Inhalation of MSC-EVs is a noninvasive strategy for ameliorating acute lung injury

Nebulized M2 macrophage-derived nanovesicles for the treatment of explosion-induced acute lung injury

Gas explosion-induced acute lung injury (ALI) presents a significant clinical challenge in industrial and military contexts, yet current therapeutic interventions remain suboptimal. Extracellular vesicles (EVs) have emerged as promising nanoscale therapeutic agents, owing to their superior biocompatibility and inherent therapeutic potential. In this study, we engineered and isolated alternatively activated macrophages extracellular vesicles (M2-EVs) and administered them via nebulization to the injured lung tissue in an established murine model of blast-induced ALI. Administration of M2-EVs led to a significant amelioration of pulmonary function, characterized by decreased lung injury scores and attenuated inflammatory markers. Mechanistically, M2-EVs promoted the M1-to-M2 phenotypic transition of pulmonary macrophages, modulated the P62-Keap1-Nrf2 signaling pathway, and consequently mitigated excessive autophagy and oxidative stress. Collectively, these findings not only offer mechanistic insights into the pathogenesis of blast-induced ALI but also highlight M2-EVs as a promising cell-free therapeutic approach for explosion-related pulmonary injuries.

Multienzyme active melanin nanodots for antioxidant-immunomodulatory therapy of hyperoxia lung injury

Supraphysiological oxygen is the most conventional method of treating patients with acute respiratory failure, but prolonged exposure to hyperoxia generates large amounts of reactive oxygen species (ROS) in the lungs, leading to hyperoxia lung injury (HLI). Nevertheless, there is no safe and effective prevention strategy. Herein, multienzyme active melanin nanodots were developed as an antioxidant-immunomodulatory defense nanoplatform for the treatment of HLI. The prepared nanodots are about 4 nm in size and are mainly composed of carbon, nitrogen and oxygen elements with high stability and multi-enzymatic activity for scavenging various reactive oxygen and reactive nitrogen radicals. Cellular experiments showed that melanin nanodots increased cell viability and ameliorated hyperoxia-induced morphological changes, mitochondrial damage and apoptosis. Meanwhile, by activating the Nrf2/Keap1/HO-1 signaling pathway, the treatment of melanin nanodots significantly inhibited the overproduction of ROS, reduced malondialdehyde, and increased the endogenous antioxidant enzyme activity in BEAS-2B cells. Interestingly, the antioxidant properties of melanin nanodots indirectly promoted the phenotypic shift of macrophages, and reduced hyperoxia-induced inflammatory responses in the damaged environment. In vivo NIR-II fluorescence imaging confirms the high retention of nanodots in the lungs and low accumulation in other major organs after inhalation administration, as well as the high biosafety of the melanin nanodots as they are metabolized out of the body over time via the liver and intestines. In addition, the melanin nanodots exhibited satisfactory antioxidant protection and inhibition of inflammatory cell infiltration in the lungs of HLI mouse models. Therefore, the melanin nanodots provide a potential and effective strategy for the treatment of HLI, showing great promise for application.

MiR-146a engineered extracellular vesicles derived from mesenchymal stromal cells more potently attenuate ischaemia-reperfusion injury in lung transplantation

BACKGROUND

The limited donor lung pool for lung transplantation (LTx) is largely due to concerns over ischaemia-reperfusion injury (IRI), a major cause of primary graft dysfunction (PGD). NLRP3 inflammasome activation is known to play a pivotal role in the onset of IRI. While human umbilical cord mesenchymal stromal cell-derived extracellular vesicles (hucMSC-EVs) have shown potential in reducing acute lung injury, their effects on NLRP3 activation in the context of LTx remain unclear.

METHODS

In this study, engineered hucMSC-EVs were delivered via nebulisation to mitigate IRI in rat LTx models. We utilised both a rat orthotopic LTx model and a cell cold preservation reperfusion model to evaluate the therapeutic efficacy of hucMSC-EVs. Bulk-RNA sequencing, single-cell sequencing analysis, immunofluorescence and Western blot techniques were employed to assess NLRP3 inflammasome activation and inflammation.

RESULTS

Nebulised hucMSC-EVs were efficiently internalised by alveolar macrophages (AMs), significantly reducing lung injury and improving oxygenation in the LTx models. Mechanistically, the engineered hucMSC-EVs, which enhance the expression of miR-146a, can more effectively suppress the activation of the NLRP3 inflammasome by targeting the IRAK1/TRAF6/NF-κB pathway, resulting in decreased levels of IL-1β, IL-18 and other inflammatory cytokines. These findings highlight the potential of miR-146a-modified EVs in modulating innate immune responses to alleviate IRI.

CONCLUSION

Our results demonstrate that nebulised delivery of engineered hucMSC-EVs effectively mitigates IRI in LTx by inhibiting NLRP3 inflammasome activation. This innovative approach presents a promising strategy for enhancing donor lung preservation and improving post-transplant outcomes in LTx.

HIGHLIGHTS

Nebulized Delivery of miR-146a Engineered hucMSC-EVs Mitigates Ischemia-Reperfusion Injury (IRI) in Lung Transplantation. This study demonstrates the therapeutic potential of nebulized, engineered human umbilical cord mesenchymal stromal cell-derived extracellular vesicles (hucMSC-EVs) modified with miR-146a to alleviate IRI in rat lung transplantation models. The treatment significantly improved lung oxygenation and reduced inflammation, highlighting the efficacy of this novel approach in enhancing donor lung preservation. Mechanistic Insights: Inhibition of NLRP3 Inflammasome Activation. Engineered hucMSC-EVs efficiently targeted alveolar macrophages and suppressed NLRP3 inflammasome activation through the IRAK1/TRAF6/NF-κB pathway. This modulation of innate immune responses played a crucial role in reducing IRI-induced lung injury and inflammation, offering a promising strategy to manage primary graft dysfunction in lung transplantation. Superior Efficacy of miR-146a-Modified EVs in Reducing Inflammatory Cytokines. The miR-146a modification enhanced the anti-inflammatory properties of hucMSC-EVs, leading to a more significant reduction in pro-inflammatory cytokines (IL-1β, IL-18, and TNF-α) compared to unmodified EVs. This targeted intervention presents a potential therapeutic avenue for improving lung transplant outcomes and mitigating IRI. Innovative Therapeutic Approach: Non-Invasive Nebulization for Direct Lung Delivery. The use of nebulized EVs for direct delivery to donor lungs represents a non-invasive and efficient method for lung-targeted therapy. This strategy could expand the applicability of MSC-EV-based treatments for improving lung transplantation outcomes, particularly in enhancing donor lung preservation during the procurement process.

Regulation of lncRNA-ENST on Myc-mediated mitochondrial apoptosis in mesenchymal stem cells: In vitro evidence implicated for acute lung injury therapeutic potential

BACKGROUND

Acute lung injury (ALI) is a fatal and heterogeneous disease. While bone marrow mesenchymal stem cells (BMSCs) have shown promise in ALI repair, their efficacy is compromised by a high apoptotic percentage. Preliminary findings have indicated that long noncoding RNA (lncRNA)-ENST expression is markedly downregulated in MSCs under ischemic and hypoxic conditions, establishing a rationale for in vitro exploration.

AIM

To elucidate the role of lncRNA-ENST00000517482 (lncRNA-ENST) in modulating MSC apoptosis.

METHODS

Founded on ALI in BEAS-2B cells with lipopolysaccharide, this study employed a transwell co-culture system to study BMSC tropism. BMSCs were genetically modified to overexpress or knockdown lncRNA-ENST. After analyzing the effects on autophagy, apoptosis and cell viability, the lncRNA-ENST/miR-539/c-MYC interaction was confirmed by dual-luciferase assays.

RESULTS

These findings have revealed a strong correlation between lncRNA-ENST levels and the apoptotic and autophagic status of BMSCs. On the one hand, the over-expression of lncRNA-ENST, as determined by Cell Counting Kit-8 assays, increased the expression of autophagy markers LC3B, ATG7, and ATG5. On the other hand, it reduced apoptosis and boosted BMSC viability. In co-cultures with BEAS-2B cells, lncRNA-ENST overexpression also improved cell vitality. Additionally, by downregulating miR-539 and upregulating c-MYC, lncRNA-ENST was found to influence mitochondrial membrane potential, enhance BMSC autophagy, mitigate apoptosis and lower the secretion of pro-inflammatory cytokines interleukin-6 and interleukin-1β. Collectively, within the in vitro framework, these results have highlighted the therapeutic potential of BMSCs in ALI and the pivotal regulatory role of lncRNA-ENST in miR-539 and apoptosis in lipopolysaccharide-stimulated BEAS-2B cells.

CONCLUSION

Our in vitro results show that enhanced lncRNA ENST expression can promote BMSC proliferation and viability by modulating the miR-539/c-MYC axis, reduce apoptosis and induce autophagy, which has suggested its therapeutic potential in the treatment of ALI.

Nebulized mesenchymal stem cell-derived exosomes attenuate airway inflammation in a rat model of chronic obstructive pulmonary disease

Chronic Obstructive Pulmonary Disease (COPD) is one of the leading causes of death worldwide, and current treatments fail to significantly halt its progression. Exosomes derived from mesenchymal stem cells (MSCs-Exos) have demonstrated promising potential in treating COPD due to their anti-inflammatory and regenerative biological properties. In this study, we investigated the potential anti-inflammatory effects of bone marrow mesenchymal stem cell-derived exosomes (BMSCs-Exos) in a COPD rat model and the possible mechanisms by which they inhibit airway remodeling, as well as identifying the optimal dosage and administration route. Our results show that nebulized BMSC-Exos significantly improve lung function in COPD rats while reducing pulmonary inflammatory infiltration, bronchial mucus secretion, and collagen deposition. Moreover, BMSC-Exos treatment notably decreased the expression of pro-inflammatory cytokines such as TNF-α, IL-6 and IL-1β, and the pro-fibrotic factor TGF-β1 in serum, bronchoalveolar lavage fluid (BALF), and lung tissue. The most pronounced therapeutic effect was observed at a low dose of exosomes. Furthermore, quantitative real-time PCR and immunohistochemical analyses revealed that nebulized BMSC-Exos significantly inhibited airway remodeling and epithelial-mesenchymal transition (EMT) by suppressing the Wnt/β-catenin signaling pathway. In conclusion, these findings indicate that nebulized BMSC-Exos offer a noninvasive therapeutic strategy for COPD by mitigating lung inflammation and airway remodeling through the suppression of abnormal Wnt/β-catenin pathway activation induced by cigarette smoke (CS) and lipopolysaccharide (LPS) in rats.

Panax notoginseng saponins ameliorate LPS-induced acute lung injury by promoting STAT6-mediated M2-like macrophage polarization

BACKGROUND

Acute lung injury (ALI) is a severe inflammatory condition characterized by dysregulated immune responses and high mortality rates, with limited effective therapeutic options currently available. Panax notoginseng saponins (PNS), bioactive compounds derived from Panax notoginseng, have shown promise in mitigating lipopolysaccharide (LPS)-induced ALI. However, the molecular mechanisms underlying their therapeutic effects remain poorly understood. Given the critical role of M2-like macrophage polarization in resolving inflammation and promoting tissue repair, we investigated whether PNS exerts its protective effects in ALI by modulating this process. Furthermore, we explored the specific involvement of the signal transducer and activator of transcription 6 (STAT6) pathway in mediating these effects.

METHODS

Chemical profiling of PNS was performed using ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS), followed by quantitative analysis of its major bioactive components via high-performance liquid chromatography (HPLC). To evaluate the therapeutic efficacy of PNS and its principal constituents, we established an ALI mouse model through intratracheal administration of LPS. Comprehensive assessments included lung field shadowing, oxygen saturation levels, pulmonary function, and systematic histopathological examination. The regulatory effects of PNS on macrophage polarization were examined in THP-1 cells and bone marrow-derived macrophages (BMDMs), with cellular phenotypes analyzed by flow cytometry. To elucidate the mechanistic role of STAT6 in PNS-mediated protection, experiments were conducted using Stat6-deficient BMDMs and Stat6 knockout mice.

RESULTS

UPLC-Q-TOF-MS and HPLC identified and quantified the principal components of PNS: Notoginsenoside R1, Ginsenoside Rg1, Ginsenoside Re, and Ginsenoside Rb1. PNS treatment dose-dependently reduced inflammatory responses in LPS-induced ALI mice, as evidenced by decreased cytokine levels. Each of the four major PNS components independently alleviated ALI symptoms in mice. Pathway analysis revealed 56 potential ALI-related targets, with Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment suggesting that PNS exerts its protective effects by modulating inflammatory signaling pathways. In vitro studies demonstrated that PNS promoted STAT6 phosphorylation and nuclear translocation, enhancing M2-like macrophage polarization and interleukin-10 (IL-10) secretion in a STAT6-dependent manner. Genetic ablation of Stat6 partially reversed the protective effects of PNS on ALI, macrophage polarization, and IL-10 production, confirming the pivotal role of STAT6 in mediating PNS activity.

CONCLUSION

This study demonstrates that PNS alleviates LPS-induced ALI by promoting STAT6-dependent M2-like macrophage polarization, highlighting its potential as a therapeutic agent for ALI. These findings provide mechanistic insights into the anti-inflammatory actions of PNS and underscore the importance of STAT6 signaling in its protective effects.

Innovations in Vascular Repair from Mechanical Intervention to Regenerative Therapies

BACKGROUND

Vascular diseases, including atherosclerosis and thrombosis, are leading causes of morbidity and mortality worldwide, often resulting in vessel stenosis that impairs blood flow and leads to severe clinical outcomes. Traditional mechanical interventions, such as balloon angioplasty and bare-metal stents, provided initial solutions but were limited by restenosis and thrombosis. The advent of drug-eluting stents improved short-term outcomes by inhibiting vascular smooth muscle cell proliferation, however, they faced challenges including delayed reendothelialization and late-stage thrombosis.

METHODS

This review highlights the progression from mechanical to biological interventions in treating vascular stenosis and underscores the need for integrated approaches that combine mechanical precision with regenerative therapies.

RESULTS

To address long-term complications, bioresorbable stents were developed to provide temporary scaffolding that gradually dissolves, yet they still encounter challenges with mechanical integrity and optimal degradation rates. Consequently, emerging therapies now focus on biological approaches, such as gene therapy, extracellular vesicle treatments, and cell therapies, that aim to promote vascular repair at the cellular level. These strategies offer the potential for true vascular regeneration by enhancing endothelialization, modulating immune responses, and stimulating angiogenesis.

CONCLUSION

Integrating mechanical precision with regenerative biological therapies offers a promising future for treating vascular stenosis. A comprehensive approach combining these modalities could achieve sustainable vascular health.

Isolation, identification, and challenges of extracellular vesicles: emerging players in clinical applications

Extracellular vesicles (EVs) serve as critical mediators of intercellular communication, encompassing exosomes, microvesicles, and apoptotic vesicles that play significant roles in diverse physiological and pathological contexts. Numerous studies have demonstrated that EVs derived from mesenchymal stem cells (MSC-EVs) play a pivotal role in facilitating tissue and organ repair, alleviating inflammation and apoptosis, enhancing the proliferation of endogenous stem cells within tissues and organs, and modulating immune function-these functions have been extensively utilized in clinical applications. The precise classification, isolation, and identification of MSC-EVs are essential for their clinical applications. This article provides a comprehensive overview of the biological properties of EVs, emphasizing both their advantages and limitations in isolation and identification methodologies. Additionally, we summarize the protein markers associated with MSC-EVs, emphasizing their significance in the treatment of various diseases. Finally, this article addresses the current challenges and dilemmas in developing clinical applications for MSC-EVs, aiming to offer valuable insights for future research.

Engineered Extracellular Vesicles as a New Class of Nanomedicine

Extracellular vesicles (EVs) are secreted from biological cells and contain many molecules with diagnostic values or therapeutic functions. There has been great interest in academic and industrial communities to utilize EVs as tools for diagnosis or therapeutics. In addition, EVs can also serve as delivery vehicles for therapeutic molecules. An indicator of the enormous interest in EVs is the large number of review articles published on EVs, with the focus ranging from their biology to their applications. An emerging trend in EV research is to produce and utilize "engineered EVs", which are essentially the enhanced version of EVs. EV engineering can be conducted by cell culture condition control, genetic engineering, or chemical engineering. Given their nanometer-scale sizes and therapeutic potentials, engineered EVs are an emerging class of nanomedicines. So far, an overwhelming majority of the research on engineered EVs is preclinical studies; there are only a very small number of reported clinical trials. This Review focuses on engineered EVs, with a more specific focus being their applications in therapeutics. The various approaches to producing engineered EVs and their applications in various diseases are reviewed. Furthermore, in vivo imaging of EVs, the mechanistic understandings, and the clinical translation aspects are discussed. The discussion is primarily on preclinical studies while briefly mentioning the clinical trials. With continued interdisciplinary research efforts from biologists, pharmacists, physicians, bioengineers, and chemical engineers, engineered EVs could become a powerful solution for many major diseases such as neurological, immunological, and cardiovascular diseases.

A game of hide-and-seek: how extracellular vesicles evade the immune system

Extracellular vesicles (EVs) are heterogeneously sized, cell-derived nanoparticles operating as proficient mediators of intercellular communication. They are produced by normal as well as diseased cells and carry a variety of cargo. While the molecular details of EV biology have been worked out over the past two decades, one question that continues to intrigue many is how are EVs able to evade the phagocytic immune cells while also being effectively internalized by the target cell or tissue. While some of the components that facilitate this process have started to be identified, many mechanisms are yet to be dissected. This review summarises some of the key mechanisms that cancer cell-derived and viral infected cell-derived EVs utilize to evade the immune system. It will discuss the diverse cloaking mechanisms, in the form of membrane proteins and cargo content that these EVs utilize to enhance pathogenesis. Further, it will highlight the different strategies that have been used to design EVs to escape the immune system, thereby increasing their circulation time with no major toxic effects in vivo. An understanding of the potential EV components that allow better immune evasion can be used to bioengineer EVs with better circulation times for therapeutic purposes.

Ultrasonic Microfluidic Method Used for siHSP47 Loaded in Human Embryonic Kidney Cell-Derived Exosomes for Inhibiting TGF-β1 Induced Fibroblast Differentiation and Migration

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and devastating lung disorder. In response to transforming growth factor-β (TGF-β), normal lung cells proliferate and differentiate into myofibroblasts, which are instrumental in promoting disease progression. Small interfering RNA (siRNA) targeting heat shock protein 47 (HSP47) has been demonstrated to alleviate IPF by blocking collagen synthesis and secretion. Exosomes (EXOs) have been investigated for drug delivery due to their superior carrier properties. However, their loading efficiency has been a limiting factor in widely application as drug carriers. In this study, an ultrasonic microfluidic method was employed to enhance the loading efficiency of siHSP47 into EXOs, achieving 31.1% efficiency rate. EXOs were isolated from human embryonic kidney cells (293F) and loaded with siHSP47 (EXO-siHSP47). The findings indicated that EXO-siHSP47 penetrated the collagen barrier and effectively silenced HSP47 expression in activated fibroblasts in vitro. Western blotting and immunofluorescence analyses confirmed that EXO-siHSP47 significantly reduced the secretion and deposition of extracellular matrix (ECM) proteins. Wound healing and Transwell migration assays demonstrated that EXO-siHSP47 inhibited fibroblast differentiation and migration. In conclusion, 293F-derived EXOs loaded with siHSP47 present a promising therapeutic strategy for IPF.

Advances in the research of immunomodulatory mechanism of mesenchymal stromal/stem cells on periodontal tissue regeneration

Periodontal disease is a highly prevalent disease worldwide that seriously affects people's oral health, including gingivitis and periodontitis. Although the current treatment of periodontal disease can achieve good control of inflammation, it is difficult to regenerate the periodontal supporting tissues to achieve a satisfactory therapeutic effect. In recent years, due to the good tissue regeneration ability, the research on Mesenchymal stromal/stem cells (MSCs) and MSC-derived exosomes has been gradually deepened, especially its ability to interact with the microenvironment of the body in the complex immunoregulatory network, which has led to many new perspectives on the therapeutic strategies for many diseases. This paper systematically reviews the immunomodulatory (including bone immunomodulation) properties of MSCs and their role in the periodontal inflammatory microenvironment, summarizes the pathways and mechanisms by which MSCs and MSC-EVs have promoted periodontal regeneration in recent years, lists potential areas for future research, and describes the issues that should be considered in future basic research and the direction of development of "cell-free therapies" for periodontal regeneration.

Administration Strategy-Dependent Mechanisms and Effects of Human Adipose Tissue Stem Cell Extracellular Vesicles in Mouse Allergic Rhinitis Treatment

We previously found that intravenous injection of extracellular vesicles (EVs) from human adipose tissue-derived stem cells (hADSC) could ameliorate allergic rhinitis (AR) in mice through immunomodulatory effects. In clinical trials, nasal delivery has been an attractive treatment for AR. We sought to determine whether there are differences in the therapeutic effects between caudal injection and their combination. We treated AR mice with ADSC-EVs via caudal vein, nasal cavity, or both. After treatment, the mice were re-sensitized and the indices of behavior, nasal mucosa morphology, and cytokine secretion of the mice under different modes of administration were calculated. The resultes show that tail vein, nasal, and combined administration could effectively relieve the inflammatory infiltration of the nasal mucosa of mice, reduce the secretion of IgE, IL-4, and other inflammatory factors, and alleviate the Th1/Th2 imbalance. Injection and nasal delivery, as well as their combination, effectively alleviated the symptoms of rhinitis in mice. Nasal administration has a better therapeutic effect when the inflammatory response is mild. It could be speculated that ADSC-EVs have excellent properties in the treatment of AR, and modes of administration can be selected for different stages of treatment in clinical therapy.

Bidirectional modulation of extracellular vesicle-autophagy axis in acute lung injury: Molecular mechanisms and therapeutic implications

Acute lung injury (ALI), a multifactorial pathological condition, manifests through heightened inflammatory responses, compromised lung epithelial-endothelial barrier function, and oxidative stress, potentially culminating in respiratory failure and mortality. This study explores the intricate interplay between two crucial cellular mechanisms-extracellular vesicles (EVs) and autophagy-in the context of ALI pathogenesis and potential therapeutic interventions.EVs, bioactive membrane-bound structures secreted by cells, serve as versatile carriers of molecular cargo, facilitating intercellular communication and significantly influencing disease progression. Concurrently, autophagy, an essential intracellular degradation process, maintains cellular homeostasis and has emerged as a promising therapeutic target in ALI and acute respiratory distress syndrome.Our research unveils a fascinating "EV-Autophagy dual-drive pathway," characterized by reciprocal regulation between these two processes. EVs modulate autophagy activation and inhibition, while autophagy influences EV production, creating a dynamic feedback loop. This study posits that precise manipulation of this pathway could revolutionize ALI treatment strategies.By elucidating the mechanisms underlying this cellular crosstalk, we open new avenues for targeted therapies. The potential for engineered EVs to fine-tune autophagy in ALI treatment is explored, alongside innovative concepts such as EV-based vaccines for ALI prevention and management. This research not only deepens our understanding of ALI pathophysiology but also paves the way for novel, more effective therapeutic approaches in critical care medicine.

Emerging Role and Mechanism of Mesenchymal Stem Cells-Derived Extracellular Vesicles in Rheumatic Disease

Mesenchymal stem cells (MSCs) are pluripotent stem cells derived from mesoderm. Through cell-to-cell contact or paracrine effects, they carry out biological tasks like immunomodulatory, anti-inflammatory, regeneration, and repair. Extracellular vesicles (EVs) are the primary mechanism for the paracrine regulation of MSCs. They deliver proteins, nucleic acids, lipids, and other active compounds to various tissues and organs, thus facilitating intercellular communication. Rheumatic diseases may be treated using MSCs and MSC-derived EVs (MSC-EVs) due to their immunomodulatory capabilities, according to mounting data. Since MSC-EVs have low immunogenicity, high stability, and similar biological effects as to MSCs themselves, they are advantageous over cell therapy for potential therapeutic applications in rheumatoid arthritis, systemic erythematosus lupus, systemic sclerosis, Sjogren's syndrome, and other rheumatoid diseases. This review integrates recent advances in the characteristics, functions, and potential molecular mechanisms of MSC-EVs in rheumatic diseases and provides a new understanding of the pathogenesis of rheumatic diseases and MSC-EV-based treatment strategies.

Cabazitaxel-Loaded Thermosensitive Hydrogel System for Suppressed Orthotopic Colorectal Cancer and Liver Metastasis

The treatment of colorectal cancer is always a major challenge in the field of cancer research. The number of estimated new cases of colorectal cancer worldwide in 2020 is 1 148 515, and the estimated number of deaths is 576 858, revealing that mortality accounted for approximately half of the disease incidence. The development of new drugs and strategies for colorectal cancer treatment is urgently needed. Thermosensitive injectable hydrogel PDLLA-PEG-PDLLA (PLEL) loaded with cabazitaxel (CTX) is used to explore its anti-tumor effect on mice with orthotopic colorectal cancer. CTX/PLEL is characterized by a solution state at room temperature and a hydrogel state at physiologic temperature. The excipients MPEG-PCL and PDLLA-PEG-PDLLA have good biocompatibility and biodegradability. The simple material synthesis and preparation process renders this system cost-effective and more conducive to clinical transformation. An orthotopic colorectal cancer model is established by transplantation subcutaneous tumors onto the cecum of mice. According to the results of experiments in vivo, CTX/PLEL significantly inhibits orthotopic colorectal cancer and liver metastasis in mice. The results indicate that CTX/PLEL nanoparticle preparations have high security and excellent anti-tumor effects, and have great application potential in colorectal cancer therapy.

Cyclic-di-GMP induces inflammation and acute lung injury through direct binding to MD2

BACKGROUND

Severe bacterial infections can trigger acute lung injury (ALI) and acute respiratory distress syndrome, with bacterial pathogen-associated molecular patterns (PAMPs) exacerbating the inflammatory response, particularly in COVID-19 patients. Cyclic-di-GMP (CDG), one of the PAMPs, is synthesized by various Gram-positve and Gram-negative bacteria. Previous studies mainly focused on the inflammatory responses triggered by intracellular bacteria-released CDG. However, how extracellular CDG, which is released by bacterial autolysis or rupture, activates the inflammatory response remains unclear.

METHODS

The interaction between extracellular CDG and myeloid differentiation protein 2 (MD2) was investigated using in vivo and in vitro models. MD2 blockade was achieved using specific inhibitor and genetic knockout mice. Site-directed mutagenesis, co-immunoprecipitation, SPR and Bis-ANS displacement assays were used to identify the potential binding sites of MD2 on CDG.

RESULTS

Our data show that extracellular CDG directly interacts with MD2, leading to activation of the TLR4 signalling pathway and lung injury. Specific inhibitors or genetic knockout of MD2 in mice significantly alleviated CDG-induced lung injury. Moreover, isoleucine residues at positions 80 and 94, along with phenylalanine at position 121, are essential for the binding of MD2 to CDG.

CONCLUSION

These results reveal that extracellular CDG induces lung injury through direct interaction with MD2 and activation of the TLR4 signalling pathway, providing valuable insights into bacteria-induced ALI mechanisms and new therapeutic approaches for the treatment of bacterial co-infection in COVID-19 patients.

Desflurane alleviates LPS-induced acute lung injury by modulating let-7b-5p/HOXA9 axis

Acute lung injury (ALI) is characterized by acute respiratory failure with tachypnea and widespread alveolar infiltrates, badly affecting patients' health. Desflurane (Des) is effective against lung injury. However, its mechanism in ALI remains unknown. BEAS-2B cells were incubated with lipopolysaccharide (LPS) to construct an ALI cell model. Cell apoptosis was evaluated using flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was employed to examine the levels of inflammatory cytokines. Interactions among let-7b-5p, homeobox A9 (HOXA9), and suppressor of cytokine signaling 2 (SOCS2) were verified using Dual luciferase activity, chromatin immunoprecipitation (ChIP), and RNA pull-down analysis. All experimental data of this study were derived from three repeated experiments. Des treatment improved LPS-induced cell viability, reduced inflammatory cytokine (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6)) levels, decreased cell apoptosis, down-regulated the pro-apoptotic proteins (Bcl-2-associated X protein (Bax) and cleaved caspase 3) expression, and up-regulated the anti-apoptotic protein B-cell-lymphoma-2 (Bcl-2) expression in LPS-induced BEAS-2B cells. Des treatment down-regulated let-7b-5p expression in LPS-induced BEAS-2B cells. Moreover, let-7b-5p inhibition improved LPS-induced cell injury. let-7b-5p overexpression weakened the protective effects of Des. Mechanically, let-7b-5p could negatively modulate HOXA9 expression. Furthermore, HOXA9 inhibited the NF-κB signaling by enhancing SOCS2 transcription. HOXA9 overexpression weakened the promotion of let-7b-5p mimics in LPS-induced cell injury. Des alleviated LPS-induced ALI via regulating let-7b-5p/ HOXA9/NF-κB axis.

Extracellular vesicles as the next-generation modulators of pharmacokinetics and pharmacodynamics of medications and their potential as adjuvant therapeutics

BACKGROUND AND MAIN BODY

Pharmacokinetics (PK) and pharmacodynamics (PD) are central concepts to guide the dosage and administration of drug therapies and are essential to consider for both healthcare professionals and researchers in therapeutic planning and drug discovery. PK/PD properties of a drug significantly influence variability in response to treatment, including therapeutic failure or excessive medication-related harm. Furthermore, suboptimal PK properties constitute a significant barrier to further development for some candidate treatments in drug discovery. This article describes how extracellular vesicles (EVs) affect different aspects of PK and PD of medications and their potential to modulate PK and PD properties to address problematic PK/PD profiles of drugs. We reviewed EVs' intrinsic effects on cell behaviours and medication responses. We also described how surface and cargo modifications can enhance EV functionalities and enable them as adjuvants to optimise the PK/PD profile of conventional medications. Furthermore, we demonstrated that various bioengineering strategies can be used to modify the properties of EVs, hence enhancing their potential to modulate PK and PD profile of medications.

CONCLUSION

This review uncovers the critical role of EVs in PK and PD modulation and motivates further research and the development of assays to unfold EVs' full potential in solving PK and PD-related problems. However, while we have shown that EVs play a vital role in modulating PK and PD properties of medications, we postulated that it is essential to define the context of use when designing and utilising EVs in pharmaceutical and medical applications.

HIGHLIGHTS

Existing solutions for pharmacokinetics and pharmacodynamics modulation are limited. Extracellular vesicles can optimise pharmacokinetics as a drug delivery vehicle. Biogenesis and administration of extracellular vesicles can signal cell response. The pharmaceutical potential of extracellular vesicles can be enhanced by surface and cargo bioengineering. When using extracellular vesicles as modulators of pharmacokinetics and pharmacodynamics, the 'context of use' must be considered.

Exosomes derived from induced cardiopulmonary progenitor cells alleviate acute lung injury in mice

Cardiopulmonary progenitor cells (CPPs) constitute a minor subpopulation of cells that are commonly associated with heart and lung morphogenesis during embryonic development but completely subside after birth. This fact offers the possibility for the treatment of pulmonary heart disease (PHD), in which the lung and heart are both damaged. A reliable source of CPPs is urgently needed. In this study, we reprogrammed human cardiac fibroblasts (HCFs) into CPP-like cells (or induced CPPs, iCPPs) and evaluated the therapeutic potential of iCPP-derived exosomes for acute lung injury (ALI). iCPPs were created in passage 3 primary HCFs by overexpressing GLI1, WNT2, ISL1 and TBX5 (GWIT). Exosomes were isolated from the culture medium of passage 6-8 GWIT-iCPPs. A mouse ALI model was established by intratracheal instillation of LPS. Four hours after LPS instillation, ALI mice were treated with GWIT-iCPP-derived exosomes (5 × 109, 5 × 1010 particles/mL) via intratracheal instillation. We showed that GWIT-iCPPs could differentiate into cell lineages, such as cardiomyocyte-like cells, endothelial cells, smooth muscle cells and alveolar epithelial cells, in vitro. Transcription analysis revealed that GWIT-iCPPs have potential for heart and lung development. Intratracheal instillation of iCPP-derived exosomes dose-dependently alleviated LPS-induced ALI in mice by attenuating lung inflammation, promoting endothelial function and restoring capillary endothelial cells and the epithelial cells barrier. This study provides a potential new method for the prevention and treatment of cardiopulmonary injury, especially lung injury, and provides a new cell model for drug screening.

From mesenchymal stem cells to their extracellular vesicles: Progress and prospects for asthma therapy

Asthma is a widespread public health concern, with an increasing incidence. Despite the implementation of current treatment strategies, asthma control, particularly for severe cases, remains suboptimal. Recent research has revealed the encouraging prospects of extracellular vesicles (EVs) secreted by mesenchymal stem cells (MSCs) as a viable therapeutic option for alleviating asthma symptoms. Therefore, the present review aims to provide an overview of the current progress and the therapeutic mechanisms of using MSC-derived EVs (MSC-EVs) for asthma treatment. Additionally, different administration approaches for EVs and their impacts on biodistribution and the curative outcomes of EVs are summarized. Notably, the potential benefits of nebulized inhalation of MSC-EVs are addressed. Also, the possibilities and challenges of using MSC-EVs for asthma treatment in clinics are highlighted. Overall, this review is intended to give new insight into the utilization of MSC-EVs as a potential biological drug for asthma treatment.

Advances in nanomaterial-targeted treatment of acute lung injury after burns

Acute lung injury (ALI) is a common complication in patients with severe burns and has a complex pathogenesis and high morbidity and mortality rates. A variety of drugs have been identified in the clinic for the treatment of ALI, but they have toxic side effects caused by easy degradation in the body and distribution throughout the body. In recent years, as the understanding of the mechanism underlying ALI has improved, scholars have developed a variety of new nanomaterials that can be safely and effectively targeted for the treatment of ALI. Most of these methods involve nanomaterials such as lipids, organic polymers, peptides, extracellular vesicles or cell membranes, inorganic nanoparticles and other nanomaterials, which are targeted to reach lung tissues to perform their functions through active targeting or passive targeting, a process that involves a variety of cells or organelles. In this review, first, the mechanisms and pathophysiological features of ALI occurrence after burn injury are reviewed, potential therapeutic targets for ALI are summarized, existing nanomaterials for the targeted treatment of ALI are classified, and possible problems and challenges of nanomaterials in the targeted treatment of ALI are discussed to provide a reference for the development of nanomaterials for the targeted treatment of ALI.

Regulation of the Nrf2/HO-1 axis by mesenchymal stem cells-derived extracellular vesicles: implications for disease treatment

This comprehensive review inspects the therapeutic potential of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) across multiple organ systems. Examining their impact on the integumentary, respiratory, cardiovascular, urinary, and skeletal systems, the study highlights the versatility of MSC-EVs in addressing diverse medical conditions. Key pathways, such as Nrf2/HO-1, consistently emerge as central mediators of their antioxidative and anti-inflammatory effects. From expediting diabetic wound healing to mitigating oxidative stress-induced skin injuries, alleviating acute lung injuries, and even offering solutions for conditions like myocardial infarction and renal ischemia-reperfusion injury, MSC-EVs demonstrate promising therapeutic efficacy. Their adaptability to different administration routes and identifying specific factors opens avenues for innovative regenerative strategies. This review positions MSC-EVs as promising candidates for future clinical applications, providing a comprehensive overview of their potential impact on regenerative medicine.

Cell-derived biomimetic nanoparticles for the targeted therapy of ALI/ARDS

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common clinical critical diseases with high morbidity and mortality. Especially since the COVID-19 outbreak, the mortality rates of critically ill patients with ARDS can be as high as 60%. Therefore, this problem has become a matter of concern to respiratory critical care. To date, the main clinical measures for ALI/ARDS are mechanical ventilation and drug therapy. Although ventilation treatment reduces mortality, it increases the risk of hyperxemia, and drug treatment lacks safe and effective delivery methods. Therefore, novel therapeutic strategies for ALI/ARDS are urgently needed. Developments in nanotechnology have allowed the construction of a safe, efficient, precise, and controllable drug delivery system. However, problems still encounter in the treatment of ALI/ARDS, such as the toxicity, poor targeting ability, and immunogenicity of nanomaterials. Cell-derived biomimetic nanodelivery drug systems have the advantages of low toxicity, long circulation, high targeting, and high bioavailability and show great therapeutic promises for ALI/ARDS owing to their acquired cellular biological features and some functions. This paper reviews ALI/ARDS treatments based on cell membrane biomimetic technology and extracellular vesicle biomimetic technology, aiming to achieve a significant breakthrough in ALI/ARDS treatments.

The Main Mechanisms of Mesenchymal Stem Cell-Based Treatments against COVID-19

BACKGROUND

Coronavirus disease 2019 (COVID-19) has a clinical manifestation of hypoxic respiratory failure and acute respiratory distress syndrome. However, COVID-19 still lacks of effective clinical treatments so far. As a promising potential treatment against COVID-19, stem cell therapy raised recently and had attracted much attention. Here we review the mechanisms of mesenchymal stem cell-based treatments against COVID-19, and provide potential cues for the effective control of COVID-19 in the future.

METHODS

Literature is obtained from databases PubMed and Web of Science. Key words were chosen for COVID- 19, acute respiratory syndrome coronavirus 2, mesenchymal stem cells, stem cell therapy, and therapeutic mechanism. Then we summarize and critically analyze the relevant articles retrieved.

RESULTS

Mesenchymal stem cell therapy is a potential effective treatment against COVID-19. Its therapeutic efficacy is mainly reflected in reducing severe pulmonary inflammation, reducing lung injury, improving pulmonary function, protecting and repairing lung tissue of the patients. Possible therapeutic mechanisms might include immunoregulation, anti-inflammatory effect, tissue regeneration, anti-apoptosis effect, antiviral, and antibacterial effect, MSC - EVs, and so on.

CONCLUSION

Mesenchymal stem cells can effectively treat COVID-19 through immunoregulation, anti-inflammatory, tissue regeneration, anti-apoptosis, anti-virus and antibacterial, MSC - EVs, and other ways. Systematically elucidating the mechanisms of mesenchymal stem cell-based treatments for COVID-19 will provide novel insights into the follow-up research and development of new therapeutic strategies in next step.

Stem Cell Extracellular Vesicles as Anti-SARS-CoV-2 Immunomodulatory Therapeutics: A Systematic Review of Clinical and Preclinical Studies

BACKGROUND

COVID-19 rapidly escalated into a worldwide pandemic with elevated infectivity even from asymptomatic patients. Complications can lead to severe pneumonia and acute respiratory distress syndrome (ARDS), which are the main contributors to death. Because of their regenerative and immunomodulatory capacities, stem cells and their derived extracellular vesicles (EVs) are perceived as promising therapies against severe pulmonary conditions, including those associated with COVID-19. Herein, we evaluate the safety and efficacy of stem cell EVs in treating COVID-19 and complicating pneumonia, acute lung injury, and ARDS. We also cover relevant preclinical studies to recapitulate the current progress in stem cell EV-based therapy.

METHODS

Using PubMed, Cochrane Central Register of Controlled Trials, Scopus, and Web of Science, we searched for all English-language published studies (2000-2023) that used stem cell EVs as a therapy for COVID-19, ARDS, or pneumonia. The risk of bias (ROB) was assessed for all studies.

RESULTS

Forty-eight studies met our inclusion criteria. Various-sized EVs derived from different types of stem cells were reported as a potentially safe and effective therapy to attenuate the cytokine storm induced by COVID-19. EVs alleviated inflammation and regenerated the alveolar epithelium by decreasing apoptosis, proinflammatory cytokines, neutrophil infiltration, and M2 macrophage polarization. They also prevented fibrin production and promoted the production of anti-inflammatory cytokines and endothelial cell junction proteins.

CONCLUSION

Similar to their parental cells, stem cell EVs mediate lung tissue regeneration by targeting multiple pathways and thus hold promise in promoting the recovery of COVID-19 patients and improving the survival rate of severely affected patients.

Mesenchymal stem cell‐derived extracellular vesicles: Recent therapeutics and targeted drug delivery advances

The targeted drug delivery field is rapidly advancing, focusing on developing biocompatible nanoparticles that meet rigorous criteria of non‐toxicity, biocompatibility, and efficient release of encapsulated molecules. Conventional synthetic nanoparticles (SNPs) face complications such as elevated immune responses, complex synthesis methods, and toxicity, which restrict their utility in therapeutics and drug delivery. Extracellular vesicles (EVs) have emerged as promising substitutes for SNPs, leveraging their ability to cross biological barriers, biocompatibility, reduced toxicity, and natural origin. Notably, mesenchymal stem cell‐derived EVs (MSC‐EVs) have garnered much curiosity due to their potential in therapeutics and drug delivery. Studies suggest that MSC‐EVs, the central paracrine contributors of MSCs, replicate the therapeutic effects of MSCs. This review explores the characteristics of MSC‐EVs, emphasizing their potential in therapeutics and drug delivery for various diseases, including CRISPR/Cas9 delivery for gene editing. It also delves into the obstacles and challenges of MSC‐EVs in clinical applications and provides insights into strategies to overcome the limitations of biodistribution and target delivery.

Manufacturing, quality control, and GLP-grade preclinical study of nebulized allogenic adipose mesenchymal stromal cells-derived extracellular vesicles

BACKGROUND

Human adipose stromal cells-derived extracellular vesicles (haMSC-EVs) have been shown to alleviate inflammation in acute lung injury (ALI) animal models. However, there are few systemic studies on clinical-grade haMSC-EVs. Our study aimed to investigate the manufacturing, quality control (QC) and preclinical safety of clinical-grade haMSC-EVs.

METHODS

haMSC-EVs were isolated from the conditioned medium of human adipose MSCs incubated in 2D containers. Purification was performed by PEG precipitation and differential centrifugation. Characterizations were conducted by nanoparticle tracking analysis, transmission electron microscopy (TEM), Western blotting, nanoflow cytometry analysis, and the TNF-α inhibition ratio of macrophage [after stimulated by lipopolysaccharide (LPS)]. RNA-seq and proteomic analysis with liquid chromatography tandem mass spectrometry (LC-MS/MS) were used to inspect the lot-to-lot consistency of the EV products. Repeated toxicity was evaluated in rats after administration using trace liquid endotracheal nebulizers for 28 days, and respiratory toxicity was evaluated 24 h after the first administration. In vivo therapeutic effects were assessed in an LPS-induced ALI/ acute respiratory distress syndrome (ARDS) rat model.

RESULTS

The quality criteria have been standardized. In a stability study, haMSC-EVs were found to remain stable after 6 months of storage at - 80°C, 3 months at - 20 °C, and 6 h at room temperature. The microRNA profile and proteome of haMSC-EVs demonstrated suitable lot-to-lot consistency, further suggesting the stability of the production processes. Intratracheally administered 1.5 × 108 particles/rat/day for four weeks elicited no significant toxicity in rats. In LPS-induced ALI/ARDS model rats, intratracheally administered haMSC-EVs alleviated lung injury, possibly by reducing the serum level of inflammatory factors.

CONCLUSION

haMSC-EVs, as an off-shelf drug, have suitable stability and lot-to-lot consistency. Intratracheally administered haMSC-EVs demonstrated excellent safety at the tested dosages in systematic preclinical toxicity studies. Intratracheally administered haMSC-EVs improved the lung function and exerted anti-inflammatory effects on LPS-induced ALI/ARDS model rats.

Next-generation treatments: Immunotherapy and advanced therapies for COVID-19

The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in 2019 following prior outbreaks of coronaviruses like SARS and MERS in recent decades, underscoring their high potential of infectivity in humans. Insights from previous outbreaks of SARS and MERS have played a significant role in developing effective strategies to mitigate the global impact of SARS-CoV-2. As of January 7, 2024, there have been 774,075,242 confirmed cases of COVID-19 worldwide. To date, 13.59 billion vaccine doses have been administered, and there have been 7,012,986 documented fatalities (https://www.who.int/) Despite significant progress in addressing the COVID-19 pandemic, the rapid evolution of SARS-CoV-2 challenges human defenses, presenting ongoing global challenges. The emergence of new SARS-CoV-2 lineages, shaped by mutation and recombination processes, has led to successive waves of infections. This scenario reveals the need for next-generation vaccines as a crucial requirement for ensuring ongoing protection against SARS-CoV-2. This demand calls for formulations that trigger a robust adaptive immune response without leading the acute inflammation linked with the infection. Key mutations detected in the Spike protein, a critical target for neutralizing antibodies and vaccine design -specifically within the Receptor Binding Domain region of Omicron variant lineages (B.1.1.529), currently dominant worldwide, have intensified concerns due to their association with immunity evasion from prior vaccinations and infections. As the world deals with this evolving threat, the narrative extends to the realm of emerging variants, each displaying new mutations with implications that remain largely misunderstood. Notably, the JN.1 Omicron lineage is gaining global prevalence, and early findings suggest it stands among the immune-evading variants, a characteristic attributed to its mutation L455S. Moreover, the detrimental consequences of the novel emergence of SARS-CoV-2 lineages bear a particularly critical impact on immunocompromised individuals and older adults. Immunocompromised individuals face challenges such as suboptimal responses to COVID-19 vaccines, rendering them more susceptible to severe disease. Similarly, older adults have an increased risk of severe disease and the presence of comorbid conditions, find themselves at a heightened vulnerability to develop COVID-19 disease. Thus, recognizing these intricate factors is crucial for effectively tailoring public health strategies to protect these vulnerable populations. In this context, this review aims to describe, analyze, and discuss the current progress of the next-generation treatments encompassing immunotherapeutic approaches and advanced therapies emerging as complements that will offer solutions to counter the disadvantages of the existing options. Preliminary outcomes show that these strategies target the virus and address the immunomodulatory responses associated with COVID-19. Furthermore, the capacity to promote tissue repair has been demonstrated, which can be particularly noteworthy for immunocompromised individuals who stand as vulnerable actors in the global landscape of coronavirus infections. The emerging next-generation treatments possess broader potential, offering protection against a wide range of variants and enhancing the ability to counter the impact of the constant evolution of the virus. Furthermore, advanced therapies are projected as potential treatment alternatives for managing Chronic Post-COVID-19 syndromeand addressing its associated long-term complications.

The efficacy of extracellular vesicles for acute lung injury in preclinical animal models: a meta-analysis

BACKGROUND

With the increasing research on extracellular vesicles (EVs), EVs have received widespread attention as biodiagnostic markers and therapeutic agents for a variety of diseases. Stem cell-derived EVs have also been recognized as a new viable therapy for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). To assess their efficacy, we conducted a meta-analysis of existing preclinical experimental animal models of EVs for ALI treatment.

METHODS

The database was systematically interrogated for pertinent data encompassing the period from January 2010 to April 2022 concerning interventions involving extracellular vesicles (EVs) in animal models of acute lung injury (ALI). The lung injury score was selected as the primary outcome measure for statistical analysis. Meta-analyses were executed utilizing RevMan 5.3 and State15.1 software tools.

RESULTS

The meta-analyses comprised 31 studies, exclusively involving animal models of acute lung injury (ALI), categorized into two cohorts based on the presence or absence of extracellular vesicle (EV) intervention. The statistical outcomes from these two study groups revealed a significant reduction in lung injury scores with the administration of stem and progenitor cell-derived EVs (SMD = -3.63, 95% CI [-4.97, -2.30], P < 0.05). Conversely, non-stem cell-derived EVs were associated with an elevation in lung injury scores (SMD = -4.34, 95% CI [3.04, 5.63], P < 0.05). EVs originating from stem and progenitor cells demonstrated mitigating effects on alveolar neutrophil infiltration, white blood cell counts, total cell counts in bronchoalveolar lavage fluid (BALF), lung wet-to-dry weight ratios (W/D), and total protein in BALF. Furthermore, pro-inflammatory mediators exhibited down-regulation, while anti-inflammatory mediators demonstrated up-regulation. Conversely, non-stem cell-derived EVs exacerbated lung injury.

CONCLUSION

In preclinical animal models of acute lung injury (ALI), the administration of extracellular vesicles (EVs) originating from stem and progenitor cells demonstrably enhances pulmonary function. This ameliorative effect is attributed to the mitigation of pulmonary vascular permeability and the modulation of immune homeostasis, collectively impeding the progression of inflammation. In stark contrast, the utilization of EVs derived from non-stem progenitor cells exacerbates the extent of lung injury. These findings substantiate the potential utility of EVs as a novel therapeutic avenue for addressing acute lung injury.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

Extracellular vesicles in the treatment of oxidative stress injury: global research status and trends

Objective: The aim of this study was to conduct a bibliometric analysis of the literature on "Extracellular Vesicles in the Treatment of Oxidative Stress Injury" and to reveal its current status, hot spots and trends. Methods: The relevant literature was obtained from the Web of Science Core Collection (WoSCC) on 29 April 2023. We performed clustering and partnership analysis of authors, institutions, countries, references and keywords in the literature through CiteSpace software and the bibliometric online analysis platform and mapped the relevant knowledge maps. Results: A total of 1,321 relevant publications were included in the bibliometric analysis, with the number of publications in this field increasing year by year. These included 944 "articles" and 377 "reviews". The maximum number of publications published in China is 512, and the maximum number of highly cited publications published in the United States is 20. Based on CiteSpace, the country collaboration network map shows close and stable collaboration among high-productivity countries. Based on WoSCC, there are 1706 relevant research institutions and 119 highly cited elite institutions, among which Kaohsing Chang Gung Men Hosp has the most extensive influence. Studies related to "Extracellular Vesicles in the Treatment of Oxidative Stress Injury" have been published in 548 journals. The keywords of the publications show the main research areas and breakthroughs. Based on WoSCC, the keywords of the research area "Extracellular Vesicles in the Treatment of Oxidative Stress Injury" were found to be as follows: exosome(s), extracellular vesicle(s), oxidative stress, inflammation, mesenchymal stem cells, apoptosis, microRNA (miRNA), mitochondria, biomarker, autophagy, angiogenesis and Alzheimer's disease. Analysis showed that "mesenchymal stem cells", "microRNA", "autophagy", "histology" and "therapeutic" emerged as highly explosive keywords. Conclusion: This study is the first to use visual software and data mining to assess the literature in the field of "Extracellular Vesicles in the Treatment of Oxidative Stress Injury". The research history, research status and direction in this field provide a theoretical basis for its scientific research.

Multitargeted Immunomodulatory Therapy for Viral Myocarditis by Engineered Extracellular Vesicles

Immune regulation therapies are considered promising for treating classically activated macrophage (M1)-driven viral myocarditis (VM). Alternatively, activated macrophage (M2)-derived extracellular vesicles (M2 EVs) have great immunomodulatory potential owing to their ability to reprogram macrophages, but their therapeutic efficacy is hampered by insufficient targeting capacity in vivo. Therefore, we developed cardiac-targeting peptide (CTP) and platelet membrane (PM)-engineered M2 EVs enriched with viral macrophage inflammatory protein-II (vMIP-II), termed CTP/PM-M2 EVsvMIP-II-Lamp2b, to improve the delivery of EVs "cargo" to the heart tissues. In a mouse model of VM, the intravenously injected CTP/PM-M2 EVsvMIP-II-Lamp2b could be carried into the myocardium via CTP, PM, and vMIP-II. In the inflammatory microenvironment, macrophages differentiated from circulating monocytes and macrophages residing in the heart showed enhanced endocytosis rates for CTP/PM-M2 EVsvMIP-II-Lamp2b. Subsequently, CTP/PM-M2 EVsvMIP-II-Lamp2b successfully released functional M2 EVsvMIP-II-Lamp2b into the cytosol, which facilitated the reprogramming of inflammatory M1 macrophages to reparative M2 macrophages. vMIP-II not only helps to increase the targeting ability of M2 EVs but also collaborates with M2 EVs to regulate M1 macrophages in the inflammatory microenvironment and downregulate the levels of multiple chemokine receptors. Finally, the cardiac immune microenvironment was protectively regulated to achieve cardiac repair. Taken together, our findings suggest that CTP-and-PM-engineered M2 EVsvMIP-II-Lamp2b represent an effective means for treating VM and show promise for clinical applications.

Precise nanodrug delivery systems with cell-specific targeting for ALI/ARDS treatment

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common acute and critical diseases in clinics and have no effective treatment to date. With the concept of "precision medicine", research into the precise drug delivery of therapeutic and diagnostic drugs has become a frontier in nanomedicine research and has entered the era of design of precise nanodrug delivery systems (NDDSs) with cell-specific targeting. Owing to the distinctive characteristics of ALI/ARDS, designing NDDSs for specific focal sites is an important strategy for changing drug distribution in the body and specifically increasing drug concentration at target sites while decreasing drug concentration at non-target sites. This strategy enhances drug efficacy, reduces adverse reactions, and ensures accurate nano-targeted treatment. On the basis of the characteristics of pathological ALI/ARDS microenvironments, this paper reviews NDDSs targeting vascular endothelial cells, neutrophils, alveolar macrophages, and alveolar epithelial cells to provide reference for designing accurate NDDSs for ALI/ARDS and novel insights into targeted treatments for ALI/ARDS.

Integrated Analysis of Non-Coding RNA and mRNA Expression Profiles in Exosomes from Lung Tissue with Sepsis-Induced Acute Lung Injury

Background

Acute lung injury (ALI) is associated with a high mortality rate; however, the underlying molecular mechanisms are poorly understood. The purpose of this study was to investigate the expression profile and related networks of long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and mRNAs in lung tissue exosomes obtained from sepsis-induced ALI.

Methods

A mouse model of sepsis was established using the cecal ligation and puncture method. RNA sequencing was performed using lung tissue exosomes obtained from mice in the sham and CLP groups. Hematoxylin-eosin staining, Western blotting, immunofluorescence, quantitative real-time polymerase chain reaction, and nanoparticle tracking analysis were performed to identify relevant phenotypes, and bioinformatic algorithms were used to evaluate competitive endogenous RNA (ceRNA) networks.

Results

Thirty lncRNA-miRNA-mRNA interactions were identified, including two upregulated lncRNAs, 30 upregulated miRNAs, and two downregulated miRNAs. Based on the expression levels of differentially expressed mRNAs(DEmRNAs), differentially expressed LncRNAs(DELncRNAs), and differentially expressed miRNAs(DEmiRNAs), 30 ceRNA networks were constructed.

Conclusion

Our study revealed, for the first time, the expression profiles of lncRNA, miRNA, and mRNA in exosomes isolated from the lungs of mice with sepsis-induced ALI, and the exosome co-expression network and ceRNA network related to ALI in sepsis.

Advances of mesenchymal stem cells and their derived extracellular vesicles as a promising therapy for acute respiratory distress syndrome: from bench to clinic

Acute respiratory distress syndrome (ARDS) is an acute inflammatory lung injury characterized by diffuse alveolar damage. The period prevalence of ARDS was 10.4% of ICU admissions in 50 countries. Although great progress has been made in supportive care, the hospital mortality rate of severe ARDS is still up to 46.1%. Moreover, up to now, there is no effective pharmacotherapy for ARDS and most clinical trials focusing on consistently effective drugs have met disappointing results. Mesenchymal stem cells (MSCs) and their derived extracellular vesicles (EVs) have spawned intense interest of a wide range of researchers and clinicians due to their robust anti-inflammatory, anti-apoptotic and tissue regeneration properties. A growing body of evidence from preclinical studies confirmed the promising therapeutic potential of MSCs and their EVs in the treatment of ARDS. Based on the inspiring experimental results, clinical trials have been designed to evaluate safety and efficacy of MSCs and their EVs in ARDS patients. Moreover, trials exploring their optimal time window and regimen of drug administration are ongoing. Therefore, this review aims to present an overview of the characteristics of mesenchymal stem cells and their derived EVs, therapeutic mechanisms for ARDS and research progress that has been made over the past 5 years.

Research progress of extracellular vesicles and exosomes derived from mesenchymal stem cells in the treatment of oxidative stress-related diseases

There is growing evidence that mesenchymal stem cell-derived extracellular vesicles and exosomes can significantly improve the curative effect of oxidative stress-related diseases. Mesenchymal stem cell extracellular vesicles and exosomes (MSC-EVs and MSC-Exos) are rich in bioactive molecules and have many biological regulatory functions. In this review, we describe how MSC-EVs and MSC-Exos reduce the related markers of oxidative stress and inflammation in various systemic diseases, and the molecular mechanism of MSC-EVs and MSC-Exos in treating apoptosis and vascular injury induced by oxidative stress. The results of a large number of experimental studies have shown that both local and systemic administration can effectively inhibit the oxidative stress response in diseases and promote the survival and regeneration of damaged parenchymal cells. The mRNA and miRNAs in MSC-EVs and MSC-Exos are the most important bioactive molecules in disease treatment, which can inhibit the apoptosis, necrosis and oxidative stress of lung, heart, kidney, liver, bone, skin and other cells, and promote their survive and regenerate.

A Bibliometric Analysis of Mesenchymal Stem Cell-Derived Exosomes in Acute Lung Injury/Acute Respiratory Distress Syndrome from 2013 to 2022

BACKGROUND

Mesenchymal stem cell-derived exosomes (MSC-exosomes) have been found to effectively improve the systemic inflammatory response caused by acute lung injury and acute respiratory distress syndrome (ALI/ARDS), regulate systemic immune disorders, and help injured cells repair. The purpose of this study was to take a holistic view of the current status and trends of MSC-exosomes research in ALI/ARDS.

METHODS

Bibliometrix, Citespace and VOSviewer software were used for bibliometric analysis of the data. We analysed the world trends, country distribution, institution contribution, most relevant journals and authors, research hotspots, and research hotspots related to Coronavirus Disease 2019 (COVID-19) based on the data collected.

RESULTS

China possessed the largest number of publications, while the USA had the highest H-index and the number of citations. Both China and the USA had a high influence in this research field. The largest number of publications in the field of MSC-exosomes and ALI/ARDS were mainly from the University of California system. Stem Cell Research & Therapy published the largest number of papers in this scope. The author with the greatest contribution was LEE JW, and ZHU YG published an article in Stem Cell with the highest local citation score. The most frequent keyword and the latest research hotspot were "NF-κB" and "Coronavirus Disease 2019". Furthermore, our bibliometric analysis results demonstrated that MSC-exosomes intervention and treatment can effectively alleviate the inflammatory response caused by ALI/ARDS.

CONCLUSION

Our bibliometric study suggested the USA and China have a strong influence in this field. COVID-19-induced ALI/ARDS had become a hot topic of research.

Drug delivery of extracellular vesicles: Preparation, delivery strategies and applications

Extracellular vesicles (EV) are cell-originated vesicles exhibited with characteristics similar to the parent cells. Several studies have suggested the therapeutic potential of EV since they played as an intercellular communicator and modulate disease microenvironment, and thus EV has been widely studied in cancer management and tissue regeneration. However, merely application of EV revealed limited therapeutic outcome in different disease scenario and co-administration of drugs may be necessary to exert proper therapeutic effect. The method of drug loading into EV and efficient delivery of the formulation is therefore important. In this review, the advantages of using EV as drug delivery system compared to traditional synthetic nanoparticles will be emphasized, followed by the method of preparing EV and drug loading. The pharmacokinetic characteristics of EV was discussed, together with the review of reported delivery strategies and related application of EV in different disease management.

A Review of Extracellular Vesicles in COVID-19 Diagnosis, Treatment, and Prevention

The 2019 novel coronavirus disease (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is ongoing, and has necessitated scientific efforts in disease diagnosis, treatment, and prevention. Interestingly, extracellular vesicles (EVs) have been crucial in these developments. EVs are a collection of various nanovesicles which are delimited by a lipid bilayer. They are enriched in proteins, nucleic acids, lipids, and metabolites, and naturally released from different cells. Their natural material transport properties, inherent long-term recycling ability, excellent biocompatibility, editable targeting, and inheritance of parental cell properties make EVs one of the most promising next-generation drug delivery nanocarriers and active biologics. During the COVID-19 pandemic, many efforts have been made to exploit the payload of natural EVs for the treatment of COVID-19. Furthermore, strategies that use engineered EVs to manufacture vaccines and neutralization traps have produced excellent efficacy in animal experiments and clinical trials. Here, the recent literature on the application of EVs in COVID-19 diagnosis, treatment, damage repair, and prevention is reviewed. And the therapeutic value, application strategies, safety, and biotoxicity in the production and clinical applications of EV agents for COVID-19 treatment, as well as inspiration for using EVs to block and eliminate novel viruses are discussed.

Cell-Based Biomaterials for Coronavirus Disease 2019 Prevention and Therapy

Coronavirus disease 2019 (COVID-19) continues to threaten human health, economic development, and national security. Although many vaccines and drugs have been explored to fight against the major pandemic, their efficacy and safety still need to be improved. Cell-based biomaterials, especially living cells, extracellular vesicles, and cell membranes, offer great potential in preventing and treating COVID-19 owing to their versatility and unique biological functions. In this review, the characteristics and functions of cell-based biomaterials and their biological applications in COVID-19 prevention and therapy are described. First the pathological features of COVID-19 are summarized, providing enlightenment on how to fight against COVID-19. Next, the classification, organization structure, characteristics, and functions of cell-based biomaterials are focused on. Finally, the progress of cell-based biomaterials in overcoming COVID-19 in different aspects, including the prevention of viral infection, inhibition of viral proliferation, anti-inflammation, tissue repair, and alleviation of lymphopenia are comprehensively described. At the end of this review, a look forward to the challenges of this aspect is presented.

Aspirin loaded extracellular vesicles inhibit inflammation of macrophages via switching metabolic phenotype in periodontitis

OBJECTIVES

Changes of macrophage in the local immune microenvironment of periodontitis cause alveolar bone resorption. This study aims to investigate the effect of a new drug delivery method of aspirin on the immune microenvironment of periodontitis to promote alveolar bone repair, and to explore mechanism of aspirin's effect on macrophage.

METHODS

We isolated extracellular vesicles (EVs) from periodontal stem cells (PDLSCs) and loaded with aspirin by sonication, and then evaluated the treatment efficacy of aspirin-loaded vesicles (EVs-ASP) in periodontitis model in mice. In vitro, we explored the role of EVs-ASP in the regulation of LPS-induced macrophages. The underlying mechanism by which EVs-ASP regulates phenotypic remodeling of macrophages in periodontitis was further investigated.

RESULTS

EVs-ASP inhibited the inflammatory environment of LPS-induced macrophage, and promoted anti-inflammatory macrophages formation both in vivo and in vitro, and reduced bone loss in periodontitis models. Moreover, EVs-ASP enhanced oxidative phosphorylation and suppressed glycolysis in macrophages.

CONCLUSIONS

Consequently, EVs-ASP improves the periodontal immune microenvironment by enhancing oxidative phosphorylation (OXPHOS) in macrophages, resulting in a certain degree of regeneration of alveolar bone height. Our study provides a new potential strategy for bone repair in periodontitis therapy.

Efficacy and safety of human umbilical cord-derived mesenchymal stem cells for COVID-19 pneumonia: a meta-analysis of randomized controlled trials

BACKGROUND

Elevated levels of inflammatory factors are associated with poor prognosis in coronavirus disease-19 (COVID-19). However, mesenchymal stem cells (MSCs) have immunomodulatory functions. Accordingly, this meta-analysis aimed to determine the efficacy and safety of MSC-based therapy in patients with COVID-19 pneumonia.

METHODS

Online global databases were used to find relevant studies. Two independent researchers then selected and evaluated the studies for suitability while the Cochrane risk of bias tool determined the quality of all articles and Cochran's Q test and I2 index assessed the degree of heterogeneity in the principal studies. Statistical analysis was performed using Review Manager software, and the effect of each study on the overall estimate was evaluated by sensitivity analysis.

RESULTS

Seven studies were included in the meta-analysis, and all MSCs used in the trials were acquired from the umbilical cord. The results of these studies (n = 328) indicated that patients with COVID-19 pneumonia who received MSCs had a 0.58 risk of death compared with controls (95% CI = 0.38, 0.87; P = 0.53; I2 = 0%). In terms of inflammatory biomarkers, MSCs reduced the levels of C-reactive protein (n = 88; MD =  - 32.49; 95% CI =  - 48.43, - 16.56; P = 0.46; I2 = 0%) and interferon-gamma (n = 44; SMD =  - 1.23; 95% CI =  - 1.89, - 0.57; P = 0.37; I2 = 0%) in severe COVID-19 patients but had no significant effect on interleukin-6 (n = 185; MD =  - 0.75; 95% CI =  - 7.76, 6.27; P = 0.57; I2 = 0%). A summary of the data revealed no significant differences in adverse events (n = 287) or serious adverse events (n = 229) between the MSC and control groups.

CONCLUSIONS

Infusion of umbilical cord-derived MSCs is an effective strategy for treating patients with COVID-19 pneumonia, with no noticeable adverse effects.

Human adipose tissue-derived small extracellular vesicles promote soft tissue repair through modulating M1-to-M2 polarization of macrophages

BACKGROUND

Successful regenerative medicine strategies need the manipulation and control of macrophages' phenotypic switching. Our previous study indicated that rat and porcine adipose tissue-derived small extracellular vesicles could successfully promote soft tissue repair. However, whether human adipose tissue-derived small extracellular vesicles (h-sEV-AT) showed the same ability to promote soft tissue regeneration and whether adipose tissue-derived small extracellular vesicles (sEV-AT) contribute to modulating the polarization of macrophages were unknown.

METHODS

In this study, we, for the first time, isolated h-sEV-AT from liposuction adipose tissue and characterized the morphology, size distribution, and marker protein. In vitro, we treated adipose-derived stromal/stem cells (ASCs), endothelial cells (ECs), and M1 macrophages with h-sEV-AT. In vivo, the ability of h-sEV-AT to promote soft tissue regeneration and polarize macrophages was investigated.

RESULTS

The results indicated that h-sEV-AT possessed the characteristics of small extracellular vesicles (sEVs). In vitro, an obvious increase in adipogenesis and angiogenesis was induced by h-sEV-AT. In vivo, h-sEV-AT successfully induced the regeneration of adipose tissue and effectively accelerated full-thickness skin wound healing. Besides, we found that h-sEV-AT showed the ability to increase the percentage of M2 macrophages both in vivo and in vitro, which had been reported to contribute to tissue repair and regeneration.

CONCLUSIONS

Taken together, these results suggested that h-sEV-AT showed the ability to induce soft tissue repair supported by not only the differentiation of ASCs and ECs but also the polarization of macrophages. Considering the abundant sources, high yield, and guaranteed effectiveness, this study provided a cell-free strategy for soft tissue regeneration that directly isolated small extracellular vesicles from human liposuction adipose tissue.

A non-invasive strategy for suppressing asthmatic airway inflammation and remodeling: Inhalation of nebulized hypoxic hUCMSC-derived extracellular vesicles

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are extremely promising nanoscale cell-free therapeutic agents. We previously identified that intravenous administration (IV) of human umbilical cord MSC-EVs (hUCMSC-EVs), especially hypoxic hUCMSC-EVs (Hypo-EVs), could suppress allergic airway inflammation and remodeling. Here, we further investigated the therapeutic effects of Hypo-EVs administration by atomizing inhalation (INH), which is a non-invasive and efficient drug delivery method for lung diseases. We found that nebulized Hypo-EVs produced by the atomization system (medical/household air compressor and nebulizer) maintained excellent structural integrity. Nebulized Dir-labeled Hypo-EVs inhaled by mice were mainly restricted to lungs. INH administration of Hypo-EVs significantly reduced the airway inflammatory infiltration, decreased the levels of IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid (BALF), declined the content of OVA-specific IgE in serum, attenuated the goblet cell metaplasia, and the expressions of subepithelial collagen-1 and α-smooth muscle actin (α-SMA). Notably, Hypo-EV INH administration was generally more potent than Hypo-EV IV in suppressing IL-13 levels and collagen-1 and α-SMA expressions. RNA sequencing revealed that various biological processes, such as cell adhesion, innate immune response, B cell activation, and extracellular space, were associated with the activity of Hypo-EV INH against asthma mice. In addition, Hypo-EVs could load exogenous miR-146a-5p (miR-146a-5p-EVs). Furthermore, INH administration of miR-146a-5p-EVs resulted in a significantly increased expression of miR-146a-5p mostly in lungs, and offered greater protection against the OVA-induced increase in airway inflammation, subepithelial collagen accumulation and myofibroblast compared with nebulized Hypo-EVs. Overall, nebulized Hypo-EVs effectively attenuated allergic airway inflammation and remodeling, potentially creating a non-invasive route for the use of MSC-EVs in asthma treatment.

Extracellular vesicles in COVID-19 prognosis, treatment, and vaccination: an update

The lethality of the COVID 19 pandemic became the trigger for one of the most meteoric races on record in the search for strategies of disease control. Those include development of rapid and sensitive diagnostic methods, therapies to treat severe cases, and development of anti-SARS-CoV-2 vaccines, the latter responsible for the current relative control of the disease. However, the commercially available vaccines are still far from conferring protection against acquiring the infection, so the development of more efficient vaccines that can cut the transmission of the variants of concerns that currently predominate and those that will emerge is a prevailing need. On the other hand, considering that COVID 19 is here to stay, the development of new diagnosis and treatment strategies is also desirable. In this sense, there has recently been a great interest in taking advantage of the benefits offered by extracellular vesicles (EVs), membrane structures of nanoscale size that carry information between cells participating in this manner in many physiological homeostatic and pathological processes. The interest has been focused on the fact that EVs are relatively easy to obtain and manipulate, allowing the design of natural nanocarriers that deliver molecules of interest, as well as the information about the pathogens, which can be exploited for the aforementioned purposes. Studies have shown that infection with SARS-CoV-2 induces the release of EVs from different sources, including platelets, and that their increase in blood, as well as some of their markers, could be used as a prognosis of disease severity. Likewise, EVs from different sources are being used as the ideal carriers for delivering active molecules and drugs to treat the disease, as well as vaccine antigens. In this review, we describe the progress that has been made in these three years of pandemic regarding the use of EVs for diagnosis, treatment, and vaccination against SARS-CoV-2 infection. KEY POINTS: • Covid-19 still requires more effective and specific treatments and vaccines. • The use of extracellular vesicles is emerging as an option with multiple advantages. • Association of EVs with COVID 19 and engineered EVs for its control are presented.

Vitiligo: An immune disease and its emerging mesenchymal stem cell therapy paradigm

Melanocyte damage, innate immune response, adaptive immune response, and immune inflammatory microenvironment disorders are involved in the development of the immunological pathogenic mechanism of vitiligo. Mesenchymal stem cells are considered an ideal type of cells for the treatment of vitiligo owing to their low immunogenicity, lower rates of transplant rejection, and ability to secrete numerous growth factors, exosomes, and cytokines in vivo. The regulation of signaling pathways related to oxidative stress and immune imbalance in the immunological pathogenesis of vitiligo can improve the immune microenvironment of tissue injury sites. In addition, co-transplantation with melanocytes can reverse the progression of vitiligo. Therefore, continuous in-depth research on the immunopathogenic mechanism involved in this disease and mesenchymal stem cell-based therapy is warranted for the treatment of vitiligo in the future.

In situ photo-crosslinked adhesive hydrogel loaded with mesenchymal stem cell-derived extracellular vesicles promotes diabetic wound healing

The delayed healing of diabetic wounds is directly affected by the disturbance of wound microenvironment, resulting from persistent inflammation, insufficient angiogenesis, and impaired cell functions. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) showed considerable therapeutic potential in diabetic wound healing. However, the low retention rate of MSC-EVs at wound sites hampers their efficacy. For skin wounds exposed to the outer environment, using a hydrogel with tissue adhesiveness under a moist wound condition is a promising strategy for wound healing. In this study, we modified methacryloyl-modified gelatin (GelMA) hydrogel with catechol motifs of dopamine to fabricate a GelMA-dopamine hydrogel. EVs isolated from MSCs were applied in the synthesized GelMA-dopamine hydrogel to prepare a GelMA-dopamine-EV hydrogel. The results demonstrated that the newly formed GelMA-dopamine hydrogel possessed improved properties of softness, adhesiveness, and absorptive capacity, as well as high biocompatibility in the working concentration (15% w/v). In addition, MSC-EVs were verified to promote cell migration and angiogenesis in vitro. In the skin wound model of diabetic rats, the GelMA-dopamine-EV hydrogel exerted prominent wound healing efficacy estimated by collagen deposition, skin appendage regeneration, and the expression of IL-6, CD31, and TGF-β. In conclusion, this combination of MSC-EVs and the modified hydrogel not only accelerates wound closure but also promotes skin structure normalization by rescuing the homeostasis of the healing microenvironment of diabetic wounds, which provides a potential approach for the treatment of diabetic wounds.

Adipose tissue-derived small extracellular vesicles modulate macrophages to improve the homing of adipocyte precursors and endothelial cells in adipose tissue regeneration

Rapid infiltration of endogenous cells induced by cell-free biomaterials is the first and crucial step in tissue regeneration and macrophage is largely involved. Our previous study reported adipose tissue-derived small extracellular vesicles (sEV-AT) could successfully promote adipose tissue regeneration. However, the role of macrophages in this process was unknown. In this study, we isolated sEV-AT and subcutaneously implanted it into the back of SD rats. The results showed sEV-AT increased macrophage infiltration significantly, which was followed by improving homing of adipocyte precursors (APs) and endothelial cells (ECs). However, when macrophages were depleted by clodronate liposome within 1 week, the homing of APs and ECs, and adipose tissue regeneration were destroyed. In vitro, sEV-AT showed the ability to promote the migration of macrophages directly. Besides, sEV-AT-pretreated macrophages improved the migration of APs and ECs, accompanied by the increase of chemokines (MCP-1, SDF-1, VEGF, and FGF) and the activation of NF-kB signaling pathway. These findings indicated sEV-AT might regulate the secretion of chemokines via activating NF-kB signaling pathway to improve homing of APs and ECs and facilitate adipose tissue regeneration. These findings deepened our understanding of small extracellular vesicle-induced tissue regeneration and laid a theoretical foundation for the clinical application of sEV-AT.