T Cell-Derived Apoptotic Extracellular Vesicles Hydrolyze cGAMP to Alleviate Radiation Enteritis via Surface Enzyme ENPP1.

Radiation enteritis is the most common complication of pelvic radiotherapy, but there is no effective prevention or treatment drug. Apoptotic T cells and their products play an important role in regulating inflammation and maintaining physiological immune homeostasis. Here it is shown that systemically infused T cell-derived apoptotic extracellular vesicles (ApoEVs) can target mice irradiated intestines and alleviate radiation enteritis. Mechanistically, radiation elevates the synthesis of intestinal 2'3' cyclic GMP-AMP (cGAMP) and activates cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) proinflammatory pathway. After systemic infusion of ApoEVs, the ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) enriches on the surface of ApoEVs hydrolyze extracellular cGAMP, resulting in inhibition of the cGAS-STING pathway activated by irradiation. Furthermore, after ApoEVs are phagocytosed by phagocytes, ENPP1 on ApoEVs hydrolyzed intracellular cGAMP, which serves as an intracellular cGAMP hydrolyzation mode, thereby alleviating radiation enteritis. The findings shed light on the intracellular and extracellular hydrolysis capacity of ApoEVs and their role in inflammation regulation.

Apoptotic Extracellular Vesicles Induced Endothelial Cell-Mediated Autologous Stem Cell Recruitment Dominates Allogeneic Stem Cell Therapeutic Mechanism for Bone Repair.

Although stem cell therapy is proved to be a promising strategy for bone repair and regeneration, transplanted allogeneic stem cells generally suffer from unfavorable apoptosis instead of differentiation into osteocytes. How the apoptotic stem cells promote bone regeneration still needs to be uncovered. In this work, we found that apoptotic extracellular vesicles released by allogeneic stem cells are critical mediators for promoting bone regeneration. Based on the results of in vivo experiments, a mechanism of apoptotic stem cells determined autologous stem cell recruitment and enhance osteogenesis was proposed. The nanoscaled apoptotic extracellular vesicles released from transplanted stem cells were endocytosed by vascular endothelial cells and preferentially distribute at endoplasmic reticular region. The oxidized phosphatidylcholine enriched in the vesicles activated the endoplasmic reticulum stress and triggered the reflective elevation of adhesion molecules, which induced the recruitment of autologous stem cells located in the blood vessels, transported them into the defect region, and promoted osteogenesis and bone repair. These findings not only reveal the mechanism of stem cell therapy of bone defects but also provide a cue for investigation of the biological process of stem cell therapy for other diseases and develop stem cell therapeutic strategies.

Engineered Extracellular Vesicles Driven by Erythrocytes Ameliorate Bacterial Sepsis by Iron Recycling, Toxin Clearing and Inflammation Regulation.

Sepsis poses a significant challenge in clinical management. Effective strategies targeting iron restriction, toxin neutralization, and inflammation regulation are crucial in combating sepsis. However, a comprehensive approach simultaneously targeting these multiple processes has not been established. Here, an engineered apoptotic extracellular vesicles (apoEVs) derived from macrophages is developed and their potential as multifunctional agents for sepsis treatment is investigated. The extensive macrophage apoptosis in a Staphylococcus aureus-induced sepsis model is discovered, unexpectedly revealing a protective role for the host. Mechanistically, the protective effects are mediated by apoptotic macrophage-released apoEVs, which bound iron-containing proteins and neutralized α-toxin through interaction with membrane receptors (transferrin receptor and A disintegrin and metalloprotease 10). To further enhance therapeutic efficiency, apoEVs are engineered by incorporating mesoporous silica nanoparticles preloaded with anti-inflammatory agents (microRNA-146a). These engineered apoEVs can capture iron and neutralize α-toxin with their natural membrane while also regulating inflammation by releasing microRNA-146a in phagocytes. Moreover, to exploit the microcosmic movement and rotation capabilities, erythrocytes are utilized to drive the engineered apoEVs. The erythrocytes-driven engineered apoEVs demonstrate a high capacity for toxin and iron capture, ultimately providing protection against sepsis associated with high iron-loaded conditions. The findings establish a multifunctional agent that combines natural and engineered antibacterial strategies.

Bone-Targeting Peptide and RNF146 Modified Apoptotic Extracellular Vesicles Alleviate Osteoporosis.

Background: Osteoporosis is a highly prevalent disease that causes fractures and loss of motor function. Current drugs targeted for osteoporosis often have inevitable side effects. Bone marrow mesenchymal stem cell (BMSCs)-derived apoptotic extracellular vesicles (ApoEVs) are nanoscale extracellular vesicles, which has been shown to promote bone regeneration with low immunogenicity and high biological compatibility. However, natural ApoEVs cannot inherently target bones, and are often eliminated by macrophages in the liver and spleen. Thus, our study aimed to reconstruct ApoEVs to enhance their bone-targeting capabilities and bone-promoting function and to provide a new method for osteoporosis treatment. Methods: We conjugated a bone-targeting peptide, (Asp-Ser-Ser)6 ((DSS)6), onto the surface of ApoEVs using standard carbodiimide chemistry with DSPE-PEG-COOH serving as the linker. The bone-targeting ability of (DSS)6-ApoEVs was determined using an in vivo imaging system and confocal laser scanning microscopy (CLSM). We then loaded ubiquitin ligase RING finger protein146 (RNF146) into BMSCs via adenovirus transduction to obtain functional ApoEVs. The bone-promoting abilities of (DSS)6-ApoEVs and (DSS)6-ApoEVsRNF146 were measured in vitro and in vivo. Results: Our study successfully synthesized bone-targeting and gained functional (DSS)6-ApoEVsRNF146 and found that engineered ApoEVs could promote osteogenesis in vitro and exert significant bone-targeting and osteogenesis-promoting effects to alleviate osteoporosis in a mouse model. Conclusion: To promote the bone-targeting ability of natural ApoEVs, we successfully synthesized engineered ApoEVs, (DSS)6-ApoEVsRNF146 and found that they could significantly promote osteogenesis and alleviate osteoporosis compared with natural ApoEVs, which holds great promise for the treatment of osteoporosis.

Humoral regulation of iron metabolism by extracellular vesicles drives antibacterial response.

Immediate restriction of iron initiated by the host is a critical process to protect against bacterial infections and has been described in the liver and spleen, but it remains unclear whether this response also entails a humoral mechanism that would enable systemic sequestering of iron upon infection. Here we show that upon bacterial invasion, host macrophages immediately release extracellular vesicles (EVs) that capture circulating iron-containing proteins. Mechanistically, in a sepsis model in female mice, Salmonella enterica subsp. enterica serovar Typhimurium induces endoplasmic reticulum stress in macrophages and activates inositol-requiring enzyme 1α signaling, triggering lysosomal dysfunction and thereby promoting the release of EVs, which bear multiple receptors required for iron uptake. By binding to circulating iron-containing proteins, these EVs prevent bacteria from iron acquisition, which inhibits their growth and ultimately protects against infection and related tissue damage. Our findings reveal a humoral mechanism that can promptly regulate systemic iron metabolism during bacterial infection.

Proteomic analysis identifies Stomatin as a biological marker for psychological stress.

Psychological stress emerges to be a common health burden in the current society for its highly related risk of mental and physical disease outcomes. However, how the quickly-adaptive stress response process connects to the long-observed organismal alterations still remains unclear. Here, we investigated the profile of circulatory extracellular vesicles (EVs) after acute stress (AS) of restraint mice by phenotypic and proteomic analyses. We surprisingly discovered that AS-EVs demonstrated significant changes in size distribution and plasma concentration compared to control group (CN) EVs. AS-EVs were further characterized by various differentially expressed proteins (DEPs) closely associated with biological, metabolic and immune regulations and were functionally important in potentially underlying multiple diseases. Notably, we first identified the lipid raft protein Stomatin as an essential biomarker expressed on the surface of AS-EVs. These findings collectively reveal that EVs are a significant function-related liquid biopsy indicator that mediate circulation alterations impinged by psychological stress, while also supporting the idea that psychological stress-associated EV-stomatin can be used as a biomarker for potentially predicting acute stress responses and monitoring psychological status. Our study will pave an avenue for implementing routine plasma EV-based theranostics in the clinic.

Hybrid Biomaterial Initiates Refractory Wound Healing via Inducing Transiently Heightened Inflammatory Responses.

Inflammation plays a crucial role in triggering regeneration, while inadequate or chronic inflammation hinders the regenerative process, resulting in refractory wounds. Inspired by the ideal regeneration mode in lower vertebrates and the human oral mucosa, realigning dysregulated inflammation to a heightened and acute response provides a promising option for refractory wound therapy. Neutrophils play important roles in inflammation initiation and resolution. Here, a hybrid biomaterial is used to stimulate transiently heightened inflammatory responses by precise tempospatial regulation of neutrophil recruitment and apoptosis. The hybrid biomaterial (Gel@fMLP/SiO2 -FasL) is constructed by loading of formyl-met-leu-phe (fMLP) and FasL-conjugated silica nanoparticles (SiO2 -FasL) into a pH-responsive hydrogel matrix. This composition enables burst release of fMLP to rapidly recruit neutrophils for heightened inflammation initiation. After neutrophils act to produce acids, the pH-responsive hydrogel degrades to expose SiO2 -FasL, which induces activated neutrophils apoptosis via FasL-Fas signaling triggering timely inflammation resolution. Apoptotic neutrophils are subsequently cleared by macrophages, and this efferocytosis activates key signalings to promote macrophage anti-inflammatory phenotypic transformation to drive regeneration. Ultimately, Gel@fMLP/SiO2 -FasL successfully promotes tissue regeneration by manipulating inflammation in critical-sized calvarial bone defects and diabetic cutaneous wound models. This work provides a new strategy for refractory wound therapy via inducing transiently heightened inflammatory responses.

Engineered neutrophil apoptotic bodies ameliorate myocardial infarction by promoting macrophage efferocytosis and inflammation resolution.

Inflammatory response plays a critical role in myocardial infarction (MI) repair. The neutrophil apoptosis and subsequent macrophage ingestion can result in inflammation resolution and initiate regeneration, while the therapeutic strategy that simulates and enhances this natural process has not been established. Here, we constructed engineered neutrophil apoptotic bodies (eNABs) to simulate natural neutrophil apoptosis, which regulated inflammation response and enhanced MI repair. The eNABs were fabricated by combining natural neutrophil apoptotic body membrane which has excellent inflammation-tropism and immunoregulatory properties, and mesoporous silica nanoparticles loaded with hexyl 5-aminolevulinate hydrochloride (HAL). The eNABs actively targeted to macrophages and the encapsulated HAL simultaneously initiated the biosynthesis pathway of heme to produce anti-inflammatory bilirubin after intracellular release, thereby further enhancing the anti-inflammation effects. In in vivo studies, the eNABs efficiently modulated inflammation responses in the infarcted region to ameliorate cardiac function. This study demonstrates an effective biomimetic construction strategy to regulate macrophage functions for MI repair.

Dental pulp stem cell-derived apoptotic bodies regulate macrophage polarization and inflammatory response / 口腔疾病防治

Objective@#To investigate the effects of apoptotic bodies (ABs) derived from dental pulp stem cells (DPSCs) on macrophage polarization and inflammation response in vivo. @*Methods @#Human DPSCs were extracted, cultured and identified. Staurosporine was used to apoptosis induction and differential methods were performed for ABs identification. The in vitro cultured macrophages were divided into 3 groups: solvent control, lipopolysaccharide (LPS), and the LPS+ABs. The macrophages were stimulated with LPS to induce inflammation followed by ABs treatment. In the untreated group, macrophages were added with an equal amount of solvent. The specific uptake of ABs by macrophages, the expression level of CD206 and the levels of inflammatory cytokines were analyzed. The mouse models of cutaneous wounds and dextran sulfate sodium (DSS)-induced colitis were established, and the mice were randomly divided into 3 groups: the PBS-treated group, the DPSCs-treated group, and the ABs-treated group. The mice were injected with the same volume of PBS, DPSCs and ABs, respectively. The body weight, histological pathology, the expression levels of CD206 and cytokines, and the extent of tissue regeneration were measured.@* Results @#DPSCs and ABs derived from DPSCs were successfully isolated and characterized. ABs could be taken up by macrophage. While lipopolysaccharide(LPS) induced production of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), ABs significantly reduced the levels of these pro-inflammatory cytokines and increased the expression of transforming growth factor-β (TGF-β) and CD206 (P < 0.01). In the cutaneous inflammatory wound model, the wound closure rate in mice intravenously injected with ABs was significantly accelerated (P < 0.05). The administration of ABs markedly reduced the pro-inflammatory factors levels and increased the CD206+ cell number. In the colitis model, treatment with ABs markedly reduced the loss in bodyweight (P < 0.05), recovered the colon length (P < 0.01), and significantly increased the CD206+ cell number.@* Conclusion@# DPSCs-derived ABs could enhance macrophage M2 polarization and attenuate inflammation. Therefore, ABs could be used as a promising cell replacement for inflammatory regulation and tissue regeneration.

On-demand manipulation of tumorigenic microenvironments by nano-modulator for synergistic tumor therapy.

Proper manipulation of tumorigenic microenvironments has been considered as one of the most effective approaches for tumor therapy, which is still a challenge to be well performed. Herein, a nano-modulator was fabricated to manipulate the hypoxia, glucose, radicals and local temperature in tumor tissue as needed, which consists of hemoglobin (Hb) and ferric ion (Fe3+) co-conjugated polydopamine (PDA) as core, glucose oxidase (GOD) as shell, and folic acid (FA) modified polyethylene glycol (PEG) as corona. The PEG-FA corona not only protected Hb and GOD against protease in blood circulation, but serve as tumor targeting agent for tumor specific accumulation of the nano-modulator. The Hb is in charge of oxygen supply to reverse the hypoxic environment of tumor tissue, which promotes the function of GOD to achieve rapid glucose consumption and hydrogen peroxide generation. The polydopamine was employed to raise local temperature under NIR irradiation, meanwhile to continuously reduce Fe3+ to produce ferrous ions (Fe2+), which further catalyze hydrogen peroxide to cytotoxic hydroxyl radicals via Fenton reaction. Both in vitro and in vivo results showed excellent tumor inhibition and high survival rate of tumor-bearing mice after treatment by our nano-modulator, indicating this synergistic therapy via on-demand manipulation of various tumorigenic microenvironments could be a green approach for tumor treatment with high efficiency and minimum side effects.

T cell-depleting nanoparticles ameliorate bone loss by reducing activated T cells and regulating the Treg/Th17 balance.

Estrogen deficiency is one of the most frequent causes of osteoporosis in postmenopausal women. Under chronic inflammatory conditions caused by estrogen deficiency, activated T cells contribute to elevated levels of proinflammatory cytokines, impaired osteogenic differentiation capabilities of bone marrow mesenchymal stem cells (BMMSCs), and disturbed regulatory T cell (Treg)/Th17 cell balance. However, therapeutic strategies that re-establish immune homeostasis in this disorder have not been well developed. Here, we produced T cell-depleting nanoparticles (TDNs) that ameliorated the osteopenia phenotype and rescued the osteogenic deficiency of BMMSCs in ovariectomized (OVX) mice. TDNs consist of monocyte chemotactic protein-1 (MCP-1)-encapsulated mesoporous silica nanoparticles as the core and Fas-ligand (FasL) as the corona. We showed that the delicate design of the TDNs enables rapid release of MCP-1 to recruit activated T cells and then induces their apoptosis through the conjugated FasL both in vitro and in vivo. Apoptotic signals recognized by macrophages help skew the Treg/Th17 cell balance and create an immune tolerant state, further attenuating the osteogenic deficiency of BMMSCs and the osteopenia phenotype. Mechanistically, we found that the therapeutic effects of TDNs were partially mediated by apoptotic T cell-derived extracellular vesicles (ApoEVs), which promoted macrophage transformation towards the M2 phenotype. These findings demonstrate that TDNs may represent a promising strategy for treating osteoporosis and other immune disorders.

Apoptotic bodies derived from mesenchymal stem cells promote cutaneous wound healing via regulating the functions of macrophages.

BACKGROUND: As the major interface between the body and the external environment, the skin is liable to various injuries. Skin injuries often lead to severe disability, and the exploration of promising therapeutic strategies is of great importance. Exogenous mesenchymal stem cell (MSC)-based therapy is a potential strategy due to the apparent therapeutic effects, while the underlying mechanism is still elusive. Interestingly, we observed the extensive apoptosis of exogenous bone marrow mesenchymal stem cells (BMMSCs) in a short time after transplantation in mouse skin wound healing models. Considering the roles of extracellular vesicles (EVs) in intercellular communication, we hypothesized that the numerous apoptotic bodies (ABs) released during apoptosis may partially contribute to the therapeutic effects. METHODS: ABs derived from MSCs were extracted, characterized, and applied in mouse skin wound healing models, and the therapeutic effects were evaluated. Then, the target cells of ABs were explored, and the effects of ABs on macrophages were investigated in vitro. RESULTS: We found ABs derived from MSCs promoted cutaneous wound healing via triggering the polarization of macrophages towards M2 phenotype. In addition, the functional converted macrophages further enhanced the migration and proliferation abilities of fibroblasts, which together facilitated the wound healing process. CONCLUSIONS: Collectively, our study demonstrated that transplanted MSCs promoted cutaneous wound healing partially through releasing apoptotic bodies which could convert the macrophages towards an anti-inflammatory phenotype that plays a crucial role in the tissue repair process.

Chimeric apoptotic bodies functionalized with natural membrane and modular delivery system for inflammation modulation.

Engineered extracellular vesicles (EVs) carrying therapeutic molecules are promising candidates for disease therapies. Yet, engineering EVs with optimal functions is a challenge that requires careful selection of functionally specific vesicles and a proper engineering strategy. Here, we constructed chimeric apoptotic bodies (cABs) for on-demand inflammation modulation by combining pure membrane from apoptotic bodies (ABs) as a bioconjugation/regulation module and mesoporous silica nanoparticles (MSNs) as a carrier module. MSNs were preloaded with anti-inflammatory agents (microRNA-21 or curcumin) and modified with stimuli-responsive molecules to achieve accurate cargo release at designated locations. The resulting cABs actively target macrophages in the inflammatory region and effectively promote M2 polarization of these macrophages to modulate inflammation due to the synergistic regulatory effects of AB membranes and the intracellular release of preloaded cargos. This work provides strategies to arbitrarily engineer modular EVs that integrate the advantages of natural EVs and synthetic materials for various applications.

Application of surgical navigation in styloidectomy for treating Eagle's syndrome.

PURPOSE: The present study aimed to evaluate the feasibility, accuracy, and clinical effect of intraoperative navigation for resection of elongated styloid process (ESP) in Eagle's syndrome. PATIENTS AND METHODS: Twelve patients with Eagle's syndrome with clinically and radiologically established diagnoses of ESP were included in this study. Preoperatively, all patients accepted three-dimensional computed tomography scan, and their skulls' digital imaging and communications in medicine data were inputed into the navigation system workstation to make a virtual surgical plan in advance. During surgery, the intraoperative navigation was performed to excise the ESP accurately for both intraoral (without tonsillectomy) and extraoral approaches following the virtual plan. Postoperatively, the amount of bleeding, duration of operation and hospitalization, and the length of resected styloid process (SP) were measured and compared with those cases that had traditional styloidectomy without the help of surgical navigation (SN). A simple visual analog scale questionnaire was also used to assess patients' satisfaction and the surgery effect after 3 months. RESULTS: In total, 17 SPs from 12 patients were precisely resected by intraoral parapharyngeal approach and small cervical approach with the aid of SN. No severe complications occurred in any patients. The length of resected SPs was 21.93±14.26 mm. The average amount of bleeding and duration of operation were 22.50±8.54 mL and 40.35±11.81 minutes, respectively, which were all less than with traditional styloidectomy. The visual analog scale analysis showed that the discomfort in all patients was relieved, while ten patients' symptoms were improved greatly, and two patients had some improvement. CONCLUSION: The higher accuracy of surgery, lesser amount of bleeding, decreased duration of surgery and hospitalization, absence of complications, and improved subjective symptoms indicated that SN is an effective and minimally invasive surgical procedure suitable for resection of ESP for treating Eagle's syndrome.