Bone marrow derived mesenchymal stem cells inhibit inflammation and preserve vascular endothelial integrity in the lungs after hemorrhagic shock

GDF11 OVEREXPRESSION ALLEVIATES SEPSIS-INDUCED LUNG MICROVASCULAR ENDOTHELIAL BARRIER DAMAGE BY ACTIVATING SIRT1/NOX4 SIGNALING TO INHIBIT FERROPTOSIS

ABSTRACT

Sepsis is a lethal clinical syndrome, and acute lung injury (ALI) is the earliest and most serious complication. We aimed to explore the role of growth differentiation factor 11 (GDF11) in sepsis-induced dysfunction of lung microvascular endothelial barrier in vivo and in vitro to elucidate its potential mechanism related to sirtuin 1 (SIRT1)/NADPH oxidase 4 (NOX4) signaling. Cecal ligation and puncture (CLP)-induced sepsis mice and lipopolysaccharide (LPS)-induced pulmonary microvascular endothelial cells (PMECs) were used in this study. Histopathological changes in lung tissues were tested by hematoxylin-eosin staining. Lung wet-to-dry weight ratio and inflammatory factors contents in bronchoalveolar lavage fluid were assessed. Evens blue index, trans-epithelial electrical resistance, and expression of zona occludens 1 (ZO-1), occludin-1, and claudin-1 were used to evaluate alveolar barrier integrity. Reactive oxygen species, lipid peroxidation, and ferroptosis markers were analyzed. Iron deposition in the lung tissues was assessed using Prussian blue staining. Intracellular Fe 2+ level was detected using FerroOrange staining. Additionally, expression of GDF11, SIRT1, and NOX4 was estimated with western blot. Then, EX527, a SIRT1 inhibitor, was employed to treat GDF11-overexpressed PMECs with LPS stimulation to clarify the regulatory mechanism. Results showed that GDF11 overexpression attenuated sepsis-induced pathological changes and inflammation and maintained alveolar barrier integrity. Moreover, GDF11 overexpression inhibited ferroptosis, upregulated SIRT1 expression and downregulated NOX4 expression. Additionally, EX527 treatment relieved the impacts of GDF11 overexpression on ferroptosis and destruction of integrity of human pulmonary microvascular endothelial cells exposed to LPS. Taken together, GDF11 overexpression could alleviate sepsis-induced lung microvascular endothelial barrier damage by activating SIRT1/NOX4 signaling to inhibit ferroptosis. Our findings potentially provide new molecular target for clinical therapy of ALI.

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.

Vascular leak in sepsis: physiological basis and potential therapeutic advances

Sepsis is a life-threatening condition characterised by endothelial barrier dysfunction and impairment of normal microcirculatory function, resulting in a state of hypoperfusion and tissue oedema. No specific pharmacological therapies are currently used to attenuate microvascular injury. Given the prominent role of endothelial breakdown and microcirculatory dysfunction in sepsis, there is a need for effective strategies to protect the endothelium. In this review we will discuss key mechanisms and putative therapeutic agents relevant to endothelial barrier function.

Bone mesenchymal stem cell extracellular vesicles delivered miR let-7-5p alleviate endothelial glycocalyx degradation and leakage via targeting ABL2

BACKGROUND

Endothelial glycocalyx (EG) is an active player and treatment target in inflammatory-related vascular leakage. The bone marrow mesenchymal stem cells (bMSCs) are promising potential treatments for leakage; however, the therapeutic effect and mechanism of bMSC on EG degradation needs to be elucidated.

METHODS

EG degradation and leakage were evaluated in both lipopolysaccharide (LPS)-induced mice ear vascular leakage model and LPS-stimulated human umbilical vein endothelial cells (HUVECs) model treated with bMSCs. Extracellular vesicles (EVs) were extracted from bMSCs and the containing microRNA profile was analyzed. EV and miR let-7-5p were inhibited to determine their function in the therapeutic process. The ABL2 gene was knockdown in HUVECs to verify its role as a therapeutic target in EG degradation.

RESULTS

bMSCs treatment could alleviate LPS-induced EG degradation and leakage in vivo and in vitro, whereas EVs/let-7-5p-deficient bMSCs were insufficient to reduce EG degradation. LPS down-regulated the expression of let-7-5p while upregulated endothelial expression of ABL2 in HUVECs and induced EG degradation and leakage. bMSC-EVs uptaken by HUVECs could deliver let-7-5p targeting endothelial ABL2, which suppressed the activation of downstream p38MAPK and IL-6, IL-1β levels, and thus reversed LPS-induced EG degradation and leakage.

CONCLUSION

bMCSs alleviate LPS-induced EG degradation and leakage through EV delivery of miR let-7-5p targeting endothelial ABL2.

The Immunomodulatory Role of Cell-Free Approaches in SARS-CoV-2-Induced Cytokine Storm-A Powerful Therapeutic Tool for COVID-19 Patients

Currently, there is still no effective and definitive cure for the coronavirus disease 2019 (COVID-19) caused by the infection of the novel highly contagious severe acute respiratory syndrome virus (SARS-CoV-2), whose sudden outbreak was recorded for the first time in China in late December 2019. Soon after, COVID-19 affected not only the vast majority of China's population but the whole world and caused a global health public crisis as a new pandemic. It is well known that viral infection can cause acute respiratory distress syndrome (ARDS) and, in severe cases, can even be lethal. Behind the inflammatory process lies the so-called cytokine storm (CS), which activates various inflammatory cytokines that damage numerous organ tissues. Since the first outbreak of SARS-CoV-2, various research groups have been intensively trying to investigate the best treatment options; however, only limited outcomes have been achieved. One of the most promising strategies represents using either stem cells, such as mesenchymal stem cells (MSCs)/induced pluripotent stem cells (iPSCs), or, more recently, using cell-free approaches involving conditioned media (CMs) and their content, such as extracellular vesicles (EVs) (e.g., exosomes or miRNAs) derived from stem cells. As key mediators of intracellular communication, exosomes carry a cocktail of different molecules with anti-inflammatory effects and immunomodulatory capacity. Our comprehensive review outlines the complex inflammatory process responsible for the CS, summarizes the present results of cell-free-based pre-clinical and clinical studies for COVID-19 treatment, and discusses their future perspectives for therapeutic applications.

Bioengineered stem cell membrane functionalized nanoparticles combine anti-inflammatory and antimicrobial properties for sepsis treatment

BACKGROUND

Sepsis is a syndrome of physiological, pathological and biochemical abnormalities caused by infection. Although the mortality rate is lower than before, many survivors have persistent infection, which means sepsis calls for new treatment. After infection, inflammatory mediators were largely released into the blood, leading to multiple organ dysfunction. Therefore, anti-infection and anti-inflammation are critical issues in sepsis management.

RESULTS

Here, we successfully constructed a novel nanometer drug loading system for sepsis management, FZ/MER-AgMOF@Bm. The nanoparticles were modified with LPS-treated bone marrow mesenchymal stem cell (BMSC) membrane, and silver metal organic framework (AgMOF) was used as the nanocore for loading FPS-ZM1 and meropenem which was delivery to the infectious microenvironments (IMEs) to exert dual anti-inflammatory and antibacterial effects. FZ/MER-AgMOF@Bm effectively alleviated excessive inflammatory response and eliminated bacteria. FZ/MER-AgMOF@Bm also played an anti-inflammatory role by promoting the polarization of macrophages to M2. When sepsis induced by cecal ligation and puncture (CLP) challenged mice was treated, FZ/MER-AgMOF@Bm could not only reduce the levels of pro-inflammatory factors and lung injury, but also help to improve hypothermia caused by septic shock and prolong survival time.

CONCLUSIONS

Together, the nanoparticles played a role in combined anti-inflammatory and antimicrobial properties, alleviating cytokine storm and protecting vital organ functions, could be a potential new strategy for sepsis management.

Bone marrow embolism: should it result from traumatic bone lesions? A histopathological human autopsy study

Bone marrow embolism (BME) is likely a consequence of fractures in which pulmonary vessels are the most affected. However, some cases of BME were reported in the absence of trauma. Thus, a traumatic injury might not be necessary for developing BME. This study discusses BME cases in patients without signs of fractures or blunt trauma. The discussion addresses various possible mechanisms for the appearance of BME. Options include cancer in which bone marrow metastasis is a suggestive cause. Another proposal is the chemical theory where bone marrow fats are released via lipoprotein lipase in a pro-inflammatory state, resulting in vascular/pulmonary obstruction. Other cases discussed in this study are hypovolemic shock and drug-abuse related BME. All autopsy cases with BME were included regardless of the cause of death for a period of 2 years. Autopsies involved complete dissection with the macroscopic evaluation of the affected organs, including the heart, lungs, and brain. Tissues were also prepared for microscopic examination. Of the 11 cases, eight showed non-traumatic BME (72%). These findings conflict with theories in the literature that BME most commonly occurs after fractures or trauma. One of the eight cases exhibited mucinous carcinoma; one is presented with hepatocellular carcinoma; and two cases showed severe congestion. Lastly, one case was found to be associated with each of the following conditions: liposuction, drug abuse, pulmonary hypertension, and heart failure. Each case suggests a different pathophysiology for developing BME, yet the exact mechanisms are not fully understood. Further study of non-traumatic associated BME is recommended.

Paracrine Signals in Calcified Conditioned Media Elicited Differential Responses in Primary Aortic Vascular Smooth Muscle Cells and in Adventitial Fibroblasts

Our goal was to determine if paracrine signals from different aortic layers can impact other cell types in the diabetic microenvironment, specifically medial vascular smooth muscle cells (VSMCs) and adventitial fibroblasts (AFBs). The diabetic hyperglycemic aorta undergoes mineral dysregulation, causing cells to be more responsive to chemical messengers eliciting vascular calcification. Advanced glycation end-products (AGEs)/AGE receptors (RAGEs) signaling has been implicated in diabetes-mediated vascular calcification. To elucidate responses shared between cell types, pre-conditioned calcified media from diabetic and non-diabetic VSMCs and AFBs were collected to treat cultured murine diabetic, non-diabetic, diabetic RAGE knockout (RKO), and non-diabetic RKO VSMCs and AFBs. Calcium assays, western blots, and semi-quantitative cytokine/chemokine profile kits were used to determine signaling responses. VSMCs responded to non-diabetic more than diabetic AFB calcified pre-conditioned media. AFB calcification was not significantly altered when VSMC pre-conditioned media was used. No significant changes in VSMCs signaling markers due to treatments were reported; however, genotypic differences existed. Losses in AFB α-smooth muscle actin were observed with diabetic pre-conditioned VSMC media treatment. Superoxide dismutase-2 (SOD-2) increased with non-diabetic calcified + AGE pre-conditioned VSMC media, while same treatment decreased diabetic AFBs levels. Overall, non-diabetic and diabetic pre-conditioned media elicited different responses from VSMCs and AFBs.

Exosome from BMMSC Attenuates Cardiopulmonary Bypass-Induced Acute Lung Injury Via YAP/β-Catenin Pathway: Downregulation of Pyroptosis

Acute lung injury (ALI) accompanied with systemic inflammatory response is an important complication after cardiopulmonary bypass (CPB). Pyroptosis, which is induced by the secretion of inflammatory factors, has been implicated in ALI. However, recent studies have suggested that bone marrow mesenchymal stem cell-derived exosomes (BMMSC-Exo) can ameliorate ALI, but the mechanism is poorly understood. Therefore, we aim to examine the effects of BMMSC-Exo in CPB-induced ALI, and its underlying mechanism. CPB rat models (male Sprague-Dawley rats) were administered BMMSC-Exo intravenously before induction of ALI. Lung tissue, bronchoalveolar lavage fluid (BALF), and alveolar macrophage (AM) were collected after the treatments for further analysis, and rat AM NR8383 cells were used for in vitro study. HE staining was performed to detect macrophage infiltration. Western blot was used to detect related proteins expression. And ELISA assay was performed to investigate secretion of inflammatory factors. These results showed that BMMSC-Exo treatment ameliorated macrophage infiltration and oxidative stress, and downregulated expression of pyroptosis-related proteins, including NLRP3, cleaved caspase-1, and GSDMD-N, in the lung tissue and AM, as well as decreased the secretion of IL-18 and IL-1β in BALF. Moreover, BMMSC-Exo activated YAP/β-catenin signaling pathway. Overall, these findings of this study indicated that BMMSC-Exo suppressed CPB-induced pyroptosis in ALI by activating YAP/β-catenin axis, which could be a novel strategy for lung protection during CPB.

Restoration of vascular endothelial integrity by mesenchymal stromal/stem cells in debilitating virus diseases

Endothelial dysfunction is one of the key cornerstone complications of emerging and re-emerging viruses which lead to vascular leakage and a high mortality rate. The mechanism that regulates the origin of endothelial dysregulation is not completely elucidated. Currently, there are no potential pharmacological treatments and curable management for such diseases. In this sense, mesenchymal stromal/stem cells (MSCs) has been emerging to be a promising therapeutic strategy in restoring endothelial barrier function in various lung disease, including ALI and ARDS. The mechanism of the role of MSCs in restoring endothelial integrity among single-strand RNA (ssRNA) viruses that target endothelial cells remains elusive. Thus, we have discussed the therapeutic role of MSCs in restoring vascular integrity by (i) inhibiting the metalloprotease activity thereby preventing the cleavage of tight junction proteins, which are essential for maintaining membrane integrity (ii) possessing antioxidant properties which neutralize the excessive ROS production due to virus infection and its associated hyper host immune response (iii) modulating micro RNAs that regulate the endothelial activation and its integrity by downregulating the inflammatory response during ssRNA infection.

Innate immunity and immunotherapy for hemorrhagic shock

Hemorrhagic shock (HS) is a shock result of hypovolemic injury, in which the innate immune response plays a central role in the pathophysiology ofthe severe complications and organ injury in surviving patients. During the development of HS, innate immunity acts as the first line of defense, mediating a rapid response to pathogens or danger signals through pattern recognition receptors. The early and exaggerated activation of innate immunity, which is widespread in patients with HS, results in systemic inflammation, cytokine storm, and excessive activation of complement factors and innate immune cells, comprised of type II innate lymphoid cells, CD4⁺ T cells, natural killer cells, eosinophils, basophils, macrophages, neutrophils, and dendritic cells. Recently, compelling evidence focusing on the innate immune regulation in preclinical and clinical studies promises new treatment avenues to reverse or minimize HS-induced tissue injury, organ dysfunction, and ultimately mortality. In this review, we first discuss the innate immune response involved in HS injury, and then systematically detail the cutting-edge therapeutic strategies in the past decade regarding the innate immune regulation in this field; these strategies include the use of mesenchymal stem cells, exosomes, genetic approaches, antibody therapy, small molecule inhibitors, natural medicine, mesenteric lymph drainage, vagus nerve stimulation, hormones, glycoproteins, and others. We also reviewed the available clinical studies on immune regulation for treating HS and assessed the potential of immune regulation concerning a translation from basic research to clinical practice. Combining therapeutic strategies with an improved understanding of how the innate immune system responds to HS could help to identify and develop targeted therapeutic modalities that mitigate severe organ dysfunction, improve patient outcomes, and reduce mortality due to HS injury.

Potential Cell-Based and Cell-Free Therapy for Patients with COVID-19

Since it was first reported, the novel coronavirus disease 2019 (COVID-19) remains an unresolved puzzle for biomedical researchers in different fields. Various treatments, drugs, and interventions were explored as treatments for COVID. Nevertheless, there are no standard and effective therapeutic measures. Meanwhile, mesenchymal stem cell (MSC) therapy offers a new approach with minimal side effects. MSCs and MSC-based products possess several biological properties that potentially alleviate COVID-19 symptoms. Generally, there are three classifications of stem cell therapy: cell-based therapy, tissue engineering, and cell-free therapy. This review discusses the MSC-based and cell-free therapies for patients with COVID-19, their potential mechanisms of action, and clinical trials related to these therapies. Cell-based therapies involve the direct use and injection of MSCs into the target tissue or organ. On the other hand, cell-free therapy uses secreted products from cells as the primary material. Cell-free therapy materials can comprise cell secretomes and extracellular vesicles. Each therapeutic approach possesses different benefits and various risks. A better understanding of MSC-based and cell-free therapies is essential for supporting the development of safe and effective COVID-19 therapy.

Immunomodulation of Mesenchymal Stem Cells in Acute Lung Injury: From Preclinical Animal Models to Treatment of Severe COVID-19

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been a major public health challenge worldwide. Owing to the emergence of novel viral variants, the risks of reinfections and vaccine breakthrough infections has increased considerably despite a mass of vaccination. The formation of cytokine storm, which subsequently leads to acute respiratory distress syndrome, is the major cause of mortality in patients with COVID-19. Based on results of preclinical animal models and clinical trials of acute lung injury and acute respiratory distress syndrome, the immunomodulatory, tissue repair, and antiviral properties of MSCs highlight their potential to treat COVID-19. This review article summarizes the potential mechanisms and outcomes of MSC therapy in COVID-19, along with the pathogenesis of the SARS-CoV-2 infection. The properties of MSCs and lessons from preclinical animal models of acute lung injury are mentioned ahead. Important issues related to the use of MSCs in COVID-19 are discussed finally.

Mesenchymal stem cells and their conditioned medium as potential therapeutic strategies in managing comorbid anxiety in rat sepsis induced by cecal ligation and puncture

OBJECTIVES

Sepsis-associated encephalopathy (SAE) is a common brain dysfunction following sepsis. Due to the beneficial effects of mesenchymal stem cells (MSCs) therapy on anxiety, an extreme and early manifestation of SAE, we hypothesized that MSCs-derived conditioned medium (CM) may be able to attenuate anxiety in cecal ligation and puncture (CLP)-induced sepsis.

MATERIALS AND METHODS

Rats were assigned into 4 groups: sham, CLP, MSC, and CM. All animals, except in the sham group, underwent the CLP procedure to induce sepsis. Two hours after sepsis induction, the rats in MSC and CM groups, received 1×10⁶ MSCs and CM derived from the same number of cells, respectively. 48 hr after the treatments, anxiety-related behaviors were assessed, and brain and right hippocampal tissues were collected.

RESULTS

MSCs and CM enhanced the percentages of open arm entries and time spent in the open arms of the elevated plus-maze and the time spent in the light side of the light-dark box. MSCs and CM decreased the Evans blue content and decreased the IL-6 and TNF-α levels in the brain tissue samples. Reductions in the expression of 5-HT2A receptors and phosphorylation of ERK1/2 and an increase in the expression of 5-HT1A receptors in the hippocampal tissue samples were observed in the MSC and CM groups.

CONCLUSION

MSCs and MSCs-derived CM attenuated anxiety-related behaviors to an equal extent by reducing inflammation, modifying 5-HT receptor expression changes, and inhibiting the ERK pathway. Therefore, MSCs-derived CM may be considered a promising therapy for comorbid anxiety in septic patients.

Ghrelin pretreatment enhanced the protective effect of bone marrow-derived mesenchymal stem cell-conditioned medium on lipopolysaccharide-induced endothelial cell injury

BACKGROUND

Lung endothelial barrier injury plays a crucial role in the pathophysiology of acute respiratory distress syndrome. It has been demonstrated that bone marrow-derived mesenchymal stem cells-conditioned medium (BMSCs-CM) and ghrelin have a protective effect. This study investigated if ghrelin pretreatment enhanced the protective effect of BMSCs-CM on lipopolysaccharide (LPS)-induced endothelial cell injury.

METHODS

BMSCs were isolated from rat bone marrow, expanded, then phenotypically tested for mesenchymal stem cell-identifying criteria by flow cytometry. The effects of the conditioned medium derived from ghrelin-pretreated BMSCs (BMSCs-^{ghrelin-pretreated}-CM) on LPS-injured endothelial cells were evaluated by migration, apoptosis, permeability, and pro-inflammatory factor (e.g., tumor necrosis factor-α, interleukin (IL)-1β, and IL-6) assays in endothelial cells. Further, AKT/GSK3β pathway activation in endothelial cells was examined by Western blot, and the gene expression profiles of ghrelin-pretreated BMSCs were examined by RNA sequencing.

RESULTS

BMSCs-^{ghrelin-pretreated}-CM had a greater protective effect on LPS-induced endothelial cell injury than BMSCs-CM by improving cell migration, alleviating apoptosis, and reducing endothelial permeability and the release of pro-inflammatory factors in endothelial cells. The mechanism is partly related to AKT/GSK3β pathway activation after BMSCs-^{ghrelin-pretreated}-CM treatment. There were five upregulated candidate genes (Wnt5a [i.e., Wnt Family Member 5A], S100b [i.e., S100 Calcium-Binding Protein B], Bmp2 [i.e., Bone Morphogenetic Protein 2], Id4 [i.e., Inhibitor Of DNA Binding 4], and PTHLH [i.e., Parathyroid Hormone Like Hormone]) in BMSCs after ghrelin treatment, and all were associated with AKT pathway activation and endothelial function.

CONCLUSIONS

Ghrelin pretreatment enhanced the protective effect of BMSCs-CM on LPS-induced endothelial cell injury, partly by activating the AKT/GSK3β pathway.

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

BACKGROUND

Hemorrhagic shock and trauma (HS/T)-induced gut injury may play a critical role in the development of multi-organ failure. Novel therapies that target gut injury and vascular permeability early after HS/T could have substantial impacts on trauma patients. In this study, we investigate the therapeutic potential of human mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (MSC EVs) in vivo in HS/T in mice and in vitro in Caco-2 human intestinal epithelial cells.

METHODS

In vivo, using a mouse model of HS/T, vascular permeability to a 10-kDa dextran dye and histopathologic injury in the small intestine and lungs were measured among mice. Groups were (1) sham, (2) HS/T + lactated Ringer's (LR), (3) HS/T + MSCs, and (4) HS/T + MSC EVs. In vitro, Caco-2 cell monolayer integrity was evaluated by an epithelial cell impedance assay. Caco-2 cells were pretreated with control media, MSC conditioned media (CM), or MSC EVs, then challenged with hydrogen peroxide (H2O2).

RESULTS

In vivo, both MSCs and MSC EVs significantly reduced vascular permeability in the small intestine (fluorescence units: sham, 456 ± 88; LR, 1067 ± 295; MSC, 765 ± 258; MSC EV, 715 ± 200) and lung (sham, 297 ± 155; LR, 791 ± 331; MSC, 331 ± 172; MSC EV, 303 ± 88). Histopathologic injury in the small intestine and lung was also attenuated by MSCs and MSC EVs. In vitro, MSC CM but not MSC EVs attenuated the increased permeability among Caco-2 cell monolayers challenged with H2O2.

CONCLUSION

Mesenchymal stem cell EVs recapitulate the effects of MSCs in reducing vascular permeability and injury in the small intestine and lungs in vivo, suggesting MSC EVs may be a potential cell-free therapy targeting multi-organ dysfunction in HS/T. This is the first study to demonstrate that MSC EVs improve both gut and lung injury in an animal model of HS/T.

Intravenous administration of mesenchymal stromal cells leads to a dose-dependent coagulopathy and is unable to attenuate acute traumatic coagulopathy in rats

BACKGROUND

Mesenchymal stromal cells (MSCs) express surface tissue factor (TF), which may affect hemostasis and detract from therapeutic outcomes of MSCs if administered intravenously. In this study, we determine a safe dose of MSCs for intravenous (IV) administration and further demonstrate the impact of IV-MSC on acute traumatic coagulopathy (ATC) in rats.

METHODS

Tissue factor expression of rat bone marrow-derived mesenchymal stromal cell (BMSC) or adipose-derived mesenchymal stromal cell (AMSC) was detected by immunohistochemistry and enzyme-linked immunosorbent assay. The coagulation properties were measured in MSC-treated rat whole blood, and blood samples were collected from rats after IV administration of MSCs. Acute traumatic coagulopathy rats underwent polytrauma and 40% hemorrhage, followed by IV administration of 5 or 10 million/kg BMSCs (BMSC-5, BMSC-10), or vehicle at 1 hour after trauma.

RESULTS

Rat MSCs expressed TF, and incubation of rat BMSCs or AMSCs with whole blood in vitro led to a significantly shortened clotting time. However, a dose-dependent prolongation of prothrombin time with reduction in platelet counts and fibrinogen was found in healthy rat treated with IV-MSCs. Bone marrow-derived mesenchymal stromal cells at 5 million/kg or less led to minimal effect on hemostasis. Mesenchymal stromal cells were not found in circulation but in the lungs after IV administration regardless of the dosage. Acute traumatic coagulopathy with prolonged prothrombin time was not significantly affected by 5 or 10 million/kg BMSCs. Intravenous administration of 10 million/kg BMSCs led to significantly lower fibrinogen and platelet counts, while significantly higher levels of lactate, wet/dry weight ratio, and leukocyte infiltration in the lung were present compared with BMSC-5 or vehicle. No differences were seen in immune or inflammatory profiles with BMSC treatment in ATC rats, at least in the acute timeframe.

CONCLUSION

Intravenous administration of MSCs leads to a risk of coagulopathy associated with a dose-dependent reduction in platelet counts and fibrinogen and is incapable of restoring hemostasis of rats with ATC after polytrauma and hemorrhagic shock.

Direct comparison of different therapeutic cell types susceptibility to inflammatory cytokines associated with COVID-19 acute lung injury

Background

Although 90% of infections with the novel coronavirus 2 (COVID-19) are mild, many patients progress to acute respiratory distress syndrome (ARDS) which carries a high risk of mortality. Given that this dysregulated immune response plays a key role in the pathology of COVID-19, several clinical trials are underway to evaluate the effect of immunomodulatory cell therapy on disease progression. However, little is known about the effect of ARDS associated pro-inflammatory mediators on transplanted stem cell function and survival, and any deleterious effects could undermine therapeutic efficacy. As such, we assessed the impact of inflammatory cytokines on the viability, and paracrine profile (extracellular vesicles) of bone marrow-derived mesenchymal stromal cells, heart-derived cells, and umbilical cord-derived mesenchymal stromal cells.

Methods

All cell products were manufactured and characterized to established clinical release standards by an accredited clinical cell manufacturing facility. Cytokines and Extracellular vesicles in the cell conditioned media were profiled using proteomic array and nanoparticle tracking analysis. Using a survey of the clinical literature, 6 cytotoxic cytokines implicated in the progression of COVID-19 ARDS. Flow cytometry was employed to determine receptor expression of these 6 cytokines in three cell products. Based on clinical survey and flow cytometry data, a cytokine cocktail that mimics cytokine storm seen in COVID-19 ARDS patients was designed and the impact on cytokine cocktail on viability and paracrine secretory ability of cell products were assessed using cell viability and nanoparticle tracking analysis.

Results

Flow cytometry revealed the presence of receptors for all cytokines but IL-6, which was subsequently excluded from further experimentation. Despite this widespread expression, exposure of each cell type to individual cytokines at doses tenfold greater than observed clinically or in combination at doses associated with severe ARDS did not alter cell viability or extracellular vesicle character/production in any of the 3 cell products.

Conclusions

The paracrine production and viability of the three leading cell products under clinical evaluation for the treatment of severe COVID-19 ARDS are not altered by inflammatory mediators implicated in disease progression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02699-7.

Extracellular Vesicles and Alveolar Epithelial-Capillary Barrier Disruption in Acute Respiratory Distress Syndrome: Pathophysiological Role and Therapeutic Potential

Extracellular vesicles (EVs) mediate intercellular communication by transferring genetic material, proteins and organelles between different cells types in both health and disease. Recent evidence suggests that these vesicles, more than simply diagnostic markers, are key mediators of the pathophysiology of acute respiratory distress syndrome (ARDS) and other lung diseases. In this review, we will discuss the contribution of EVs released by pulmonary structural cells (alveolar epithelial and endothelial cells) and immune cells in these diseases, with particular attention to their ability to modulate inflammation and alveolar-capillary barrier disruption, a hallmark of ARDS. EVs also offer a unique opportunity to develop new therapeutics for the treatment of ARDS. Evidences supporting the ability of stem cell-derived EVs to attenuate the lung injury and ongoing strategies to improve their therapeutic potential are also discussed.

Therapeutically Targeting Microvascular Leakage in Experimental Hemorrhagic SHOCK: A Systematic Review and Meta-Analysis

BACKGROUND

Microvascular leakage is proposed as main contributor to disturbed microcirculatory perfusion following hemorrhagic shock and fluid resuscitation, leading to organ dysfunction and unfavorable outcome. Currently, no drugs are available to reduce or prevent microvascular leakage in clinical practice. We therefore aimed to provide an overview of therapeutic agents targeting microvascular leakage following experimental hemorrhagic shock and fluid resuscitation.

METHODS

PubMed, EMBASE.com, and Cochrane Library were searched in January 2021 for preclinical studies of hemorrhagic shock using any therapeutic agent on top of standard fluid resuscitation. Primary outcome was vascular leakage, defined as edema, macromolecule extravasation, or glycocalyx degradation. Drugs were classified by targeting pathways and subgroup analyses were performed per organ.

RESULTS

Forty-five studies, published between 1973 and 2020, fulfilled eligibility criteria. The included studies tested 54 different therapeutics mainly in pulmonary and intestinal vascular beds. Most studies induced trauma besides hemorrhagic shock. Forty-four therapeutics (81%) were found effective to reduce microvascular leakage, edema formation, or glycocalyx degradation in at least one organ. Targeting oxidative stress and apoptosis was the predominantly effective strategy (SMD: -2.18, CI [-3.21, -1.16], P < 0.0001). Vasoactive agents were found noneffective in reducing microvascular leakage (SMD: -0.86, CI [-3.07, 1.36], P = 0.45).

CONCLUSION

Pharmacological modulation of pathways involved in cell metabolism, inflammation, endothelial barrier regulation, sex hormones and especially oxidative stress and apoptosis were effective in reducing microvascular leakage in experimental hemorrhagic shock with fluid resuscitation. Future studies should investigate whether targeting these pathways can restore microcirculatory perfusion and reduce organ injury following hemorrhagic shock.

SYSTEMATIC REVIEW REGISTRATION NUMBER

CRD42018095432.

Therapeutic Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Prevention of Organ Injuries Induced by Traumatic Hemorrhagic Shock

Severe trauma is the principal cause of death among young people worldwide. Hemorrhagic shock is the leading cause of death after severe trauma. Traumatic hemorrhagic shock (THS) is a complex phenomenon associating an absolute hypovolemia secondary to a sudden and significant extravascular blood loss, tissue injury, and, eventually, hypoxemia. These phenomena are responsible of secondary injuries such as coagulopathy, endotheliopathy, microcirculation failure, inflammation, and immune activation. Collectively, these dysfunctions lead to secondary organ failures and multi-organ failure (MOF). The development of MOF after severe trauma is one of the leading causes of morbidity and mortality, where immunological dysfunction plays a central role. Damage-associated molecular patterns induce an early and exaggerated activation of innate immunity and a suppression of adaptive immunity. Severe complications are associated with a prolonged and dysregulated immune–inflammatory state. The current challenge in the management of THS patients is preventing organ injury, which currently has no etiological treatment available. Modulating the immune response is a potential therapeutic strategy for preventing the complications of THS. Mesenchymal stromal cells (MSCs) are multipotent cells found in a large number of adult tissues and used in clinical practice as therapeutic agents for immunomodulation and tissue repair. There is growing evidence that their efficiency is mainly attributed to the secretion of a wide range of bioactive molecules and extracellular vesicles (EVs). Indeed, different experimental studies revealed that MSC-derived EVs (MSC-EVs) could modulate local and systemic deleterious immune response. Therefore, these new cell-free therapeutic products, easily stored and available immediately, represent a tremendous opportunity in the emergency context of shock. In this review, the pathophysiological environment of THS and, in particular, the crosstalk between the immune system and organ function are described. The potential therapeutic benefits of MSCs or their EVs in treating THS are discussed based on the current knowledge. Understanding the key mechanisms of immune deregulation leading to organ damage is a crucial element in order to optimize the preparation of EVs and potentiate their therapeutic effect.

Current Status of Cell-Based Therapies for COVID-19: Evidence From Mesenchymal Stromal Cells in Sepsis and ARDS

The severe respiratory consequences of the coronavirus disease 2019 (COVID-19) pandemic have prompted the urgent need for novel therapies. Cell-based therapies, primarily using mesenchymal stromal cells (MSCs), have demonstrated safety and potential efficacy in the treatment of critical illness, particularly sepsis and acute respiratory distress syndrome (ARDS). However, there are limited preclinical data for MSCs in COVID-19. Recent studies have shown that MSCs could decrease inflammation, improve lung permeability, enhance microbe and alveolar fluid clearance, and promote lung epithelial and endothelial repair. In addition, MSC-based therapy has shown promising effects in preclinical studies and phase 1 clinical trials in sepsis and ARDS. Here, we review recent advances related to MSC-based therapy in the context of sepsis and ARDS and evaluate the potential value of MSCs as a therapeutic strategy for COVID-19.

Soluble factors of mesenchimal stem cells (FS-MSC) as a potential tool to reduce inflammation in donor's lungs after hypovolemic shock

OBJECTIVE

The shortage of viable lungs is still a major obstacle for transplantation. Trauma victims who represent potential lung donors commonly present hypovolemic shock leading to pulmonary inflammation and deterioration and rejection after transplantation. Seeking to improve lung graft, new approaches to donor treatment have been tested. This study focuses on treatment with mesenchymal stem cells (MSCs) or soluble factors produced by MSCs (FS-MSC) using a rat model for lung donors after hemorrhagic shock.

METHODS

Forty-eight rats were divided into four groups: Sham (n=12), animals without induction of hypovolemic shock; Shock (n=12), animals submitted to hypovolemic shock (mean arterial pressure 40 mmHg); MSC (n=12), animals submitted to hypovolemic shock and treated with MSCs, and FS (n=12), animals submitted to hypovolemic shock and treated with FS-MSC. The animals were subjected to a 50-minute hypovolemic shock (40 mmHg) procedure. The treated animals were monitored for 115 minutes. We performed histopathology of lung tissue and quantification of inflammatory markers (TNF-α, IL-1β, IL-6, IL-10, iCAM and vCAM) in lung tissue and peripheral blood leukocytes (PBLs).

RESULTS

Hemorrhagic shock resulted in higher PBLs and neutrophil infiltrate in the lungs. FS animals had lower neutrophil density comparing with Shock and MSC animals (p<0.001). No differences in the cytokine levels in lung tissue were observed between the groups.

CONCLUSIONS

The lungs of rats submitted to hemorrhagic shock and treated with FS-MSC showed reduced inflammation indicated in a decrease in lung neutrophil infiltrate.

IL-1β primed mesenchymal stromal cells moderate hemorrhagic shock-induced organ injuries

Background

Organ damages following hemorrhagic shock (HS) have been partly attributed to an immunological dysfunction. The current challenge in the management of HS patients is to prevent organ injury-induced morbidity and mortality which currently has not etiological treatment available. Mesenchymal stromal cells (MSC) are used in clinical cell therapy for immunomodulation and tissue repair. In vitro priming is often used to improve the immunomodulation efficiency of MSC before administration.

Objective

Assess the effect of naive MSC (MSCn) or interleukin (IL)-1β primed (MSCp) treatment in a context of HS-induced organ injury.

Methods

Rats underwent fixed pressure HS and were treated with allogenic MSCn or MSCp. Liver and kidney injuries were evaluated 6h later by histological and biochemical analysis. Whole blood was collected to measure leukocytes phenotypes. Then, in vitro characterization of MSCn or MSCp was carried out.

Results

Plasma creatinine, blood urea nitrogen, and cystatin C were decrease by MSCp infusion as well as kidney injury molecule (KIM)-1 on histological kidney sections. Transaminases, GGT, and liver histology were normalized by MSCp. Systemic cytokines (IL-1α, IL-6, and IL-10) as well as CD80, 86, and PD-1/PDL-1 axis were decreased by MSCp on monocytes and granulocytes. In vitro, MSCp showed higher level of secreted immunomodulatory molecules than MSCn.

Conclusion

An early administration of MSCp moderates HS-induced kidney and liver injury. IL-1β priming improves MSC efficiency by promoting their immunomodulatory activity. These data provide proof of concept that MSCp could be a therapeutic tool to prevent the appearance of organs injury following HS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02505-4.

Cell therapy strategies for COVID-19: Current approaches and potential applications

Coronavirus disease 2019 (COVID-19) continues to burden society worldwide. Despite most patients having a mild course, severe presentations have limited treatment options. COVID-19 manifestations extend beyond the lungs and may affect the cardiovascular, nervous, and other organ systems. Current treatments are nonspecific and do not address potential long-term consequences such as pulmonary fibrosis, demyelination, and ischemic organ damage. Cell therapies offer great potential in treating severe COVID-19 presentations due to their customizability and regenerative function. This review summarizes COVID-19 pathogenesis, respective areas where cell therapies have potential, and the ongoing 89 cell therapy trials in COVID-19 as of 1 January 2021.

Mesenchymal stromal cells reduce evidence of lung injury in patients with ARDS

BACKGROUND

Whether airspace biomarkers add value to plasma biomarkers in studying acute respiratory distress syndrome (ARDS) is not well understood. Mesenchymal stromal cells (MSCs) are an investigational therapy for ARDS, and airspace biomarkers may provide mechanistic evidence for MSCs’ impact in patients with ARDS.

METHODS

We carried out a nested cohort study within a phase 2a safety trial of treatment with allogeneic MSCs for moderate-to-severe ARDS. Nonbronchoscopic bronchoalveolar lavage and plasma samples were collected 48 hours after study drug infusion. Airspace and plasma biomarker concentrations were compared between the MSC (n = 17) and placebo (n = 10) treatment arms, and correlation between the two compartments was tested. Airspace biomarkers were also tested for associations with clinical and radiographic outcomes.

RESULTS

Compared with placebo, MSC treatment significantly reduced airspace total protein, angiopoietin-2 (Ang-2), IL-6, and soluble TNF receptor-1 concentrations. Plasma biomarkers did not differ between groups. Each 10-fold increase in airspace Ang-2 was independently associated with 6.7 fewer days alive and free of mechanical ventilation (95% CI, –12.3 to –1.0, P = 0.023), and each 10-fold increase in airspace receptor for advanced glycation end-products (RAGE) was independently associated with a 6.6-point increase in day 3 radiographic assessment of lung edema score (95% CI, 2.4 to 10.8, P = 0.004).

CONCLUSION

MSCs reduced biological evidence of lung injury in patients with ARDS. Biomarkers from the airspaces provide additional value for studying pathogenesis, treatment effects, and outcomes in ARDS.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02097641.

FUNDING

National Heart, Lung, and Blood Institute.

Therapeutic mechanisms of mesenchymal stem cells in acute respiratory distress syndrome reveal potentials for Covid-19 treatment

The mortality rate of critically ill patients with acute respiratory distress syndrome (ARDS) is 30.9% to 46.1%. The emergence of the coronavirus disease 2019 (Covid-19) has become a global issue with raising dire concerns. Patients with severe Covid-19 may progress toward ARDS. Mesenchymal stem cells (MSCs) can be derived from bone marrow, umbilical cord, adipose tissue and so on. The easy accessibility and low immunogenicity enable MSCs for allogeneic administration, and thus they were widely used in animal and clinical studies. Accumulating evidence suggests that mesenchymal stem cell infusion can ameliorate ARDS. However, the underlying mechanisms of MSCs need to be discussed. Recent studies showed MSCs can modulate immune/inflammatory cells, attenuate endoplasmic reticulum stress, and inhibit pulmonary fibrosis. The paracrine cytokines and exosomes may account for these beneficial effects. In this review, we summarize the therapeutic mechanisms of MSCs in ARDS, analyzed the most recent animal experiments and Covid-19 clinical trial results, discussed the adverse effects and prospects in the recent studies, and highlight the potential roles of MSC therapy for Covid-19 patients with ARDS.

Therapeutic potential of mesenchymal stem cells in multiple organs affected by COVID-19

Currently, the world has been devastated by an unprecedented pandemic in this century. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the agent of coronavirus disease 2019 (COVID-19), has been causing disorders, dysfunction and morphophysiological alterations in multiple organs as the disease evolves. There is a great scientific community effort to obtain a therapy capable of reaching the multiple affected organs in order to contribute for tissue repair and regeneration. In this regard, mesenchymal stem cells (MSCs) have emerged as potential candidates concerning the promotion of beneficial actions at different stages of COVID-19. MSCs are promising due to the observed therapeutic effects in respiratory preclinical models, as well as in cardiac, vascular, renal and nervous system models. Their immunomodulatory properties and secretion of paracrine mediators, such as cytokines, chemokines, growth factors and extracellular vesicles allow for long range tissue modulation and, particularly, blood-brain barrier crossing. This review focuses on SARS-CoV-2 impact to lungs, kidneys, heart, vasculature and central nervous system while discussing promising MSC's therapeutic mechanisms in each tissue. In addition, MSC's therapeutic effects in high-risk groups for COVID-19, such as obese, diabetic and hypertensive patients are also explored.

Stem Cell Therapy Potency in Personalizing Severe COVID-19 Treatment

Currently, there are no specific and efficient vaccines or drugs for COVID-19, particularly in severe cases. A wide range of variations in the clinical symptoms of different patients attributed to genomic differences. Therefore, personalized treatments seem to play a critical role in improving these symptoms and even similar conditions. Prompted by the uncertainties in the area of COVID-19 therapies, we reviewed the published papers and concepts to gather and provide useful information to clinicians and researchers interested in personalized medicine and cell-based therapy. One novel aspect of this study focuses on the potential application of personalized medicine in treating severe cases of COVID-19. However, it is theoretical, as any real-world examples of the use of genuinely personalized medicine have not existed yet. Nevertheless, we know that stem cells, especially MSCs, have immune-modulatory effects and can be stored for future personalized medicine applications. This theory has been conjugated with some evidence that we review in the present study. Besides, we discuss the importance of personalized medicine and its possible aspects in COVID-19 treatment, then review the cell-based therapy studies for COVID-19 with a particular focus on stem cell-based therapies as a primary personalized tool medicine. However, the idea of cell-based therapy has not been accepted by several scientific communities due to some concerns of lack of satisfactory clinical studies; still, the MSCs and their clinical outcomes have been revealed the safety and potency of this therapeutic approach in several diseases, especially in the immune-mediated inflammatory diseases and some incurable diseases. Promising outcomes have resulted in that clinical studies are going to continue.

Stem cell therapy in COVID-19: Pooled evidence from SARS-CoV-2, SARS-CoV, MERS-CoV and ARDS: A systematic review

BACKGROUND

SARS-CoV-2, which majorly affects the lungs and respiratory tract is thought due to dysregulation of the immune system which causes an immense imbalance of the cytokines. However, till now no standard treatment has been developed in treating the disease. On the other hand, it becomes important to prevent the acute respiratory tract infection due to COVID-19 which is the most dangerous phase leading to increased mortality. Hence this systematic review has been framed by pooling the available data of the use of stem cells in SARS-CoV-2, SARS-CoV, MERS-CoV and ARDS.

METHODS

6 literature databases (PubMed, EMBASE, Scopus, Google Scholar, Clinicaltrials.gov, and Clinical trial registry of India) were searched for relevant studies till 10th August 2020 using keywords stem cells, mesenchymal stem cells, cell therapy, SARS CoV-2, SARS Coronavirus, Coronavirus 2, COVID-19, nCoV-19, Novel Coronavirus, MERS CoV, ARDS, acute respiratory distress syndrome.

RESULTS

The observations of this systematic review suggest capability of MSCs in reducing the systemic inflammation and protecting against SARS-CoV-2 as evidenced by the available clinical data.

CONCLUSION

MSCs can overcome the clinical challenges currently faced by SARS-CoV-2 infected patients, specifically who are seriously ill and not responding to conventional therapies. Though the available clinical data is motivating, still predicting the therapeutic potential of MSCs will be too early in COVID-19. Hence, further studies in a larger cohort of patients becomes a prerequisite to validate their potential efficacy.

Perinatal Cells: A Promising COVID-19 Therapy?

The COVID-19 pandemic has become a priority in the health systems of all nations worldwide. In fact, there are currently no specific drugs or preventive treatments such as vaccines. The numerous therapies available today aim to counteract the symptoms caused by the viral infection that in some subjects can evolve causing acute respiratory distress syndromes (ARDS) with consequent admission to intensive care unit. The exacerbated response of the immune system, through cytokine storm, causes extensive damage to the lung tissue, with the formation of edema, fibrotic tissues and susceptibility to opportunistic infections. The inflammatory picture is also aggravated by disseminated intravascular coagulation which worsens the damage not only to the respiratory system, but also to other organs. In this context, perinatal cells represent a valid strategy thanks to their strong immunomodulatory potential, their safety profile, the ability to reduce fibrosis and stimulate reparative processes. Furthermore, perinatal cells exert antibacterial and antiviral actions. This review therefore provides an overview of the characteristics of perinatal cells with a particular focus on the beneficial effects that they could have in patients with COVID-19, and more specifically for their potential use in the treatment of ARDS and sepsis.

Anti-Inflammatory and Immunomodulatory Role of Bone Marrow-Derived MSCs in Mice with Acute Lung Injury

Recently, studies suggested that the mesenchymal stem cells (MSCs) have anti-inflammatory and immune-modulatory roles in the induced acute lung injury in mice via controlling innate, humoral, and cell-mediated immunity. Sixty adult male mice were divided equally into three groups. Group A (control group) received an intraperitoneal (IP) phosphate-buffered saline. Group B was injected IP with lipopolysaccharide (LPS). Group C was injected IP with LPS, followed after 2 h by intravenous labeled bone marrow-derived MSCs (BM-MSCs). The plasma and bronchioalveolar lavage (BAL) fluid were collected at 12, 24, and 72 h postinjection. Estimation of total cell and neutrophils count and immunoglobulin M (IgM) in BAL fluid was performed. Enzyme-linked immunosorbent assay (ELISA) was used to analyze tumor necrosis factor-α (TNF-α) that is a proinflammatory cytokine and interleukin-10 (IL-10), which is an anti-inflammatory cytokine, in plasma. Lung samples were collected for histopathological examination at 12, 24, 72 h, and 1 week postinjection. Decreased TNF-α and increased IL-10 levels in the plasma of MSC-treated group compared to the LPS-infected group were observed. Also, decreased IgM level in BAL fluid of the MSC-treated group after 72 h compared to the LPS-infected group was detected with a resolution of inflammation and improvement in lung injury. Moreover, MSC-treated group showed a reduction in total leukocyte count and neutrophil percentage in comparison to control and LPS-infected groups. Histopathological improvement was detected in MSC-treated group as well. In conclusion, systemic MSCs injection has an anti-inflammatory and immune-modulatory effect in LPS-induced acute lung injury in mice.

Mesenchymal stromal cells for acute respiratory distress syndrome (ARDS), sepsis, and COVID-19 infection: optimizing the therapeutic potential

Introduction: Mesenchymal stromal (stem) cell (MSC) therapies are emerging as a promising therapeutic intervention in patients with Acute Respiratory Distress Syndrome (ARDS) and sepsis due to their reparative, immunomodulatory, and antimicrobial properties.Areas covered: This review provides an overview of Mesenchymal stromal cells (MSCs) and their mechanisms of effect in ARDS and sepsis. The preclinical and clinical evidence to support MSC therapy in ARDS and sepsis is discussed. The potential for MSC therapy in COVID-19 ARDS is discussed with insights from respiratory viral models and early clinical reports of MSC therapy in COVID-19. Strategies to optimize the therapeutic potential of MSCs in ARDS and sepsis are considered including preconditioning, altered gene expression, and alternative cell-free MSC-derived products, such as extracellular vesicles and conditioned medium.Expert opinion: MSC products present considerable therapeutic promise for ARDS and sepsis. Preclinical investigations report significant benefits and early phase clinical studies have not highlighted safety concerns. Optimization of MSC function in preclinical models of ARDS and sepsis has enhanced their beneficial effects. MSC-derived products, as cell-free alternatives, may provide further advantages in this field. These strategies present opportunity for the clinical development of MSCs and MSC-derived products with enhanced therapeutic efficacy.

Mechanically Stretched Mesenchymal Stem Cells Can Reduce the Effects of LPS-Induced Injury on the Pulmonary Microvascular Endothelium Barrier

Mesenchymal stem cells (MSCs) may improve the treatment of acute respiratory distress syndrome (ARDS). However, few studies have investigated the effects of mechanically stretched -MSCs (MS-MSCs) in in vitro models of ARDS. The aim of this study was to evaluate the potential therapeutic effects of MS-MSCs on pulmonary microvascular endothelium barrier injuries induced by LPS. We introduced a cocultured model of pulmonary microvascular endothelial cell (EC) and MSC medium obtained from MSCs with or without mechanical stretch. We found that Wright-Giemsa staining revealed that MSC morphology changed significantly and cell plasma shrank separately after mechanical stretch. Cell proliferation of the MS-MSC groups was much lower than the untreated MSC group; expression of cell surface markers did not change significantly. Compared to the medium from untreated MSCs, inflammatory factors elevated statistically in the medium from MS-MSCs. Moreover, the paracellular permeability of endothelial cells treated with LPS was restored with a medium from MS-MSCs, while LPS-induced EC apoptosis decreased. In addition, protective effects on the remodeling of intercellular junctions were observed when compared to LPS-treated endothelial cells. These data demonstrated that the MS-MSC groups had potential therapeutic effects on the LPS-treated ECs; these results might be useful in the treatment of ARDS.

Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Disease 2019

A workshop entitled "Stem Cells, Cell Therapies and Bioengineering in Lung Biology and Diseases" was hosted by the University of Vermont Larner College of Medicine in collaboration with the National Heart, Lung and Blood Institute, the Alpha-1 Foundation, the Cystic Fibrosis Foundation, the International Society for Cell and Gene Therapy and the Pulmonary Fibrosis Foundation. The event was held from July 15 to 18, 2019 at the University of Vermont, Burlington, Vermont. The objectives of the conference were to review and discuss the current status of the following active areas of research: 1) technological advancements in the analysis and visualisation of lung stem and progenitor cells; 2) evaluation of lung stem and progenitor cells in the context of their interactions with the niche; 3) progress toward the application and delivery of stem and progenitor cells for the treatment of lung diseases such as cystic fibrosis; 4) progress in induced pluripotent stem cell models and application for disease modelling; and 5) the emerging roles of cell therapy and extracellular vesicles in immunomodulation of the lung. This selection of topics represents some of the most dynamic research areas in which incredible progress continues to be made. The workshop also included active discussion on the regulation and commercialisation of regenerative medicine products and concluded with an open discussion to set priorities and recommendations for future research directions in basic and translation lung biology.

Down-Regulation of miR-301a-3p Reduces Burn-Induced Vascular Endothelial Apoptosis by potentiating hMSC-Secreted IGF-1 and PI3K/Akt/FOXO3a Pathway

Vascular endothelium dysfunction plays a pivotal role in the initiation and progression of multiple organ dysfunction. The mesenchymal stem cell (MSC) maintains vascular endothelial barrier survival via secreting bioactive factors. However, the mechanism of human umbilical cord MSC (hMSC) in protecting endothelial survival remains unclear. Here, we found IGF-1 secreted by hMSC suppressed severe burn-induced apoptosis of human umbilical vein endothelial cells (HUVECs) and alleviated the dysfunction of vascular endothelial barrier and multiple organs in severely burned rats. Severe burn repressed miR-301a-3p expression, which directly regulated IGF-1 synthesis and secretion in hMSC. Down-regulation of miR-301a-3p decreased HUVECs apoptosis, stabilized endothelial barrier permeability, and subsequently protected against multiple organ dysfunction in vivo. Additionally, miR-301a-3p negatively regulated PI3K/Akt/FOXO3 signaling through IGF-1. Taken together, our study highlights the protective function of IGF-1 against the dysfunction of multiple organs negatively regulated by miR-301a-3p, which may provide the theoretical foundation for further clinical application of hMSC.

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IGF-1 secreted by hMSC suppressed severe burn-induced apoptosis of HUVECs

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miR-301a-3p directly regulated IGF-1 synthesis and secretion in hMSC

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DomiR-301a-3p protected against multiple organ dysfunction

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miR-301a-3p regulated PI3K/Akt/FOXO3 signaling through hMSC-secreted IGF-1

The Mechanisms Involved in Mesenchymal Stem Cell Alleviation of Sepsis-Induced Acute Lung Injury in Mice: A Pilot Study

Background

Acute lung injury is a common complication of sepsis in intensive care unit patients. Inflammation is among the main mechanisms of sepsis. Therefore, suppression of inflammation is an important mechanism for sepsis treatment. Mesenchymal stem cells (MSCs) have been reported to exhibit antimicrobial properties.

Objective

The present study investigated the effects of MSCs on sepsis-induced acute lung injury.

Methods

Male C57BL/6 mice underwent a cecal ligation and puncture (CLP) operation to induce sepsis and then received either normal saline or MSCs (1 × 10⁶ cells intravenously) at 3 hours after surgery. Survival after surgery was assessed. Lung injury was assessed by histology score, the presence of lung edema, vascular permeability, inflammatory cell infiltration, and cytokine levels in bronchoalveolar lavage fluid. Finally, we tested nuclear factor kappa-light-chain-enhancer of activated B cells activation in lung tissue.

Results

As expected, CLP caused lung injury as indicated by significant increases in the histopathology score, lung wet to dry weight ratio, and total protein concentration. However, mice treated with MSCs had amelioration of the lung histopathologic changes, lung wet to dry weight ratio, and total protein concentration. The levels of cytokines tumor necrosis factor alpha, interleukin 6, interleukin 1β, and interleukin 17 in bronchoalveolar lavage fluid were dramatically decreased after MSCs treatment. In contrast, expression of interleukin 10 was increased after MSCs treatment. Moreover, mice treated with MSCs had a higher survival rate than the CLP group. Neutrophil infiltration into bronchoalveolar lavage fluid was attenuated after MSCs injection, but the amounts of macrophages observed in the MSC group showed no significant differences compared with the CLP group. In addition, MSCs treatment significantly reduced nuclear factor kappa-light-chain-enhancer of activated B cells activation in lung tissue.

Conclusions

Based on the above findings, treatment with MSCs dampened the inflammatory response and inhibited nuclear factor kappa-light-chain-enhancer of activated B cells activation in the mouse CLP model. Thus, MSCs may be a potential new agent for the treatment of sepsis-induced acute lung injury. (Curr Ther Res Clin Exp. 2020; 81:XXX-XXX).

Adult Neurogenesis Following Ischemic Stroke and Implications for Cell-Based Therapeutic Approaches

Ischemic stroke is one of the most intractable diseases of the central nervous system and is also a major cause of mortality and disability in adult humans. Unfortunately, current therapies target vessel recanalization, which has a narrow treatment window, and the potential adverse effects lead to a low rate of clinical employment; in addition, neuroprotective strategies are not effective for stroke treatment. It is necessary to discover new approaches to develop neuroprotective, neuroregenerative treatment strategies for stroke. At present, accumulating evidence suggests that adult neurogenesis is a novel topic with extensive research on its potential to be harnessed for therapy in various neurologic disorders, and the neurogenesis capacity in the subventricular zone was shown to be increased in response to brain ischemic stroke. In this review, we describe the cellular and molecular mechanisms underlying potential adult neurogenesis and review current preclinical and clinical cell-based therapies for enhancing neural regeneration after adult ischemic stroke. Although stroke-induced neurogenesis in humans does not seem to translate to neurofunctional recovery, we also summarize factors of potential treatment strategies with transplanted cells, including transplantation time, cell dosage, and administration route, to achieve optimum and effective cell-based therapy, thereby harnessing this neuroregenerative response to improve neurofunctional recovery after ischemic stroke.

Procoagulant in vitro effects of clinical cellular therapeutics in a severely injured trauma population

Clinical trials in trauma populations are exploring the use of clinical cellular therapeutics (CCTs) like human mesenchymal stromal cells (MSC) and mononuclear cells (MNC). Recent studies demonstrate a procoagulant effect of these CCTs related to their expression of tissue factor (TF). We sought to examine this relationship in blood from severely injured trauma patients and identify methods to reverse this procoagulant effect. Human MSCs from bone marrow, adipose, and amniotic tissues and freshly isolated bone marrow MNC samples were tested. TF expression and phenotype were quantified using flow cytometry. CCTs were mixed individually with trauma patients' whole blood, assayed with thromboelastography (TEG), and compared with healthy subjects mixed with the same cell sources. Heparin was added to samples at increasing concentrations until TEG parameters normalized. Clotting time or R time in TEG decreased relative to the TF expression of the CCT treatment in a logarithmic fashion for trauma patients and healthy subjects. Nonlinear regression curves were significantly different with healthy subjects demonstrating greater relative decreases in TEG clotting time. In vitro coadministration of heparin normalized the procoagulant effect and required dose escalation based on TF expression. TF expression in human MSC and MNC has a procoagulant effect in blood from trauma patients and healthy subjects. The procoagulant effect is lower in trauma patients possibly because their clotting time is already accelerated. The procoagulant effect due to MSC/MNC TF expression could be useful in the bleeding trauma patient; however, it may emerge as a safety release criterion due to thrombotic risk. The TF procoagulant effect is reversible with heparin.

Secretome Conveys the Protective Effects of ASCs: Therapeutic Potential Following Hemorrhagic Shock?

OBJECTIVES

We tested whether resuscitation supplemented with rat adipose-derived stem cells (ASCs) or secretome (conditioned media) of ASCs can ameliorate inflammation, cell/organ injury, and/or improve outcome after hemorrhagic traumatic shock (HTS).

INTERVENTIONS

Rats were subjected to HTS and a resuscitation protocol that mimics prehospital restrictive reperfusion followed by an adequate reperfusion phase. Twenty minutes into the restrictive reperfusion, animals received an intravenous bolus of 2 × 10 cells (ASC group) or the secretome produced by 2 × 10 ASCs/24 h (ASC-Secretome group). Controls received the vehicle (Vehicle group). All rats were observed for 28-day survival.

MEASUREMENTS AND MAIN RESULTS

HTS-induced inflammation represented by IL-6 was inhibited in the ASC (80%, P < 0.001) and in ASC-Secretome (59%, P < 0.01) group at 48 h compared with Vehicle group. At 24 h, HTS-induced liver injury reflected in plasma alanine aminotransferase was ameliorated by 36% (P < 0.001) in both the ASC and ASC-Secretome groups when compared with the Vehicle. There was no effect on kidney function and/or general cell injury markers. HTS induced a moderate 28-day mortality (18%) that was prevented (P = 0.08) in the ASC but not in the ASC-Secretome group (12%).

CONCLUSIONS

Our data suggest that the ASC-secretome supplemented resuscitation following HTS, in the absence of the stem cells, exerts anti-inflammatory and liver protective effects. Given its ease of preparation, storage, availability, and application (in contrast to the stem cells) we believe that the cell-free secretome has a better therapeutic potential in the early phase of an acute hemorrhagic shock scenario.

Current understanding of the therapeutic benefits of mesenchymal stem cells in acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a multifaceted lung disorder in which no specific therapeutic intervention is able to effectively improve clinical outcomes. Despite an improved understanding of molecular mechanisms and advances in supportive care strategies, ARDS remains associated with high mortality, and survivors usually face long-term morbidity. In recent years, preclinical studies have provided mounting evidence of the potential of mesenchymal stem cell (MSC)-based therapies in lung diseases and critical illnesses. In several models of ARDS, MSCs have been demonstrated to induce anti-inflammatory and anti-apoptotic effects, improve epithelial and endothelial cell recovery, and enhance microbial and alveolar fluid clearance, thus resulting in improved lung and distal organ function and survival. Early-stage clinical trials have also demonstrated the safety of MSC administration in patients with ARDS, but further, large-scale investigations are required to assess the safety and efficacy profile of these therapies. In this review, we summarize the main mechanisms whereby MSCs have been shown to exert therapeutic effects in experimental ARDS. We also highlight questions that need to be further elucidated and barriers that must be overcome in order to efficiently translate MSC research into clinical practice.

Human Adipose Tissue-Derived Stromal Cells Attenuate the Multiple Organ Injuries Induced by Sepsis and Mechanical Ventilation in Mice

Mechanical ventilation (MV) can augment sepsis-induced organ injury. Previous studies indicate that human mesenchymal stem cells (hMSCs) have immune-modulatory effect. We hypothesize that human adipose tissue-derived stromal cells (hADSCs) could attenuate MV and sepsis-induced organ injury. Male C57BL/6 mice were randomized to five groups: Sham group; MV group; cecal ligation and puncture (CLP) group; CLP + MV group; and CLP + MV + hADSC group. Anesthetized mice were subjected to cecal ligation and puncture surgery. The mice then received mechanical ventilation (12 ml/kg), with or without the intervention of hADSCs. The survival rate, organ injury of the liver and kidney, total protein and cells in bronchoalveolar lavage fluid (BALF), and histological changes of the lung and liver were examined. The level of IL-6 in BALF was measured by ELISA. Real-time quantitative PCR was used to analyze mRNA of IL-6 and tumor necrosis factor-α (TNF-α). hADSC treatment increased survival rate of septic mice with MV. hADSCs attenuated dysfunction of the liver and kidney and decreased lung inflammation and tissue injury of the liver and lung. IL-6 level in BALF and TNF-α and IL-6 mRNA expression in the tissue of the lung, liver, and kidney were significantly reduced by hADSC treatment. MV with conventional tidal volume aggravates CLP-induced multiple organ injuries. hADSCs inhibited the compound injuries possibly through modulation of immune responses.

Mesenchymal stem cell-secreted factors delayed spermatogenesis injuries induced by busulfan involving intercellular adhesion molecule regulation

The present study was designed to investigate the therapeutic effect of bone marrow MSC-derived factors on gonadotropic toxicity induced by busulfan in vivo. The conditioned media (CM) was obtained from MSCs in serum-free incubation for 48 hr and concentrated ~25-fold by ultrafiltration. The CM of HEK 293 cells was treated as control (293-CM). MSC-CM was injected into busulfan mice via caudal veins after 1 day of busulfan treatment for 2 weeks (200 μl per dose/twice weekly）. Compared to the 293-CM group, testicular injury was delayed in MSC-CM group, including reduced vacuolations of cells in the basal compartment of the seminiferous epithelium and detachment of cells from basement membrane. Apoptotic spermatogenic cells were significantly decreased in MSC-CM group (p ＜ 0.05). Interesting N-cadherin，ICAM-1 and P-cadherin expressions significantly increased in MSC-CM group, while occludin, ZO-1 and connexin 43 expressions showed no difference among MSC-CM, 293-CM and busulfan groups. Present results suggest MSC-secreted factors protect spermatogenesis impairment after busulfan treatment by reducing the apoptosis of spermatogenic cells and enhancing intercellular adhesion molecule expressions.

Mesenchymal stem cells with downregulated Hippo signaling attenuate lung injury in mice with lipopolysaccharide‑induced acute respiratory distress syndrome

Mesenchymal stem cell (MSC)-mediated repair of injured alveolar epithelial cells is a promising potential cure for acute respiratory distress syndrome (ARDS); however, the repairing effect of MSCs is limited by poor homing and differentiation. Our previous study revealed that the inhibition of the Hippo signaling pathway promotes the proliferation, migration and differentiation of MSCs in vitro, leading to the hypothesis that MSCs with downregulated Hippo signaling could further ameliorate lipopolysaccharide (LPS)-induced ARDS in vivo. In the current study, mouse bone marrow-derived MSCs (mMSCs) with downregulated Hippo signaling were constructed by shRNA-mediated knockdown of large tumor suppressor kinase 1 (Lats1) and were intratracheally administered to LPS-induced mouse models of ARDS. The inhibition of Hippo signaling increased the retention of mMSC in ARDS lung tissue and their differentiation toward alveolar type II epithelial cells. Furthermore, mMSCs with downregulated Hippo signaling led to a decreased lung wet weight/body weight ratio, decreased total protein and albumin concentrations in bronchoalveolar lavage fluid, decreased levels of proinflammatory factors and increased levels of anti-inflammatory factors. Finally, mMSCs with downregulated Hippo signaling improved pathological changes and decreased pulmonary fibrosis in lungs of mice with ARDS. These results suggest that the inhibition of the Hippo signaling pathway in mouse mMSCs by knockdown of Lats1 could further improve the protective effects of mMSCs against epithelial damage and the therapeutic potential of mMSCs on mice with ARDS.

Therapeutic potential of products derived from mesenchymal stem/stromal cells in pulmonary disease

Multipotent mesenchymal stem/stromal cells (MSCs) possess robust self-renewal characteristics and the ability to differentiate into tissue-specific cells. Their therapeutic potential appears promising as evident from their efficacy in several animal models of pulmonary disorders as well as early-phase clinical trials of acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). Such therapeutic efficacy might be attributed to MSC-derived products (the "secretome"), namely conditioned media (CM) and extracellular vesicles (EVs), which have been shown to play pivotal roles in the regenerative function of MSCs. Importantly, the EVs secreted by MSCs can transfer a variety of bioactive factors to modulate the function of recipient cells via various mechanisms, including ligand-receptor interactions, direct membrane fusion, endocytosis, or phagocytosis.Herein, we review the current state-of-the-science of MSC-derived CM and EVs as potential therapeutic agents in lung diseases. We suggest that the MSC-derived secretome might be an appropriate therapeutic agent for treating aggressive pulmonary disorders because of biological and logistical advantages over live cell therapy. Nonetheless, further studies are warranted to elucidate the safety and efficacy of these components in combating pulmonary diseases.

Clinical Cellular Therapeutics Accelerate Clot Formation

Clinical cellular therapeutics (CCTs) have shown preliminary efficacy in reducing inflammation after trauma, preserving cardiac function after myocardial infarction, and improving functional recovery after stroke. However, most clinically available cell lines express tissue factor (TF) which stimulates coagulation. We sought to define the degree of procoagulant activity of CCTs as related to TF expression. CCT samples from bone marrow, adipose, amniotic fluid, umbilical cord, multi-potent adult progenitor cell donors, and bone marrow mononuclear cells were tested. TF expression and phenotype were quantified using flow cytometry. Procoagulant activity of the CCTs was measured in vitro with thromboelastography and calibrated thrombogram. Fluorescence-activated cell sorting (FACS) separated samples into high- and low-TF expressing populations to isolate the contribution of TF to coagulation. A TF neutralizing antibody was incubated with samples to demonstrate loss of procoagulant function. All CCTs tested expressed procoagulant activity that correlated with expression of tissue factor. Time to clot and thrombin formation decreased with increasing TF expression. High-TF expressing cells decreased clotting time more than low-TF expressing cells when isolated from a single donor using FACS. A TF neutralizing antibody restored clotting time to control values in some, but not all, CCT samples. CCTs demonstrate wide variability in procoagulant activity related to TF expression. Time to clot and thrombin formation decreases as TF load increases and this procoagulant effect is neutralized by a TF blocking antibody. Clinical trials using CCTs are in progress and TF expression may emerge as a safety release criterion. Stem Cells Translational Medicine 2018;7:731-739.