A phase Ib/IIa, randomised, double-blind, multicentre trial to assess the safety and efficacy of expanded Cx611 allogeneic adipose-derived stem cells (eASCs) for the treatment of patients with community-acquired bacterial pneumonia admitted to the intensive care unit

Human mesenchymal stromal cells inhibit Mycobacterium avium replication in clinically relevant models of lung infection

INTRODUCTION

Novel therapeutic strategies are urgently needed for Mycobacterium avium complex pulmonary disease (MAC-PD). Human mesenchymal stromal cells (MSCs) can directly inhibit MAC growth, but their effect on intracellular bacilli is unknown. We investigated the ability of human MSCs to reduce bacterial replication and inflammation in MAC-infected macrophages and in a murine model of MAC-PD.

METHODS

Human monocyte-derived macrophages (MDMs) were infected with M. avium Chester strain and treated with human bone marrow-derived MSCs. Intracellular and extracellular colony-forming units (CFUs) were counted at 72 hours. Six-week-old female balb/c mice were infected by nebulisation of M. avium Chester. Mice were treated with 1×106 intravenous human MSCs or saline control at 21 and 28 days post-infection. Lungs, liver and spleen were harvested 42 days post-infection for bacterial counts. Cytokines were quantified by ELISA.

RESULTS

MSCs reduced intracellular bacteria in MDMs over 72 hours (median 35% reduction, p=0.027). MSC treatment increased extracellular concentrations of prostaglandin E2 (PGE2) (median 10.1-fold rise, p=0.002) and reduced tumour necrosis factor-α (median 28% reduction, p=0.025). Blocking MSC PGE2 production by cyclo-oxygenase-2 (COX-2) inhibition with celecoxib abrogated the antimicrobial effect, while this was restored by adding exogenous PGE2. MSC-treated mice had lower pulmonary CFUs (median 18% reduction, p=0.012), but no significant change in spleen or liver CFUs compared with controls.

CONCLUSION

MSCs can modulate inflammation and reduce intracellular M. avium growth in human macrophages via COX-2/PGE2 signalling and inhibit pulmonary bacterial replication in a murine model of chronic MAC-PD.

The safety and efficacy of stem cells for the treatment of severe community-acquired bacterial pneumonia: A randomized clinical trial

PURPOSE

Evaluate the safety profile of expanded allogeneic adipose-derived mesenchymal stem cell (eASC) for the treatment of severe community-acquired bacterial pneumonia (CABP).

MATERIALS AND METHODS

Randomized, multicenter, double-blind, placebo-controlled, phase 1b/2a trial. Patients with severe CABP were enrolled to receive intravenous infusions of Cx611 or placebo. The primary objective was safety including hypersensitivity reactions, thromboembolic events, and immunological responses to Cx611. The secondary endpoints included the clinical cure rate, ventilation-free days, and overall survival (Day 90).

RESULTS

Eighty-three patients were randomized and received infusions (Cx611: n = 42]; placebo: n = 41]. The mean age was similar (Cx611: 61.1 [11.2] years; placebo: 63.4 [10.4] years). The number of AEs and treatment-emergent AEs were similar (243; 184 and 2; 1) in Cx611 and placebo respectively. Hypersensitivity reactions or thromboembolic events were similar (Cx611: n = 9; placebo: n = 12). Each study arm had similar anti-HLA antibody/DSA levels at Day 90. The clinical cure rate (Cx611: 86.7%; placebo: 93.8%), mean number of ventilator-free days (Cx611: 12.2 [10.29] days; placebo: 15.4 [10.75] days), and overall survival (Cx611: 71.5%; placebo: 77.0%) did not differ between study arms.

CONCLUSION

Cx611 was well tolerated in severe CABP. These data provide insights for future stem cell clinical study designs, endpoints and sample size calculation.

TRIAL REGISTRATION

NCT03158727 (retrospectively registered: May 09, 2017). Full study protocol: https://clinicaltrials.gov/ProvidedDocs/27/NCT03158727/Prot_000.pdf.

Mesenchymal stem cells in lung diseases and their potential use in COVID-19 ARDS: A systematized review

COVID-19 can converge with the pro-inflammatory immunoregulatory mechanisms of chronic lung diseases. Given the disorders inherent to lung transplantation and the inexistence of other definitive therapeutic alternatives, Adipose tissue-derived Stem Cells (ASCs) presented themselves as a therapeutic hope. The purpose of this review is to assess the basis for the potential use of ASCs in lung diseases unresponsive to conventional therapy, relating to their possible use in COVID-19 ARDS. 35 studies comprised this review, 14 being narrative reviews, 19 preclinical trials and two proofs of concept. COVID-19 can converge with the pro-inflammatory immunoregulatory mechanisms of chronic lung diseases. In view of the disorders inherent to lung transplantation and the inexistence of definitive therapeutic alternatives, Adipose tissue-derived Stem Cells (ASCs) presented themselves as a therapeutic hope. Its detailed reading indicated the absence of serious adverse effects and toxicity to the administration of ASCs and suggested possible effectiveness in reducing lung damage, in addition to promoting the recovery of leukocytes and lymphocytes with its immunomodulatory and anti-apoptotic effects. The revised clinical data suggests optimism in the applicability of ASCs in other immunoinflammatory diseases and in severe COVID-19 ARDS. However, further studies are needed to develop a consensus on the methods of collection of ASCs, the ideal dosage schedule, the most effective time and route of administration, as well as on the definition of indications for the administration of ASCs in cases of COVID-19 for conducting clinical trials in near future.

Role of the regulation of mesenchymal stem cells on macrophages in sepsis

Sepsis is a common clinical critical disease with high mortality. The excessive release of cytokines from macrophages is the main cause of out-of-control immune response in sepsis. Mesenchymal stem cells (MSCs) are thought to be useful in adjunctive therapy of sepsis and related diseases, due to their function in immune regulation, anti-inflammatory, antibacterial, and tissue regeneration. Also there have been several successful cases in clinical treatment. Some previous studies have shown that MSCs regulate the function of macrophages through secreting cytokines and extracellular vesicles, or transferring mitochondria directly to target cells, which affects the progress of sepsis. Here, we review the regulation of MSCs on macrophages in sepsis, mainly focus on the regulation ways. We hope that will help to understand the immunological mechanism and also provide some clues for the clinical application of MSCs in the biotherapy of sepsis.

Dose-specific efficacy of adipose-derived mesenchymal stem cells in septic mice

BACKGROUND

Mesenchymal stem cells (MSCs) therapy for sepsis has been extensively studied in the past decade; however, the treatment regimen and mechanism of action of MSCs remain elusive. Here, we attempted to understand the efficacy and mechanism of action of MSCs on rescuing mice with sepsis.

METHODS

A mouse model of sepsis was produced by cecal ligation and puncture (CLP). Allogeneic adipose-derived MSCs (ADSCs) were administered by intravenous infusion at 6 h after CLP, and dose-related effects of ADSCs on these mice were determined by survival rate, histopathological changes, biochemical and coagulation parameters, bacterial load, and plasma levels of endotoxin and inflammatory cytokines. The tissue distribution of intravenously infused ADSCs in septic mice was investigated by pre-labeling ADSCs with the lipophilic membrane dye PKH26. RNA sequencing analysis was performed to assess the transcriptional changes in peripheral blood mononuclear cells (PBMCs) and the liver.

RESULTS

A significant therapeutic effect of ADSCs at a dose of 2 × 10⁷ cells/kg in septic mice was evidenced by a remarkable reduction in mortality (35.89% vs. 8.89% survival rate), blood bacterial burden, systemic inflammation, and multiple organ damage. In contrast, ADSCs at a lower dose (1 × 10⁷ cells/kg) failed to achieve any beneficial outcomes, while ADSCs at a higher dose (4 × 10⁷ cells/kg) caused more early death within 24 h after CLP, retaining a steady survival rate of 21.42% thereafter. PKH26-labeled ADSCs were predominantly localized in the lungs of septic mice after intravenous infusion, with only a smaller proportion of PKH26-positive signals appearing in the liver and spleen. RNA sequencing analysis identified that insufficient phagocytic activity of PBMCs in addition to a hyperactivation of the hepatic immune response was responsible for the ineffectiveness of low-dose ADSCs therapy, and acute death caused by high-dose ADSCs infusion was associated with impaired coagulation signaling in PBMCs and exacerbated hepatic hypoxic injury.

CONCLUSIONS

Our findings demonstrate a dose-specific effect of ADSCs on the treatment of sepsis due to dose-related interactions between exogenous stem cells and the host's microenvironment. Therefore, a precise dosing regimen is a prerequisite for ADSCs therapy for sepsis.

CD146+ Umbilical Cord Mesenchymal Stem Cells Exhibit High Immunomodulatory Activity and Therapeutic Efficacy in Septic Mice

Background

Several studies have shown that MSCs can significantly improve the survival of sepsis animals. CD146+ mesenchymal stem cells (MSCs) correlate with high therapeutic potency. However, their therapeutic effect on sepsis and detail mechanisms have not been explored.

Methods

The effect of CD146±MSCs on differentiation of Treg, Th1, Th17 subsets was evaluated by flow cytometry. The effects of CD146±MSCs on RAW264.7 phagocytosis and LPS-stimulated polarization were studied using a co-culture protocol. Luminex bead array and RNA sequencing were employed to determine the mechanisms of MSCs on LPS-stimulated RAW264.7. The Arg1 protein was detected by Western blot. CD146±MSCs were injected into LPS-induced sepsis mice by tail vein. The therapeutic effect was assessed by organ HE staining, T-cell subsets, cytokine in plasma, peritoneal macrophages, infiltrating monocytes subpopulations.

Results

In vitro, CD146+MSCs could significantly increase the proportion of Treg cells. Co-culture with CD146+MSCs increase the phagocytic rate of RAW264.7. CD146+MSCs regulate M2-type macrophages production more rapidly. The transcript profile differences between the CD146+MSCs and CD146-MSCs groups were clustered in arginine metabolism pathways. CD146+MSCs decreased NO production and increased ARG1 expression. CD146+MSCs secreted higher level of IL15,IFNγ, VEGF and lower level of IL1β, IL8 under LPS stimuli. In vivo, The level of IL10 at 24h and CXCL1, IFNγ at 12h in CD146+MSCs group was the highest. CD146+MSCs treatment enhances the phagocytic capacity of peritoneal macrophages. CD146+MSCs also increases the ratios of CD11b+Ly6C^lo reparative monocytes and CD11b+Ly6C^hi inflammatory monocytes until 24h.

Conclusion

Compared with CD146-MSCs, CD146+MSCs can accelerate the end of the inflammatory response and have robust anti-inflammatory effects, by increasing the Treg cells, promoting macrophage phagocytosis, enhancing the reparative macrophage, secreting more VEGF, etc.

Pathophysiology of Sepsis and Genesis of Septic Shock: The Critical Role of Mesenchymal Stem Cells (MSCs)

The treatment of sepsis and septic shock remains a major public health issue due to the associated morbidity and mortality. Despite an improvement in the understanding of the physiological and pathological mechanisms underlying its genesis and a growing number of studies exploring an even higher range of targeted therapies, no significant clinical progress has emerged in the past decade. In this context, mesenchymal stem cells (MSCs) appear more and more as an attractive approach for cell therapy both in experimental and clinical models. Pre-clinical data suggest a cornerstone role of these cells and their secretome in the control of the host immune response. Host-derived factors released from infected cells (i.e., alarmins, HMGB1, ATP, DNA) as well as pathogen-associated molecular patterns (e.g., LPS, peptidoglycans) can activate MSCs located in the parenchyma and around vessels to upregulate the expression of cytokines/chemokines and growth factors that influence, respectively, immune cell recruitment and stem cell mobilization. However, the way in which MSCs exert their beneficial effects in terms of survival and control of inflammation in septic states remains unclear. This review presents the interactions identified between MSCs and mediators of immunity and tissue repair in sepsis. We also propose paradigms related to the plausible roles of MSCs in the process of sepsis and septic shock. Finally, we offer a presentation of experimental and clinical studies and open the way to innovative avenues of research involving MSCs from a prognostic, diagnostic, and therapeutic point of view in sepsis.

Clinical applications of mesenchymal stromal cell-based therapies for pulmonary diseases: An Update and Concise Review

Lung disorders are a leading cause of morbidity and death worldwide. For many disease conditions, no effective and curative treatment options are available. Mesenchymal stromal cell (MSC)-based therapy is one of the cutting-edge topics in medical research today. It offers a novel and promising therapeutic option for various acute and chronic lung diseases due to its potent and broad-ranging immunomodulatory activities, bacterial clearance, tissue regeneration, and proangiogenic and antifibrotic properties, which rely on both cell-to-cell contact and paracrine mechanisms. This review covers the sources and therapeutic potential of MSCs. In particular, a total of 110 MSC-based clinical applications, either completed clinical trials with safety and early efficacy results reported or ongoing worldwide clinical trials of pulmonary diseases, are systematically summarized following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, including acute/viral pulmonary disease, community-acquired pneumonia (CAP), chronic obstructive pulmonary disease (COPD), bronchopulmonary dysplasia (BPD), interstitial lung diseases (ILD), chronic pulmonary fibrosis, bronchiolitis obliterans syndrome (BOS) and lung cancer. The results of recent clinical studies suggest that MSCs are a promising therapeutic approach for the treatment of lung diseases. Nevertheless, large-scale clinical trials and evaluation of long-term effects are necessary in further studies.