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

Bone marrow mesenchymal stromal cells attenuate smoke inhalation injury by regulating the M1/M2-Th17/Treg immune homeostasis axis

Smoke inhalation injury (SII) is the leading cause of death in fire burn patients. The inflammatory response induced by smoke inhalation is a significant factor in the development of acute lung injury or acute respiratory distress syndrome (ALI/ARDS). Mesenchymal stem cells (MSCs) can alleviate various inflammatory diseases by regulating the polarization of macrophages from the M1 to the M2 phenotype. Moreover, MSCs can facilitate the inflammatory response by regulating Th17/Treg homeostasis. However, little is known about the associations among MSCs, M1/M2 macrophages and Th17/Treg homeostasis. Therefore, the purpose of this study was to evaluate whether MSCs affect subsequent Th17/Treg differentiation and immune homeostasis by regulating M1/M2 polarization in SII. Our results showed that bone marrow mesenchymal stem cells (BMSCs) ameliorated lung inflammatory injury and fibrosis after SII by affecting the polarization of alveolar macrophages (AMs) from the M1 to the M2 phenotype. Moreover, BMSCs maintain Th17/Treg immune homeostasis by increasing the proportion of Treg cells and decreasing the proportion of Th17 cells. In vitro, we further demonstrated that BMSCs promoted the polarization of AMs from the M1 to the M2 phenotype and decreased IL-23 levels. Reduced IL-23 decreased Th17 differentiation and promoted Th17/Treg balance. Therefore, BMSCs ameliorate the inflammatory response and lung damage after SII through regulating M1/M2 polarization and subsequent Th17/Treg immune homeostasis, which are linked to alveolar macrophage-derived IL-23. These findings provide novel insight into how BMSCs regulate the M1/M2-Th17/Treg immune homeostasis axis and provide new therapeutic targets for more effective control of the inflammatory response after SII.

The Effects of the Pneumonia Lung Microenvironment on MSC Function

BACKGROUND

Despite promise in preclinical models of acute respiratory distress syndrome (ARDS), mesenchymal stem cells (MSC) have failed to translate to therapeutic benefit in clinical trials. The MSC is a live cell medicine and interacts with the patient's disease state. Here, we explored this interaction, seeking to devise strategies to enhance MSC therapeutic function.

METHODS

Human bone-marrow-derived MSCs were exposed to lung homogenate from healthy and E. coli-induced ARDS rat models. Apoptosis and functional assays of the MSCs were performed.

RESULTS

The ARDS model showed reduced arterial oxygenation, decreased lung compliance and an inflammatory microenvironment compared to controls. MSCs underwent more apoptosis after stimulation by lung homogenate from controls compared to E. coli, which may explain why MSCs persist longer in ARDS subjects after administration. Changes in expression of cell surface markers and cytokines were associated with lung homogenate from different groups. The anti-microbial effects of MSCs did not change with the stimulation. Moreover, the conditioned media from lung-homogenate-stimulated MSCs inhibited T-cell proliferation.

CONCLUSIONS

These findings suggest that the ARDS microenvironment plays an important role in the MSC's therapeutic mechanism of action, and changes can inform strategies to modulate MSC-based cell therapy for ARDS.

Translational potential of mesenchymal stem cells in regenerative therapies for human diseases: challenges and opportunities

Advances in stem cell technology offer new possibilities for patients with untreated diseases and disorders. Stem cell-based therapy, which includes multipotent mesenchymal stem cells (MSCs), has recently become important in regenerative therapies. MSCs are multipotent progenitor cells that possess the ability to undergo in vitro self-renewal and differentiate into various mesenchymal lineages. MSCs have demonstrated promise in several areas, such as tissue regeneration, immunological modulation, anti-inflammatory qualities, and wound healing. Additionally, the development of specific guidelines and quality control methods that ultimately result in the therapeutic application of MSCs has been made easier by recent advancements in the study of MSC biology. This review discusses the latest clinical uses of MSCs obtained from the umbilical cord (UC), bone marrow (BM), or adipose tissue (AT) in treating various human diseases such as pulmonary dysfunctions, neurological disorders, endocrine/metabolic diseases, skin burns, cardiovascular conditions, and reproductive disorders. Additionally, this review offers comprehensive information regarding the clinical application of targeted therapies utilizing MSCs. It also presents and examines the concept of MSC tissue origin and its potential impact on the function of MSCs in downstream applications. The ultimate aim of this research is to facilitate translational research into clinical applications in regenerative therapies.

Optimizing the connection of CRRT and ECMO lines with additional pressure regulator on the therapeutic effect, filter life, and incidence of complications

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used for severe cardiopulmonary failure, with veno-arterial ECMO for cardiogenic shock and veno-venous ECMO for acute respiratory failure. ECMO's application has expanded to ICUs, emergency departments, and operating rooms. ECMO patients are at high risk for complications, including acute kidney injury (AKI), often requiring renal replacement therapy (RRT), posing significant management challenges.

METHODS

From August 2015 to June 2022, 120 patients were cured with veno-venous ECMO (n = 60) or veno-arterial ECMO (VA-ECMO, n = 60) combined with CRRT in our hospital. In the control group (n = 60), the input end (arterial end) of CRRT was connected to the ECMO oxygenator. The reinfusion end (venous end) of CRRT was connected to the oxygenator of ECMO for CRRT + ECMO treatment. In the experimental group (n = 60), the input end (arterial end) of CRRT was connected to the oxygenator of ECMO, and an additional pressure regulating device was installed on the connection of the 2 lines. The observation indexes including clinical therapeutic effect, clinical therapeutic effect, the incidence of complications, and the incidence of complications were compared.

RESULTS

There was a notable decrease in serum creatinine, and the differences in blood urea nitrogen, procalcitonin, and C-reactive protein after operation were statistically significant (P < .05). The filter use time in the study group was notably longer (P < .01). There exhibited no remarkable difference in the incidences of bleeding, thrombosis, numbness of hands and feet, metabolic alkalosis, disseminated intravascular coagulation, organ dysfunction syndrome, hyperbilirubinemia, and infection.

CONCLUSION

This study demonstrates that additional pressure regulation devices are installed at the line connection between the CRRT input end and the CRRT return end to ensure that the flow rate of ECMO does not affect the CRRT treatment. ECMO and CRRT provide a safe pressure range so that the ECMO line can be safely connected to the CRRT machine at physiological pressure, reducing the occurrence of complications related to CRRT machine interruption and improving the efficiency of CRRT without affecting the efficiency of ECMO, ensuring patient safety.

The MSC-EV-microRNAome: A Perspective on Therapeutic Mechanisms of Action in Sepsis and ARDS

Mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (EVs) have emerged as innovative therapeutic agents for the treatment of sepsis and acute respiratory distress syndrome (ARDS). Although their potential remains undisputed in pre-clinical models, this has yet to be translated to the clinic. In this review, we focused on the role of microRNAs contained in MSC-derived EVs, the EV microRNAome, and their potential contribution to therapeutic mechanisms of action. The evidence that miRNA transfer in MSC-derived EVs has a role in the overall therapeutic effects is compelling. However, several questions remain regarding how to reconcile the stochiometric issue of the low copy numbers of the miRNAs present in the EV particles, how different miRNAs delivered simultaneously interact with their targets within recipient cells, and the best miRNA or combination of miRNAs to use as therapy, potency markers, and biomarkers of efficacy in the clinic. Here, we offer a molecular genetics and systems biology perspective on the function of EV microRNAs, their contribution to mechanisms of action, and their therapeutic potential.

Plasma proteomics-based biomarkers for predicting response to mesenchymal stem cell therapy in severe COVID-19

BACKGROUND

The objective of this study was to identify potential biomarkers for predicting response to MSC therapy by pre-MSC treatment plasma proteomic profile in severe COVID-19 in order to optimize treatment choice.

METHODS

A total of 58 patients selected from our previous RCT cohort were enrolled in this study. MSC responders (n = 35) were defined as whose resolution of lung consolidation ≥ 51.99% (the median value for resolution of lung consolidation) from pre-MSC to 28 days post-MSC treatment, while non-responders (n = 23) were defined as whose resolution of lung consolidation < 51.99%. Plasma before MSC treatment was detected using data-independent acquisition (DIA) proteomics. Multivariate logistic regression analysis was used to identify pre-MSC treatment plasma proteomic biomarkers that might distinguish between responders and non-responders to MSC therapy.

RESULTS

In total, 1101 proteins were identified in plasma. Compared with the non-responders, the responders had three upregulated proteins (CSPG2, CTRB1, and OSCAR) and 10 downregulated proteins (ANXA1, AGRG6, CAPG, DDX55, KV133, LEG10, OXSR1, PICAL, PTGDS, and S100A8) in plasma before MSC treatment. Using logistic regression model, lower levels of DDX55, AGRG6, PICAL, and ANXA1 and higher levels of CTRB1 pre-MSC treatment were predictors of responders to MSC therapy, with AUC of the ROC at 0.910 (95% CI 0.818-1.000) in the training set. In the validation set, AUC of the ROC was 0.767 (95% CI 0.459-1.000).

CONCLUSIONS

The responsiveness to MSC therapy appears to depend on baseline level of DDX55, AGRG6, PICAL, CTRB1, and ANXA1. Clinicians should take these factors into consideration when making decision to initiate MSC therapy in patients with severe COVID-19.

The Influence of Exosomes Derived from Mesenchymal Stem Cells on the Development of Fibrosis In Vitro

We studied the effect of exosomes derived from mesenchymal stem cells on the synthesis of collagen I and α-smooth muscle actin (α-SMA) by rat fibroblast culture. Exosomes were isolated from the verified culture of mesenchymal stem cells and also verified. Fibrosis was modeled using a fibroblast culture supplemented with recombinant TGF-β1 (5 ng/ml) and immunocytochemical analysis of the expression of collagen I and α-SMA markers was carried out. After 6-day incubation, the expression of the studied markers increased in comparison with the control. Addition of exosomes to the fibroblast culture reduced the production of collagen and SMA, which allows considering exosomes as a promising drug for the treatment of pathologies associated with fibrosis.

Biodistribution of mesenchymal stromal cell-derived extracellular vesicles administered during acute lung injury

BACKGROUND

Mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) are a promising cell-free therapy for acute lung injury (ALI). To date, no studies have investigated their biodistribution in ALI or discerned the timing of administration for maximal lung targeting, which are crucial considerations for clinical translation. Our study aimed to characterize a mouse model of ALI and establish the distribution kinetics and optimal timing of MSC-EV delivery during lung injury.

METHODS

MSC-EVs were isolated by ultracentrifugation alone (U/C) or tangential flow filtration with ultracentrifugation (TFF-U/C) and characterized by nanoparticle tracking analysis and western blot. A lipopolysaccharide (LPS)-induced mouse model of ALI was established to study the inflammatory response over 72 h. ALI was assessed by histological lung injury score, bronchoalveolar lavage fluid cell count and inflammatory cytokines. For biodistribution studies, ALI mice were intravenously administered fluorescently labeled MSC-EVs to determine the optimal timing of administration and organ-specific biodistribution. Live in vivo and ex vivo fluorescence imaging was conducted at various timepoints post-EV injection.

RESULTS

EVs isolated by either ultracentrifugation alone or TFF-U/C displayed comparable size distribution (~ 50-350 nm) and EV marker expression (CD63/81). TFF-U/C generated a 5.4-fold higher particle concentration and 3.9-fold higher total protein when compared to ultracentrifugation alone. From the inflammatory time-course study, cell count and IL-1β peaked in bronchoalveolar lavage fluid at 24 h after ALI induction. MSC-EVs delivered at 24 h (as opposed to 0.5 h, 5 h or 10 h) after disease induction resulted in a 2.7-4.4-fold higher lung uptake of EVs. Biodistribution studies comparing organ-specific MSC-EV uptake showed progressive lung accumulation up to 48 h post-delivery (threefold higher than the spleen/liver), with a decline at 72 h. Importantly, lung EV fluorescence at 48 h in ALI mice was significantly elevated as compared to control mice. The lung tropism of MSC-EVs was further validated as therapeutically inert EVs derived from HEK293T cells accumulated mainly to the spleen and liver with a 5.5-fold lower distribution to the lungs as compared to MSC-EVs.

CONCLUSION

MSC-EVs exhibit maximal lung accumulation when administered during heightened inflammation at 24 h after ALI induction. This lung tropism suggests that MSC-EVs may serve as a practical rescue treatment for acute inflammatory respiratory conditions.

Anti-inflammatory therapies for acute respiratory distress syndrome

INTRODUCTION

Treatments for the acute respiratory distress syndrome (ARDS) are mainly supportive, and ventilatory management represents a key approach in these patients. Despite progress in pharmacotherapy, anti-inflammatory strategies for the treatment of ARDS have shown controversial results. Positive outcomes with pharmacologic and nonpharmacologic treatments have been found in two different biological subphenotypes of ARDS, suggesting that, with a personalized medicine approach, pharmacotherapy for ARDS can be effective.

AREAS COVERED

This article reviews the literature concerning anti-inflammatory therapies for ARDS, focusing on pharmacological and stem-cell therapies, including extracellular vesicles.

EXPERT OPINION

Despite advances, ARDS treatments remain primarily supportive. Ventilatory and fluid management are important strategies in these patients that have demonstrated significant impacts on outcome. Anti-inflammatory drugs have shown some benefits, primarily in preclinical research and in specific clinical scenarios, but no recommendations are available from guidelines to support their use in patients with ARDS, except in particular settings such as different subphenotypes, specific etiologies, or clinical trials. Personalized medicine seems promising insofar as it may identify specific subgroups of patients with ARDS who may benefit from anti-inflammatory treatment. However, additional efforts are needed to move subphenotype characterization from bench to bedside.

Functional enhancement strategies to potentiate the therapeutic properties of mesenchymal stromal cells for respiratory diseases

Respiratory diseases remain a major health concern worldwide because they subject patients to considerable financial and psychosocial burdens and result in a high rate of morbidity and mortality. Although significant progress has been made in understanding the underlying pathologic mechanisms of severe respiratory diseases, most therapies are supportive, aiming to mitigate symptoms and slow down their progressive course but cannot improve lung function or reverse tissue remodeling. Mesenchymal stromal cells (MSCs) are at the forefront of the regenerative medicine field due to their unique biomedical potential in promoting immunomodulation, anti-inflammatory, anti-apoptotic and antimicrobial activities, and tissue repair in various experimental models. However, despite several years of preclinical research on MSCs, therapeutic outcomes have fallen far short in early-stage clinical trials for respiratory diseases. This limited efficacy has been associated with several factors, such as reduced MSC homing, survival, and infusion in the late course of lung disease. Accordingly, genetic engineering and preconditioning methods have emerged as functional enhancement strategies to potentiate the therapeutic actions of MSCs and thus achieve better clinical outcomes. This narrative review describes various strategies that have been investigated in the experimental setting to functionally potentiate the therapeutic properties of MSCs for respiratory diseases. These include changes in culture conditions, exposure of MSCs to inflammatory environments, pharmacological agents or other substances, and genetic manipulation for enhanced and sustained expression of genes of interest. Future directions and challenges in efficiently translating MSC research into clinical practice are discussed.

Early effects of bone marrow-derived mononuclear cells on lung and kidney in experimental sepsis

BACKGROUND

In experimental sepsis, functional and morphological effects of bone marrow-derived mononuclear cell (BMDMC) administration in lung tissue have been evaluated 1 and 7 days after therapy. However, to date no study has evaluated the early effects of BMDMCs in both lung and kidney in experimental polymicrobial sepsis.

MATERIAL AND METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: 1) cecal ligation and puncture (CLP)-induced sepsis; and 2) Sham (surgical procedure without CLP). After 1 h, CLP animals received saline (NaCl 0.9%) (CLP-Saline) or 10⁶ BMDMCs (CLP-Cell) via the jugular vein. At 6, 12, and 24 h after saline or BMDMC administration, lungs and kidneys were removed for histology and molecular biology analysis.

RESULTS

In lungs, CLP-Saline, compared to Sham, was associated with increased lung injury score (LIS) and keratinocyte chemoattractant (KC) mRNA expression at 6, 12, and 24 h. BMDMCs were associated with reduced LIS and KC mRNA expression regardless of the time point of analysis. Interleukin (IL)- 10 mRNA content was higher in CLP-Cell than CLP-Saline at 6 and 24 h. In kidney tissue, CLP-Saline, compared to Sham, was associated with tubular cell injury and increased neutrophil gelatinase-associated lipocalin (NGAL) levels, which were reduced after BMDMC therapy at all time points. Surface high-mobility-group-box (HMGB)- 1 levels were higher in CLP-Saline than Sham at 6, 12, and 24 h, whereas nuclear HMGB-1 levels were increased only at 24 h. BMDMCs were associated with decreased surface HMGB-1 and increased nuclear HMGB-1 levels. Kidney injury molecule (KIM)- 1 and IL-18 gene expressions were reduced in CLP-Cell compared to CLP-Saline at 12 and 24 h.

CONCLUSION

In the present experimental polymicrobial sepsis, early intravenous therapy with BMDMCs was able to reduce lung and kidney damage in a time-dependent manner. BMDMCs thus represent a potential therapy in well-known scenarios of sepsis induction.

PURPOSE

To evaluate early bone marrow-derived mononuclear cell (BMDMC) therapy on lung and kidney in experimental polymicrobial sepsis.

METHODS

Twenty-five female C57BL/6 mice were randomly divided into the following groups: cecal ligation and puncture (CLP)-induced sepsis; and sham (surgical procedure without CLP). After 1 h, CLP animals received saline (CLP-saline) or 10⁶ BMDMCs (CLP-cell) via the jugular vein. Lungs and kidneys were evaluated for histology and molecular biology after 6, 12, and 24 h.

RESULTS

In lungs, BMDMCs reduced the lung injury score and keratinocyte chemoattractant mRNA expression regardless of the time point of analysis; interleukin-10 mRNA content was higher in CLP-cell than CLP-saline at 6 and 24 h. In kidneys, BMDMCs reduced neutrophil gelatinase-associated lipocalin levels at all time points. BMDMCs decreased surface high mobility group box (HMGB)- 1 but increased nuclear HMGB-1 levels.

CONCLUSION

Early BMDMC therapy reduced lung and kidney damage in a time-dependent manner.

Stanniocalcin-1 secreted by human umbilical mesenchymal stem cells regulates interleukin-10 expression via the PI3K/AKT/mTOR pathway in alveolar macrophages

Acute respiratory distress syndrome (ARDS) is a syndrome of acute respiratory failure caused by infection, trauma, shock, aspiration or drug reaction. The pathogenesis of ARDS is characterized as an unregulated inflammatory storm, which causes endothelial and epithelial layer damage, leading to alveolar fluid accumulation and pulmonary edema. Previous studies have shown the potential role of mesenchymal stem cells (MSC) in combating the inflammatory cascade by increasing the anti-inflammatory mediator interleukin-10 (IL-10). However, the involved mechanisms are unclear. Here we investigated whether a key immunomodulatory regulator, stanniocalcin-1 (STC-1), was secreted by MSC to activate phosphoinositide 3-kinase/protein kinase B (PI3K/AKT)/ mammalian target of rapamycin (mTOR) signaling pathway to increase IL-10 expression in alveolar macrophages. Lipopolysaccharide (LPS)-stimulated alveolar macrophages co-cultured with human umbilical mesenchymal stem cells (HUMSC) secreted high levels of IL-10. HUMSC co-cultured with alveolar macrophages expressed high STC-1 levels and increased PI3K, AKT and mTOR phosphorylation after LPS activation in alveolar macrophages. STC-1 knockdown in HUMSC decreased the phosphorylation of PI3K, AKT and mTOR and suppressed IL-10 expression in alveolar macrophages. Rapamycin (an mTOR inhibitor) reduced IL-10 secretion in alveolar macrophages. These results, together with our previous study and others, indicate that the PI3K/AKT/mTOR pathway is involved in the regulation of IL-10 production by STC-1 secreted by HUMSC in alveolar macrophages.

A Review of Pathology and Analysis of Approaches to Easing Kidney Disease Impact: Host-Pathogen Communication and Biomedical Visualization Perspective : Advanced Microscopy and Visualization of Host-Pathogen Communication

INTRODUCTION

In addition to affecting the upper respiratory tract, severe acute respiratory syndrome-coronavirus (SARS-CoV) and SARS-CoV-2) can target kidneys resulting in disease impact. There is a lack of effective treatment for SARs-CoV and SARS-CoV-2, and so one approach could be to consider to lower the probable risk and onset of disease amongst immunocompromised and immunosuppressed individuals and patients. Angiotensin Converting Enzyme 2 (ACE2) has a promising impact including acting against SARs-CoV and SARS-CoV-2 symptoms. Current literature states that ACE2 is expressed across several physiological systems, including the lungs, cardiovascular, gut, kidneys, and central nervous, and across endothelia.

AIMS

This chapter seeks to investigate causes and potential mechanisms during SARS infection (CoV-2), renal interaction, and the effects of acute kidney Injury (AKI).

OBJECTIVES

This chapter will provide an overview of microscopy and visualization of host-pathogen communication and principles of ACE2 in the context of immunology and impact on renal pathophysiology.

DESIGN

This chapter focuses to provide basic principles of ACE2 and the analysis and effect of immunology and pathological components important in relation to SARs infection.

DISCUSSION

There has been a surge in literature surrounding mechanisms attributing to SARS-CoV and SARS-CoV-2 action on immune response to pathogens. There is an advantage to implementing ACE2 treatment to improve immune response against infection.

CONCLUSION

ACE2 may provide appropriate strategies for the management of symptoms that relate to SARS-CoV and SARS-CoV-2 in most immunocompromised or immunosuppressed patients. Visualization of ACE2 action can be achieved through microscopy to understand host-pathogen communication.

The Effect of Lipopolysaccharide-Stimulated Adipose-Derived Mesenchymal Stem Cells on NAFLD Treatment in High-Fat Diet-Fed Rats

Background

Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are 2 common liver diseases that currently lack effective treatment options.

Objectives

This study aimed to investigate the effect of lipopolysaccharide (LPS)-stimulated adipose-derived stem cells (ADSCs) on NAFLD treatment in an animal model.

Methods

Male Wistar rats were fed a high-fat diet (HFD) to induce NAFLD for 7 weeks. The rats were then categorized into 3 groups: Mesenchymal stem cell (MSC), MSC + LPS, and fenofibrate (FENO) groups. Liver and body weight were measured, and the expression of genes involved in fatty acid biosynthesis, β-oxidation, and inflammatory responses was assessed.

Results

Lipopolysaccharide-stimulated ADSCs were more effective in regulating liver and body weight gain and reducing liver triglyceride (TG) levels compared to the other groups. Treatment with LPS-stimulated ADSCs effectively corrected liver enzymes, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and lipid factors, including low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) values, better than treatment with both FENO and MSCs. ADSCs + LPS treatment significantly decreased transforming growth factor β (TGF-β) and genes associated with inflammatory responses. Additionally, there was a significant reduction in reactive oxygen species (ROS) levels in the rats treated with ADSCs + LPS.

Conclusions

Lipopolysaccharide-stimulated ADSCs showed potential in alleviating NAFLD by reducing inflammatory genes and ROS levels in HFD rats, demonstrating better results than treatment with ADSCs and FENO groups alone.

Proteomics profile of mesenchymal stromal cells and extracellular vesicles in normoxic and hypoxic conditions

BACKGROUND AIMS

Although bone marrow-derived mesenchymal stromal cells (MSCs) have demonstrated success in pre-clinical studies, they have shown only mild therapeutic effects in clinical trials. Hypoxia pre-conditioning may optimize the performance of bone marrow-derived MSCs because it better reflects the physiological conditions of their origin. It is not known whether changes in the protein profile caused by hypoxia in MSCs can be extended to the extracellular vesicles (EVs) released from them. The aim of this study was to evaluate the proteomics profile of MSCs and their EVs under normoxic and hypoxic conditions.

METHODS

Bone marrow-derived MSCs were isolated from six healthy male Wistar rats. After achieving 80% confluence, MSCs were subjected to normoxia (MSC-Norm) (21% oxygen, 5% carbon dioxide, 74% nitrogen) or hypoxia (MSC-Hyp) (1% oxygen, 5% carbon dioxide, 94% nitrogen) for 48 h. Cell viability and oxygen consumption rate were assessed. EVs were extracted from MSCs for each condition (EV-Norm and EV-Hyp) by ultracentrifugation. Total proteins were isolated from MSCs and EVs and prepared for mass spectrometry. EVs were characterized by nanoparticle tracking analysis. Proteomics data were analyzed by PatternLab 4.0, Search Tool for the Retrieval of Interacting Genes/Proteins, Gene Ontology, MetaboAnalyst and Reactome software.

RESULTS

Cell viability was higher in MSC-Hyp than MSC-Norm (P = 0.007). Basal respiration (P = 0.001), proton leak (P = 0.004) and maximal respiration (P = 0.014) were lower in MSC-Hyp than MSC-Norm, and no changes in adenosine triphosphate-linked and residual respiration were observed. The authors detected 2177 proteins in MSC-Hyp and MSC-Norm, of which 147 were identified in only MSC-Hyp and 512 were identified in only MSC-Norm. Furthermore, 718 proteins were identified in EV-Hyp and EV-Norm, of which 293 were detected in only EV-Hyp and 30 were detected in only EV-Norm. Both MSC-Hyp and EV-Hyp showed enrichment of pathways and biological processes related to glycolysis, the immune system and extracellular matrix organization.

CONCLUSIONS

MSCs subjected to hypoxia showed changes in their survival and metabolic activity. In addition, MSCs under hypoxia released more EVs, and their content was related to expression of regulatory proteins of the immune system and extracellular matrix organization. Because of the upregulation of proteins involved in glycolysis, gluconeogenesis and glucose uptake during hypoxia, production of reactive oxygen species and expression of immunosuppressive properties may be affected.

A Comprehensive Review on the Efficacy of Several Pharmacologic Agents for the Treatment of COVID-19

SARS-CoV-2, the coronavirus disease-2019 (COVID-19), and the cause of the pandemic is extremely contagious among people and has spread around the world. Antivirals, immunomodulators, and other medications, such as antibiotics, stem cells, and plasma therapy, have all been utilized in the treatment of COVID-19. To better understand the clinical efficacy of these agents and to aid in the selection of effective COVID-19 therapies in various countries, this study reviewed the effectiveness of the various pharmacologic agents that have been used for COVID-19 therapy globally by summarizing the clinical outcomes that have been obtained from the clinical trials published on each drug related to COVID-19 infection. The Food and Drug Administration (FDA) has authorized the use of remdesivir, paxlovid, molnupiravir, baricitinib, tixagevimab-cilgavimab, and bebtelovimab for the management of COVID-19. On the other hand, most research advises against using chloroquine and hydroxychloroquine to treat COVID-19 patients because they are not beneficial. Although the FDA has given emergency use authorization for some monoclonal antibodies, including bamlanivimab, etesevimab, casirivimab, and imdevimab for managing COVID-19, they are not currently approved for use because the Omicron variant has significantly reduced their in vitro susceptibility. In this study, we also included a wide range of alternative therapy strategies that effectively treat COVID-19 patients, although further randomized studies are necessary to support and assess their applicability.

Extracellular Vesicles Derived from Mesenchymal Stem Cells: A Potential Biodrug for Acute Respiratory Distress Syndrome Treatment

Acute respiratory distress syndrome (ARDS) is a severe respiratory disease associated with high morbidity and mortality in the clinic. In the face of limited treatment options for ARDS, extracellular vesicles derived from mesenchymal stem cells (MSC-EVs) have recently shown promise. They regulate levels of growth factors, cytokines, and other internal therapeutic molecules. The possible therapeutic mechanisms of MSC-EVs include anti-inflammatory, cell injury repair, alveolar fluid clearance, and microbe clearance. The potent therapeutic ability and biocompatibility of MSC-EVs have enabled them as an alternative option to ameliorate ARDS. In this review, recent advances, therapeutic mechanisms, advantages and limitations, as well as improvements of using MSC-EVs to treat ARDS are summarized. This review is expected to provide a brief view of the potential applications of MSC-EVs as novel biodrugs to treat ARDS.

Bone Marrow-Derived Mesenchymal Stromal Cell Therapy in Severe COVID-19: Preliminary Results of a Phase I/II Clinical Trial

Background

Treatment of acute respiratory distress syndrome (ARDS) associated with COronaVIrus Disease-2019 (COVID-19) currently relies on dexamethasone and supportive mechanical ventilation, and remains associated with high mortality. Given their ability to limit inflammation, induce immune cells into a regulatory phenotype and stimulate tissue repair, mesenchymal stromal cells (MSCs) represent a promising therapy for severe and critical COVID-19 disease, which is associated with an uncontrolled immune-mediated inflammatory response.

Methods

In this phase I-II trial, we aimed to evaluate the safety and efficacy of 3 intravenous infusions of bone marrow (BM)-derived MSCs at 3-day intervals in patients with severe COVID-19. All patients also received dexamethasone and standard supportive therapy. Between June 2020 and September 2021, 8 intensive care unit patients requiring supplemental oxygen (high-flow nasal oxygen in 7 patients, invasive mechanical ventilation in 1 patient) were treated with BM-MSCs. We retrospectively compared the outcomes of these MSC-treated patients with those of 24 matched control patients. Groups were compared by paired statistical tests.

Results

MSC infusions were well tolerated, and no adverse effect related to MSC infusions were reported (one patient had an ischemic stroke related to aortic endocarditis). Overall, 3 patients required invasive mechanical ventilation, including one who required extracorporeal membrane oxygenation, but all patients ultimately had a favorable outcome. Survival was significantly higher in the MSC group, both at 28 and 60 days (100% vs 79.2%, p = 0.025 and 100% vs 70.8%, p = 0.0082, respectively), while no significant difference was observed in the need for mechanical ventilation nor in the number of invasive ventilation-free days, high flow nasal oxygenation-free days, oxygen support-free days and ICU-free days. MSC-treated patients also had a significantly lower day-7 D-dimer value compared to control patients (median 821.0 µg/L [IQR 362.0-1305.0] vs 3553 µg/L [IQR 1155.0-6433.5], p = 0.0085).

Conclusions

BM-MSC therapy is safe and shows very promising efficacy in severe COVID-19, with a higher survival in our MSC cohort compared to matched control patients. These observations need to be confirmed in a randomized controlled trial designed to demonstrate the efficacy of BM-MSCs in COVID-19 ARDS.

Clinical Trial Registration

(www.ClinicalTrials.gov), identifier NCT04445454

Human Placental Mesenchymal Stem Cells for the Treatment of ARDS in Rat

The acute respiratory distress syndrome (ARDS) is one of the main causes of high mortality in patients with coronavirus (COVID-19). In recent years, due to the coronavirus pandemic, the number of patients with ARDS has increased significantly. Unfortunately, until now, there are no effective treatments for ARDS caused by COVID-19. Many drugs are either ineffective or have a low effect. Currently, there have been reports of efficient use of mesenchymal stem cells (MSCs) for the treatment of ARDS caused by COVID-19. We investigated the influence of freeze-dried human placenta-derived mesenchymal stem cells (HPMSCs) in ARDS rat model. All animals have received intratracheal injection of 6 mg/kg of lipopolysaccharide (LPS). The rats were randomly divided into five groups: I: LPS, II: LPS+dexamethasone, III: LPS+HPMSCs, IV: HPMSC, and V: saline. ARDS observation time was short-term and amounted to 168 hours. The study has shown that HPMSCs are able to migrate and attach to damaged lung tissue, contributing to the resolution of pathology, restoration of function, and tissue repair in the alveolar space. Studies have also shown that the administration of HPMSCs in animals with ARDS model significantly reduced the levels of key cytokines such as IL-1β, IL-6, and TNF-α. Freeze-dried placental stem cell is a very promising biomaterial for the treatment of ARDS. The human placenta can be easily obtained because it is considered as a medical waste. At the same time, a huge number of MSCs can be obtained from the placental tissue, and there is no ethical controversy around their use. The freeze-dried MSCs from human placental tissue can be stored sterile at room temperature for a long time before use.

Therapeutic Effects of Human Pluripotent Stem Cell-Derived Mesenchymal Stem Cells on a Murine Model of Acute Type-2-Dominated Airway Inflammation

Allergic rhinitis and allergic asthma are the most common type-2 inflammatory diseases, which are hardly curable and cause heavy burden to general well-being. Mesenchymal stem cells (MSCs) are multipotent nonhematopoietic cells with potential immunomodulatory effects that have been showning to have a therapeutic effect on allergic diseases. Here, we investigated the effects of human induced pluripotent stem cell (iPSC)-derived MSCs on airway hyperresponsiveness and acute type-2-dominated inflammation throughout the upper and lower airways. In this study, human MSCs, MSC cell culture supernatant, and culture medium (control) was injected into the acute airway inflammatory model via the tail vein. Mouse behavioristics were recorded immediately and mouse lung function was measured 24 hours after the last ovalbumin (OVA) challenge. Histological staining, Luminex, Elisa and flow cytometry were employed to evaluate the effects on the production of total/OVA-specific IgG1 and IgE, cytokines expression in lung tissues, and inflammatory cells infiltration in the lung and spleen of the experimental mice. Expressions of eotaxin, IL-4, IL-5, IL-13, IL-33 in nasal and lung lavage were evaluated by Luminex and Elisa. We found that for this acute inflammatory mouse model, human MSC transplantation significantly mitigated the decreased motoring time and the increased lung function Rrs caused by OVA challenge. Serum OVA-IgG1, OVA-IgE, and eosinophil percentages in the splenocytes were significantly decreased. Injection of the MSC supernatant also showed the same trend, but not significantly changed. After treatment, IL-4 and IL-13 were significantly decreased in the lung tissue, and IL-5 and IL-13 were significantly decreased in lung lavage. In conclusion, both human MSC culture supernatant and cell transplantation could alleviate AHR and inflammation in acute inflammatory experimental animals, which demonstrated their potential for clinical therapeutics. Human iPSC-MSCs, MSC cell culture supernatant, or culture medium (control) was injected into the OVA-induced acute airway inflammatory model via the tail vein. Behavioral changes, AHR, serum OVA-specific IgG1 and IgE concentrations, and type-2 inflammations were alleviated.

Safety and long-term improvement of mesenchymal stromal cell infusion in critically COVID-19 patients: a randomized clinical trial

BACKGROUND

COVID-19 is a multisystem disease that presents acute and persistent symptoms, the postacute sequelae (PASC). Long-term symptoms may be due to consequences from organ or tissue injury caused by SARS-CoV-2, associated clotting or inflammatory processes during acute COVID-19. Various strategies are being chosen by clinicians to prevent severe cases of COVID-19; however, a single treatment would not be efficient in treating such a complex disease. Mesenchymal stromal cells (MSCs) are known for their immunomodulatory properties and regeneration ability; therefore, they are a promising tool for treating disorders involving immune dysregulation and extensive tissue damage, as is the case with COVID-19. This study aimed to assess the safety and explore the long-term efficacy of three intravenous doses of UC-MSCs (umbilical cord MSCs) as an adjunctive therapy in the recovery and postacute sequelae reduction caused by COVID-19. To our knowledge, this is one of the few reports that presents the longest follow-up after MSC treatment in COVID-19 patients.

METHODS

This was a phase I/II, prospective, single-center, randomized, double-blind, placebo-controlled clinical trial. Seventeen patients diagnosed with COVID-19 who require intensive care surveillance and invasive mechanical ventilation-critically ill patients-were included. The patient infusion was three doses of 5 × 105 cells/kg UC-MSCs, with a dosing interval of 48 h (n = 11) or placebo (n = 6). The evaluations consisted of a clinical assessment, viral load, laboratory testing, including blood count, serologic, biochemical, cell subpopulation, cytokines and CT scan.

RESULTS

The results revealed that in the UC-MSC group, there was a reduction in the levels of ferritin, IL-6 and MCP1-CCL2 on the fourteen day. In the second month, a decrease in the levels of reactive C-protein, D-dimer and neutrophils and an increase in the numbers of TCD3, TCD4 and NK lymphocytes were observed. A decrease in extension of lung damage was observed at the fourth month. The improvement in all these parameters was maintained until the end of patient follow-up.

CONCLUSIONS

UC-MSCs infusion is safe and can play an important role as an adjunctive therapy, both in the early stages, preventing severe complications and in the chronic phase with postacute sequelae reduction in critically ill COVID-19 patients. Trial registration Brazilian Registry of Clinical Trials (ReBEC), UTN code-U1111-1254-9819. Registered 31 October 2020-Retrospectively registered, https://ensaiosclinicos.gov.br/rg/RBR-3fz9yr.

Mesenchymal stem cell treatment for COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has caused a global pandemic since late 2019 that resulted in more than 360 million population infection. Among them, less than 7% of infected individuals develop severe or critical illness. Mass vaccination has been carried out, but reinfection and vaccine breakthrough cases still occur. Besides supportive and antiviral medications, much attention has been paid in immunotherapies that aim at reducing pathological changes in the lungs. Mesenchymal stem cells (MSCs) is used as an option because of their immunomodulatory, anti-inflammatory, and regenerative properties. As of January 16, 2022, when ClinicalTrials.gov was searched for "Mesenchymal stem cells and COVID-19," over 80 clinical trials were registered. MSC therapy was found to be safe and some effective in preclinical and clinical studies. Here, we summarize the major pathological characteristics of COVID-19 and provide scientific and rational evidence for the safety and possible effectiveness of MSCs in COVID-19 treatment.

Safety and efficacy study of allogeneic human menstrual blood stromal cells secretome to treat severe COVID-19 patients: clinical trial phase I & II

BACKGROUND

Cell-free Mesenchymal stromal cells (MSCs) have been considered due to their capacity to modulate the immune system and suppress cytokine storms caused by SARS-CoV-2. This prospective randomized double-blind placebo-controlled clinical trial aimed to assess the safety and efficacy of secretome derived from allogeneic menstrual blood stromal cells (MenSCs) as a treatment in patients with severe COVID-19.

METHODS

Patients with severe COVID-19 were randomized (1:1) to either MenSC-derived secretome treatment or the control group. Subjects received five intravenous infusions of 5 mL secretome or the same volume of placebo for five days and were monitored for safety and efficacy for 28 days after treatment. Adverse events, laboratory parameters, duration of hospitalization, clinical symptom improvement, dynamic of O₂ saturation, lymphocyte number, and serial chest imaging were analyzed.

RESULTS

All safety endpoints were observed without adverse events after 72 h of secretome injection. Within 28 days after enrollment, 7 patients (50%) were intubated in the treated group versus 12 patients (80%) in the control group. Overall, 64% of patients had improved oxygen levels within 5 days of starting treatment (P < 0.0001) and there was a survival rate of 57% in the treatment group compared to 28% in the control group was (P < 0.0001). Laboratory values revealed that significant acute phase reactants declined, with mean C-reactive protein, ferritin, and D-dimer reduction of 77% (P < 0.001), 43% (P < 0.001), and 42% (P < 0.05), respectively. Significant improvement in lymphopenia was associated with an increase in mean CD4⁺ and CD8⁺ lymphocyte counts of 20% (P = 0.06) and 15% (P < 0.05), respectively. Following treatment, percentage of pulmonary involvement showed a significant improvement in the secretome group (P < 0.0001). This improvement differed significantly between survivors and those who were dying (P < 0.005).

CONCLUSIONS

For the first time, this study demonstrated that in hospitalized patients with severe COVID-19, therapy with MenSCs-derived secretome leads to reversal of hypoxia, immune reconstitution, and downregulation of cytokine storm, with no adverse effects attributable to the treatment. Given these outcomes, it may be possible to use this type of treatment for serious inflammatory lung disease with a mechanism similar to COVID-19 in the future. However, it is necessary to evaluate the safety and efficacy of MenSCs-derived secretome therapy in clinical trials on a larger population of patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05019287. Registered 24AGUEST 2021, retrospectively registered, https://clinicaltrials.gov/ct2/show/record/NCT05019287 . IRCT, IRCT20180619040147N6. Registered 04/01/2021.

Clinical efficacy and mechanism of mesenchymal stromal cells in treatment of COVID-19

Coronavirus disease 2019 (COVID-19) is a highly infectious epidemic disease that has seriously affected human health worldwide. To date, however, there is still no definitive drug for the treatment of COVID-19. Cell-based therapies could represent a new breakthrough. Over the past several decades, mesenchymal stromal cells (MSCs) have proven to be ideal candidates for the treatment of many viral infectious diseases due to their immunomodulatory and tissue repair or regeneration promoting properties, and several relevant clinical trials for the treatment of COVID-19 have been registered internationally. Herein, we systematically summarize the clinical efficacy of MSCs in the treatment of COVID-19 based on published results, including mortality, time to symptom improvement, computed tomography (CT) imaging, cytokines, and safety, while elaborating on the possible mechanisms underpinning the effects of MSCs, to provide a reference for subsequent studies.

Stem cells or their exosomes: which is preferred in COVID-19 treatment?

It only took 8 months for the pneumonia caused by a previously unknown coronavirus to turn into a global pandemic of unprecedentedly far-reaching implications. Failure of the already discovered treatment measures opened up a new opportunity to evaluate the potentials of mesenchymal stem cells and their extracellular vesicles (EVs), exosomes in particular. Eventually, the initial success experienced after the use of MSCs in treating the new pneumonia by Lnge and his team backed up the idea of MSC-based therapies and pushed them closer to becoming a reality. However, MSC-related concerns regarding safety such as abnormal differentiation, spontaneous malignant and the formation of ectopic tissues have triggered the replacement of MSCs by their secreted exosomes. The issue has been further strengthened by the fact that the exosomes leave similar treatment impacts when compared to their parental cells. In recent years, much attention has been paid to the use of MSC-derived exosomes in the treatment of a variety of diseases. With a primary focus on COVID-19 and its current treatment methods, the present review looks into the potentials of MSCs and MSC-derived exosomes in battling the ongoing pandemic. Finally, the research will draw an analogy between exosomes and their parental cells, when it comes to the progresses and challenges in using exosomes as a large-scale treatment method.

Stem cell-derived biofactors fight against coronavirus infection

Despite various treatment protocols and newly recognized therapeutics, there are no effective treatment approaches against coronavirus disease. New therapeutic strategies including the use of stem cells-derived secretome as a cell-free therapy have been recommended for patients with critical illness. The pro-regenerative, pro-angiogenic, anti-inflammatory, anti-apoptotic, immunomodulatory, and trophic properties of stem cells-derived secretome, extracellular vesicles (EVs), and bioactive factors have made them suitable candidates for respiratory tract regeneration in coronavirus disease 2019 (COVID-19) patients. EVs including microvesicles and exosomes can be applied for communication at the intercellular level due to their abilities in the long-distance transfer of biological messages such as mRNAs, growth factors, transcription factors, microRNAs, and cytokines, and therefore, simulate the specifications of the parent cell, influencing target cells upon internalization and/or binding. EVs exhibit both anti-inflammatory and tolerogenic immune responses by regulation of proliferation, polarization, activation, and migration of different immune cells. Due to effective immunomodulatory and high safety including a minimum risk of immunogenicity and tumorigenicity, mesenchymal stem cell (MSC)-EVs are more preferable to MSC-based therapies. Thus, as an endogenous repair and inflammation-reducing agent, MSC-EVs could be used against COVID-19 induced morbidity and mortality after further mechanistic and preclinical/clinical investigations. This review is focused on the therapeutic perspective of the secretome of stem cells in alleviating the cytokine storm and organ injury in COVID-19 patients.

Mesenchymal stem cell therapy for COVID-19

The coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) started in December 2019 and affected the whole world in a short time. The course of the disease depends on the person's immune system, physical properties, health status, etc. as it varies according to its characteristics while it is asymptomatic in some people, it causes fatal processes that start with flu-like symptoms such as cough, fever, respiratory distress in some people and progress to acute respiratory distress syndrome (ARDS), severe pneumonia and multi-organ dysfunction, and the basic mechanism underlying these effects known as a cytokine storm. There is no specific effective antiviral drug or vaccine in treatment yet. Supportive/alternative treatment methods are needed as both the desired effect cannot be achieved and undesirable side effects are seen with the current treatments used in the clinic. Mesenchymal stem cells (MSCs) are frequently preferred recently from basic studies to clinical studies and are effective and safe in immune-mediated inflammatory diseases such as Systemic Lupus Erythematosus, Graft-versus-Host disease. MSCs can secrete many types of cytokines through paracrine secretion or directly interact with immune cells leading to immunomodulation. According to the results of the completed studies; it has been stated that the cytokine storm caused by the overstimulation of the immune system decreases and even damage of the cytokine storm on organs decreases, respiratory distress is relieved and contributes to the healing process by repairing damaged tissues. In this review, clinical trials completed/ongoing on MSCs recommended for treating COVID-19, a global problem, are reviewed and the review is prepared to specify the existence of such a route to clinicians.

Identification and characterization of pulmonary mesenchymal stem cells derived from rat fetal lung tissue

Pulmonary mesenchymal stem cells (PMSCs) have great potential in lung tissue repair and regeneration, which have been isolated from some mammalian species, including mice, bovine and pig. However, the isolation, characteristics and differentiation potential of rat PMSCs have not been reported. In this study, we successfully isolated PMSCs from Sprague-Dawley rat fetal lung tissue in vitro for the first time and attempted to evaluate its multilineage differentiation potentials. The cultured PMSCs showed typical spindle-shaped morphology and high proliferative potential, and could be passaged for at least 13 passages and maintained high hereditary stability with more than 93.6 % of cells were diploid (2n = 42) by G-banding analysis. Furthermore, the PMSCs could express mesenchymal markers Sca-1, CD29, CD44, CD73 and CD90, but not hematopoietic markers CD34 and CD45. Besides, the expression of cell markers of AT2 (SFTPC), AT1 (PDPN) and macrophage (CD11b) were also negative. Cell cycle examination revealed majority of the PMSCs were in G0/G1 phase, which are similar with previously reported pig PMSCs. In addition, the PMSCs were multipotent and could differentiated into osteocytes, adipocytes, hepatocytes and neurons in vitro. Together, the present study demonstrated the stemness and multi-differentiation potentials of rat PMSCs, which conferred a potential regenerative cell resource for cell regenerative therapy of lung injury.

The Potential of Mesenchymal Stem Cells for the Treatment of Cytokine Storm due to COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has seriously affected public health and social stability. The main route of the transmission is droplet transmission, where the oral cavity is the most important entry point to the body. Due to both the direct harmful effects of SARS-CoV-2 and disordered immune responses, some COVID-19 patients may progress to acute respiratory distress syndrome or even multiple organ failure. Genetic variants of SARS-CoV-2 have been emerging and circulating around the world. Currently, there is no internationally approved precise treatment for COVID-19. Mesenchymal stem cells (MSCs) can traffic and migrate towards the affected tissue, regulate both the innate and acquired immune systems, and participate in the process of healing. Here, we will discuss and investigate the mechanisms of immune disorder in COVID-19 and the therapeutic activity of MSCs, in particular human gingiva mesenchymal stem cells.

Astrocytes Downregulate Inflammation in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome: Applicability to COVID-19

Background: An acute respiratory distress syndrome (ARDS) is caused by the increased amounts of pro-inflammatory cytokines and neutrophil-mediated tissue injury. To date, there is no effective treatment for the ARDS available, while the need for one is growing due to the most severe complications of the current coronavirus disease-2019 (COVID-19) pandemic. The human astrocytes (AstroRx) have shown immunomodulatory properties in the central nervous system (CNS). This study aimed to evaluate the capacity of astrocytes to decrease lung inflammation and to be applied as a treatment therapy in ARDS.

Methods: First, we assessed the ability of clinical-grade AstroRx to suppress T-cell proliferation in a mixed lymphocyte reaction test. Next, we tested the therapeutical potential of AstroRx cells in a lipopolysaccharide (LPS)-based ARDS mouse model by injecting AstroRx intravenously (i.v). We determined the degree of lung injury by using a severity scoring scale of 0–2, based on the American Thoracic Society. The scoring measured the presence of neutrophils, fibrin deposits, and the thickening of alveolar walls. The state of inflammation was further assessed by quantifying the immune-cell infiltration to the bronchoalveolar lavage fluid (BALF) and by the presence of proinflammatory cytokines and chemokines in the BALF and serum.

Results: We detected that AstroRx cells were capable to suppress T-cell proliferation in vitro after exposure to the mitogen concanavalin A (ConA). In vivo, AstroRx cells were able to lower the degree of lung injury in LPS-treated animals compared with the sham injected animals (P = 0.039). In this study, 30% of AstroRx treated mice showed no lung lesions (responder mice), these mice presented a steady number of eosinophils, T cells, and neutrophils comparable with the level of naïve control mice. The inflammatory cytokines and chemokines, such as TNFα, IL1b, IL-6, and CXCL1, were also kept in check in responder AstroRx-treated mice and were not upregulated as in the sham-injected mice (P < 0.05). As a result, the LPS-treated ARDS mice had a higher survival rate when they were treated with AstroRx.

Conclusions: Our results demonstrate that the immunosuppressive activity of AstroRx cells support the application of AstroRx cells as a cell therapy treatment for ARDS. The immunoregulatory activity may also be a part of the mechanism of action of AstroRx reported in the amyotrophic lateral sclerosis (ALS) neurodegenerative disease.

Mesenchymal Stromal Cells: Potential Option for COVID-19 Treatment

The COVID-19 pandemic has significantly impacted the way of life worldwide and continues to bring high mortality rates to at-risk groups. Patients who develop severe COVID-19 pneumonia, often complicated with ARDS, are left with limited treatment options with no targeted therapy currently available. One of the features of COVID-19 is an overaggressive immune reaction that leads to multiorgan failure. Mesenchymal stromal cell (MSC) treatment has been in development for various clinical indications for over a decade, with a safe side effect profile and promising results in preclinical and clinical trials. Therefore, the use of MSCs in COVID-19-induced respiratory failure and ARDS was a logical step in order to find a potential treatment option for the most severe patients. In this review, the main characteristics of MSCs, their proposed mechanism of action in COVID-19 treatment and the effect of this therapy in published case reports and clinical trials are discussed.

Mitochondria-Rich Fraction Isolated From Mesenchymal Stromal Cells Reduces Lung and Distal Organ Injury in Experimental Sepsis

OBJECTIVES

To ascertain whether systemic administration of mitochondria-rich fraction isolated from mesenchymal stromal cells would reduce lung, kidney, and liver injury in experimental sepsis.

DESIGN

Animal study.

SETTING

Laboratory investigation.

SUBJECTS

Sixty C57BL/6 male mice.

INTERVENTIONS

Sepsis was induced by cecal ligation and puncture; sham-operated animals were used as control. At 24 hours after surgery, cecal ligation and puncture and Sham animals were further randomized to receive saline or mitochondria-rich fraction isolated from mesenchymal stromal cells (3 × 106) IV. At 48 hours, survival, peritoneal bacterial load, lung, kidney, and liver injury were analyzed. Furthermore, the effects of mitochondria on oxygen consumption rate and reactive oxygen species production of lung epithelial and endothelial cells were evaluated in vitro.

MEASUREMENTS AND MAIN RESULTS

In vitro exposure of lung epithelial and endothelial cells from cecal ligation and puncture animals to mitochondria-rich fraction isolated from mesenchymal stromal cells restored oxygen consumption rate and reduced total reactive oxygen species production. Infusion of exogenous mitochondria-rich fraction from mesenchymal stromal cells (mitotherapy) reduced peritoneal bacterial load, improved lung mechanics and histology, and decreased the expression of interleukin-1β, keratinocyte chemoattractant, indoleamine 2,3-dioxygenase-2, and programmed cell death protein 1 in lung tissue, while increasing keratinocyte growth factor expression and survival rate in cecal ligation and puncture-induced sepsis. Mitotherapy also reduced kidney and liver injury, plasma creatinine levels, and messenger RNA expressions of interleukin-18 in kidney, interleukin-6, indoleamine 2,3-dioxygenase-2, and programmed cell death protein 1 in liver, while increasing nuclear factor erythroid 2-related factor-2 and superoxide dismutase-2 in kidney and interleukin-10 in liver.

CONCLUSIONS

Mitotherapy decreased lung, liver, and kidney injury and increased survival rate in cecal ligation and puncture-induced sepsis.

Current therapeutic strategies for respiratory diseases using mesenchymal stem cells

Mesenchymal stromal/stem cells (MSCs) have a great potential to proliferate, undergo multi-directional differentiation, and exert immunoregulatory effects. There is already much enthusiasm for their therapeutic potentials for respiratory inflammatory diseases. Although the mechanism of MSCs-based therapy has been well explored, only a few articles have summarized the key advances in this field. We hereby provide a review over the latest progresses made on the MSCs-based therapies for four types of inflammatory respiratory diseases, including idiopathic pulmonary fibrosis, acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, and the uncovery of their underlying mechanisms from the perspective of biological characteristics and functions. Furthermore, we have also discussed the advantages and disadvantages of the MSCs-based therapies and prospects for their optimization.

Overexpression of HOXB4 Promotes Protection of Bone Marrow Mesenchymal Stem Cells Against Lipopolysaccharide-Induced Acute Lung Injury Partially Through the Activation of Wnt/β-Catenin Signaling

Purpose

Pulmonary vascular endothelial cell (EC) injury is recognized as one of the pathological factors of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). Bone marrow mesenchymal stem cell (BMSC)-based cytotherapy has attracted substantial attention over recent years as a promising therapeutic approach for ALI/ARDS; however, its use remains limited due to inconsistent efficacy. Currently, gene modification techniques are widely applied to MSCs. In the present study, we aimed to investigate the effect of BMSCs overexpressing Homeobox B4 (HOXB4) on lipopolysaccharide (LPS)-induced EC injury.

Methods

We used LPS to induce EC injury and established EC-BMSC coculture system using transwell chambers. The effect of BMSCs on ECs was explored by detecting EC proliferation, apoptosis, migration, tube formation, and permeability, and determining whether the Wnt/β-catenin pathway is involved in the regulatory mechanism using XAV-939, inhibitor of Wnt/ β-catenin.

Results

As compared to BMSC^WT, BMSC^HOXB4 coculture promoted EC proliferation, migration, and tube formation after LPS stimulation and attenuated LPS-induced EC apoptosis and vascular permeability. Mechanistically, BMSC^HOXB4 coculture prevented LPS-induced EC injury by activating the Wnt/β-catenin pathway, which is partially reversible by XAV-939. When cocultured with BMSC^HOXB4, pro-inflammatory factors were dramatically decreased and anti-inflammatory factors were greatly increased in the EC medium compared to those in the LPS group (P<0.05). Additionally, when compared to BMSC^WT coculture, the BMSC^HOXB4 coculture showed an enhanced modulation of IL-6, TNF-α, and IL-10, but there was no statistically significant effect on IL-1β and IL-4.

Conclusion

Coculturing of BMSC^HOXB4 prevented LPS-induced EC injury by reversing the inactivation of the Wnt/β-catenin signaling pathway. An in vivo study remains warranted to ascertain whether engraftment of BMSC^HOXB4 can be an attractive strategy for the treatment of ALI/ARDS.

Is there a place for mesenchymal stromal cell-based therapies in the therapeutic armamentarium against COVID-19?

The COVID-19 pandemic, caused by the rapid global spread of the novel coronavirus (SARS-CoV-2), has caused healthcare systems to collapse and led to hundreds of thousands of deaths. The clinical spectrum of COVID-19 is not only limited to local pneumonia but also represents multiple organ involvement, with potential for systemic complications. One year after the pandemic, pathophysiological knowledge has evolved, and many therapeutic advances have occurred, but mortality rates are still elevated in severe/critical COVID-19 cases. Mesenchymal stromal cells (MSCs) can exert immunomodulatory, antiviral, and pro-regenerative paracrine/endocrine actions and are therefore promising candidates for MSC-based therapies. In this review, we discuss the rationale for MSC-based therapies based on currently available preclinical and clinical evidence of safety, potential efficacy, and mechanisms of action. Finally, we present a critical analysis of the risks, limitations, challenges, and opportunities that place MSC-based products as a therapeutic strategy that may complement the current arsenal against COVID-19 and reduce the pandemic's unmet medical needs.

Mesenchymal Stromal Cells From Emphysematous Donors and Their Extracellular Vesicles Are Unable to Reverse Cardiorespiratory Dysfunction in Experimental Severe Emphysema

Although bone marrow-derived mesenchymal stromal cells (BM-MSCs) from patients with chronic obstructive pulmonary disease (COPD) appear to be phenotypically and functionally similar to BM-MSCs from healthy sources in vitro, the impact of COPD on MSC metabolism and mitochondrial function has not been evaluated. In this study, we aimed to comparatively characterize MSCs from healthy and emphysematous donors (H-MSCs and E-MSCs) in vitro and to assess the therapeutic potential of these MSCs and their extracellular vesicles (H-EVs and E-EVs) in an in vivo model of severe emphysema. For this purpose, C57BL/6 mice received intratracheal porcine pancreatic elastase once weekly for 4 weeks to induce emphysema; control animals received saline under the same protocol. Twenty-four hours after the last instillation, animals received saline, H-MSCs, E-MSCs, H-EVs, or E-EVs intravenously. In vitro characterization demonstrated that E-MSCs present downregulation of anti-inflammatory (TSG-6, VEGF, TGF-β, and HGF) and anti-oxidant (CAT, SOD, Nrf2, and GSH) genes, and their EVs had larger median diameter and lower average concentration. Compared with H-MSC, E-MSC mitochondria also exhibited a higher respiration rate, were morphologically elongated, expressed less dynamin-related protein-1, and produced more superoxide. When co-cultured with alveolar macrophages, both H-MSCs and E-MSCs induced an increase in iNOS and arginase-1 levels, but only H-MSCs and their EVs were able to enhance IL-10 levels. In vivo, emphysematous mice treated with E-MSCs or E-EVs demonstrated no amelioration in cardiorespiratory dysfunction. On the other hand, H-EVs, but not H-MSCs, were able to reduce the neutrophil count, the mean linear intercept, and IL-1β and TGF-β levels in lung tissue, as well as reduce pulmonary arterial hypertension and increase the right ventricular area in a murine model of elastase-induced severe emphysema. In conclusion, E-MSCs and E-EVs were unable to reverse cardiorespiratory dysfunction, whereas H-EVs administration was associated with a reduction in cardiovascular and respiratory damage in experimental severe emphysema.

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.

Effects of different concentrations of mesenchymal stem cells treatment on LPS-induced acute respiratory distress syndrome rat model

PURPOSE

This study was prospectively designed to investigate the effects of different concentrations of mesenchymal stem cells treatment on respiratory mechanics, oxygenation, hemodynamics and inflammatory response in LPS-induced acute respiratory distress syndrome (ARDS) rat model. Methods: One hundred and twenty six LPS-induced ARDS model rats (weighted 200-220 g) were randomly divided into three groups: 1) Control group (N = 42); 2) low-dose hUC-MSC treatment group (MSC group 1, 1x107 cell/kg, N = 42); 3) high-dose hUC-MSC treatment group (MSC group 2, 2x107 cell/kg, N = 42), sham operation group as healthy group (N = 15). The rats were observed closely for 24 hours after hUC-MSC treatment, and the survival rate was calculated. At 24 hours, all rats were tested for hemodynamics, blood gas analysis, heart, lung, liver and kidney functions, inflammatory factors detection in blood samples and broncho-alveolar lavage fluid (BALF). The lung tissue of the rats was collected for HE staining analysis. Results: After LPS injection, ARDS was obvious in all LPS-infused rat groups, consistent with severe acute lung injury and high death rate. However, compared with the control group, a single intravenous injection hUC-MSC at dose of 1 × 107 cells/kg (low dose group) and 2 × 107 cells/kg (high dose group) reduced the mortality of rats with LPS-induced ARDS, as well as improving the lung function, increased the arterial oxygen pressure, improved the heart function, and reduced the levels of inflammatory factors including IL-1β, IL-6, and TNF-α. In addition, the high dose MSC group showed better lung injury therapeutic effects than the low dose MSC group. Data from this study demonstrated that injection of hUC-MSC had a significant therapeutic effect in treating the rat model of LPS-induced ARDS and multiple organ function injury.

Therapeutic Applications of Stem Cells and Extracellular Vesicles in Emergency Care: Futuristic Perspectives

Regenerative medicine (RM) is an interdisciplinary field that aims to repair, replace or regenerate damaged or missing tissue or organs to function as close as possible to its physiological architecture and functions. Stem cells, which are undifferentiated cells retaining self-renewal potential, excessive proliferation and differentiation capacity into offspring or daughter cells that form different lineage cells of an organism, are considered as an important part of the RM approaches. They have been widely investigated in preclinical and clinical studies for therapeutic purposes. Extracellular vesicles (EVs) are the vital mediators that regulate the therapeutic effects of stem cells. Besides, they carry various types of cargo between cells which make them a significant contributor of intercellular communication. Given their role in physiological and pathological conditions in living cells, EVs are considered as a new therapeutic alternative solution for a variety of diseases in which there is a high unmet clinical need. This review aims to summarize and identify therapeutic potential of stem cells and EVs in diseases requiring acute emergency care such as trauma, heart diseases, stroke, acute respiratory distress syndrome and burn injury. Diseases that affect militaries or societies including acute radiation syndrome, sepsis and viral pandemics such as novel coronavirus disease 2019 are also discussed. Additionally, featuring and problematic issues that hamper clinical translation of stem cells and EVs are debated in a comparative manner with a futuristic perspective. Graphical Abstract.

Mesenchymal stem cell immunomodulation: In pursuit of controlling COVID-19 related cytokine storm

The coronavirus disease 2019 (COVID-19) pandemic has grown to be a global public health crisis with no safe and effective treatments available yet. Recent findings suggest that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the coronavirus pathogen that causes COVID-19, could elicit a cytokine storm that drives edema, dysfunction of the airway exchange, and acute respiratory distress syndrome in the lung, followed by acute cardiac injury and thromboembolic events leading to multiorgan failure and death. Mesenchymal stem cells (MSCs), owing to their powerful immunomodulatory abilities, have the potential to attenuate the cytokine storm and have therefore been proposed as a potential therapeutic approach for which several clinical trials are underway. Given that intravenous infusion of MSCs results in a significant trapping in the lung, MSC therapy could directly mitigate inflammation, protect alveolar epithelial cells, and reverse lung dysfunction by normalizing the pulmonary microenvironment and preventing pulmonary fibrosis. In this review, we present an overview and perspectives of the SARS-CoV-2 induced inflammatory dysfunction and the potential of MSC immunomodulation for the prevention and treatment of COVID-19 related pulmonary disease.

HGF-Modified Dental Pulp Stem Cells Mitigate the Inflammatory and Fibrotic Responses in Paraquat-Induced Acute Respiratory Distress Syndrome

Paraquat (PQ) poisoning can cause acute lung injury and progress to pulmonary fibrosis and eventually death without effective therapy. Mesenchymal stem cells (MSCs) and hepatocyte growth factor (HGF) have been shown to partially reverse this damage. MSCs can be derived from bone marrow (BM-MSCs), adipose tissue (AD-MSCs), umbilical cord (UC-MSCs), dental pulp (DPSCs), and other sources. The biological characteristics of MSCs are specific to the tissue source. To develop an effective treatment for PQ poisoning, we compared the anti-inflammatory and antifibrotic effects of UC-MSCs and DPSCs and chose and modified a suitable source with HGF to investigate their therapeutic effects in vitro and in vivo. In this study, MSCs' supernatant was beneficial to the viability and proliferation of human lung epithelial cell BEAS-2B. Inflammatory and fibrosis-related cytokines were analyzed by real-time PCR. The results showed that MSCs' supernatant could suppress the expression of proinflammatory and profibrotic cytokines and increase the expression of anti-inflammatory and antifibrotic cytokines in BEAS-2B cells and human pulmonary fibroblast MRC-5. Extracellular vesicles (EVs) derived from MSCs performed more effectively than MSCs' supernatant. The effect of DPSCs was stronger than that of UC-MSCs and was further strengthened by HGF modification. PQ-poisoned mice were established, and UC-MSCs, DPSCs, and DPSCs-HGF were administered. Histopathological assessments revealed that DPSCs-HGF mitigated lung inflammation and collagen accumulation more effectively than the other treatments. DPSCs-HGF reduced lung permeability and increased the survival rate of PQ mice from 20% to 50%. Taken together, these results indicated that DPSCs can suppress inflammation and fibrosis in human lung cells better than UC-MSCs. The anti-inflammatory and antifibrotic effects were significantly enhanced by HGF modification. DPSCs-HGF ameliorated pulmonitis and pulmonary fibrosis in PQ mice, effectively improving the survival rate, which might be mediated by paracrine mechanisms. The results suggested that DPSCs-HGF transplantation was a potential therapeutic approach for PQ poisoning.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Lung Diseases: Current Status and Perspectives

Extracellular vesicles (EVs) have emerged as a potential therapy for several diseases. These plasma membrane-derived fragments are released constitutively by virtually all cell types-including mesenchymal stromal cells (MSCs)-under stimulation or following cell-to-cell interaction, which leads to activation or inhibition of distinct signaling pathways. Based on their size, intracellular origin, and secretion pathway, EVs have been grouped into three main populations: exosomes, microvesicles (or microparticles), and apoptotic bodies. Several molecules can be found inside MSC-derived EVs, including proteins, lipids, mRNA, microRNAs, DNAs, as well as organelles that can be transferred to damaged recipient cells, thus contributing to the reparative process and promoting relevant anti-inflammatory/resolutive actions. Indeed, the paracrine/endocrine actions induced by MSC-derived EVs have demonstrated therapeutic potential to mitigate or even reverse tissue damage, thus raising interest in the regenerative medicine field, particularly for lung diseases. In this review, we summarize the main features of EVs and the current understanding of the mechanisms of action of MSC-derived EVs in several lung diseases, such as chronic obstructive pulmonary disease (COPD), pulmonary infections [including coronavirus disease 2019 (COVID-19)], asthma, acute respiratory distress syndrome (ARDS), idiopathic pulmonary fibrosis (IPF), and cystic fibrosis (CF), among others. Finally, we list a number of limitations associated with this therapeutic strategy that must be overcome in order to translate effective EV-based therapies into clinical practice.

Pathogenesis of Multiple Organ Injury in COVID-19 and Potential Therapeutic Strategies

Severe acute respiratory disease coronavirus 2 (SARS-CoV-2, formerly 2019-nCoV) is a novel coronavirus that has rapidly disseminated worldwide, causing the coronavirus disease 2019 (COVID-19) pandemic. As of January 6th, 2021, there were over 86 million global confirmed cases, and the disease has claimed over 1.87 million lives (a ∼2.2% case fatality rate). SARS-CoV-2 is able to infect human cells by binding its spike (S) protein to angiotensin-conversing enzyme 2 (ACE2), which is expressed abundantly in several cell types and tissues. ACE2 has extensive biological activities as a component of the renin-angiotensin-aldosterone system (RAAS) and plays a pivotal role as counter-regulator of angiotensin II (Ang II) activity by converting the latter to Ang (1-7). Virion binding to ACE2 for host cell entry leads to internalization of both via endocytosis, as well as activation of ADAM17/TACE, resulting in downregulation of ACE2 and loss of its protective actions in the lungs and other organs. Although COVID-19 was initially described as a purely respiratory disease, it is now known that infected individuals can rapidly progress to a multiple organ dysfunction syndrome. In fact, all human structures that express ACE2 are susceptible to SARS-CoV-2 infection and/or to the downstream effects of reduced ACE2 levels, namely systemic inflammation and injury. In this review, we aim to summarize the major features of SARS-CoV-2 biology and the current understanding of COVID-19 pathogenesis, as well as its clinical repercussions in the lung, heart, kidney, bowel, liver, and brain. We also highlight potential therapeutic targets and current global efforts to identify safe and effective therapies against this life-threatening condition.

Neglected No More: Emerging Cellular Therapies in Traumatic Injury

Traumatic injuries are a leading cause of death and disability in both military and civilian populations. Given the complexity and diversity of traumatic injuries, novel and individualized treatment strategies are required to optimize outcomes. Cellular therapies have potential benefit for the treatment of acute or chronic injuries, and various cell-based pharmaceuticals are currently being tested in preclinical studies or in clinical trials. Cellular therapeutics may have the ability to complement existing therapies, especially in restoring organ function lost due to tissue disruption, prolonged hypoxia or inflammatory damage. In this article we highlight the current status and discuss future directions of cellular therapies for the treatment of traumatic injury. Both published research and ongoing clinical trials are discussed here.

Acute Lung Injury: Disease Modelling and the Therapeutic Potential of Stem Cells

Acute lung injury (ALI) is a severe clinical condition with high morbidity and mortality that usually results in the development of multiple organ dysfunction. The complex pathophysiology of ALI seems to provide a wide range of targets that offer numerous therapeutic options. However, despite extensive studies of ALI pathophysiology and treatment, no effective pharmacotherapy is available. Increasing evidence from both preclinical and clinical studies supports the preventive and therapeutic effects of mesenchymal stem cells (MSCs) for treating ALI. As cell-based therapy poses the risk of occlusion in microvasculature or unregulated growth, MSC-derived extracellular vesicles (MSC-EVs) have been extensively studied as a new therapeutic strategy for non-cell based therapy. It is widely accepted that the therapeutic properties of MSCs are derived from soluble factors with paracrine or endocrine effects, and EVs are among the most important paracrine or endocrine vehicles that can deliver various soluble factors with a similar phenotype as the parent cell. Therapeutic effects of MSCs have been reported for various delivery approaches, diverse doses, multiple origins, and different times of administration, and MSC-EVs treatment may include but is not limited to these choices. The mechanisms by which MSCs and MSC-EVs may contribute to ALI treatment remain elusive and need further exploration. This review provides an overview of preclinical studies that support the application of MSC-EVs for treating ALI, and it discusses emerging opportunities and their associated challenges.

Mesenchymal stem cell therapy for acute respiratory distress syndrome: from basic to clinics

The 2019 novel coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has occurred in China and around the world. SARS-CoV-2-infected patients with severe pneumonia rapidly develop acute respiratory distress syndrome (ARDS) and die of multiple organ failure. Despite advances in supportive care approaches, ARDS is still associated with high mortality and morbidity. Mesenchymal stem cell (MSC)-based therapy may be an potential alternative strategy for treating ARDS by targeting the various pathophysiological events of ARDS. By releasing a variety of paracrine factors and extracellular vesicles, MSC can exert anti-inflammatory, anti-apoptotic, anti-microbial, and pro-angiogenic effects, promote bacterial and alveolar fluid clearance, disrupt the pulmonary endothelial and epithelial cell damage, eventually avoiding the lung and distal organ injuries to rescue patients with ARDS. An increasing number of experimental animal studies and early clinical studies verify the safety and efficacy of MSC therapy in ARDS. Since low cell engraftment and survival in lung limit MSC therapeutic potentials, several strategies have been developed to enhance their engraftment in the lung and their intrinsic, therapeutic properties. Here, we provide a comprehensive review of the mechanisms and optimization of MSC therapy in ARDS and highlighted the potentials and possible barriers of MSC therapy for COVID-19 patients with ARDS.

DNA Methylation in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a lung disease affected by both genetic and environmental factors. Therefore, the role of epigenetics in the pathogenesis of COPD has attracted much attention. As one of the three epigenetic mechanisms, DNA methylation has been extensively studied in COPD. The present review aims at overviewing the effect of DNA methylation on etiology, pathogenesis, pathophysiological changes, and complications of COPD. The clarification of aberrant methylation of target genes, which play important roles in the initiation and progression of COPD, will provide new disease-specific biomarker and targets for early diagnosis and therapy.

New normal: two aspects of adipose tissue in COVID-19-treat and threat?

INTRODUCTION

Adipose-derived stromal cells (ADSCs) can be an important alternative in COVID-19 prevention, treatment, and subsequent sequelae repair. However, ACE-2 plays a common role in the pathogenesis of adipocyte hypertrophy and COVID 19.

AREAS COVERED

In this 'Perspective,' the author would like to emphasize the use of adipose tissue-derived stromal cells in COVID 19 and the issues that clinicians should pay attention to in fat graft applications in terms of adipose tissue-RAS relationship. The new normal for adipose tissue in COVID 19 will be highlighted.

EXPERT OPINION

ADSCs may potentially be used in COVID-19. However, it has been speculated that ACE2 receptors are responsible for the pathogenesis of adipose tissue overgrowth and may be a potential danger in terms of the relationship between ACE2 receptors and COVID19. We speculate that reducing the size of overgrown fat tissue by ultra-sharp blades and using near-normal adipocytes will create a 'new normal.'