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

Understanding how methyltransferase-like 3 functions in lung diseases: From pathogenesis to clinical application

Lung diseases have complex pathogenesis and treatment challenges, showing an obvious increase in the rate of diagnosis and death every year. Therefore, elucidating the mechanism for their pathogenesis and treatment ineffective from novel views is essential and urgent. Methyltransferase-like 3 (METTL3) is a novel post-transcriptional regulator for gene expression that has been implicated in regulating lung diseases, including that observed in chronic conditions such as pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), and chronic obstructive pulmonary disease (COPD), as well as acute conditions such as pneumonia, severe acute respiratory syndrome coronavirus 2 infection, and sepsis-induced acute respiratory distress syndrome. Notably, a comprehensive summary and analysis of findings from these studies might help understand lung diseases from the novel view of METTL3-regulated mechanism, however, such a review is still lacking. Therefore, this review aims to bridge such shortage by summarising the roles of METTL3 in lung diseases, establishing their interrelationships, and elucidating the potential applications of METTL3 regarding diagnosis, treatment, and prognosis. The analysis collectively suggests METTL3 is contributable to the onset and progression of these lung diseases, thereby prospecting METTL3 as a valuable biomarker for their diagnosis, treatment, and prognosis. In conclusion, this review offers elucidation into the correlation between METTL3 and lung diseases in both research and clinical settings and highlights potential avenues for exploring the roles of METTL3 in the respiratory system.

High throughput screening of mesenchymal stromal cell morphological response to inflammatory signals for bioreactor-based manufacturing of extracellular vesicles that modulate microglia

Due to their immunomodulatory function, mesenchymal stromal cells (MSCs) are a promising therapeutic with the potential to treat neuroinflammation associated with neurodegenerative diseases. This function is mediated by secreted extracellular vesicles (MSC-EVs). Despite established safety, MSC clinical translation has been unsuccessful due to inconsistent clinical outcomes resulting from functional heterogeneity. Current approaches to mitigate functional heterogeneity include 'priming' MSCs with inflammatory signals to enhance function. However, comprehensive evaluation of priming and its effects on MSC-EV function has not been performed. Furthermore, clinical translation of MSC-EV therapies requires significant manufacturing scale-up, yet few studies have investigated the effects of priming in bioreactors. As MSC morphology has been shown to predict their immunomodulatory function, we screened MSC morphological response to an array of priming signals and evaluated MSC-EV identity and potency in response to priming in flasks and bioreactors. We identified unique priming conditions corresponding to distinct morphologies. These conditions demonstrated a range of MSC-EV preparation quality and lipidome, allowing us to discover a novel MSC-EV manufacturing condition, as well as gain insight into potential mechanisms of MSC-EV microglia modulation. Our novel screening approach and application of priming to MSC-EV bioreactor manufacturing informs refinement of larger-scale manufacturing and enhancement of MSC-EV function.

Nasal mucosa-derived mesenchymal stem cells prolonged the survival of septic rats by protecting macrophages from pyroptosis

Sepsis is characterized by an exacerbated inflammatory response, driven by the overproduction of cytokines, a phenomenon known as a cytokine storm. This condition is further compounded by the extensive infiltration of M1 macrophages and the pyroptosis of these cells, leading to immune paralysis. To counteract this, we sought to transition M1 macrophages into the M2 phenotype and safeguard them from pyroptosis. For this purpose, we employed ectodermal mesenchymal stem cells (EMSCs) sourced from the nasal mucosa to examine their impact on both macrophages and septic animal models. The co-culture protocol involving LPS-stimulated rat bone marrow macrophages and EMSCs was employed to examine the paracrine influence of EMSCs on macrophages. The intravenous administration of EMSCs was utilized to observe the enhancement in the survival rate of septic rat models and the protection of associated organs. The findings indicated that EMSCs facilitated M2 polarization of macrophages, which were stimulated by LPS, and significantly diminished levels of pro-inflammatory cytokines and NLRP3. Furthermore, EMSCs notably restored the mitochondrial membrane potential (MMP) of macrophages through paracrine action, eliminated excess reactive oxygen species (ROS), and inhibited macrophage pyroptosis. Additionally, the systemic integration of EMSCs substantially reduced injuries to multiple organs and preserved the fundamental functions of the heart, liver, and kidney in CLP rats, thereby extending their survival.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects: Update from 2015 review

Mesenchymal stromal cells (MSCs) have become one of the most investigated and applied cells for cellular therapy and regenerative medicine. In this update of our review published in 2015, we show that studies continue to abound regarding the characterization of MSCs to distinguish them from other similar cell types, the discovery of new tissue sources of MSCs, and the confirmation of their properties and functions that render them suitable as a therapeutic. Because cryopreservation is widely recognized as the only technology that would enable the on-demand availability of MSCs, here we show that although the traditional method of cryopreserving cells by slow cooling in the presence of 10% dimethyl sulfoxide (Me2SO) continues to be used by many, several novel MSC cryopreservation approaches have emerged. As in our previous review, we conclude from these recent reports that viable and functional MSCs from diverse tissues can be recovered after cryopreservation using a variety of cryoprotectants, freezing protocols, storage temperatures, and periods of storage. We also show that for logistical reasons there are now more studies devoted to the cryopreservation of tissues from which MSCs are derived. A new topic included in this review covers the application in COVID-19 of MSCs arising from their immunomodulatory and antiviral properties. Due to the inherent heterogeneity in MSC populations from different sources there is still no standardized procedure for their isolation, identification, functional characterization, cryopreservation, and route of administration, and not likely to be a "one-size-fits-all" approach in their applications in cell-based therapy and regenerative medicine.

Antimicrobial peptide LL37 and regulatory T cell associated with late-onset sepsis in very preterm infants

Stem cell therapy may prevent late-onset sepsis (LOS) via antimicrobial peptide LL37 secretion and regulatory T cell (Treg) regulation. The early prediction of LOS is still a challenge. This study evaluated whether immunological state of LL37 or Tregs precedes LOS. We firstly analyzed the LL37 level, Treg proportion, and LOS incidence in very preterm infants treated with autologous cord blood mononuclear cells (ACBMNCs) in our previous trial. Then, we constructed a prediction model and built validation cohort. We found ACBMNC intervention reduced the incidence of LOS from 27.3% to 6.9% (p = 0.021). LL37 and Treg abundances were higher in the ACBMNCs group. The nomogram demonstrated that early-life Treg and LL37 characteristics were closely associated with LOS (area under the curve, AUC 0.936), with implications for early prediction and timely clinical management. This composite model was also helpful to evaluate the beneficial effect of ACBMNCs intervention on LOS, thus promoting translational research.

The impact understanding of exosome therapy in COVID-19 and preparations for the future approaches in dealing with infectious diseases and inflammation

Cytokine storms, which result from an abrupt, acute surge in the circulating levels of different pro-inflammatory cytokines, are one of the complications associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study aimed to assess the effect of exosomes on the release of pro-inflammatory cytokines in patients with coronavirus disease 2019 (COVID-19) and compare it with a control group. The cytokines evaluated in this study were TNF-α, IL-6, IL-17, and IFN-γ. The study compared the levels of these pro-inflammatory cytokines in the peripheral blood mononuclear cells (PBMCs) of five COVID-19 patients in the intensive care unit, who were subjected to both inactivated SARS-CoV-2 and exosome therapy, with those of five healthy controls. The cytokine levels were quantified using the ELISA method. The collected data was analyzed in SPSS Version 26.0 and GraphPad Prism Version 9. According to the study findings, when PBMCs were exposed to inactivated SARS-CoV-2, pro-inflammatory cytokines increased in both patients and healthy controls. Notably, the cytokine levels were significantly elevated in the COVID-19 patients compared to the control group P-values were < 0.001, 0.001, 0.008, and 0.008 for TNF-α, IL-6, IL-17, and IFN-γ, respectively. Conversely, when both groups were exposed to exosomes, there was a marked reduction in the levels of pro-inflammatory cytokines. This suggests that exosome administration can effectively mitigate the hyperinflammation induced by COVID-19 by suppressing the production of pro-inflammatory cytokines in patients. These findings underscore the potential safety and efficacy of exosomes as a therapeutic strategy for COVID-19.

Umbilical cord MSC-derived exosomes improve alveolar macrophage function and reduce LPS-induced acute lung injury

Acute lung injury (ALI) is a severe condition that can progress to acute respiratory distress syndrome (ARDS), with a high mortality rate. Currently, no specific and compelling drug treatment plan exists. Mesenchymal stem cells (MSCs) have shown promising results in preclinical and clinical studies as a potential treatment for ALI and other lung-related conditions due to their immunomodulatory properties and ability to regenerate various cell types. The present study focuses on analyzing the role of umbilical cord MSC (UC-MSC))-derived exosomes in reducing lipopolysaccharide-induced ALI and investigating the mechanism involved. The study demonstrates that UC-MSC-derived exosomes effectively improved the metabolic function of alveolar macrophages and promoted their shift to an anti-inflammatory phenotype, leading to a reduction in ALI. The findings also suggest that creating three-dimensional microspheres from the MSCs first can enhance the effectiveness of the exosomes. Further research is needed to fully understand the mechanism of action and optimize the therapeutic potential of MSCs and their secretome in ALI and other lung-related conditions.

Targeting the host response in sepsis: current approaches and future evidence

Sepsis, a dysregulated host response to infection characterized by organ failure, is one of the leading causes of death worldwide. Disbalances of the immune response play an important role in its pathophysiology. Patients may develop simultaneously or concomitantly states of systemic or local hyperinflammation and immunosuppression. Although a variety of effective immunomodulatory treatments are generally available, attempts to inhibit or stimulate the immune system in sepsis have failed so far to improve patients' outcome. The underlying reason is likely multifaceted including failure to identify responders to a specific immune intervention and the complex pathophysiology of organ dysfunction that is not exclusively caused by immunopathology but also includes dysfunction of the coagulation system, parenchymal organs, and the endothelium. Increasing evidence suggests that stratification of the heterogeneous population of septic patients with consideration of their host response might led to treatments that are more effective. The purpose of this review is to provide an overview of current studies aimed at optimizing the many facets of host response and to discuss future perspectives for precision medicine approaches in sepsis.

High throughput screening of mesenchymal stromal cell morphological response to inflammatory signals for bioreactor-based manufacturing of extracellular vesicles that modulate microglia

Due to their immunomodulatory function, mesenchymal stromal cells (MSCs) are a promising therapeutic with the potential to treat neuroinflammation associated with neurodegenerative diseases. This function can be mediated by secreted extracellular vesicles (MSC-EVs). Despite established safety, MSC clinical translation has been unsuccessful due to inconsistent clinical outcomes resulting from functional heterogeneity. Current approaches to mitigate functional heterogeneity include 'priming' MSCs with inflammatory signals to enhance function. However, comprehensive evaluation of priming and its effects on MSC-EV function has not been performed. Clinical translation of MSC-EV therapies requires significant manufacturing scale-up, yet few studies have investigated the effects of priming in bioreactors. As MSC morphology has been shown to predict their immunomodulatory function, we screened MSC morphological response to an array of priming signals and evaluated MSC-EV identity and potency in response to priming in flasks and bioreactors. We identified unique priming conditions corresponding to distinct morphologies. These conditions demonstrated a range of MSC-EV preparation quality and lipidome, allowing us to discover a novel MSC-EV manufacturing condition, as well as gain insight into potential mechanisms of MSC-EV microglia modulation. Our novel screening approach and application of priming to MSC-EV bioreactor manufacturing informs refinement of larger-scale manufacturing and enhancement of MSC-EV function.

Host and Pathogen-Directed Therapies against Microbial Infections Using Exosome- and Antimicrobial Peptide-derived Stem Cells with a Special look at Pulmonary Infections and Sepsis

Microbial diseases are a great threat to global health and cause considerable mortality and extensive economic losses each year. The medications for treating this group of diseases (antibiotics, antiviral, antifungal drugs, etc.) directly attack the pathogenic agents by recognizing the target molecules. However, it is necessary to note that excessive use of any of these drugs can lead to an increase in microbial resistance and infectious diseases. New therapeutic methods have been studied recently using emerging drugs such as mesenchymal stem cell-derived exosomes (MSC-Exos) and antimicrobial peptides (AMPs), which act based on two completely different strategies against pathogens including Host-Directed Therapy (HDT) and Pathogen-Directed Therapy (PDT), respectively. In the PDT approach, AMPs interact directly with pathogens to interrupt their intrusion, survival, and proliferation. These drugs interact directly with the cell membrane or intracellular components of pathogens and cause the death of pathogens or inhibit their replication. The mechanism of action of MSC-Exos in HDT is based on immunomodulation and regulation, promotion of tissue regeneration, and reduced host toxicity. This review studies the potential of mesenchymal stem cell-derived exosomes/ATPs therapeutic properties against microbial infectious diseases especially pulmonary infections and sepsis.

Efficacy of Wharton Jelly Mesenchymal Stromal Cells infusions in moderate to severe SARS-Cov-2 related acute respiratory distress syndrome: a phase 2a double-blind randomized controlled trial

Background

The COVID-19 pandemic caused a wave of acute respiratory distress syndrome (ARDS) with a high in-hospital mortality, especially in patients requiring invasive mechanical ventilation. Wharton Jelly-derived Mesenchymal Stromal Cells (WJ-MSCs) may counteract the pulmonary damage induced by the SARS-CoV-2 infection through pro-angiogenic effects, lung epithelial cell protection, and immunomodulation.

Methods

In this randomized, double-blind, placebo-controlled phase 2a trial, adult patients receiving invasive mechanical ventilation for SARS-CoV-2 induced moderate or severe ARDS were assigned to receive 1 intravenous infusion of 1 × 106 WJ-MSCs/kg or placebo within 48 h of invasive ventilation followed by 2 infusions of 0.5 × 106 WJ-MSCs/kg or placebo over 5 days. The primary endpoint was the percentage of patients with a PaO2/FiO2 > 200 on day 10.

Results

Thirty patients were included from November 2020 to May 2021, 15 in the WJ-MSC group and 15 in the placebo group. We did not find any significant difference in the PaO2/FiO2 ratio at day 10, with 18 and 15% of WJ-MSCs and placebo-treated patients reaching a ratio >200, respectively. Survival did not differ in the 2 groups with a 20% mortality rate at day 90. While we observed a higher number of ventilation-free days at 28 days in the WJ-MSC arm, this difference was not statistically significant (median of 11 (0-22) vs. 0 (0-18), p = 0.2). The infusions were well tolerated, with a low incidence of anti-HLA alloimmunization after 90 days.

Conclusion

While treatment with WJ-MSCs appeared safe and feasible in patients with SARS-CoV2 moderate or severe ARDS in this phase 2a trial, the treatment was not associated with an increased percentage of patients with P/F > 200 at 10d, nor did 90 day mortality improve in the treated group.

Clinical trial registration

https://beta.clinicaltrials.gov/study/NCT04625738, identifier NCT04625738.

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

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

Repair of Acute Respiratory Distress Syndrome in COVID-19 by Stromal Cells (REALIST-COVID Trial): A Multicenter, Randomized, Controlled Clinical Trial

Rationale: Mesenchymal stromal cells (MSCs) may modulate inflammation, promoting repair in coronavirus disease (COVID-19)-related acute respiratory distress syndrome (ARDS). Objectives: We investigated the safety and efficacy of ORBCEL-C (CD362 [cluster of differentiation 362]-enriched, umbilical cord-derived MSCs) in COVID-19-related ARDS. Methods: In this multicenter, randomized, double-blind, allocation-concealed, placebo-controlled trial (NCT03042143), patients with moderate to severe COVID-19-related ARDS were randomized to receive ORBCEL-C (400 million cells) or placebo (Plasma-Lyte 148). The primary safety and efficacy outcomes were the incidence of serious adverse events and oxygenation index at Day 7, respectively. Secondary outcomes included respiratory compliance, driving pressure, PaO2:FiO2 ratio, and Sequential Organ Failure Assessment score. Clinical outcomes relating to duration of ventilation, lengths of ICU and hospital stays, and mortality were collected. Long-term follow-up included diagnosis of interstitial lung disease at 1 year and significant medical events and mortality at 2 years. Transcriptomic analysis was performed on whole blood at Days 0, 4, and 7. Measurements and Main Results: Sixty participants were recruited (final analysis: n = 30 received ORBCEL-C, n = 29 received placebo; 1 participant in the placebo group withdrew consent). Six serious adverse events occurred in the ORBCEL-C group and three in the placebo group (risk ratio, 2.9 [95% confidence interval, 0.6-13.2]; P = 0.25). Day 7 mean (SD) oxygenation index did not differ (ORBCEL-C, 98.3 [57.2] cm H2O/kPa; placebo, 96.6 [67.3] cm H2O/kPa). There were no differences in secondary surrogate outcomes or in mortality at Day 28, Day 90, 1 year, or 2 years. There was no difference in the prevalence of interstitial lung disease at 1 year or significant medical events up to 2 years. ORBCEL-C modulated the peripheral blood transcriptome. Conclusion: ORBCEL-C MSCs were safe in subjects with moderate to severe COVID-19-related ARDS but did not improve surrogates of pulmonary organ dysfunction.

Delayed MSC therapy enhances resolution of organized pneumonia induced by antibiotic resistant Klebsiella pneumoniae infection

Introduction

Mesenchymal stromal cells (MSC) are a promising therapeutic for pneumonia-induced sepsis. Here we sought to determine the efficacy of delayed administration of naïve and activated bone marrow (BM), adipose (AD), and umbilical cord (UC) derived MSCs in organized antibiotic resistant Klebsiella pneumosepsis.

Methods

Human BM-, AD-, and UC-MSCs were isolated and expanded and used either in the naïve state or following cytokine pre-activation. The effect of MSC tissue source and activation status was assessed first in vitro. Subsequent experiments assessed therapeutic potential as a delayed therapy at 48 h post infection of rodents with Klebsiella pneumoniae, with efficacy assessed at 120 h.

Results

BM-, AD-, and UC-MSCs accelerated epithelial healing, increased phagocytosis, and reduced ROS-induced epithelial injury in vitro, with AD-MSCs less effective, and naïve MSCs more effective than pre-activated MSCs. Delayed MSC administration in pre-clinical organized Klebsiella pneumosepsis had no effect on physiologic indices, but enhanced resolution of structural lung injury. Delayed therapy with pre-activated MSCs reduced mRNA concentrations of fibrotic factors. Naïve MSC treatment reduced key circulating cell proportions and increased bacterial killing capacity in the lungs whereas pre-activated MSCs enhanced the phagocytic index of pulmonary white cells.

Discussion

Delayed MSC therapy enhanced resolution of lung injury induced by antibiotic resistant Klebsiella infection and favorably modulated immune cell profile. Overall, AD-MSCs were less effective than either UC- or BM-MSCs, while naïve MSCs had a more favorable effect profile compared to pre-activated MSCs.

Investigational Use of Mesenchymal Stem/Stromal Cells and Their Secretome as Add-On Therapy in Severe Respiratory Virus Infections: Challenges and Perspectives

Serious manifestations of respiratory virus infections such as influenza and coronavirus disease 2019 (COVID-19) are associated with a dysregulated immune response and systemic inflammation. Treating the immunological/inflammatory dysfunction with glucocorticoids, Janus kinase inhibitors, and monoclonal antibodies against the interleukin-6 receptor has significantly reduced the risk of respiratory failure and death in hospitalized patients with severe COVID-19, but the proportion of those requiring invasive mechanical ventilation (IMV) and dying because of respiratory failure remains elevated. Treatment of severe influenza-associated pneumonia and acute respiratory distress syndrome (ARDS) with available immunomodulators and anti-inflammatory compounds is still not recommended. New therapies are therefore needed to reduce the use of IMV and the risk of death in hospitalized patients with rapidly increasing oxygen demand and systemic inflammation who do not respond to the current standard of care. This paper provides a critical assessment of the published clinical trials that have tested the investigational use of intravenously administered allogeneic mesenchymal stem/stromal cells (MSCs) and MSC-derived secretome with putative immunomodulatory/antiinflammatory/regenerative properties as add-on therapy to improve the outcome of these patients. Increased survival rates are reported in 5 of 12 placebo-controlled or open-label comparative trials involving patients with severe and critical COVID-19 and in the only study concerning patients with influenza-associated ARDS. Results are encouraging but inconclusive for the following reasons: small number of patients tested in each trial; differences in concomitant treatments and respiratory support; imbalances between study arms; differences in MSC source, MSC-derived product, dosing and starting time of the investigational therapy; insufficient/inappropriate reporting of clinical data. Solutions are proposed for improving the clinical development plan, with the aim of facilitating regulatory approval of the MSC-based investigational therapy for life-threatening respiratory virus infections in the future. Major issues are the absence of a biomarker predicting responsiveness to MSCs and MSC-derived secretome and the lack of pharmacoeconomic evaluations.

Current status and prospects of basic research and clinical application of mesenchymal stem cells in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a common and clinically devastating disease that causes respiratory failure. Morbidity and mortality of patients in intensive care units are stubbornly high, and various complications severely affect the quality of life of survivors. The pathophysiology of ARDS includes increased alveolar-capillary membrane permeability, an influx of protein-rich pulmonary edema fluid, and surfactant dysfunction leading to severe hypoxemia. At present, the main treatment for ARDS is mechanical treatment combined with diuretics to reduce pulmonary edema, which primarily improves symptoms, but the prognosis of patients with ARDS is still very poor. Mesenchymal stem cells (MSCs) are stromal cells that possess the capacity to self-renew and also exhibit multilineage differentiation. MSCs can be isolated from a variety of tissues, such as the umbilical cord, endometrial polyps, menstrual blood, bone marrow, and adipose tissues. Studies have confirmed the critical healing and immunomodulatory properties of MSCs in the treatment of a variety of diseases. Recently, the potential of stem cells in treating ARDS has been explored via basic research and clinical trials. The efficacy of MSCs has been shown in a variety of in vivo models of ARDS, reducing bacterial pneumonia and ischemia-reperfusion injury while promoting the repair of ventilator-induced lung injury. This article reviews the current basic research findings and clinical applications of MSCs in the treatment of ARDS in order to emphasize the clinical prospects of MSCs.

Multipotent Mesenchymal Stem Cell-Based Therapies for Spinal Cord Injury: Current Progress and Future Prospects

Spinal cord injury (SCI) represents a significant medical challenge, often resulting in permanent disability and severely impacting the quality of life for affected individuals. Traditional treatment options remain limited, underscoring the need for novel therapeutic approaches. In recent years, multipotent mesenchymal stem cells (MSCs) have emerged as a promising candidate for SCI treatment due to their multifaceted regenerative capabilities. This comprehensive review synthesizes the current understanding of the molecular mechanisms underlying MSC-mediated tissue repair in SCI. Key mechanisms discussed include neuroprotection through the secretion of growth factors and cytokines, promotion of neuronal regeneration via MSC differentiation into neural cell types, angiogenesis through the release of pro-angiogenic factors, immunomodulation by modulating immune cell activity, axonal regeneration driven by neurotrophic factors, and glial scar reduction via modulation of extracellular matrix components. Additionally, the review examines the various clinical applications of MSCs in SCI treatment, such as direct cell transplantation into the injured spinal cord, tissue engineering using biomaterial scaffolds that support MSC survival and integration, and innovative cell-based therapies like MSC-derived exosomes, which possess regenerative and neuroprotective properties. As the field progresses, it is crucial to address the challenges associated with MSC-based therapies, including determining optimal sources, intervention timing, and delivery methods, as well as developing standardized protocols for MSC isolation, expansion, and characterization. Overcoming these challenges will facilitate the translation of preclinical findings into clinical practice, providing new hope and improved treatment options for individuals living with the devastating consequences of SCI.

Low-Dose Radiotherapy for Patients with Pneumonia Due to COVID-19: A Single-Institution Prospective Study

Purpose: Results of the low-dose radiation therapy (LDRT) in patients with pneumonia due to COVID-19 has been presented. Methods: Fifteen patients received a single-fraction radiation dose of 1 Gy to the bilateral lungs due to pre-ARDS pneumonia in the course of COVID-19. Follow-up was performed on days 1, 3, 5, 7, 14 after LDRT. Results: Eleven patients (73%) were released up until day 28. Median hospitalization was 20 days; 28-day mortality was 13%. Median O2 saturation improved within 24 h after LDRT in 14/15, with median SpO2 values of 84.5% vs. 87.5% p = 0.016, respectively. At day 14 of hospitalization, 46% did not require oxygen supplementation. Significant decline in CRP and IL-6 was observed within 24 h post LDRT. No organ toxicities were noted. Conclusion: LDRT is feasible, well tolerated and may translate to early clinical recovery in patients with severe pneumonia. Further studies are needed to determine optimal candidate, time and dose of LDRT for COVID-19 patients with pneumonia.

Efficacy and Safety of Mesenchymal Stromal Cells Therapy for COVID-19 Infection: A Systematic Review and Meta-analysis

BACKGROUND

Coronavirus disease 2019 (COVID-19) is an infectious respiratory disease prevalent worldwide with a high mortality rate, and there is currently no specific medicine to treat patients.

OBJECTIVE

We aimed to assess the safety and efficacy of stem cell therapy for COVID-19 by providing references for subsequent clinical treatments and trials.

METHOD

We systematically searched PubMed, Embase, Cochrane, and Web of Science, using the following keywords: "stem cell" or "stromal cell" and "COVID-19." Controlled clinical trials published in English until 24th August 2021 were included. We followed the PRISMA guidelines and used Cochrane Collaboration's tool for assessing the risk of bias. We analysed the data using a fixed-effect model.

RESULTS

We identified 1779 studies, out of which eight were eligible and included in this study. Eight relevant studies consisted of 156 patients treated with stem cells and 144 controls (300 individuals in total). There were no SAEs associated with stem cell therapy in all six studies, and no significant differences in AEs (p = 0.09, I² = 40%, OR = 0.53, 95% CI: 0.26 to 1.09) between the experimental group and control group were observed. Moreover, the meta-analysis found that stem cell therapy effectively reduced the high mortality rate of COVID-19 (14/156 vs. 43/144; p<0.0001, I2 = 0%, OR=0.18, 95% CI: 0.08 to 0.41).

CONCLUSION

This study suggests that MSCs therapy for COVID-19 has shown some promising results in safety and efficacy. It effectively reduces the high mortality rate of COVID-19 and does not increase the incidence of adverse events.

Perinatal Stem Cell Therapy to Treat Type 1 Diabetes Mellitus: A Never-Say-Die Story of Differentiation and Immunomodulation

Human term placenta and other postpartum-derived biological tissues are promising sources of perinatal cells with unique stem cell properties. Among the massive current research on stem cells, one medical focus on easily available stem cells is to exploit them in the design of immunotherapy protocols, in particular for the treatment of chronic non-curable human diseases. Type 1 diabetes is characterized by autoimmune destruction of pancreatic beta cells and perinatal cells can be harnessed both to generate insulin-producing cells for beta cell replenishment and to regulate autoimmune mechanisms via immunomodulation capacity. In this study, the strong points of cells derived from amniotic epithelial cells and from umbilical cord matrix are outlined and their potential for supporting cell therapy development. From a basic research and expert stem cell point of view, the aim of this review is to summarize information regarding the regenerative medicine field, as well as describe the state of the art on possible cell therapy approaches for diabetes.

Acute respiratory distress syndrome in adults: diagnosis, outcomes, long-term sequelae, and management

Acute respiratory distress syndrome (ARDS) is characterised by acute hypoxaemic respiratory failure with bilateral infiltrates on chest imaging, which is not fully explained by cardiac failure or fluid overload. ARDS is defined by the Berlin criteria. In this Series paper the diagnosis, management, outcomes, and long-term sequelae of ARDS are reviewed. Potential limitations of the ARDS definition and evidence that could inform future revisions are considered. Guideline recommendations, evidence, and uncertainties in relation to ARDS management are discussed. The future of ARDS strives towards a precision medicine approach, and the framework of treatable traits in ARDS diagnosis and management is explored.

Therapeutic Benefits of Mesenchymal Stem Cells in Acute Respiratory Distress Syndrome: Potential Mechanisms and Challenges

Acute respiratory distress syndrome (ARDS) presents as a form of acute respiratory failure resulting from non-cardiogenic pulmonary edema due to excessive alveolocapillary permeability, which may be pulmonary or systemic in origin. In the last 3 years, the coronavirus disease 2019 pandemic has resulted in an increase in ARDS cases and highlighted the challenges associated with this syndrome, as well as the unacceptably high mortality rates and lack of effective treatments. Currently, clinical treatment remains primarily supportive, including mechanical ventilation and drug-based therapy. Mesenchymal stem cell (MSC) therapies are emerging as a promising intervention in patients with ARDS and have promising therapeutic effects and safety. The therapeutic mechanisms include modifying the immune response and assisting with tissue repair. This review provides an overview of the general properties of MSCs and outlines their role in mitigating lung injury and promoting tissue repair in ARDS. Finally, we summarize the current challenges in the study of translational MSC research and identify avenues by which the discipline may progress in the coming years.

Mesenchymal stromal cells alleviate acute respiratory distress syndrome through the cholinergic anti-inflammatory pathway

Mesenchymal stromal cells (MSCs) have been considered a promising alternative for treatment of acute respiratory distress syndrome (ARDS). However, there is significant heterogeneity in their therapeutic efficacy, largely owing to the incomplete understanding of the mechanisms underlying the therapeutic activities of MSCs. Here, we hypothesize that the cholinergic anti-inflammatory pathway (CAP), which is recognized as a neuroimmunological pathway, may be involved in the therapeutic mechanisms by which MSCs mitigate ARDS. Using lipopolysaccharide (LPS) and bacterial lung inflammation models, we found that inflammatory cell infiltration and Evans blue leakage were reduced and that the expression levels of choline acetyltransferase (ChAT) and vesicular acetylcholine transporter (VAChT) in lung tissue were significantly increased 6 hours after MSC infusion. When the vagus nerve was blocked or α7 nicotinic acetylcholine (ACh) receptor (α7nAChR)-knockout mice were used, the therapeutic effects of MSCs were significantly reduced, suggesting that the CAP may play an important role in the effects of MSCs in ARDS treatment. Our results further showed that MSC-derived prostaglandin E2 (PGE2) likely promoted ACh synthesis and release. Additionally, based on the efficacy of nAChR and α7nAChR agonists, we found that lobeline, the nicotinic cholinergic receptor excitation stimulant, may attenuate pulmonary inflammation and alleviate respiratory symptoms of ARDS patients in a clinical study (ChiCTR2100047403). In summary, we reveal a previously unrecognized MSC-mediated mechanism of CAP activation as the means by which MSCs alleviate ARDS-like syndrome, providing insight into the clinical translation of MSCs or CAP-related strategies for the treatment of patients with ARDS.

Mesenchymal stromal cells-derived extracellular vesicles reprogramme macrophages in ARDS models through the miR-181a-5p-PTEN-pSTAT5-SOCS1 axis

RATIONALE

A better understanding of the mechanism of action of mesenchymal stromal cells (MSCs) and their extracellular vesicles (EVs) is needed to support their use as novel therapies for acute respiratory distress syndrome (ARDS). Macrophages are important mediators of ARDS inflammatory response. Suppressor of cytokine signalling (SOCS) proteins are key regulators of the macrophage phenotype switch. We therefore investigated whether SOCS proteins are involved in mediation of the MSC effect on human macrophage reprogramming.

METHODS

Human monocyte-derived macrophages (MDMs) were stimulated with lipopolysaccharide (LPS) or plasma samples from patients with ARDS (these samples were previously classified into hypo-inflammatory and hyper-inflammatory phenotype) and treated with MSC conditioned medium (CM) or EVs. Protein expression was measured by Western blot. EV micro RNA (miRNA) content was determined by miRNA sequencing. In vivo: LPS-injured C57BL/6 mice were given EVs isolated from MSCs in which miR-181a had been silenced by miRNA inhibitor or overexpressed using miRNA mimic.

RESULTS

EVs were the key component of MSC CM responsible for anti-inflammatory modulation of human macrophages. EVs significantly reduced secretion of tumour necrosis factor-α and interleukin-8 by LPS-stimulated or ARDS plasma-stimulated MDMs and this was dependent on SOCS1. Transfer of miR-181a in EVs downregulated phosphatase and tensin homolog (PTEN) and subsequently activated phosphorylated signal transducer and activator of transcription 5 (pSTAT5) leading to upregulation of SOCS1 in macrophages. In vivo, EVs alleviated lung injury and upregulated pSTAT5 and SOCS1 expression in alveolar macrophages in a miR181-dependent manner. Overexpression of miR-181a in MSCs significantly enhanced therapeutic efficacy of EVs in this model.

CONCLUSION

miR-181a-PTEN-pSTAT5-SOCS1 axis is a novel pathway responsible for immunomodulatory effect of MSC EVs in ARDS.

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.

Updated Living Systematic Review and Meta-analysis of Controlled Trials of Mesenchymal Stromal Cells to Treat COVID-19: A Framework for Accelerated Synthesis of Trial Evidence for Rapid Approval-FASTER Approval

Background

Mesenchymal stromal cells (MSCs) may reduce mortality in patients with COVID-19; however, early evidence is based on few studies with marked interstudy heterogeneity. The second iteration of our living systematic review and meta-analysis evaluates a framework needed for synthesizing evidence from high-quality studies to accelerate consideration for approval.

Methods

A systematic search of the literature was conducted on November 15, 2021, to identify all English-language, full-text, and controlled clinical studies examining MSCs to treat COVID-19 (PROSPERO: CRD42021225431).

Findings

Eleven studies were identified (403 patients with severe and/or critical COVID-19, including 207 given MSCs and 196 controls). All 11 studies reported mortality and were pooled through random-effects meta-analysis. MSCs decreased relative risk of death at study endpoint (RR: 0.50 [95% CI, 0.34-0.75]) and RR of death at 28 days after treatment (0.19 [95% CI], 0.05-0.78) compared to controls. MSCs also decreased length of hospital stay (mean difference (MD: −3.97 days [95% CI, −6.09 to −1.85], n = 5 studies) and increased oxygenation levels at study endpoint compared to controls (MD: 105.62 mmHg O₂ [95% CI, 73.9-137.3,], n = 3 studies). Only 2 of 11 studies reported on all International Society for Cellular Therapy (ISCT) criteria for MSC characterization. Included randomized controlled trials were found to have some concerns (n = 2) to low (n = 4) risk of bias (RoB), while all non-randomized studies were found to have moderate (n = 5) RoB.

Interpretation

Our updated living systematic review concludes that MSCs can likely reduce mortality in patients with severe or critical COVID-19. A master protocol based on our Faster Approval framework appears necessary to facilitate the more accelerated accumulation of high-quality evidence that would reduce RoB, improve consistency in product characterization, and standardize outcome reporting.

Repair of acute respiratory distress syndrome by stromal cell administration (REALIST): a structured study protocol for an open-label dose-escalation phase 1 trial followed by a randomised, triple-blind, allocation concealed, placebo-controlled phase 2 trial

BACKGROUND

Mesenchymal stromal cells (MSCs) may be of benefit in ARDS due to immunomodulatory and reparative properties. This trial investigates a novel CD362 enriched umbilical cord derived MSC product (REALIST ORBCEL-C), produced to Good Manufacturing Practice standards, in patients with moderate to severe ARDS due to COVID-19 and ARDS due to other causes.

METHODS

Phase 1 is a multicentre open-label dose-escalation pilot trial. Patients will receive a single infusion of REALIST ORBCEL-C (100 × 106 cells, 200 × 106 cells or 400 × 106 cells) in a 3 + 3 design. Phase 2 is a multicentre randomised, triple blind, allocation concealed placebo-controlled trial. Two cohorts of patients, with ARDS due to COVID-19 or ARDS due to other causes, will be recruited and randomised 1:1 to receive either a single infusion of REALIST ORBCEL-C (400 × 106 cells or maximal tolerated dose in phase 1) or placebo. Planned recruitment to each cohort is 60 patients. The primary safety outcome is the incidence of serious adverse events. The primary efficacy outcome is oxygenation index at day 7. The trial will be reported according to the Consolidated Standards for Reporting Trials (CONSORT 2010) statement.

DISCUSSION

The development and manufacture of an advanced therapy medicinal product to Good Manufacturing Practice standards within NHS infrastructure are discussed, including challenges encountered during the early stages of trial set up. The rationale to include a separate cohort of patients with ARDS due to COVID-19 in phase 2 of the trial is outlined.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03042143. Registered on 3 February 2017. EudraCT Number 2017-000584-33.

Stem cell therapy for COVID-19 pneumonia

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) virus is a highly contagious microorganism, and despite substantial investigation, no progress has been achieved in treating post-COVID complications. However, the virus has made various mutations and has spread around the world. Researchers have tried different treatments to reduce the side effects of the COVID-19 symptoms. One of the most common and effective treatments now used is steroid therapy to reduce the complications of this disease. Long-term steroid therapy for chronic inflammation following COVID-19 is harmful and increases the risk of secondary infection, and effective treatment remains challenging owing to fibrosis and severe inflammation and infection. Sometimes our immune system can severely damage ourselves in disease. In the past, many researchers have conducted various studies on the immunomodulatory properties of stem cells. This property of stem cells led them to modulate the immune system of autoimmune diseases like diabetes, multiple sclerosis, and Parkinson's. Because of their immunomodulatory properties, stem cell-based therapy employing mesenchymal or hematopoietic stem cells may be a viable alternative treatment option in some patients. By priming the immune system and providing cytokines, chemokines, and growth factors, stem cells can be employed to build a long-term regenerative and protective response. This review addresses the latest trends and rapid progress in stem cell treatment for Acute Respiratory Distress Syndrome (ARDS) following COVID-19.

Mesenchymal Stem Cell-Based COVID-19 Therapy: Bioengineering Perspectives

The novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). Mesenchymal stem cells (MSCs) are currently utilized in clinics for pulmonary inflammatory diseases, including acute respiratory distress syndrome and acute lung injury. Given that MSCs offer a promising treatment against COVID-19, they are being used against COVID-19 in more than 70 clinical trials with promising findings. Genetically engineered MSCs offer promising therapeutic options in pulmonary diseases. However, their potential has not been explored yet. In this review, we provide perspectives on the functionally modified MSCs that can be developed and harnessed for COVID-19 therapy. Options to manage the SARS-CoV-2 infection and its variants using various bioengineering tools to increase the therapeutic efficacy of MSCs are highlighted.

Mesenchymal stem/stromal cell-based therapies for severe viral pneumonia: therapeutic potential and challenges

Severe viral pneumonia is a significant cause of morbidity and mortality globally, whether due to outbreaks of endemic viruses, periodic viral epidemics, or the rarer but devastating global viral pandemics. While limited anti-viral therapies exist, there is a paucity of direct therapies to directly attenuate viral pneumonia-induced lung injury, and management therefore remains largely supportive. Mesenchymal stromal/stem cells (MSCs) are receiving considerable attention as a cytotherapeutic for viral pneumonia. Several properties of MSCs position them as a promising therapeutic strategy for viral pneumonia-induced lung injury as demonstrated in pre-clinical studies in relevant models. More recently, early phase clinical studies have demonstrated a reassuring safety profile of these cells. These investigations have taken on an added importance and urgency during the COVID-19 pandemic, with multiple trials in progress across the globe. In parallel with clinical translation, strategies are being investigated to enhance the therapeutic potential of these cells in vivo, with different MSC tissue sources, specific cellular products including cell-free options, and strategies to ‘licence’ or ‘pre-activate’ these cells, all being explored. This review will assess the therapeutic potential of MSC-based therapies for severe viral pneumonia. It will describe the aetiology and epidemiology of severe viral pneumonia, describe current therapeutic approaches, and examine the data suggesting therapeutic potential of MSCs for severe viral pneumonia in pre-clinical and clinical studies. The challenges and opportunities for MSC-based therapies will then be considered.

High Induction of IL-6 Secretion From hUCMSCs Optimize the Potential of hUCMSCs and TCZ as Therapy for COVID-19-Related ARDS

Biological and cellular interleukin-6 (IL-6)-related therapies have been used to treat severe COVID-19 pneumonia with hyperinflammatory syndrome and acute respiratory failure, which prompted further exploration of the role of IL-6 in human umbilical cord mesenchymal stem cell (hUCMSC) therapy. Peripheral blood mononuclear cells (PBMCs) were responders cocultured with hUCMSCs or exogenous IL-6. A PBMC suppression assay was used to analyze the anti-inflammatory effects via MTT assay. The IL-6 concentration in the supernatant was measured using ELISA. The correlation between the anti-inflammatory effect of hUCMSCs and IL-6 levels and the relevant roles of IL-6 and IL-6 mRNA expression was analyzed using the MetaCore functional network constructed from gene microarray data. The location of IL-6 and IL-6 receptor (IL-6R) expression was further evaluated. We reported that hUCMSCs did not initially exert any inhibitory effect on PHA-stimulated proliferation; however, a potent inhibitory effect on PHA-stimulated proliferation was observed, and the IL-6 concentration reached approximately 1000 ng/mL after 72 hours. Exogenous 1000 ng/mL IL-6 inhibited PHA-stimulated inflammation but less so than hUCMSCs. The inhibitory effects of hUCMSCs on PHA-stimulated PBMCs disappeared after adding an IL-6 neutralizing antibody or pretreatment with tocilizumab (TCZ), an IL-6R antagonist. hUCMSCs exert excellent anti-inflammatory effects by inducing higher IL-6 levels, which is different from TCZ. High concentration of IL-6 cytokine secretion plays an important role in the anti-inflammatory effect of hUCMSC therapy. Initial hUCMSC therapy, followed by TCZ, seems to optimize the therapeutic potential to treat COVID-19-related acute respiratory distress syndrome (ARDS).

Mesenchymal Stromal Cells: an Antimicrobial and Host-Directed Therapy for Complex Infectious Diseases

There is an urgent need for new antimicrobial strategies for treating complex infections and emerging pathogens. Human mesenchymal stromal cells (MSCs) are adult multipotent cells with antimicrobial properties, mediated through direct bactericidal activity and modulation of host innate and adaptive immune cells. More than 30 in vivo studies have reported on the use of human MSCs for the treatment of infectious diseases, with many more studies of animal MSCs in same-species models of infection. MSCs demonstrate potent antimicrobial effects against the major classes of human pathogens (bacteria, viruses, fungi, and parasites) across a wide range of infection models. Mechanistic studies have yielded important insight into their immunomodulatory and bactericidal activity, which can be enhanced through various forms of preconditioning. MSCs are being investigated in over 80 clinical trials for difficult-to-treat infectious diseases, including sepsis and pulmonary, intra-abdominal, cutaneous, and viral infections. Completed trials consistently report MSCs to be safe and well tolerated, with signals of efficacy against some infectious diseases. Although significant obstacles must be overcome to produce a standardized, affordable, clinical-grade cell therapy, these studies suggest that MSCs may have particular potential as an adjunct therapy in complex or resistant infections.

Induction of the NEK family of kinases in the lungs of mice subjected to cecal ligation and puncture model of sepsis

Endothelial barrier dysfunction (EBD) is the hallmark of Acute Respiratory Distress Syndrome (ARDS), a potentially lethal respiratory disorder associated with the COVID-19 - related deaths. Herein, we employed a cecal ligation and puncture (CLP) murine model of sepsis, to evaluate the effects of sepsis-induced EBD in the expression of the never in mitosis A (NIMA)-related kinases (NEKs). Members of that family of kinases regulate the activity and expression of the tumor suppressor P53, previously shown to modulate the actin cytoskeleton remodeling. Our results introduce the induction of NEK2, NEK3, NEK4, NEK7, and NEK9 in a CLP model of sepsis. Hence, we suggest that NEKs are involved in inflammatory processes and are holding the potential to serve as novel therapeutic targets for pathologies related to EBD, including ARDS and sepsis. Further studies will delineate the underlying molecular events and their interrelations with P53.

The future of acute and emergency care

Improved outcomes for acutely unwell patients are predicated on early identification of deterioration, accelerating the time to accurate diagnosis of the underlying condition, selection and titration of treatments that target biological phenotypes, and personalised endpoints to achieve optimal benefit yet minimise iatrogenic harm. Technological developments entering routine clinical practice over the next decade will deliver a sea change in patient management. Enhanced point of care diagnostics, more sophisticated physiological and biochemical monitoring with superior analytics and computer-aided support tools will all add considerable artificial intelligence to complement clinical skills. Experts in different fields of emergency and critical care medicine offer their perspectives as to which research developments could make a big difference within the next decade.

Stem cell therapies and benefaction of somatic cell nuclear transfer cloning in COVID-19 era

BACKGROUND

The global health emergency of COVID-19 has necessitated the development of multiple therapeutic modalities including vaccinations, antivirals, anti-inflammatory, and cytoimmunotherapies, etc. COVID-19 patients suffer from damage to various organs and vascular structures, so they present multiple health crises. Mesenchymal stem cells (MSCs) are of interest to treat acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 infection.

MAIN BODY

Stem cell-based therapies have been verified for prospective benefits in copious preclinical and clinical studies. MSCs confer potential benefits to develop various cell types and organoids for studying virus-human interaction, drug testing, regenerative medicine, and immunomodulatory effects in COVID-19 patients. Apart from paving the ways to augment stem cell research and therapies, somatic cell nuclear transfer (SCNT) holds unique ability for a wide range of health applications such as patient-specific or isogenic cells for regenerative medicine and breeding transgenic animals for biomedical applications. Being a potent cell genome-reprogramming tool, the SCNT has increased prominence of recombinant therapeutics and cellular medicine in the current era of COVID-19. As SCNT is used to generate patient-specific stem cells, it avoids dependence on embryos to obtain stem cells.

CONCLUSIONS

The nuclear transfer cloning, being an ideal tool to generate cloned embryos, and the embryonic stem cells will boost drug testing and cellular medicine in COVID-19.