBC) is limited by the special pathological characteristics of this disease. In recent years, photodynamic therapy (PDT) has created new hope for the treatment of TNBC. Moreover, PDT can induce immunogenic cell death (ICD) and improve tumor immunogenicity. However, even though PDT can improve the immunogenicity of TNBC, the inhibitory immune microenvironment of TNBC still weakens the antitumor immune response. Therefore, we used the neutral sphingomyelinase inhibitor GW4869 to inhibit the secretion of small extracellular vesicles (sEVs) by TNBC cells to improve the tumor immune microenvironment and enhance antitumor immunity. In addition, bone mesenchymal stem cell (BMSC)-derived sEVs have good biological safety and a strong drug loading capacity, which can effectively improve the efficiency of drug delivery. In this study, we first obtained primary BMSCs and sEVs, and then the photosensitizers Ce6 and GW4869 were loaded into the sEVs by electroporation to produce immunomodulatory photosensitive nanovesicles (Ce6-GW4869/sEVs). When administered to TNBC cells or orthotopic TNBC models, these photosensitive sEVs could specifically target TNBC and improve the tumor immune microenvironment. Moreover, PDT combined with GW4869-based therapy showed a potent synergistic antitumor effect mediated by direct killing of TNBC and activation of antitumor immunity. Here, we designed photosensitive sEVs that could target TNBC and regulate the tumor immune microenvironment, providing a potential approach for improving the effectiveness of TNBC treatment. Statement of SignificanceWe designed an immunomodulatory photosensitive nanovesicle (Ce6-GW4869/sEVs) with the photosensitizer Ce6 to achieve photodynamic therapy and the neutral sphingomyelinase inhibitor GW4869 to inhibit the secretion of small extracellular vesicles (sEVs) by triple-negative breast cancer (TNBC) cells to improve the tumor immune microenvironment and enhance antitumor immunity. In this study, the immunomodulatory photosensitive nanovesicle could target TNBC cells and regulate the tumor immune microenvironment, thus providing a potential approach for improving the treatment effect in TNBC. We found that the reduction in tumor sEVs secretion induced by GW4869 improved the tumor-suppressive immune microenvironment.Moreover, similar therapeutic strategies can also be applied in other kinds of tumors, especially immunosuppressive tumors, which is of great value for the clinical translation of tumor immunotherapy.

Macrophages and small extracellular vesicle mediated-intracellular communication in the peritoneal microenvironment: Impact on endometriosis development.

Endometriosis is an inflammatory disease that is defined as the growth of endometrium-like tissue outside the uterus, commonly on the lining of the pelvic cavity, visceral organs and in the ovaries. It affects around 190 million women of reproductive age worldwide and is associated with chronic pelvic pain and infertility, which greatly impairs health-related life quality. The symptoms of the disease are variable, this combined with a lack of diagnostic biomarkers and necessity of surgical visualisation to confirm disease, the prognosis can take an average timespan of 6-8 years. Accurate non-invasive diagnostic tests and the identification of effective therapeutic targets are essential for disease management. To achieve this, one of the priorities is to define the underlying pathophysiological mechanisms that contribute to endometriosis. Recently, immune dysregulation in the peritoneal cavity has been linked to endometriosis progression. Macrophages account for over 50% of immune cells in the peritoneal fluid and are critical for lesion growth, angiogenesis, innervation and immune regulation. Apart from the secretion of soluble factors like cytokines and chemokines, macrophages can communicate with other cells and prime disease microenvironments, such as the tumour microenvironment, via the secretion of small extracellular vesicles (sEVs). The sEV-mediated intracellular communication pathways between macrophages and other cells within the peritoneal microenvironment in endometriosis remain unclear. Here, we give an overview of peritoneal macrophage (pMΦ) phenotypes in endometriosis and discuss the role of sEVs in the intracellular communication within disease microenvironments and the impact they may have on endometriosis progression.

Vascular smooth muscle cell senescence accelerates medin aggregation via small extracellular vesicle secretion and extracellular matrix reorganization.

Vascular amyloidosis, caused when peptide monomers aggregate into insoluble amyloid, is a prevalent age-associated pathology. Aortic medial amyloid (AMA) is the most common human amyloid and is composed of medin, a 50-amino acid peptide. Emerging evidence has implicated extracellular vesicles (EVs) as mediators of pathological amyloid accumulation in the extracellular matrix (ECM). To determine the mechanisms of AMA formation with age, we explored the impact of vascular smooth muscle cell (VSMC) senescence, EV secretion, and ECM remodeling on medin accumulation. Medin was detected in EVs secreted from primary VSMCs. Small, round medin aggregates colocalized with EV markers in decellularized ECM in vitro and medin was shown on the surface of EVs deposited in the ECM. Decreasing EV secretion with an inhibitor attenuated aggregation and deposition of medin in the ECM. Medin accumulation in the aortic wall of human subjects was strongly correlated with age and VSMC senescence increased EV secretion, increased EV medin loading and triggered deposition of fibril-like medin. Proteomic analysis showed VSMC senescence induced changes in EV cargo and ECM composition, which led to enhanced EV-ECM binding and accelerated medin aggregation. Abundance of the proteoglycan, HSPG2, was increased in the senescent ECM and colocalized with EVs and medin. Isolated EVs selectively bound to HSPG2 in the ECM and its knock-down decreased formation of fibril-like medin structures. These data identify VSMC-derived EVs and HSPG2 in the ECM as key mediators of medin accumulation, contributing to age-associated AMA development.

Slingshot homolog-1 mediates the secretion of small extracellular vesicles containing misfolded proteins by regulating autophagy cargo receptors and actin dynamics.

Increasing evidence indicates that the accumulation misfolded proteins in Alzheimer’s disease (AD) arises from clearance defects in the autophagy-lysosome pathway. Misfolded proteins such as Aβ and tau are secreted in small extracellular vesicles (i.e., exosomes) and are propagated from cell to cell in part through secreted small extracellular vesicles (sEVs). Recent studies suggest that autophagic activity and exosome secretion are coregulated events, and multiple autophagy-related proteins are found in sEVs, including the cargo receptors Sqstm1/p62 and optineurin. However, whether and how autophagy cargo receptors per se regulate the secretion of sEVs is unknown. Moreover, despite the prominent role of actin dynamics in secretory vesicle release, its role in EV secretion is unknown. In this study, we leveraged the dual axes of Slingshot Homolog-1 (SSH1), which inhibits Sqstm1/p62-mediated autophagy and activates cofilin-mediated actin dynamics, to study the regulation of sEV secretion. Here we show that cargo receptors Sqstm1/p62 and optineurin inhibit sEV secretion, an activity that requires their ability to bind ubiquitinated cargo. Conversely, SSH1 increases sEV secretion by dephosphorylating Sqstm1/p62 at pSer403, the phospho-residue that allows Sqstm1/p62 to bind ubiquitinated cargo. In addition, increasing actin dynamics through the SSH1-cofilin activation pathway also increases sEV secretion, which is mimicked by latrunculin B treatment. Finally, Aβ42 oligomers and mutant tau increase sEV secretion and are physically associated with secreted sEVs. These findings suggest that increasing cargo receptor engagement with autophagic cargo and reducing actin dynamics (i.e., SSH1 inhibition) represents an attractive strategy to promote misfolded protein degradation while reducing sEV-mediated cell to cell spread of pathology.

Abstract 1581: Uncovering mechanisms of biogenesis and secretion of small extracellular vesicles in non small cell lung cancer (NSCLC)

Abstract Non-small cell lung cancer (NSCLC), the most common type of lung cancer, is the leading cause of cancer related deaths in United States. Only 24% of NSCLC patients survive 5-years post diagnosis, which could be attributed to the lack of efficient treatment strategies at the metastatic stage. Thus, understanding the biological mechanisms that promote NSCLC metastasis is critical for developing effective cancer-specific therapeutic agents. The development of cancer metastasis is greatly driven and influenced by intercellular communication. Key mediators of cell-to-cell communication are small extracellular vesicles (sEVs) of approximately 100-150 nm in diameter, often referred as exosomes. Previous report revealed that increased levels of exosomes in NSCLC patients correlated with lower overall survival. Indeed, secretion of sEVs by cancer cells can induce malignant transformation of non-cancerous cells nearby or at distant locations through influencing pre-metastatic niche formation. Therefore, biogenesis and release of cancer derived sEVs are determinant steps for the development of tumor metastasis. However, the mechanisms through which sEVs are produced and secreted by cancer cells are yet to be determined. Here, we isolated and characterized sEVs from a panel of NSCLC cell lines (H358, Calu6, H460, SKMES-1) and non-tumorigenic cells (BEAS-2B and HBEC) to identify mechanisms involved in the elevated secretion of EVs by cancer cells. Contrary to what has been previously reported in literature, our data demonstrated that not all cancer cell lines release high levels of sEVs. Our data suggests that elevated secretion of sEVs could be driven by specific mutations and oncogenic signaling in cancer cells. Among all the cell lines tested, H358 cells which harbor the infamous G12C mutation in KRAS, had the highest sEV release. Therefore, we hypothesize that the KRASG12C can drive high sEV production and secretion in H358 cells. Our preliminary data suggests that siRNA mediated knockdown of oncogenic KRAS signaling in H358 cells significantly decreases secretion of sEVs. Ongoing studies aim to pinpoint the detailed mechanisms by which cancer cells utilize KRAS oncogenic signaling to promote EV biogenesis pathways and tumorigenesis. The current study will provide the foundation to developed new therapeutic strategies against tumor sEVs-driven metastasis. Citation Format: Zulaida M. Soto Vargas, Ikjot Singh Sohal, Humna Hasan, David Arteaga, Andrea L. Kasinski. Uncovering mechanisms of biogenesis and secretion of small extracellular vesicles in non small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1581.

Neuropilin-1 is present on Foxp3+ T regulatory cell-derived small extracellular vesicles and mediates immunity against skin transplantation.

Among the mechanisms of suppression that T regulatory (Treg) cells exert to control the immune responses, the secretion of small extracellular vesicles (sEV) has been recently proposed as a novel contact‐independent immunomodulatory mechanism. Previous studies have demonstrated that Treg cells produce sEV, including exosomes, able to modulate the effector function of CD4+ T cells, and antigen presenting cells (APCs) such as dendritic cells (DCs) through the transfer of microRNA, cytokines, the production of adenosine, among others. Previously, we have demonstrated that Neuropilin‐1 (Nrp1) is required for Tregs‐mediated immunosuppression mainly by impacting on the phenotype and function of effector CD4+ T cells. Here, we show that Foxp3+ Treg cells secrete sEV, which bear Nrp1 in their membrane. These sEV modulate effector CD4+ T cell phenotype and proliferation in vitro in a Nrp1‐dependent manner. Proteomic analysis indicated that sEV obtained from wild type (wt) and Nrp1KO Treg cells differed in proteins related to immune tolerance, finding less representation of CD73 and Granzyme B in sEV obtained from Nrp1KO Treg cells. Likewise, we show that Nrp1 is required in Treg cell‐derived sEV for inducing skin transplantation tolerance, since a reduction in graft survival and an increase on M1/M2 ratio were found in animals treated with Nrp1KO Treg cell‐derived sEV. Altogether, this study describes for the first time that Treg cells secrete sEV containing Nrp1 and that this protein, among others, is necessary to promote transplantation tolerance in vivo via sEV local administration.

An emerging role of KRAS in biogenesis, cargo sortingand uptake of cancer-derived extracellular vesicles.

Extracellular vesicles (EVs) are nanovesicles secreted for intercellular communication with endosomal network regulating secretion of small EVs (or exosomes) that play roles in cancer progression. As an essential oncoprotein, Kirsten rat sarcoma virus (KRAS) is tightly regulated by its endosomal trafficking for membrane attachment. However, the crosstalk between KRAS and EVs has been scarcely discussed despite its endocytic association. An overview of the oncogenic role of KRAS focusing on its correlation with cancer-associated EVs should provide important clues for disease prognosis and inspire novel therapeutic approaches for treating KRAS mutant cancers. Therefore, this review summarizes the relevant studies that provide substantial evidence linking KRAS mutation to EVs and discusses the oncogenic implication from the aspects of biogenesis, cargo sorting, and release and uptake of the EVs.

Dendrobium officinale Polysaccharide Alleviates Intestinal Inflammation by Promoting Small Extracellular Vesicle Packaging of miR-433-3p.

Dendrobium officinale polysaccharide (DOP) attenuates inflammatory bowel disease (IBD), but its role in regulating cross-talk between intestinal epithelial cells (IEC) and macrophages against IBD is unclear. This study aimed to investigate DOP protective effects on the intestinal inflammatory response through regulation by miRNA in small extracellular vesicles (sEVs). Our results show that DOP interfered with the secretion of small extracellular vesicles (DIEs) by IEC, which reduced the levels of inflammatory mediators. Increased miR-433-3p expression in DIEs was identified as an important protector against intestinal inflammation. DOP regulated the loading of miR-433-3p by hnRNPA2B1 into the intestinal sEV to increase the abundance of miR-433-3p. DIEs delivered miR-433-3p to lipopolysaccharide-induced macrophages and targeted the MAPK8 gene, leading to inhibition of the MAPK signaling pathway and reduced production of inflammatory cytokines. One protective mechanism of DOP is mediated by intestinal sEV containing miR-433-3p, which is a potential therapeutic agent for the prevention of inflammatory factor accumulation from excessive intestinal macrophage activity and for restoring homeostasis in the intestinal microenvironment.

Trophoblasts Modulate the Ca2+ Oscillation and Contraction of Myometrial Smooth Muscle Cells by Small Extracellular Vesicle- (sEV-) Mediated Exporting of miR-25-3p during Premature Labor.

The placenta could transmit information to the maternal circulation via the secretion of small extracellular vesicles (sEVs), but little is known about whether and how these sEVs participate in premature labor (PTL). We speculate that miRNA plays an important role in sEV-mediated fetal-maternal information transmission. The present study was aimed at investigating whether the placenta can regulate the contraction of the maternal myometrium via sEV-mediated transmit of miR-25-3p during PTL. The expression of miR-25-3p and its targets Cav3.2 and SERCA2a in clinical samples, cells, and animal specimens was detected. The role of miR-25-3p was observed in the LPS-induced preterm labor mouse model. The sEVs from HTR-8/SVneo cells were characterized by transmission electron microscopy and nanoparticle tracking analysis. The Ca2+ oscillation in HMSMs was analyzed by an intracellular Ca2+ change tracking assay on a confocal microscope. The contraction of HMSMs was detected by a collagen matrix contraction assay. We found that miR-25-3p can directly bind to the 3′UTR of Cav3.2 and SERCA2a. The miR-25-3p level was decreased, and the expression of its targets Cav3.2 and SERCA2a was increased in the placenta and myometrium tissues of PTL patients. Forced upregulation of miR-25-3p reduced the oxidative stress and inflammation responses and the incidence of PTL in LPS-treated mice. The expression of miR-25-3p was not changed in LPS-stimulated human myometrial smooth muscle cells (HMSMs) but was strongly reduced in the trophoblast cell and its sEVs. Additionally, the trophoblast cell line HTR-8/SVneo could transmit miR-25-3p into HMSMs via sEVs. The sEVs derived from LPS-stimulated trophoblasts upregulated the expression of Cav3.2 and SERCA2a and triggered Ca2+ oscillation as well as the contraction of HMSMs; these effects were partially reversed by the overexpression of miR-25-3p in the trophoblasts. Further, the upregulation of miR-25-3p induced changes of Ca2+ oscillation and contraction of HMSMs mediated by sEVs which were also abrogated by the knockdown of miR-25-3p in HMSMs. The results demonstrated that miR-25-3p plays a crucial role in PTL via Cav3.2- and SERCA2a-mediated Ca2+ oscillation and contraction of HMSMs. PTL seems to be related to the decreased exosomal miR-25-3p content transmitted by the trophoblasts under inflammatory conditions.

Critical considerations for the development of potency tests for therapeutic applications of mesenchymal stromal cell-derived small extracellular vesicles

Mesenchymal stromal/stem cells (MSCs) have been widely tested against many diseases, with more than 1000 registered clinical trials worldwide. Despite many setbacks, MSCs have been approved for the treatment of graft-versus-host disease and Crohn disease. However, it is increasingly clear that MSCs exert their therapeutic functions in a paracrine manner through the secretion of small extracellular vesicles (sEVs) of 50–200 nm in diameter. Unlike living cells that can persist long-term, sEVs are non-living and non-replicative and have a transient presence in the body. Their small size also renders sEV preparations highly amenable to sterilization by filtration. Together, acellular MSC-sEV preparations are potentially safer and easier to translate into the clinic than cellular MSC products. Nevertheless, there are inherent challenges in the development of MSC-sEV drug products. MSC-sEVs are products of living cells, and living cells are sensitive to changes in the external microenvironment. Consequently, quality control metrics to measure key identity and potency features of MSC-sEV preparations have to be specified during development of MSC-sEV therapeutics. The authors have previously described quantifiable assays to define the identity of MSC-sEVs. Here the authors discuss requirements for prospective potency assays to predict the therapeutic effectiveness of the drug substance in accordance with International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. Although potency assays should ideally reflect the mechanism of action (MoA), this is challenging because the MoA for the reported efficacy of MSC-sEV preparations against multiple diseases of diverse underlying pathology is likely to be complex and different for each disease and difficult to fully elucidate. Nevertheless, robust potency assays could be developed by identifying the EV attribute most relevant to the intended biological activity in EV-mediated therapy and quantifying the EV attribute. Specifically, the authors highlight challenges and mitigation measures to enhance the manufacture of consistent and reproducibly potent sEV preparations, to identify and select the appropriate EV attribute for potency assays despite a complex “work-in-progress” MoA and to develop assays likely to be compliant with regulatory guidance for assay validation.