Apoptotic Vesicles Research Articles

MSCs-derived apoptotic extracellular vesicles promote muscle regeneration by inducing Pannexin 1 channel-dependent creatine release by myoblasts

Severe muscle injury is hard to heal and always results in a poor prognosis. Recent studies found that extracellular vesicle-based therapy has promising prospects for regeneration medicine, however, whether extracellular vesicles have therapeutic effects on severe muscle injury is still unknown. Herein, we extracted apoptotic extracellular vesicles derived from mesenchymal stem cells (MSCs-ApoEVs) to treat cardiotoxin induced tibialis anterior (TA) injury and found that MSCs-ApoEVs promoted muscles regeneration and increased the proportion of multinucleated cells. Besides that, we also found that apoptosis was synchronized during myoblasts fusion and MSCs-ApoEVs promoted the apoptosis ratio as well as the fusion index of myoblasts. Furthermore, we revealed that MSCs-ApoEVs increased the relative level of creatine during myoblasts fusion, which was released via activated Pannexin 1 channel. Moreover, we also found that activated Pannexin 1 channel was highly expressed on the membrane of myoblasts-derived ApoEVs (Myo-ApoEVs) instead of apoptotic myoblasts, and creatine was the pivotal metabolite involved in myoblasts fusion. Collectively, our findings firstly revealed that MSCs-ApoEVs can promote muscle regeneration and elucidated that the new function of ApoEVs as passing inter-cell messages through releasing metabolites from activated Pannexin 1 channel, which will provide new evidence for extracellular vesicles-based therapy as well as improving the understanding of new functions of extracellular vesicles.

Extracellular Vesicles for Dental Pulp and Periodontal Regeneration.

Extracellular vesicles (EVs) are lipid bound particles derived from their original cells, which play critical roles in intercellular communication through their cargoes, including protein, lipids, and nucleic acids. According to their biogenesis and release pathway, EVs can be divided into three categories: apoptotic vesicles (ApoVs), microvesicles (MVs), and small EVs (sEVs). Recently, the role of EVs in oral disease has received close attention. In this review, the main characteristics of EVs are described, including their classification, biogenesis, biomarkers, and components. Moreover, the therapeutic mechanism of EVs in tissue regeneration is discussed. We further summarize the current status of EVs in pulp/periodontal tissue regeneration and discuss the potential mechanisms. The therapeutic potential of EVs in pulp and periodontal regeneration might involve the promotion of tissue regeneration and immunomodulatory capabilities. Furthermore, we highlight the current challenges in the translational use of EVs. This review would provide valuable insights into the potential therapeutic strategies of EVs in dental pulp and periodontal regeneration.

Hepatectomy-induced apoptotic extracellular vesicles stimulate neutrophils to secrete regenerative growth factors.

Surgical resection of the cancerous tissue represents one of the few curative treatment options for neoplastic liver disease. Such partial hepatectomy (PHx) induces hepatocyte hyperplasia, which restores liver function. PHx is associated with bacterial translocation, leading to an immediate immune response involving neutrophils and macrophages, which are indispensable for the priming phase of liver regeneration. Additionally, PHx induces longer-lasting intrahepatic apoptosis. Herein, we investigated the effect of apoptotic extracellular vesicles (aEVs) on neutrophil function and their role in this later phase of liver regeneration. A total of 124 patients undergoing PHx were included in this study. Blood levels of the apoptosis marker caspase-cleaved cytokeratin-18 (M30) and circulating aEVs were analyzed preoperatively and on the first and fifth postoperative days. Additionally, the invitro effects of aEVs on the secretome, phenotype and functions of neutrophils were investigated. Circulating aEVs increased at the first postoperative day and were associated with higher concentrations of M30, which was only observed in patients with complete liver recovery. Efferocytosis of aEVs by neutrophils induced an activated phenotype (CD11bhighCD16highCD66bhighCD62Llow); however, classical inflammatory responses such as NETosis, respiratory burst, degranulation, or secretion of pro-inflammatory cytokines were not observed. Instead, efferocytosing neutrophils released various growth factors including fibroblast growth factor-2 and hepatocyte growth factor (HGF). Accordingly, we observed an increase of HGF-positive neutrophils after PHx and a correlation of plasma HGF with M30 levels. These data suggest that the clearance of PHx-induced aEVs leads to a population of non-inflammatory but regenerative neutrophils, which may support human liver regeneration. In this study, we show that the surgical removal of a diseased part of the liver triggers a specific type of programmed cell death in the residual liver tissue. This results in the release of vesicles from dying cells into the blood, where they are cleared by circulating immune cells. These respond by secreting hepatocyte growth factors that could potentially support the regeneration of the liver remnant.

Glycocalyx Acts as a Central Player in the Development of Tumor Microenvironment by Extracellular Vesicles for Angiogenesis and Metastasis.

Angiogenesis in tumor growth and progression involves a series of complex changes in the tumor microenvironment. Extracellular vesicles (EVs) are important components of the tumor microenvironment, which can be classified as exosomes, apoptotic vesicles, and matrix vesicles according to their origins and properties. The EVs that share many common biological properties are important factors for the microenvironmental modification and play a vital role in tumor growth and progression. For example, vascular endothelial growth factor (VEGF) exosomes, which carry VEGF, participate in the tolerance of anti-angiogenic therapy (AAT). The glycocalyx is a mucopolysaccharide structure consisting of glycoproteins, proteoglycans, and glycosaminoglycans. Both endothelial and tumor cells have glycocalyx at their surfaces. Glycocalyx at both cells mediates the secretion and uptake of EVs. On the other hand, many components carried by EVs can modify the glycocalyx, which finally facilitates the development of the tumor microenvironment. In this short review, we first summarize the role of EVs in the development of the tumor microenvironment. Then we review how the glycocalyx is associated with the tumor microenvironment and how it is modulated by the EVs, and finally, we review the role of the glycocalyx in the synthesis, release, and uptake of EVs that affect tumor microenvironments. This review aims to provide a basis for the mechanistic study of AAT and new clues to address the challenges in AAT tolerance, tumor angiogenesis and metastasis.

Inhibitory Effect of Trihydroxy Isoflavone on Neuronal Apoptosis in Natural Aging Rats.

Objective To explore the impact of genistein (Gen) on the apoptosis of neuronal cells in naturally aged rats and its mechanism. Methods Fifty SD male rats were allocated into five groups at random, including youth group (3M group), natural aging group (24M group), and Gen low-, medium-, and high-dose groups. Starting from 18 months of age, Gen 10, 30, and 60 mg-kg−1 were administered via gavage to the Gen low-, medium-, and high-dose groups, respectively, while the rats in the natural aging group was given saline by gavage until 24 months of age, and the drug was stopped for 1 d per week for 6 months. The protein expression of target genes was examined using western blotting. Results In contrast to the 3M group, the 24M group rats showed disturbed neuronal cell arrangement and massive cell degeneration. After 6 months of Gen intervention, in contrast to the 24M group, the neural cell pathology in the CA3 area of the hippocampus improved and cell apoptotic decreased observably. In contrast to the 3M group, the protein expression of c-Jun amino-terminal kinase (p-JNK), C/EBP homologous protein (CHOP), inflammatory vesicle 3-associated factor (NLRP3), cysteine protease-1 (Caspase-1), and apoptosis-related punctate protein (ASC) and downstream inflammatory factors in the hippocampus was obviously increased in the 24M group. In contrast to the 24M group, the protein expression of p-JNK, CHOP, NLRP3, Caspase-1, and ASC and downstream inflammatory factors in the hippocampus was observably declined in Gen groups. Conclusion Gen has a protective effect on hippocampal neurons in aging rat brain tissue via the inhibition of the ERS apoptotic signaling pathway and NLRP3 inflammatory vesicle activation.

Apoptotic extracellular vesicles alleviate Pg-LPS induced inflammatory responses of macrophages via AMPK/SIRT1/NF-κB pathway and inhibit osteoclast formation.

Periodontitis is caused by the imbalance of anti-bacteria immune response and excessive inflammation whereas macrophages play an important role in inflammation. Thus, it is critical for finding efficient anti-inflammatory strategies to alleviate periodontal inflammation and prevent bone destruction. Apoptosis of mesenchymal stem cells (MSCs) exerts immune silencing effects, however, using these effects to develop anti-inflammatory strategies remains unknown. In our study, we extracted apoptotic extracellular vesicles (ApoEVs) from bone marrow MSCs (BMMSCs) and found ApoEVs inhibited macrophages polarizing into proinflammatory condition via AMPK/SIRT1/NF-κB pathway. Besides that, we also found ApoEVs inhibited adjacent osteoclast formation by suppressing the secretion of TNF-α of proinflammatory macrophages. BMMSCs derived ApoEVs were extracted by gradient centrifugation. Protein expression level and secreted cytokines of ApoEVs treated macrophages were examined by western blot and ELISA, respectively. Besides, the change of NF-κB pathway and related molecules were examined by immunofluorescence and western blot. The osteoclast formation under the different conditioned mediums from macrophages was measured by TRAP staining, MMP-9 expression, and pit assay. ApoEVs were extracted from staurosporine-induced apoptotic BMMSCs and were in sphere shapes whose diameters are between 100 and 1000nm. ApoEVs could be phagocyted by macrophages and in turn reduce the expression of COX2 in proinflammatory macrophages. Besides that, ApoEVs suppressed the secretions of TNF-α and IL-6 while elevating the secretion of IL-10 in a dose-dependent manner. Further studies revealed that ApoEVs inhibited macrophages polarizing into proinflammatory phenotypes via AMPK/SIRT1/NF-κB pathway. In addition, ApoEVs inhibited osteoclasts differentiation and bone resorption measured by TRAP staining, MMP-9 expression, and pit resorption area by downregulating the secretion of TNF-α of proinflammatory macrophages. The results suggest that ApoEVs inhibited macrophages to skew into proinflammatory phenotypes via AMPK/SIRT1/NF-κB pathway and suppress adjacent osteoclasts formation by reducing the secretion of TNF-α. Our findings shed a light on the treatment for periodontitis based on EVs therapy.

Extracellular Vesicles for Immunomodulation in Tissue Regeneration.

A large number of people suffer from tissue injury and defect worldwide, which constitutes a critical challenge for regenerative medicine. During the complicated process of tissue repair and regeneration, immune response that involves many kinds of immune cells often concurrently exists and plays a significant role, thus providing a promising target for the development of therapeutic strategies. As a critical player in cell-cell communication, extracellular vesicles (EVs) are a cluster of nano-sized vesicles of different categories, which have been reported to possess favorable immunoregulatory potential, and participate in the process of tissue repair and regeneration. Furthermore, EVs can be engineered with genetic or chemical strategies for optimized performance as therapeutic mediators. Here, we provide an outline on the biology of EVs as well as the role of EVs in immune regulation, focusing on exosomes, microvesicles, and apoptotic vesicles. We further summarize the applications of EV-based therapies for tissue regeneration, with particular emphasis on the modulation of immune system. Also, we have discussed the construction strategies of engineered EVs and the immunomodulatory capability of engineered EVs as well as their therapeutic potential in tissue repair. This review will highlight the outstanding potential of EV-based therapeutic strategies for tissue repair and regeneration. Impact statement Extracellular vesicles (EVs) have been shown to possess potent immunomodulatory abilities and thus hold great therapeutic potential for regenerative medicine via immune modulation. Also, the development of engineering technology has provided a feasible tool for optimizing the performance of natural EVs. We hereby outline the current knowledge regarding the features of EVs and the construction strategies of engineered EVs as well as the immunomodulation effects of natural and engineered EVs. We also highlight the applications of EV-based therapies for tissue regeneration, with particular emphasis on the modulation of immune system.

Macrophage-derived apoptotic vesicles regulate fate commitment of mesenchymal stem cells via miR155

BackgroundIn tissue engineering, mesenchymal stem cells (MSCs) are common seed cells because of abundant sources, strong proliferation ability and immunomodulatory function. Numerous researches have demonstrated that MSC-macrophage crosstalk played a key role in the tissue engineering. Macrophages could regulate the differentiation of MSCs via different molecular mechanisms, including extracellular vesicles. Apoptotic macrophages could generate large amounts of apoptotic vesicles (apoVs). ApoVs are rich in proteins, RNA (microRNAs, mRNAs, ncRNAs, etc.) and lipids, and are a key intercellular communication mediator that can exert different regulatory effects on recipient cells. MiRNAs account for about half of the total RNAs of extracellular vesicles, and play important roles in biological processes such as cell proliferation and differentiation, whereas the functions of macrophage-derived apoVs remain largely unknown. There was no research to clarify the role of macrophage-derived apoVs in MSC fate choices. In this study, we aimed to characterize macrophage-derived apoVs, and investigate the roles of macrophage-derived apoVs in the fate commitment of MSCs.MethodsWe characterized macrophage-derived apoVs, and investigated their role in MSC osteogenesis and adipogenesis in vitro and in vivo. Furthermore, we performed microRNA loss- and gain-of-function experiments and western blot to determine the molecular mechanism.ResultsMacrophages could produce a large number of apoVs after apoptosis. MSCs could uptake apoVs. Then, we found that macrophage-derived apoVs inhibited osteogenesis and promoted adipogenesis of MSCs in vitro and in vivo. In mechanism, apoVs were enriched for microRNA155 (miR155), and apoVs regulated osteogenesis and adipogenesis of MSCs by delivering miR155. Besides, miR155 regulated osteogenesis and adipogenesis of MSCs cultured with macrophage-derived apoVs via the SMAD2 signaling pathway.ConclusionsMacrophage-derived apoVs could regulate the osteogenesis and adipogenesis of MSCs through delivering miR155, which provided novel insights for MSC-mediated tissue engineering.

Apoptotic vesicles inherit SOX2 from pluripotent stem cells to accelerate wound healing by energizing mesenchymal stem cells

Billions of cells undergo apoptosis every day in the human body, resulting in the generation of a large number of apoptotic vesicles (apoVs) to maintain organ and tissue homeostasis. However, the characteristics and function of pluripotent stem cell (PSC)-derived apoVs (PSC-apoVs) are largely unknown. In this study, we showed that human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) produced larger numbers of apoVs than human umbilical cord mesenchymal stem cells (UMSCs) do when induced by staurosporine. In addition to expressing the general apoV markers cleaved caspase 3, Annexin V, calreticulin, ALIX, CD63 and TSG101, ESC-apoVs inherited pluripotent-specific molecules SOX2 from ESCs in a caspase 3-dependent manner. Moreover, ESC-apoVs could promote mouse skin wound healing via transferring SOX2 into skin MSCs via activating Hippo signaling pathway. Collectively, these findings reveal that apoVs are capable of inheriting pluripotent molecules from ESCs to energize adult stem cells, suggesting the potential to use PSC-apoVs for clinical applications. Statement of significanceApoptotic vesicles (apoVs) are essential to maintain organ and tissue homeostasis. However, the characteristics and function of pluripotent stem cell (PSC)-derived apoVs (PSC-apoVs) are largely unknown. This study showed that PSC-apoVs produced 100 times more apoVs than human umbilical cord mesenchymal stem cells (UMSCs). Despite expressing the general apoV makers, PSC-apoVs inherited pluripotent-specific molecule SOX2 from PSCs in a caspase 3-dependent manner. Moreover, PSC-apoVs promote mouse skin wound healing via transferring SOX2 into skin MSCs, thus activating Hippo signaling pathway. These findings reveal that apoVs are capable of inheriting pluripotent molecules from PSCs to energize adult stem cells, thus providing a cell-free strategy for clinical applications of PSCs.

Blood Cell-Derived Microvesicles in Hematological Diseases and beyond.

Microvesicles or ectosomes represent a major type of extracellular vesicles that are formed by outward budding of the plasma membrane. Typically, they are bigger than exosomes but smaller than apoptotic vesicles, although they may overlap with both in size and content. Their release by cells is a means to dispose redundant, damaged, or dangerous material; to repair membrane lesions; and, primarily, to mediate intercellular communication. By participating in these vital activities, microvesicles may impact a wide array of cell processes and, consequently, changes in their concentration or components have been associated with several pathologies. Of note, microvesicles released by leukocytes, red blood cells, and platelets, which constitute the vast majority of plasma microvesicles, change under a plethora of diseases affecting not only the hematological, but also the nervous, cardiovascular, and urinary systems, among others. In fact, there is evidence that microvesicles released by blood cells are significant contributors towards pathophysiological states, having inflammatory and/or coagulation and/or immunomodulatory arms, by either promoting or inhibiting the relative disease phenotypes. Consequently, even though microvesicles are typically considered to have adverse links with disease prognosis, progression, or outcomes, not infrequently, they exert protective roles in the affected cells. Based on these functional relations, microvesicles might represent promising disease biomarkers with diagnostic, monitoring, and therapeutic applications, equally to the more thoroughly studied exosomes. In the current review, we provide a summary of the features of microvesicles released by blood cells and their potential implication in hematological and non-hematological diseases.

The expanding family of neutrophil-derived extracellular vesicles.

Neutrophils are immune cells involved in several inflammatory and homeostatic processes. Their capacity to release cargo can be classified based on whether the cargo is released on its own, or in conjunction with plasma membrane structures. Examples of plasma membrane-free secretion modes are degranulation, neutrophil extracellular trap (NET) release, and cytokine release through inflammasome formation. The most studied membrane-covered neutrophil-derived structures are exosomes and ectosomes that are collectively called extracellular vesicles (EV). Apoptotic vesicles are another recognized EV subtype. Over the last decade, additional membrane-covered neutrophil-derived structures were characterized: migratory cytoplasts, migrasomes, and elongated neutrophil-derived structures (ENDS). All these structures are smaller than the neutrophils, cannot reproduce themselves, and thus meet the latest consensus definition of EVs. In this review, we focus on the less well-studied neutrophil EVs: apoptotic vesicles, cytoplasts, migrasomes, and ENDS.

Proteomic analysis of MSC-derived apoptotic vesicles identifies Fas inheritance to ameliorate haemophilia a via activating platelet functions.

Apoptotic vesicles (apoVs) are apoptotic cell-derived nanosized vesicles that play a crucial role in multiple pathophysiological settings. However, their detailed characteristics, specific surface markers, and biological properties are not fully elucidated. In this study, we compared mesenchymal stem cell (MSC)-derived apoVs and exosomes from three different types of MSCs including human bone marrow MSCs (hBMSCs), human adipose MSCs (hASCs), and mouse bone marrow MSCs (mBMSCs). We established a unique protein map of MSC-derived apoVs and identified the differences between apoVs and exosomes in terms of functional protein cargo and surface markers. Furthermore, we identified 13 proteins specifically enriched in apoVs compared to exosomes, which can be used as apoV-specific biomarkers. In addition, we showed that apoVs inherited apoptotic imprints such as Fas to ameliorate haemophilia A in factor VIII knockout mice via binding to the platelets' FasL to activate platelet functions, and therefore rescuing the blood clotting disorder. In summary, we systemically characterized MSC-derived apoVs and identified their therapeutic role in haemophilia A treatment through a previously unknown Fas/FasL linkage mechanism.

Apoptotic extracellular vesicles are metabolized regulators nurturing the skin and hair.

Over 300 billion of cells die every day in the human body, producing a large number of endogenous apoptotic extracellular vesicles (apoEVs). Also, allogenic stem cell transplantation, a commonly used therapeutic approach in current clinical practice, generates exogenous apoEVs. It is well known that phagocytic cells engulf and digest apoEVs to maintain the body's homeostasis. In this study, we show that a fraction of exogenous apoEVs is metabolized in the integumentary skin and hair follicles. Mechanistically, apoEVs activate the Wnt/β-catenin pathway to facilitate their metabolism in a wave-like pattern. The migration of apoEVs is enhanced by treadmill exercise and inhibited by tail suspension, which is associated with the mechanical force-regulated expression of DKK1 in circulation. Furthermore, we show that exogenous apoEVs promote wound healing and hair growth via activation of Wnt/β-catenin pathway in skin and hair follicle mesenchymal stem cells. This study reveals a previously unrecognized metabolic pathway of apoEVs and opens a new avenue for exploring apoEV-based therapy for skin and hair disorders.

Apoptotic vesicles activate autophagy in recipient cells to induce angiogenesis and dental pulp regeneration

Extracellular vesicles (EVs) derived from living cells play important roles in donor cell-induced recipient tissue regeneration. Although numerous studies have found that cells undergo apoptosis after implantation in an ischemic-hypoxic environment, the roles played by the EVs released by apoptotic cells are largely unknown. In this study, we obtained apoptotic vesicles (apoVs) derived from human deciduous pulp stem cells and explored their effects on the dental pulp regeneration process. Our work showed that apoVs were ingested by endothelial cells (ECs) and elevated the expression of angiogenesis-related genes, leading to pulp revascularization and tissue regeneration. Furthermore, we found that, at the molecular level, apoV-carried mitochondrial Tu translation elongation factor was transported and regulated the angiogenic activation of ECs via the transcription factor EB-autophagy pathway. In a beagle model of dental pulp regeneration in situ, apoVs recruited endogenous ECs and facilitated the formation of dental-pulp-like tissue rich in blood vessels. These findings revealed the significance of apoptosis in tissue regeneration and demonstrated the potential of using apoVs to promote angiogenesis in clinical applications.

Chemokines and anionic phospholipids: new binding partners for microbial killing and apoptotic cell clearance

Abstract Chemokines constitute a large family of small cytokines that regulate leukocyte migration in immunity and inflammation, some of which also have direct bacteria-killing properties. While the molecular mechanism by which chemokines kill bacteria remains poorly understood, chemokines mediate cell migration by interacting with cell surface glycosaminoglycans (GAGs) and G protein-coupled receptors (GPCRs). We have discovered that many chemokines interact with high affinity with anionic membrane phospholipids, including phosphatidylserine (PS) and cardiolipin (CL) which are selectively exposed on the membrane of apoptotic cells and apoptotic extracellular vesicles (ApoEV), and bacteria, respectively. This adds to GPCRs and GAGs a third class of cell surface binding site for chemokines and expands the scope of chemokine action to the biological niches occupied by PS and CL. For instance, we found that ApoEV induce phagocyte migration for apoptotic cell clearance by presenting PS-binding chemokines on the vesicle surface to GPCRs expressed by phagocytes. This is a novel PS-dependent mechanism for chemokine delivery by extracellular vesicles potentially relevant to other areas of immunology and indicates that chemokines may play a more prominent role in the removal of dying cells than previously reported. On the other hand, we discovered that only CL-binding chemokines are antimicrobial and that CL-deficient bacteria are resistant to chemokine treatment, indicating that chemokines kill bacteria by targeting CL on the bacterial membrane. In short, we have identified chemokines as the first family of soluble cytokines whose bioactivities can be regulated by direct interaction with membrane phospholipids. Supported by NIAID/NIH intramural research program

Anionic membrane phospholipids: A New Class of Chemokine‐Binding Site Important for both Apoptotic Cell Clearance and Antibiotic Activity by Chemokines

Chemokines are small cytokines that orchestrate immune cell migration by binding to cell surface glycosaminoglycans (GAGs) and activating G protein‐couple receptors (GPCRs) expressed by leukocytes. We have discovered that chemokines selectively bind with high affinity to anionic membrane phospholipids, including phosphatidylserine (PS) and cardiolipin (CL). This adds to GPCRs and GAGs a third class of high affinity membrane binding site for chemokines and expands the scope of chemokine action to new areas of biology dictated by the specific biological niches occupied by their phospholipid binding partners. PS, for example, is usually restricted to the cytosolic face of the phospholipid bilayer of the plasma membrane of healthy eukaryotic cells, but it is flipped to the outer leaflet of the membrane of apoptotic cells and apoptotic extracellular vesicles (ApoEVs), where it acts as an ‘eat‐me’ signal recognized by phagocytes for apoptotic cell clearance. In this regard, we have recently demonstrated that ApoEVs generated in vivo from mouse thymus induce phagocyte migration using endogenous chemokines bound to the vesicle surface via PS. Our results indicate that PS‐bound chemokines on ApoEVs may serve as ‘find‐me’ signals that recruit phagocytes toward apoptotic cells for the removal of dying cells. This is a new PS‐dependent mechanism for chemokine delivery by extracellular vesicles. On the other hand, CL is absent in the plasma membrane of eukaryotic cells but it is a major and naturally exposed anionic phospholipid in the bacterial plasma membrane. As such, we have found that chemokines act as potent direct bacteria‐killing agents by binding to bacterial CL. This finding identifies the molecular mechanism for antimicrobial action by chemokines and launch new avenues of research in antimicrobial therapies and bacteria‐host interactions. In short, we have identified chemokines as the first example of a family of soluble cytokines whose functions are regulated by direct interaction with membrane phospholipids.

Electrostatic Charge‐Mediated Apoptotic Vesicle Biodistribution Attenuates Sepsis by Switching Neutrophil NETosis to Apoptosis

AbstractMesenchymal stem cell (MSC) therapy can attenuate organ damage and reduce mortality in sepsis; however, the detailed mechanism is not fully elucidated. In this study, it is shown that MSC‐derived apoptotic vesicles (apoVs) can ameliorate multiple organ dysfunction and improve survival in septic mice. Mechanistically, it is found that tail vein‐infused apoVs mainly accumulate in the bone marrow of septic mice via electrostatic charge interactions with positively charged neutrophil extracellular traps (NETs). Moreover, apoVs switch neutrophils NETosis to apoptosis via the apoV‐Fas ligand (FasL)‐activated Fas pathway. In summary, these findings uncover a previously unknown role of apoVs in sepsis treatment and an electrostatic charge‐directed target therapeutic mechanism, suggesting that cell death is associated with disease development and therapy.

Autolysosomes and caspase-3 control the biogenesis and release of immunogenic apoptotic exosomes

Apoptotic exosome-like vesicles (ApoExos) are a novel type of extracellular vesicle that contribute to the propagation of inflammation at sites of vascular injury when released by dying cells. ApoExos are characterized by the presence of the C-terminal perlecan LG3 fragment and 20S proteasome, and they are produced downstream of caspase-3 activation. In the present study, we assessed the relative roles of autophagy and caspase-3-mediated pathways in controlling the biogenesis and secretion of immunogenic ApoExos. Using electron microscopy and confocal immunofluorescence microscopy in serum-starved endothelial cells, we identified large autolysosomes resulting from the fusion of lysosomes, multivesicular bodies, and autophagosomes as a site of ApoExo biogenesis. Inhibition of autophagy with ATG7 siRNA or biochemical inhibitors (wortmannin and bafilomycin) coupled with proteomics analysis showed that autophagy regulated the processing of perlecan into LG3 and its loading onto ApoExos but was dispensable for ApoExo biogenesis. Caspase-3 activation was identified using caspase-3-deficient endothelial cells or caspase inhibitors as a pivotal regulator of fusion events between autolysosomes and the cell membrane, therefore regulating the release of immunogenic ApoExos. Collectively, these findings identified autolysosomes as a site of ApoExo biogenesis and caspase-3 as a crucial regulator of autolysosome cell membrane interactions involved in the secretion of immunogenic ApoExos.

Apoptotic Vesicles Resist Oxidative Damage in Noise-Induced Hearing Loss Through Activation of FOXO3a-SOD2 Pathway

Apoptotic Vesicles Resist Oxidative Damage in Noise-Induced Hearing Loss Through Activation of FOXO3a-SOD2 Pathway

Apoptotic Extracellular Vesicles Ameliorate Multiple Myeloma by Restoring Fas-Mediated Apoptosis.

Apoptosis is critical for maintaining bodily homeostasis and produces a large number of apoptotic extracellular vesicles (apoEVs). Several types of cancer cells display reduced expression of Fas on the cell surface and are thus capable of escaping Fas ligand-induced apoptosis. However, it is unknown whether normal cell-derived apoEVs can regulate tumor growth. In this study, we show that apoEVs can induce multiple myeloma (MM) cell apoptosis and inhibit MM cell growth. Systemic infusion of mesenchymal stem cell (MSC)-derived apoEVs significantly prolongs the lifespan of MM mice. Mechanistically, apoEVs directly contact MM cells to facilitate Fas trafficking from the cytoplasm to the cell membrane by evoking Ca2+ influx and elevation of cytosolic Ca2+. Subsequently, apoEVs use their Fas ligand to activate the Fas pathway in MM cells, leading to the initiation of apoptosis. This study identifies the role of apoEVs in inducing MM apoptosis and suggests a potential for apoEVs to treat MM.