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

ACSL1 Aggravates Thromboinflammation by LPC/LPA Metabolic Axis in Hyperlipidemia Associated Myocardial Ischemia-Reperfusion Injury

Acute myocardial infarction (AMI) is associated with well-established metabolic risk factors, especially hyperlipidemia and obesity. Myocardial ischemia-reperfusion injury (mIRI) significantly offsets the therapeutic efficacy of revascularization. Previous studies indicated that disrupted lipid homeostasis can lead to lipid peroxidation damage and inflammation, yet the underlying mechanisms remain unclear. Here, the study demonstrates that hyperlipidemia is a key driver of mIRI. Long-chain fatty acyl-CoA synthetase 1 (ACSL1) is upregulated in both hyperlipidemia and AMI patients. ACSL1 expression is induced by a high-fat microenvironment (oxLDL and palmitic acid) in a concentration-dependent manner. Interestingly, the protein level is positively correlated with total cholesterol level and thromboinflammatory biomarkers. Furthermore, ACSL1 reprogrammed lipid metabolism in monocytes, leading to the accumulation of lysophosphatidylcholine (LPC)/lysophosphatidic acid (LPA). The monocytic LPC/LPA axis accelerated lipid peroxidation and neutrophil extracellular traps (NETs)-induced thromboinflammation via the paracrine effect. The main LPA producer Autotaxinis is also induced under high-fat conditions and then exerts thromboinflammation response through converted LPC to LPA. Finally, ACSL1 knockdown or NETs release inhibitor (DNase I or GSK484) significantly alleviated mIRI in mice. These findings highlight ACSL1 and NETosis as potential key targets for preventing mIRI and underscore the lipid peroxidation in the mechanisms of ACSL1-mediated thromboinflammation.

Astragaloside IV- loaded biomimetic nanoparticles target IκBα to regulate neutrophil extracellular trap formation for sepsis therapy

This study explored the novel mechanism of Astragaloside IV (As) in treating sepsis and its application through a biomimetic nano-delivery system (As@ZM). Sepsis, a condition of organ dysfunction caused by an abnormal host response to infection, poses a significant threat to global health due to its high mortality rate. Our findings revealed a new mechanism for As in treating sepsis, which involved the reduction of neutrophil extracellular traps (NETs) release, potentially related to As binding with IκBα to inhibit the activation of the NF-κB pathway. As treated neutrophils also improved the immune microenvironment by crosstalk with endothelial cells and lung epithelial cells. However, the stability and bioavailability of As limited its clinical application. To address this issue, we had developed a ZIF-8-based nano-delivery system that achieved targeted delivery through neutrophil membrane coating, significantly enhancing the therapeutic efficacy of As. The innovative design of As@ZM offered a new strategy for sepsis treatment, with the potential to improve clinical outcomes.

Lyophilized apoptotic vesicles improve hemostasis and bone regeneration in traumatic patients with impacted third molar extraction

Uncontrollable bleeding and tissue defects caused by trauma are significant clinical issues. Apoptotic vesicles (apoVs) derived from mesenchymal stem cells (MSCs) have shown promise for hemostasis and tissue regeneration, but their clinical safety and efficacy remain unverified. We investigated the procoagulant and regenerative function of lyophilized MSC-derived apoVs (MSC-apoVs) using in vitro experiments and in vivo rat models. In addition, we conducted a double-blind, randomized, self-controlled clinical trial to evaluate the safety and efficiency of lyophilized MSC-apoVs for hemostasis and bone regeneration following extraction of impacted mandibular third molars. We show that lyophilized MSC-apoVs maintain their procoagulant and regenerative functions after storage at 4°C for 3 months and upregulate tripartite motif containing 71 to activate the extracellular signal-regulated kinase signaling pathway. Furthermore, among the 43 enrolled subjects, 39 patients completed all follow-ups and 4 patients were lost to contact. All 39 patients tolerated MSC-apoVs well, with no serious adverse events or abnormal blood test results observed. The MSC-apoV group exhibited shortened hemostatic time and accelerated alveolar bone regeneration compared with the control group. This is the first clinical study to demonstrate that apoVs are safe, well tolerated, and effective as a cell-free biological therapy for hemostasis and bone regeneration.

Apoptotic mesenchymal stem cells and their secreted apoptotic extracellular vesicles: therapeutic applications and mechanisms

Mesenchymal stem cells (MSCs), an accessible and less ethically controversial class of adult stem cells, have demonstrated significant efficacy in treating a wide range of diseases in both the preclinical and clinical phases. However, we do not yet have a clear understanding of the mechanisms by which MSCs exert their therapeutic effects in vivo. We found that the transplanted MSCs go an apoptotic fate within 24 h in vivo irrespective of the route of administration. Still, the short-term survival of MSCs do not affect their long-term therapeutic efficacy. An increasing number of studies have demonstrated that transplantation of apoptotic MSCs (ApoMSCs) show similar or even better efficacy than viable MSCs, including a variety of preclinical disease models such as inflammatory diseases, skin damage, bone damage, organ damage, etc. Although the exact mechanism has yet to be explored, recent studies have shown that transplanted MSCs undergo apoptosis in vivo and are phagocytosed by phagocytes, thereby exerting immunomodulatory effects. The apoptotic extracellular vesicles secreted by ApoMSCs (MSC-ApoEVs) play a significant role in promoting immunomodulation, endogenous stem cell regeneration, and angiogenesis due to their apoptotic properties and inheritance of molecular characteristics from their parental MSCs. On this basis, this review aims to deeply explore the therapeutic applications and mechanisms of ApoMSCs and their secretion of MSC-ApoEVs, as well as the challenges they face.

Fate and long-lasting therapeutic effects of mesenchymal stromal/stem-like cells: mechanistic insights

A large body of evidence suggests that mesenchymal stromal cells (MSCs) are able to respond rapidly to the cytokine milieu following systemic infusion. This encounter has the potential to dictate their therapeutic efficacy (also referred to as licensing). MSCs are able to rapidly react to cellular damage by migrating to the inflamed tissue and ultimately modifying the inflammatory microenvironment. However, the limited use of MSCs in clinical practice can be attributed to a lack of understanding of the fate of MSCs in patients after administration and long term MSC-derived therapeutic activity. While the known physiological effectors of viable MSCs make a relative contribution, an innate property of MSCs as a therapeutic agent is their caspase-dependent cell death. These mechanisms may be involving the functional reprogramming of myeloid phagocytes via efferocytosis, the process by which apoptotic bodies (ABs) are identified for engulfment by both specialized and non-specialized phagocytic cells. Recent studies have provided evidence that the uptake of ABs with a distinct genetic component can induce changes in gene expression through the process of epigenetic remodeling. This phenomenon, known as 'trained immunity', has a significant impact on immunometabolism processes. It is hypothesized that the diversity of recipient cells within the inflammatory stroma adjacent to MSCs may potentially serve as a biomarker for predicting the clinical outcome of MSC treatment, while also contributing to the variable outcomes observed with MSC-based therapies. Therefore, the long-term reconstructive process of MSCs may potentially be mediated by MSC apoptosis and subsequent phagocyte-mediated efferocytosis.

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.

The Mechanisms of Sepsis Induced Coagulation Dysfunction and Its Treatment

Sepsis is a critical condition characterized by organ dysfunction due to a dysregulated response to infection that poses significant global health challenges. Coagulation dysfunction is nearly ubiquitous among sepsis patients. Its mechanisms involve platelet activation, coagulation cascade activation, inflammatory reaction imbalances, immune dysregulation, mitochondrial damage, neuroendocrine network disruptions, and endoplasmic reticulum (ER) stress. These factors not only interact but also exacerbate one another, leading to severe organ dysfunction. This review illustrates the mechanisms of sepsis-induced coagulopathy, with a focus on tissue factor activation, endothelial glycocalyx damage, and the release of neutrophil extracellular traps (NETs), all of which are potential targets for therapeutic interventions.

Emerging role of exosomes in cancer therapy: progress and challenges

This review highlights recent progress in exosome-based drug delivery for cancer therapy, covering exosome biogenesis, cargo selection mechanisms, and their application across multiple cancer types. As small extracellular vesicles, exosomes exhibit high biocompatibility and low immunogenicity, making them ideal drug delivery vehicles capable of efficiently targeting cancer cells, minimizing off-target damage and side effects. This review aims to explore the potential of exosomes in cancer therapy, with a focus on applications in chemotherapy, gene therapy, and immunomodulation. Additionally, challenges related to exosome production and standardization are analyzed, highlighting the importance of addressing these issues for their clinical application. In conclusion, exosome-based drug delivery systems offer promising potential for future cancer therapies. Further research should aim to enhance production efficiency and facilitate clinical translation, paving the way for innovative cancer treatment strategies.

Apoptotic Vesicles Attenuate Acute Lung Injury via CD73-Mediated Inhibition of Platelet Activation and NETosis

Introduction

Acute respiratory distress syndrome (ARDS) is a life-threatening type of acute lung injury (ALI) characterized by elevated mortality rates and long-term effects. To date, no pharmacological treatment has proven effective for ARDS. Mesenchymal stem cell-derived apoptotic vesicles (apoVs) were recently found to have excellent therapeutic potential for inflammatory diseases. In this study, our aim was to investigate the therapeutic effects and underlying mechanisms of apoVs in ALI.

Methods

ALI was induced in mice through intratracheal instillation of lipopolysaccharide (LPS). ApoVs were then administered two hours post-induction, and their impacts on platelet activation, neutrophil infiltration, and NETosis were assessed. Additionally, the role of CD73 in mediating these effects was thoroughly investigated.

Results

ApoVs inhibit platelet activation, thereby impeding the infiltration of neutrophils into the lung and the initiation of NETosis, ultimately alleviating ALI. Remarkably, apoVs were enriched with CD73, which was critical for apoV-mediated repression of platelet activation and neutrophil NETosis, as well as the therapeutic effects observed in lung injury.

Conclusion

This study reveals that apoVs inhibit platelet activity and neutrophil NETosis via CD73, offering an innovative and effective cell-free therapeutic strategy for ALI/ARDS.

Apoptotic body based biomimetic hybrid nanovesicles to attenuate cytokine storms for sepsis treatment

Sepsis is a severe immune response to pathogens that is associated with high mortality rate and a paucity of efficacious treatment options. It is characterized by the hyperactivation of macrophages and the occurrence of cytokine storms. Given the anti-inflammatory properties of M2 macrophages and their derived apoptotic bodies (AB), as well as the specific uptake of these by macrophages, a novel approach was employed to combine AB with artificial liposomes to create apoptotic body based biomimetic hybrid nanovesicles (L-AB). The L-AB effectively inherited "eat me" signaling molecules on the surface of the AB, thereby facilitating their targeted uptake by macrophages in both in vitro and in vivo settings. The administration of L-AB for the delivery of dexamethasone effectively augmented the therapeutic efficacy of the drug, mitigated macrophage hyperactivation and tissue damage in vivo, and consequently enhanced the survival rate of septic mice. Taken together, these findings suggest that the apoptotic body biomimetic nanovesicles may represent a potential drug delivery system capable of specifically targeting macrophages for the treatment of sepsis.

Innate immunity-modulating nanobiomaterials for controlling inflammation resolution

The acute inflammatory response is an inherent protective mechanism, its unsuccessful resolution can contribute to disease pathogenesis and potentially lead to death. Innate immune cells are the first line of host defenders and play a substantial role in inflammation initiation, amplification, resolution, or subsequent disease progression. As the resolution of inflammation is an active and highly regulated process, modulating innate immune cells, including neutrophils, monocytes and macrophages, and endothelial cells, and their interactions offer opportunities to control excessive inflammation. Nanobiomaterials have shown superior therapeutic potential in inflammation-related diseases by manipulating inflammatory responses because nanobiomaterials can target and interact with innate immune cells. Versatile nanobiomaterials can be designed for targeted modulation of specific innate immune responses. Nanopro-resolving medicines have been prepared both with pro-resolving lipid mediators and peptides each demonstrated to active resolution of inflammation in animal disease models. Here, we review innovative nanobiomaterials for modulating innate immunity and alleviating inflammation. We summarise the strategies converging the design of nanobiomaterials and the nano-bio interaction in modulating innate immune profiles and propelling the advancement of nanobiomaterials for inflammatory disease treatments. We also propose the future perspectives and translational challenges of nanobiomaterials that need to be overcome in this swiftly rising field.

Apoptotic Vesicles: Therapeutic Mechanisms and Critical Issues

Apoptosis is the most prominent mode of programmed cell death and is necessary for the maintenance of tissue homeostasis. During cell apoptosis, a distinctive population of extracellular vesicles is generated, termed apoptotic vesicles (apoVs). ApoVs inherit a variety of biological molecules such as proteins, RNAs, nuclear components, lipids, and gasotransmitters from their parent cells. ApoVs have shown promising therapeutic potential for inflammation, tumors, immune disorders, and tissue regeneration. In addition, apoVs can be used as drug carriers, vaccine development, and disease diagnosis. Recently, apoVs have been used in clinical trials to treat a variety of diseases, such as temporomandibular joint osteoarthritis and the regeneration of functional alveolar bone. Here, we review the history of apoV research, current preclinical and clinical studies, and the potential issues of apoV application.

Construction of a NETosis-related gene signature for predicting the prognostic status of sepsis patients

Background

Sepsis is a common traumatic complication of response disorder of the body to infection. Some studies have found that NETosis may be associated with the progression of sepsis.

Methods

Data of the sepsis samples were acquired from Gene Expression Omnibus (GEO) database. Gene set enrichment score was calculated using single-sample gene set enrichment analysis (ssGSEA). Weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) networks analysis, and stepwise multivariable regression analysis were performed to identify NETosis-associated genes for sepsis prognosis. To assess the infiltration of immune cells, the ESTIMATE and CIBERPSORT algorithms were used. Functional enrichment analysis was conducted in the clusterProfiler package.

Results

Different programmed death pathways were abnormally activated in sepsis patients as compared to normal samples. We screened five important NETosis associated genes, namely, CEACAM8, PGLYRP1, MAPK14, S100A12, and LCN2. These genes were significantly positively correlated with entotic cell death and ferroptosis and negatively correlated with autophagy. A clinical prognostic model based on riskscore was established using the five genes. The ROC curves of the model at 7 days, 14 days and 21 days all had high AUC values, indicating a strong stability of the model. Patients with high riskscore had lower survival rate than those with low riskscore. After the development of a nomogram, calibration curve and decision curve evaluation also showed a strong prediction performance and reliability of the model. As for clinicopathological features, older patients and female patients had a relatively high riskscore. The riskscore was significantly positively correlated with cell cycle-related pathways and significantly negatively correlated with inflammatory pathways.

Conclusion

We screened five NETosis-associated genes that affected sepsis prognosis, and then established a riskscore model that can accurately evaluate the prognosis and survival for sepsis patients. Our research may be helpful for the diagnosis and clinical treatment of sepsis.

Hypericum perforatum-derived exosomes-like nanovesicles for adipose tissue photodynamic therapy

BACKGROUND

Recent investigations underscore the capacity of photodynamic therapy (PDT) to induce adipocyte apoptosis, thereby mitigating obesity. Nonetheless, extant synthetic photosensitizers manifest limitations that hinder their clinical viability.

PURPOSE

In the current study, we used Hypericum perforatum-derived exosomes-like nanovesicles (HPExos) as a novel photosensitizer, and investigated its PDT effects in adipose tissue during obesity.

METHOD

HPExos-were administered to high fat diet mice via intraperitoneal injection, followed by targeted irradiation with specialized LED lights. Mass spectrometric analysis was analyzed in adipose tissues. CCK8 assay and Oil Red O staining were used to investigate lipid accumulation in 3T3-L1 cells to clarify adipocyte differentiation. The expression levels of related markers associated with adipogenesis and lipogenesis were assessed by RT-PCR. Apoptosis analysis was performed by TUNEL staining of and western blotting.

RESULTS

HPExos combined with PDT accumulated in visceral white adipose tissues results in a reduced body weight and improved insulin sensitivity. HPExos combined with PDT induced apoptosis by driving high levels of ROS. In addition, HPExos combined with PDT significantly downregulated the expression of transcription factors, PPARγ, C/EBPα, and SREBP and lipogenesis protein FABP4 both in vitro and in vivo, associated with a decreased FFA levels.

CONCLUSION

These findings suggest that HPExos could act as an effective photosensitizer in regulating glucose hemostasis by inhibiting adipocyte differentiation and lipogenesis, offering a promising approach for obesity treatment.

Carbon Dot-Loaded Apoptotic Vesicles Improve the Liver Kupffer Cell-Mediated Antibacterial Effect to Synergistically Alleviate Sepsis

Sepsis is a lethal systemic inflammatory disease against infection that lacks effective therapeutic approaches. Liver resident macrophage Kupffer cell (KC)-initiated bacterial clearance is crucial for the host to defend against infection. However, it remains unclear whether this process also governs the antibacterial therapy of sepsis that would be used to improve therapeutic outcomes. Here, we found that copper-doped carbon dots (Cu-CDs) exhibited superior antibacterial capabilities in vitro but displayed limited therapeutic effects in septic mice due to their limited ability to target the liver and restore KC antimicrobial capacity. Thus, we developed a composite nanodrug of copper-doped carbon dot-loaded apoVs (CC-apoVs) that combined the antibacterial ability of Cu-CDs and liver KC targeting features of apoV. Moreover, intravenous injection of CC-apoVs markedly alleviated the systemic infection and decreased the mortality of septic mice compared to Cu-CD and apoV infusion alone. Mechanistically, CC-apoV injection rescued impaired liver KCs during sepsis and enhanced their ability to capture and kill bloodborne bacteria. In addition, apoV-promoted macrophage killing of bacteria could be blocked by the inhibition of small GTPase Rab5. This study reveals a liver KC-targeted therapeutic strategy for sepsis and provides a nanodrug CC-apoV to improve the host antibacterial defense and amplify the therapeutic effect of the nanodrug.

Activating Macrophage Continual Efferocytosis via Microenvironment Biomimetic Short Fibers for Reversing Inflammation in Bone Repair

Efferocytosis-mediated inflammatory reversal plays a crucial role in bone repairing process. However, in refractory bone defects, the macrophage continual efferocytosis may be suppressed due to the disrupted microenvironment homeostasis, particularly the loss of apoptotic signals and overactivation of intracellular oxidative stress. In this study, a polydopamine-coated short fiber matrix containing biomimetic "apoptotic signals" to reconstruct the microenvironment and reactivate macrophage continual efferocytosis for inflammatory reversal and bone defect repair is presented. The "apoptotic signals" (AM/CeO2) are prepared using CeO2 nanoenzymes with apoptotic neutrophil membrane coating for macrophage recognition and oxidative stress regulation. Additionally, a short fiber "biomimetic matrix" is utilized for loading AM/CeO2 signals via abundant adhesion sites involving π-π stacking and hydrogen bonding interactions. Ultimately, the implantable apoptosis-mimetic nanoenzyme/short-fiber matrixes (PFS@AM/CeO2), integrating apoptotic signals and biomimetic matrixes, are constructed to facilitate inflammatory reversal and reestablish the pro-efferocytosis microenvironment. In vitro and in vivo data indicate that the microenvironment biomimetic short fibers can activate macrophage continual efferocytosis, leading to the suppression of overactivated inflammation. The enhanced repair of rat femoral defect further demonstrates the osteogenic potential of the pro-efferocytosis strategy. It is believed that the regulation of macrophage efferocytosis through microenvironment biomimetic materials can provide a new perspective for tissue repair.

In situ neutrophil apoptosis and macrophage efferocytosis mediated by Glycyrrhiza protein nanoparticles for acute inflammation therapy

In the progression of acute inflammation, the activation and recruitment of macrophages and neutrophils are mutually reinforcing, leading to amplified inflammatory response and severe tissue damage. Therefore, to regulate the axis of neutrophils and macrophages is essential to avoid tissue damage induced from acute inflammatory. Apoptotic neutrophils can regulate the anti-inflammatory activity of macrophages through the efferocytosis. The strategy of in situ targeting and inducing neutrophil apoptosis has the potential to modulate macrophage activity and transfer anti-inflammatory drugs. Herein, a natural glycyrrhiza protein nanoparticle loaded with dexamethasone (Dex@GNPs) was constructed, which could simultaneously regulate neutrophil and macrophage function during acute inflammation treatment by combining in situ neutrophil apoptosis and macrophage efferocytosis. Dex@GNPs can be rapidly and selectively internalized by neutrophils and subsequently induce neutrophils apoptosis through a ROS-dependent mechanism. The efferocytosis of apoptotic neutrophils not only promoted the polarization of macrophages into anti-inflammatory state, but also facilitated the transfer of Dex@GNPs to macrophages. This enabled dexamethasone to further modulate macrophage function. In mouse models of acute respiratory distress syndrome and sepsis, Dex@GNPs significantly ameliorated the disordered immune microenvironment and alleviated tissue injury. This study presents a novel strategy for drug delivery and inflammation regulation to effectively treat acute inflammatory diseases.

Apoptotic vesicles are required to repair DNA damage and suppress premature cellular senescence

It is well known that DNA damage can cause apoptosis. However, whether apoptosis and its metabolites contribute to DNA repair is largely unknown. In this study, we found that apoptosis-deficient Fasmut and Bim- /- mice show significantly elevated DNA damage and premature cellular senescence, along with a significantly reduced number of 16,000 g apoptotic vesicles (apoVs). Intravenous infusion of mesenchymal stromal cell (MSC)-derived 16,000 g apoVs rescued the DNA damage and premature senescence in Fasmut and Bim-/- mice. Moreover, a sublethal dose of radiation exposure caused more severe DNA damage, reduced survival rate, and loss of body weight in Fasmut mice than in wild-type mice, which can be recovered by the infusion of MSC-apoVs. Mechanistically, we showed that apoptosis can assemble multiple nuclear DNA repair enzymes, such as the full-length PARP1, into 16,000 g apoVs. These DNA repair components are directly transferred by 16,000 g apoVs to recipient cells, leading to the rescue of DNA damage and elimination of senescent cells. Finally, we showed that embryonic stem cell-derived 16,000 g apoVs have superior DNA repair capacity due to containing a high level of nuclear DNA repair enzymes to rescue lethal dose-irradiated mice. This study uncovers a previously unknown role of 16,000 g apoVs in safeguarding tissues from DNA damage and demonstrates a strategy for using stem cell-derived apoVs to ameliorate irradiation-induced DNA damage.

Calcified apoptotic vesicles from PROCR+ fibroblasts initiate heterotopic ossification

Heterotopic ossification (HO) comprises the abnormal formation of ectopic bone in extraskeletal soft tissue. The factors that initiate HO remain elusive. Herein, we found that calcified apoptotic vesicles (apoVs) led to increased calcification and stiffness of tendon extracellular matrix (ECM), which initiated M2 macrophage polarization and HO progression. Specifically, single-cell transcriptome analyses of different stages of HO revealed that calcified apoVs were primarily secreted by a PROCR+ fibroblast population. In addition, calcified apoVs enriched calcium by annexin channels, absorbed to collagen I via electrostatic interaction, and aggregated to produce calcifying nodules in the ECM, leading to tendon calcification and stiffening. More importantly, apoV-releasing inhibition or macrophage deletion both successfully reversed HO development. Thus, we are the first to identify calcified apoVs from PROCR+ fibroblasts as the initiating factor of HO, and might serve as the therapeutic target for inhibiting pathological calcification.

Platelets in Alcohol-Associated Liver Disease: Interaction With Neutrophils

Alcohol-associated liver disease (ALD) is a major contributor to liver-related mortality globally. An increasing body of evidence underscores the pivotal role of platelets throughout the spectrum of liver injury and recovery, offering unique insights into liver homeostasis and pathobiology. Alcoholic-associated steatohepatitis is characterized by the infiltration of hepatic neutrophils. Recent studies have highlighted the extensive distance neutrophils travel through sinusoids to reach the liver injury site, relying on a platelet-paved endothelium for efficient crawling. The adherence of platelets to neutrophils is crucial for accurate migration from circulation to the inflammatory site. A gradual decline in platelet levels leads to diminished neutrophil recruitment. Platelets exhibit the ability to activate neutrophils. Platelet activation is heightened upon the release of platelet granule contents, which synergistically activate neutrophils through their respective receptors. The sequence culminates in the formation of platelet-neutrophil complexes and the release of neutrophil extracellular traps intensifies liver damage, fosters inflammatory immune responses, and triggers hepatotoxic processes. Neutrophil infiltration is a hallmark of alcohol-associated steatohepatitis, and the roles of neutrophils in ALD pathogenesis have been studied extensively, however, the involvement of platelets in ALD has received little attention. The current review consolidates recent findings on the intricate and diverse roles of platelets and neutrophils in liver pathophysiology and in ALD. Potential therapeutic strategies are highlighted, focusing on targeting platelet-neutrophil interactions and activation in ALD. The anticipation is that innovative methods for manipulating platelet and neutrophil functions will open promising avenues for future ALD therapy.

ASC-expressing pyroptotic extracellular vesicles alleviate sepsis by protecting B cells

Pyroptosis is an inflammatory programmed cell death process characterized by membrane rupture. Interestingly, pyroptotic cells can generate plenty of nanosized vesicles. Non-inflammatory apoptotic cell death-derived apoptotic vesicles (apoVs) were systemically characterized and displayed multiple physiological functions and therapeutic potentials. However, the characteristics of pyroptotic cell-generated extracellular vesicles (EVs) are largely unknown. Here, we identified a group of pyroptotic EVs (pyroEVs) from in vitro cultured pyroptotic mesenchymal stem cells (MSCs), as well as from septic mouse blood. Compared with apoVs, pyroEVs express similar levels of annexin V, calreticulin, and common EV markers, but express a decreased level of apoptotic marker cleave caspase-3. PyroEVs, but not apoVs and exosomes, specifically express pyroptotic maker apoptosis-associated speck-like protein containing CARD (ASC). More importantly, MSC-derived pyroEVs protect B cells in the spleen and bone marrow to relieve inflammatory responses and enhance the survival rate of the septic mice. Mechanistically, pyroEV membrane-expressed ASC binds to B cells to repress cell death by repressing Toll-like receptor 4. This study uncovered the characteristics of pyroEVs and their therapeutic role in sepsis and B cell-mediated immune response.

Apoptotic Extracellular Vesicles Derived from Human Umbilical Vein Endothelial Cells Promote Skin Repair by Enhancing Angiogenesis: From Death to Regeneration

Purpose

The promotion of angiogenesis is an effective strategy for skin wound repair. While the transplantation of endothelial cells has shown promise in vascularization, the underlying mechanism remains unclear. Recent studies have suggested that transplanted cells undergo apoptosis in a short period and release apoptotic extracellular vesicles (ApoEVs) that may have therapeutic potential.

Methods

In this study, we isolated ApoEVs from human umbilical vein endothelial cells (HUVECs) and characterized their properties. In vitro, we assessed the effects of ApoEVs on the proliferation, migration, and differentiation of endothelial cells and fibroblasts. In vivo, we investigated the therapeutic role of ApoEVs-AT in full-thickness skin wounds, evaluating wound closure rate, re-epithelialization, granulation tissue formation, vascularization, scar area, and collagen 3(Col3)/collagen 1(Col 1) ratio.

Results

ApoEVs derived from HUVECs displayed typical characteristics. In vitro, ApoEVs significantly enhanced the proliferation, migration, tube formation, and expression of angiogenic-related genes in endothelial cells and slightly promoted the proliferation and migration of fibroblasts. In vivo, ApoEVs improved the wound closure rate, re-epithelialization, the formation of granulation tissue, and vascularization. Besides, ApoEVs reduced scar formation, accompanied by an increase in the Col 3/ Col 1 ratio.

Conclusion

Given their abundant source and effectiveness, this study provided a novel approach for angiogenesis in tissue regeneration and deepened the understanding of from death to regeneration.

Apoptosis releases hydrogen sulfide to inhibit Th17 cell differentiation

Over 50 billion cells undergo apoptosis each day in an adult human to maintain immune homeostasis. Hydrogen sulfide (H2S) is also required to safeguard the function of immune response. However, it is unknown whether apoptosis regulates H2S production. Here, we show that apoptosis-deficient MRL/lpr (B6.MRL-Faslpr/J) and Bim-/- (B6.129S1-Bcl2l11tm1.1Ast/J) mice exhibit significantly reduced H2S levels along with aberrant differentiation of Th17 cells, which can be rescued by the additional H2S. Moreover, apoptotic cells and vesicles (apoVs) express key H2S-generating enzymes and generate a significant amount of H2S, indicating that apoptotic metabolism is an important source of H2S. Mechanistically, H2S sulfhydrates selenoprotein F (Sep15) to promote signal transducer and activator of transcription 1 (STAT1) phosphorylation and suppress STAT3 phosphorylation, leading to the inhibition of Th17 cell differentiation. Taken together, this study reveals a previously unknown role of apoptosis in maintaining H2S homeostasis and the unique role of H2S in regulating Th17 cell differentiation via sulfhydration of Sep15C38.

Platelet-Derived Apoptotic Vesicles Promote Bone Regeneration via Golgi Phosphoprotein 2 (GOLPH2)-AKT Signaling Axis

Apoptotic vesicles (apoVs) are apoptotic-cell-derived nanosized vesicles that take on dominant roles in regulating bone homeostasis. We have demonstrated that mesenchymal stem cell (MSC)-derived apoVs are promising therapeutic agents for bone regeneration. However, clinical translation of MSC-derived apoVs has been hindered due to cell expansion and nuclear substance. As another appealing source for apoV therapy, blood cells could potentially eliminate these limitations. However, whether blood cells can release apoVs during apoptosis is uncertain, and the detailed characteristics and biological properties of respective apoVs are not elucidated. In this study, we showed that platelets (PLTs) could rapidly release abundant apoVs during apoptosis in a short time. To recognize the different protein expressions between PLT-derived apoVs and PLTs, we established their precise protein landscape. Furthermore, we identified six proteins specifically enriched in PLT-derived apoVs, which could be considered as specific biomarkers. More importantly, PLT-derived apoVs promoted osteogenesis of MSCs and rescued bone loss via Golgi phosphoprotein 2 (GOLPH2)-induced AKT phosphorylation, therefore, leading to the emergence of their potential in bone regeneration. In summary, we comprehensively determined characteristics of PLT-derived apoVs and confirmed their roles in bone metabolism through previously unrecognized GOPLH2-dependent AKT signaling, providing more understanding for exploring apoV-based therapy in bone tissue engineering.

Apoptotic Vesicles of MSCs: The Natural Therapeutic Agents and Bio-Vehicles for Targeting Drug Delivery

Mesenchymal stem cell (MSC)-based therapies are increasingly recognized as promising cellular therapeutics and show the ability to treat various diseases. However, the underlying mechanism is not fully elucidated. Some recent studies have shown an unexpected result whereby MSCs undergo rapid apoptosis following administration but still exert therapeutic effects in some disease treatments. Such a therapeutic mechanism is believed to associate with the released apoptotic vesicles from apoptotic MSCs (MSC-ApoVs). This finding inspires a novel therapeutic strategy for using MSC-ApoVs for disease treatment. The present review aims to summarize the biogenesis, physiological functions, therapeutic potentials, and related mechanisms of apoptotic vesicles in MSC-based therapy. In addition, the potential applications of MSC-ApoVs as natural therapeutic agents and natural drug delivery vehicles are proposed and highlighted. The present review is hoped to provide a general understanding of MSC-ApoVs in disease treatment and inspire potential applications in targeted drug delivery.

Encapsulation of Nano-Bortezomib in Apoptotic Stem Cell-Derived Vesicles for the Treatment of Multiple Myeloma

Extracellular vesicles (EVs) are lipid bilayer nanovesicles released from living or apoptotic cells that can transport DNA, RNA, protein, and lipid cargo. EVs play critical roles in cell-cell communication and tissue homeostasis, and have numerous therapeutic uses including serving as carriers for nanodrug delivery. There are multiple ways to load EVs with nanodrugs, such as electroporation, extrusion, and ultrasound. However, these approaches may have limited drug-loading rates, poor EV membrane stability, and high cost for large-scale production. Here, it is shown that apoptotic mesenchymal stem cells (MSCs) can encapsulate exogenously added nanoparticles into apoptotic vesicles (apoVs) with a high loading efficiency. When nano-bortezomib is incorporated into apoVs in culture-expanded apoptotic MSCs, nano-bortezomib-apoVs show a synergistic combination effect of bortezomib and apoVs to ameliorate multiple myeloma (MM) in a mouse model, along with significantly reduced side effects of nano-bortezomib. Moreover, it is shown that Rab7 regulates the nanoparticle encapsulation efficiency in apoptotic MSCs and that activation of Rab7 can increase nanoparticle-apoV production. In this study, a previously unknown mechanism to naturally synthesize nano-bortezomib-apoVs to improve MM therapy is revealed.

Advances in biological functions and applications of apoptotic vesicles

BACKGROUND

Apoptotic vesicles are extracellular vesicles generated by apoptotic cells that were previously regarded as containing waste or harmful substances but are now thought to play an important role in signal transduction and homeostasis regulation.

METHODS

In the present review, we reviewed many articles published over the past decades on the subtypes and formation of apoptotic vesicles and the existing applications of these vesicles.

RESULTS

Apoptotic bodies were once regarded as vesicles released by apoptotic cells, however, apoptotic vesicles are now regarded to include apoptotic bodies, apoptotic microvesicles and apoptotic exosomes, which exhibit variation in terms of biogenesis, sizes and properties. Applications of apoptotic vesicles were first reported long ago, but such reports have been rarer than those of other extracellular vesicles. At present, apoptotic vesicles have been utilized mainly in four aspects, including in direct therapeutic applications, in their engineering as carriers, in their construction as vaccines and in their utilization in diagnosis.

CONCLUSION

Building on a deeper understanding of their composition and characteristics, some studies have utilized apoptotic vesicles to treat diseases in more novel ways. However, their limitations for clinical translation, such as heterogeneity, have also emerged. In general, apoptotic vesicles have great application potential, but there are still many barriers to overcome in their investigation. Video Abstract.

Role and Therapeutic Targeting Strategies of Neutrophil Extracellular Traps in Inflammation

Neutrophil extracellular traps (NETs) are large DNA reticular structures secreted by neutrophils and decorated with histones and antimicrobial proteins. As a key mechanism for neutrophils to resist microbial invasion, NETs play an important role in the killing of microorganisms (bacteria, fungi, and viruses). Although NETs are mostly known for mediating microbial killing, increasing evidence suggests that excessive NETs induced by stimulation of physical and chemical components, microorganisms, and pathological factors can exacerbate inflammation and organ damage. This review summarizes the induction and role of NETs in inflammation and focuses on the strategies of inhibiting NETosis and the mechanisms involved in pathogen evasion of NETs. Furthermore, herbal medicine inhibitors and nanodelivery strategies improve the efficiency of inhibition of excessive levels of NETs.

Apoptotic vesicles ameliorate lupus and arthritis via phosphatidylserine-mediated modulation of T cell receptor signaling

Mesenchymal stem cells (MSCs) influence T cells in health, disease and therapy through messengers of intercellular communication including extracellular vesicles (EVs). Apoptosis is a mode of cell death that tends to promote immune tolerance, and a large number of apoptotic vesicles (apoVs) are generated from MSCs during apoptosis. In an effort to characterize these apoVs and explore their immunomodulatory potential, here we show that after replenishing them systemically, the apoV deficiency in Fas mutant mice and pathological lymphoproliferation were rescued, leading to the amelioration of inflammation and lupus activity. ApoVs directly interacted with CD4+ T cells and inhibited CD25 expression and IL-2 production in a dose-dependent manner. A broad range of Th1/2/17 subsets and cytokines including IFNγ, IL17A and IL-10 were suppressed while Foxp3+ cells were maintained. Mechanistically, exposed phosphatidylserine (PtdSer/PS) on apoVs mediated the interaction with T cells to disrupt proximal T cell receptor signaling transduction. Remarkably, administration of apoVs prevented Th17 differentiation and memory formation, and ameliorated inflammation and joint erosion in murine arthritis. Collectively, our findings unveil a previously unrecognized crosstalk between MSC apoVs and CD4+ T cells and suggest a promising therapeutic use of apoVs for autoimmune diseases.

Extracellular vesicles and their indispensable roles in pathogenesis and treatment of inflammatory bowel disease: A comprehensive review

Inflammatory bowel disease (IBD) is a global disease with rising incidence worldwide, and its debilitating symptoms and dissatisfactory therapies have brought heavy burdens for patients. Extracellular vesicles (EVs), a heterogeneous population of lipid bilayer membranes containing abundant bioactive molecules, have been indicated to play important roles in the pathogenesis and treatment of many diseases. However, to our knowledge, comprehensive reviews summarizing the various roles of diverse source-derived EVs in the pathogenesis and treatment of IBD are still lacking. This review, not only summarizes the EV characteristics, but also focuses on the multiple roles of diverse EVs in IBD pathogenesis and their treatment potential. In addition, hoping to push forward the research frontiers, we point out several challenges that the researchers are faced, about EVs in current IBD research and future therapeutic applications. We also put forward our prospects on future exploration regarding EVs in IBD treatment, including developing IBD vaccines and paying more attention on apoptotic vesicles. This review is aimed to enrich the knowledge on the indispensable roles of EVs in IBD pathogenesis and treatment, providing ideas and reference for future therapeutic strategy for IBD treatment.

Preparation of Apoptotic Extracellular Vesicles from Adipose Tissue and Their Efficacy in Promoting High-Quality Skin Wound Healing

Purpose

A lot of strategies have been attempted to achieve high-quality skin wound healing, among them, fat transplantation has been used for skin wound repair and scar management and has shown beneficial effects. However, the underlying mechanism is still unclear. Recently, studies found that transplanted cells underwent apoptosis within a short period and apoptotic extracellular vesicles (ApoEVs) might play the therapeutic role.

Methods

In this study, we directly isolated apoptotic extracellular vesicles from adipose tissue (ApoEVs-AT) and evaluated their characteristics. In vivo, we investigated the therapeutic role of ApoEVs-AT in full-thickness skin wounds. The rate of wound healing, the quality of granulation tissue, and the area of scars were evaluated here. In vitro, we investigated the cellular behaviors of fibroblasts and endothelial cells induced by ApoEVs-AT, including cellular uptake, proliferation, migration, and differentiation.

Results

ApoEVs-AT could be successfully isolated from adipose tissue and possessed the basic characteristics of ApoEVs. In vivo, ApoEVs-AT could accelerate skin wound healing, improve the quality of granulation tissue, and reduce the area of scars. In vitro, ApoEVs-AT could be engulfed by fibroblasts and endothelial cells, significantly enhancing their proliferation and migration. Moreover, ApoEVs-AT could promote adipogenic differentiation and inhibit the fibrogenic differentiation of fibroblasts.

Conclusion

These findings indicated that ApoEVs could be successfully prepared from adipose tissue and showed the ability to promote high-quality skin wound healing by modulating fibroblasts and endothelial cells.

Mesenchymal stem cell-derived extracellular vesicles protect against abdominal aortic aneurysm formation by inhibiting NET-induced ferroptosis

Neutrophil extracellular traps (NETs) play an important role in abdominal aortic aneurysm (AAA) formation; however, the underlying molecular mechanisms remain unclear. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) may exert therapeutic effects on AAA through their immunomodulatory and regenerative abilities. This study aimed to examine the role and mechanism of MSC-EVs in regulating the development of NET-mediated AAA. Excessive release of NETs was observed in patients with AAA, and the levels of NET components were associated with the clinical outcomes of the patients. Datasets from the Gene Expression Omnibus database were analyzed and revealed that the PI3K/AKT pathway and ferroptosis were strongly associated with NETosis during AAA formation. Further experiments verified that NETs promoted AAA formation by inducing ferroptosis in smooth muscle cells (SMCs) by inhibiting the PI3K/AKT pathway. The PI3K agonist 740 Y-P, the ferroptosis inhibitor ferrostatin-1, and Padi4 deficiency significantly prevented AAA formation. MSC-EVs attenuated AAA formation by reducing NET release in an angiotensin II-induced AAA mouse model. In vitro experiments revealed that MSC-EVs reduced the release of NETs by shifting NETosis to apoptosis. Our study indicates an important role for NET-induced SMC ferroptosis in AAA formation and provides several potential targets for AAA treatment.

Apoptotic vesicles: emerging concepts and research progress in physiology and therapy

Apoptosis represents the dominant form of programmed cell death and plays critical roles in maintaining tissue and organ homeostasis. A notable population of extracellular vesicles (EVs) is generated during apoptosis, known as apoptotic vesicles (apoVs). These apoVs are increasingly the subject of studies concerning their identity and mechanisms of production, which have been revealed unique biological and functional characteristics that are emerging as crucial regulators for diverse processes. Furthermore, apoVs have been gradually noticed for their essential role in regulating the physiology of various organ systems in vivo, and growing evidence suggests that apoV dysregulation contributes to age- and pathology-associated tissue alterations. Importantly, apoVs can be therapeutically harnessed to unleash their potential in treating several diseases such as immune disorders, osteoporosis, cutaneous wound and acute liver failure; these vesicles, mainly derived from cultured mesenchymal stem cells, hold great translational promise. Here we review the current landscape of scientific knowledge about apoVs, with emphasis on mechanistic insights into how apoVs contribute to organismal health and disease, which also provide novel cell-free strategies for EV-based regenerative therapeutics.

Immunomodulatory properties of mesenchymal stem cells/dental stem cells and their therapeutic applications

Mesenchymal stem/stromal cells (MSCs) are widely distributed in the body and play essential roles in tissue regeneration and homeostasis. MSCs can be isolated from discarded tissues, expanded in vitro and used as therapeutics for autoimmune diseases and other chronic disorders. MSCs promote tissue regeneration and homeostasis by primarily acting on immune cells. At least six different types of MSCs have been isolated from postnatal dental tissues and have remarkable immunomodulatory properties. Dental stem cells (DSCs) have been demonstrated to have therapeutic effects on several systemic inflammatory diseases. Conversely, MSCs derived from nondental tissues such as the umbilical cord exhibit great benefits in the management of periodontitis in preclinical studies. Here, we discuss the main therapeutic uses of MSCs/DSCs, their mechanisms, extrinsic inflammatory cues and the intrinsic metabolic circuitries that govern the immunomodulatory functions of MSCs/DSCs. Increased understanding of the mechanisms underpinning the immunomodulatory functions of MSCs/DSCs is expected to aid in the development of more potent and precise MSC/DSC-based therapeutics.

Mesenchymal Stem Cell-Derived Apoptotic Bodies: Biological Functions and Therapeutic Potential

Mesenchymal stem cells (MSCs) are non-hematopoietic progenitor cells with self-renewal ability and multipotency of osteogenic, chondrogenic, and adipogenic differentiation. MSCs have appeared as a promising approach for tissue regeneration and immune therapies, which are attributable not only to their differentiation into the desired cells but also to their paracrine secretion. MSC-sourced secretome consists of soluble components including growth factors, chemokines, cytokines, and encapsulated extracellular vesicles (EVs). Apoptotic bodies (ABs) are large EVs (diameter 500𠀓2000 nm) harboring a variety of cellular components including microRNA, mRNA, DNA, protein, and lipids related to the characteristics of the originating cell, which are generated during apoptosis. The released ABs as well as the genetic information they carry are engulfed by target cells such as macrophages, dendritic cells, epithelial cells, and fibroblasts, and subsequently internalized and degraded in the lysosomes, suggesting their ability to facilitate intercellular communication. In this review, we discuss the current understanding of the biological functions and therapeutic potential of MSC-derived ABs, including immunomodulation, tissue regeneration, regulation of inflammatory response, and drug delivery system.

Translating extracellular vesicle packaging into therapeutic applications

Extracellular vesicles (EVs) are membrane-bound particles released by cells in various (patho)physiological conditions. EVs can transfer effector molecules and elicit potent responses in recipient cells, making them attractive therapeutic agents and drug delivery platforms. In contrast to their tremendous potential, only a few EV-based therapies and drug delivery have been approved for clinical use, which is largely attributed to limited therapeutic loading technologies and efficiency. As EV cargo has major influence on their functionality, understanding and translating the biology underlying the packaging and transferring of biomolecule cargos (e.g. miRNAs, pathogen antigens, small molecule drugs) into EVs is key in harnessing their therapeutic potential. In this review, through recent insights into EVs’ content packaging, we discuss different mechanisms utilized by EVs during cargo packaging, and how one might therapeutically exploit this process. Apart from the well-characterized EVs like exosomes and microvesicles, we also cover the less-studied and other EV subtypes like apoptotic bodies, large oncosomes, bacterial outer membrane vesicles, and migrasomes to highlight therapeutically-diverse opportunities of EV armoury.

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 SIGNIFICANCE: Apoptotic 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.