Mesenchymal stem cell extracellular vesicles mitigate vascular permeability and injury in the small intestine and lung in a mouse model of hemorrhagic shock and trauma

Pericyte-derived extracellular vesicles improve vascular barrier function in sepsis via the Angpt1/PI3K/AKT pathway and pericyte recruitment: an in vivo and in vitro study

BACKGROUND

Extracellular vesicles derived from pericytes (PCEVs) have been shown to improve vascular permeability, with their therapeutic effects attributed to the presence of pro-regenerative molecules. We hypothesized that angiopoietin 1 (Angpt1) carried by PCEVs contributes to their therapeutic effects after sepsis.

METHODS

A cecal ligation and puncture (CLP)-induced sepsis rat model was used in vivo, and the effects of PCEVs on vascular endothelial cells were studied in vitro. First, proteomic and Gene Ontology enrichment analyses were performed to analyze the therapeutic mechanism of PCEVs, revealing that the angiogenesis-related protein Angpt1 was highly expressed in PCEVs. We then down-regulated Angpt1 in PCEVs. The role of PCEV-carried Angpt1 on intestinal barrier function, PCs recruitment, and inflammatory cytokines was measured by using septic Sprague-Dawley rats and platelet-derived growth factor receptor beta (PDGFR-β)-Cre + mT/mG transgenic mice.

RESULTS

PCEVs significantly improved vascular permeability, proliferation, and angiogenesis in CLP-induced gut barrier injury both in vivo and in vitro. Further studies have shown that PCEVs exert a protective effect on intestinal barrier function and PC recruitment. Additionally, PCEVs reduced serum inflammatory factor levels. Our data also demonstrated that the protein levels of phospho-PI3K and phospho-Akt both increased after PCEVs administration, whereas knocking out Angpt1 suppressed the protective effects of PCEVs through decreased activation of PI3K/Akt signaling.

CONCLUSION

PCEVs protect against sepsis by regulating the vascular endothelial barrier, promoting PC recruitment, protecting intestinal function, and restoring properties via activation of the Angpt1/PI3K/AKT pathway.

Mesenchymal Stem Cell-Derived Extracellular Vesicles for Regenerative Applications and Radiotherapy

Tissue repair is an extremely crucial part of clinical treatment. During the course of disease treatment, surgery, chemotherapy, and radiotherapy cause tissue damage. On the other hand, Normal tissue from accidental or therapeutic exposure to high-dose radiation can cause severe tissue damage. There is an urgent need for developing medical countermeasures against radiation injury for tissue repair. Tissue repair involves the regeneration, proliferation, differentiation, and migration of tissue cells; imbalance of local tissue homeostasis, progressive chronic inflammation; decreased cell activity and stem cell function; and wound healing. Although many clinical treatments are currently available for tissue repair, they are expensive. The long recovery time and some unavoidable complications such as cell damage and the inflammatory reaction caused by radiotherapy have led to unsatisfactory results. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) have similar tissue repair functions as MSCs. In tissue damage, EVs can be used as an alternative to stem cell therapy, thereby avoiding related complications such as immunological rejection. EVs play a major role in regulating tissue damage, anti-inflammation, pro-proliferation, and immune response, thus providing a diversified and efficient solution for the repair of disease- and radiotherapy-induced tissue damage. This article reviews the research progress of mesenchymal stem cell-derived EVs in promoting the repair of tissue including heart, lung, liver, intestine, skin, blood system, central nervous system, and tissue damage caused by radiotherapy, thereby aiming to offer new directions and ideas for the radiotherapy and regenerative applications.

IL-1β primed mesenchymal stromal cells moderate hemorrhagic shock-induced vascular permeability

BACKGROUND

Hemorrhagic shock (HS) corresponds to absolute hypovolemia creating an imbalance between oxygen supply and consumption. This causes an impaired hemostasis, a systemic inflammatory response, and microvascular permeability which can lead to multiple organ failure (MOF). There is no specific treatment for the endothelial dysfunction that plays a major role in the evolution towards MOF. Mesenchymal stromal cells (MSC) have been used in clinical trials for their immunomodulation and tissue repair capabilities for many years. Moreover, we previously showed that IL-1β-primed-MSC (MSCp) attenuated HS-induced organ injuries. The objective of the study was to determine whether MSCp could prevent the onset of MOF after HS by preventing endothelial dysfunction.

METHODS

We established a rat model of HS, inducing 90 min of HS at a fixed mean arterial pressure of 35 mmHg, followed by resuscitation and transfusion. MSCp treatment was administered intravenously at the onset of resuscitation. After 6 h, we assessed plasma levels of endothelial markers, vascular permeability using Evans Blue (EB) dye, and renal and hepatic water content by measuring the wet-to-dry weight difference. Additionally, we investigated the ability of MSCp to inhibit leukocyte adhesion to activated endothelium in vitro.

RESULTS

Our results indicate that early administration of MSCp significantly reduced the percentage of water content and EB dye in the liver but not in the kidney. These results were associated with a trend toward decreased plasma levels of Syndecan-1, ICAM-1, vWF, and VCAM-1. In vitro, MSCp reduced leukocyte-endothelial cell adhesion. Together, our results suggest that MSCp help to prevent endothelial dysfunction and vascular leakage, which, in turn, could protect the liver from injury.

Regulation of vascular endothelial integrity by mesenchymal stem cell extracellular vesicles after hemorrhagic shock and trauma

BACKGROUND

Patients with hemorrhagic shock and trauma (HS/T) are vulnerable to the endotheliopathy of trauma (EOT), characterized by vascular barrier dysfunction, inflammation, and coagulopathy. Cellular therapies such as mesenchymal stem cells (MSCs) and MSC extracellular vesicles (EVs) have been proposed as potential therapies targeting the EOT. In this study we investigated the effects of MSCs and MSC EVs on endothelial and epithelial barrier integrity in vitro and in vivo in a mouse model of HS/T. This study addresses the systemic effects of HS/T on multiorgan EOT.

METHODS

In vitro, pulmonary endothelial cell (PEC) and Caco-2 intestinal epithelial cell monolayers were treated with control media, MSC conditioned media (CM), or MSC EVs in varying doses and subjected to a thrombin or hydrogen peroxide (H2O2) challenge, respectively. Monolayer permeability was evaluated with a cell impedance assay, and intercellular junction integrity was evaluated with immunofluorescent staining. In vivo, a mouse model of HS/T was used to evaluate the effects of lactated Ringer's (LR), MSCs, and MSC EVs on endothelial and epithelial intercellular junctions in the lung and small intestine as well as on plasma inflammatory biomarkers.

RESULTS

MSC EVs and MSC CM attenuated permeability and preserved intercellular junctions of the PEC monolayer in vitro, whereas only MSC CM was protective of the Caco-2 epithelial monolayer. In vivo, both MSC EVs and MSCs mitigated the loss of endothelial adherens junctions in the lung and small intestine, though only MSCs had a protective effect on epithelial tight junctions in the lung. Several plasma biomarkers including MMP8 and VEGF were elevated in LR- and EV-treated but not MSC-treated mice.

CONCLUSIONS

In conclusion, MSC EVs could be a potential cell-free therapy targeting endotheliopathy after HS/T via preservation of the vascular endothelial barrier in multiple organs early after injury. Further research is needed to better understand the immunomodulatory effects of these products following HS/T and to move toward translating these therapies into clinical studies.

Regulation of Vascular Endothelial Integrity by Mesenchymal Stem Cell Extracellular Vesicles after Hemorrhagic Shock and Trauma

BACKGROUND

Patients with hemorrhagic shock and trauma (HS/T) are vulnerable to the endotheliopathy of trauma (EOT), characterized by vascular barrier dysfunction, inflammation, and coagulopathy. Cellular therapies such as mesenchymal stem cells (MSCs) and MSC extracellular vesicles (EVs) have been proposed as potential therapies targeting the EOT. In this study we investigated the effects of MSCs and MSC EVs on endothelial and epithelial barrier integrity in vitro and in vivo in a mouse model of HS/T. This study addresses systemic effects of HS/T on multiorgan EOT in HS/T model.

METHODS

In vitro, pulmonary endothelial cell (PEC) and Caco-2 intestinal epithelial cell monolayers were treated with control media, MSC conditioned media (CM), or MSC EVs in varying doses and subjected to a thrombin or hydrogen peroxide (H2O2) challenge, respectively. Monolayer permeability was evaluated with a cell impedance assay, and intercellular junction integrity was evaluated with immunofluorescent staining. In vivo, a mouse model of HS/T was used to evaluate the effects of lactated Ringer's (LR), MSCs, and MSC EVs on endothelial and epithelial intercellular junctions in the lung and small intestine as well as on plasma inflammatory biomarkers.

RESULTS

MSC EVs and MSC CM attenuated permeability and preserved intercellular junctions of the PEC monolayer in vitro, whereas only MSC CM was protective of the Caco-2 epithelial monolayer. In vivo, both MSC EVs and MSCs mitigated the loss of endothelial adherens junctions in the lung and small intestine, though only MSCs had a protective effect on epithelial tight junctions in the lung. Several plasma biomarkers including MMP8 and VEGF were elevated in LR- and EV-treated but not MSC-treated mice.

CONCLUSIONS

In conclusion, MSC EVs could be a potential cell-free therapy targeting endotheliopathy after HS/T via preservation of the vascular endothelial barrier in multiple organs early after injury. Further research is needed to better understand the immunomodulatory effects of these products following HS/T and to move toward translating these therapies into clinical studies.

Magnesium hydride attenuates intestinal barrier injury during hemorrhage shock by regulating neutrophil extracellular trap formation via the ROS/MAPK/PAD4 pathway

Magnesium hydride (MgH2) is a hydrogen storage material that is known for its high capacity and safety and is capable of releasing hydrogen in a controlled manner when administered orally. This release of hydrogen has been associated with a range of biological effects, including anti-inflammatory properties, antioxidant activity, and protection of the intestinal barrier. Previous research has shown that neutrophil extracellular traps (NETs) play a role in the dysfunction of the intestinal barrier in conditions such as sepsis and critical illnesses. However, it remains unclear as to whether MgH2 can protect the intestinal barrier by inhibiting NET formation, and the underlying mechanisms have yet to be elucidated. A rat model of hemorrhagic shock was created, and pretreatment or posttreatment procedures with MgH2 were performed. After 24 h, samples from the small intestine and blood were collected for analysis. In vitro, human neutrophils were incubated with either phorbol-12-myristate-13-acetate (PMA) or MgH2. Reactive oxygen species generation and the expression of key proteins were assessed. The results demonstrated that MgH2 administration led to a decrease in inflammatory cytokines in the serum and mitigated distant organ dysfunction in rats with HS. Furthermore, MgH2 treatment reversed histopathological damage in the intestines, improved intestinal permeability, and enhanced the expression of tight junction proteins (TJPs) during HS. Additionally, MgH2 treatment was found to suppress NET formation in the intestines. In vitro pretreatment with MgH2 alleviated intestinal monolayer barrier disruption that was induced by NETs. Mechanistically, MgH2 pretreatment reduced ROS production and NET formation, inhibited the activation of ERK and p38, and suppressed the expression of the PAD4 protein. These findings indicated that MgH2 may inhibit NET formation in a ROS/MAPK/PAD4-dependent manner, which reduces NET-related intestinal barrier damage, thus offering a novel protective role in preventing intestinal barrier dysfunction during HS.

Extracellular Vesicles: A Crucial Player in the Intestinal Microenvironment and Beyond

The intestinal ecological environment plays a crucial role in nutrient absorption and overall well-being. In recent years, research has focused on the effects of extracellular vesicles (EVs) in both physiological and pathological conditions of the intestine. The intestine does not only consume EVs from exogenous foods, but also those from other endogenous tissues and cells, and even from the gut microbiota. The alteration of conditions in the intestine and the intestinal microbiota subsequently gives rise to changes in other organs and systems, including the central nervous system (CNS), namely the microbiome-gut-brain axis, which also exhibits a significant involvement of EVs. This review first gives an overview of the generation and isolation techniques of EVs, and then mainly focuses on elucidating the functions of EVs derived from various origins on the intestine and the intestinal microenvironment, as well as the impacts of an altered intestinal microenvironment on other physiological systems. Lastly, we discuss the role of microbial and cellular EVs in the microbiome-gut-brain axis. This review enhances the understanding of the specific roles of EVs in the gut microenvironment and the central nervous system, thereby promoting more effective treatment strategies for certain associated diseases.

EFFECTS OF MESENCHYMAL STEM CELLS ON POSTRESUSCITATION RENAL AND INTESTINAL INJURIES IN A PORCINE CARDIAC ARREST MODEL

ABSTRACT

Objectives: Systemic ischemia-reperfusion triggered by cardiac arrest (CA) and resuscitation often causes postresuscitation multiple organ injuries. Mesenchymal stem cells (MSCs) have been proven to be a promising treatment for regional renal and intestinal ischemia reperfusion injuries. This study aimed to investigate the effects of MSCs on renal and intestinal injuries after cardiopulmonary resuscitation (CPR) in a porcine CA model. Methods: Twenty-two male pigs were randomly assigned to the sham (n = 6), CA/CPR (n = 8), and CA/CPR + MSC (n = 8) groups. Mesenchymal stem cells were differentiated from human embryonic stem cells and then intravenously administered at a dose of 2.5 × 10 6 /kg at 1.5 and 3 d before the CA/CPR procedure. The experimental model was established by 8 min of untreated CA, followed by 8 min of CPR. Renal and intestinal injuries were evaluated based on the serum levels of creatinine, serum urea nitrogen, intestinal fatty acid-binding protein, and diamine oxidase at 1, 2, 4, and 24 h after resuscitation. At the end of the experiment, pathological damage was determined by cell apoptosis and ferroptosis in the renal and intestinal tissues. Results: During CPR, five pigs in the CA/CPR group and seven pigs in the CA/CPR + MSC group were successfully resuscitated. After resuscitation, the serum levels of creatinine, serum urea nitrogen, intestinal fatty acid-binding protein, and diamine oxidase were significantly increased in the CA/CPR and CA/CPR + MSC groups compared with those in the sham group. However, MSC administration significantly decreased the levels of renal and intestinal injury biomarkers compared with those in the CA/CPR group. Cell apoptosis and ferroptosis, which were indicated by the levels of apoptotic cells, iron deposition, lipid peroxidation, antioxidants, and ferroptosis-related proteins, were observed in renal and intestinal tissues after resuscitation in the CA/CPR and CA/CPR + MSC groups. Nevertheless, both were significantly milder in the CA/CPR + MSC group than in the CA/CPR group. Conclusions: MSC administration was effective in alleviating postresuscitation renal and intestinal injuries possibly through inhibition of cell apoptosis and ferroptosis in a porcine CA model.

EXTRACELLULAR VESICLES AS REGULATORS OF IMMUNE FUNCTION IN TRAUMATIC INJURIES AND SEPSIS

ABSTRACT

Despite advancements in critical care and resuscitation, traumatic injuries are one of the leading causes of death around the world and can bring about long-term disabilities in survivors. One of the primary causes of death for trauma patients are secondary phase complications that can develop weeks or months after the initial insult. These secondary complications typically occur because of systemic immune dysfunction that develops in response to injury, which can lead to immunosuppression, coagulopathy, multiple organ failure, unregulated inflammation, and potentially sepsis in patients. Recently, extracellular vesicles (EVs) have been identified as mediators of these processes because their levels are increased in circulation after traumatic injury and they encapsulate cargo that can aggravate these secondary complications. In this review, we will discuss the role of EVs in the posttrauma pathologies that arise after burn injuries, trauma to the central nervous system, and infection. In addition, we will examine the use of EVs as biomarkers for predicting late-stage trauma outcomes and as therapeutics for reversing the pathological processes that develop after trauma. Overall, EVs have emerged as critical mediators of trauma-associated pathology and their use as a therapeutic agent represents an exciting new field of biomedicine.

Mesenchymal stem cell-based therapy as a new therapeutic approach for acute inflammation

Acute inflammatory diseases such as acute colitis, kidney injury, liver failure, lung injury, myocardial infarction, pancreatitis, septic shock, and spinal cord injury are significant causes of death worldwide. Despite advances in the understanding of its pathophysiology, there are many restrictions in the treatment of these diseases, and new therapeutic approaches are required. Mesenchymal stem cell-based therapy due to immunomodulatory and regenerative properties is a promising candidate for acute inflammatory disease management. Based on preclinical results, mesenchymal stem cells and their-derived secretome improved immunological and clinical parameters. Furthermore, many clinical trials of acute kidney, liver, lung, myocardial, and spinal cord injury have yielded promising results. In this review, we try to provide a comprehensive view of mesenchymal stem cell-based therapy in acute inflammatory diseases as a new treatment approach.