Mesenchymal stromal cell therapy in COPD: from bench to bedside

Mesenchymal stromal cell-based therapy in lung diseases; from research to clinic

Recent studies demonstrated that mesenchymal stem cells (MSCs) are important for the cell-based therapy of diseased or injured lung due to their immunomodulatory and regenerative properties as well as limited side effects in experimental animal models. Preclinical studies have shown that MSCs have also a remarkable effect on the immune cells, which play major roles in the pathogenesis of multiple lung diseases, by modulating their activity, proliferation, and functions. In addition, MSCs can inhibit both the infiltrated immune cells and detrimental immune responses in the lung and can be used in treating lung diseases caused by a virus infection such as Tuberculosis and SARS-COV-2. Moreover, MSCs are a source for alveolar epithelial cells such as type 2 (AT2) cells. These MSC-derived functional AT2-like cells can be used to treat and diminish serious lung disorders, including acute lung injury, asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis in animal models. As an alternative MSC-based therapy, extracellular vesicles that are derived from MSC-derived can be employed in regenerative medicine. Herein, we discussed the key research findings from recent clinical and preclinical studies on the functions of MSCs in treating some common and well-studied lung diseases. We also discussed the mechanisms underlying MSC-based therapy of well-studied lung diseases, and the recent employment of MSCs in both the attenuation of lung injury/inflammation and promotion of the regeneration of lung alveolar cells after injury. Finally, we described the role of MSC-based therapy in treating major pulmonary diseases such as pneumonia, COPD, asthma, and idiopathic pulmonary fibrosis (IPF).

Use of Biologics and Stem Cells in the Treatment of Other Inflammatory Diseases in the Horse

Mesenchymal stem cells (MSCs) are powerful immunomodulatory cells that act via multiple mechanisms to coordinate, inhibit, and control the cells of the immune system. MSCs act as rescuers for various damaged or degenerated cells of the body via (1) cytokines, growth factors, and signaling molecules; (2) extracellular vesicle (exosome) signaling; and (3) direct donation of mitochondria. Several studies evaluating the efficacy of MSCs have used MSCs grown using xenogeneic media, which may reduce or eliminate efficacy. Although more research is needed to optimize the anti-inflammatory potential of MSCs, there is ample evidence that MSC therapeutics are worthy of further development.

The wonders of stem cells therapeutic application towards chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a respiratory condition characterized by its heterogeneous nature, progressive course, and significant impact on individuals' quality of life. It is a prevalent global health issue affecting a substantial number of individuals and can pose life-threatening complications if left unmanaged. The development and course of COPD can be influenced by a range of risk factors, including genetic predisposition and environmental exposures. Nevertheless, as researchers adopt a more comprehensive and expansive viewpoint of therapeutic techniques, the associated obstacles become more apparent. Indeed, a definitive medication for COPD that reliably leads to symptom alleviation has not yet been discovered. Therefore, the limitations of conventional therapy methods prompted researchers to focus on the advancement of novel procedures, potentially leading to significant outcomes. In contemporary times, the field of regenerative medicine and cell therapy has presented unprecedented opportunities for the exploration of innovative treatments for COPD, owing to the distinctive attributes exhibited by stem cells. Hence, it is imperative to provide due consideration to preclinical investigations and notable characteristics of stem cells as they serve as a means to comprehensively comprehend the fundamental mechanisms of COPD and uncover novel therapeutic strategies with enhanced efficacy for patients.

[Mesenchymal stem cells: Therapeutic option in ARDS, COPD, and COVID-19 patients]

Acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD) and COVID-19 have as a common characteristic the inflammatory lesion of the lung epithelium. The therapeutic options are associated with opportunistic infections, a hyperglycemic state, and adrenal involvement. Therefore, the search for new treatment strategies that reduce inflammation, and promote re-epithelialization of damaged tissue is very important. This work describes the relevant pathophysiological characteristics of these diseases and evaluates recent findings on the immunomodulatory, anti-inflammatory and regenerative effect of mesenchymal stem cells (MSC) and their therapeutic use. In Pubmed we selected the most relevant studies on the subject, published between 2003 and 2022 following the PRISMA guide. We conclude that MSCs are an important therapeutic option for regenerative treatment in COPD, ARDS, and COVID-19, because of their ability to differentiate into type II pneumocytes and maintain the size and function of lung tissue by replacing dead or damaged cells.

Effect of Hyaluronic Acid and Mesenchymal Stem Cells Secretome Combination in Promoting Alveolar Regeneration

Pharmacological therapies in lung diseases are nowadays useful in reducing the symptomatology of lung injury. However, they have not yet been translated to effective treatment options able to restore the lung tissue damage. Cell-therapy based on Mesenchymal Stem Cells (MSCs) is an attractive, as well as new therapeutic approach, although some limitations can be ascribed for therapeutic use, such as tumorigenicity and immune rejection. However, MSCs have the capacity to secrete multiple paracrine factors, namely secretome, capable of regulating endothelial and epithelial permeability, decrease inflammation, enhancing tissue repair, and inhibiting bacterial growth. Furthermore, Hyaluronic acid (HA) has been demonstrated to have particularly efficacy in promoting the differentiation of MSCs in Alveolar type II (ATII) cells. In this frame, the combination of HA and secretome to achieve the lung tissue regeneration has been investigated for the first time in this work. Overall results showed how the combination of HA (low and medium molecular weight HA) plus secretome could enhance MSCs differentiation in ATII cells (SPC marker expression of about 5 ng/mL) compared to the only HA or secretome solutions alone (SPC about 3 ng/mL, respectively). Likewise, cell viability and cell rate of migration were reported to be improved for HA and secretome blends, indicating an interesting potentiality of such systems for lung tissue repair. Moreover, an anti-inflammatory profile has been revealed when dealing with HA and secretome mixtures. Therefore, these promising results can allow important advance in the accomplishment of the future therapeutic approach in respiratory diseases, up to date still missing.

Key Role of Mesenchymal Stromal Cell Interaction with Macrophages in Promoting Repair of Lung Injury

Lung macrophages (Mφs) are essential for pulmonary innate immunity and host defense due to their dynamic polarization and phenotype shifts. Mesenchymal stromal cells (MSCs) have secretory, immunomodulatory, and tissue-reparative properties and have shown promise in acute and chronic inflammatory lung diseases and in COVID-19. Many beneficial effects of MSCs are mediated through their interaction with resident alveolar and pulmonary interstitial Mφs. Bidirectional MSC-Mφ communication is achieved through direct contact, soluble factor secretion/activation, and organelle transfer. The lung microenvironment facilitates MSC secretion of factors that result in Mφ polarization towards an immunosuppressive M2-like phenotype for the restoration of tissue homeostasis. M2-like Mφ in turn can affect the MSC immune regulatory function in MSC engraftment and tissue reparatory effects. This review article highlights the mechanisms of crosstalk between MSCs and Mφs and the potential role of their interaction in lung repair in inflammatory lung diseases.

Optimized Protocol for Isolation and Culture of Murine Neonatal Primary Lung Fibroblasts

During all the stages of lung development, the lung mesoderm (or mesenchyme) is closely related to the endoderm, and their cross-regulation promotes, controls, and drives all lung developmental processes. Generation of 3D organoids in vitro, RNA assays, and mitochondrial respiration studies are used to analyze lung development and regeneration to better understand the interactions between epithelium and mesenchyme, as well as for the study of redox alterations and the metabolic status of the cells. Moreover, to avoid using immortalized cell lines in these in vitro approaches, standardized murine neonatal primary lung fibroblast isolation techniques are essential. Here, we present an optimized method to isolate, culture, and freeze primary lung fibroblasts from neonatal lungs. Our current method includes step-by-step instructions accompanied by graphical explanations and critical steps.

Impaired Alveolar Re-Epithelialization in Pulmonary Emphysema

Alveolar type II (ATII) cells are progenitors in alveoli and can repair the alveolar epithelium after injury. They are intertwined with the microenvironment for alveolar epithelial cell homeostasis and re-epithelialization. A variety of ATII cell niches, transcription factors, mediators, and signaling pathways constitute a specific environment to regulate ATII cell function. Particularly, WNT/β-catenin, YAP/TAZ, NOTCH, TGF-β, and P53 signaling pathways are dynamically involved in ATII cell proliferation and differentiation, although there are still plenty of unknowns regarding the mechanism. However, an imbalance of alveolar cell death and proliferation was observed in patients with pulmonary emphysema, contributing to alveolar wall destruction and impaired gas exchange. Cigarette smoking causes oxidative stress and is the primary cause of this disease development. Aberrant inflammatory and oxidative stress responses result in loss of cell homeostasis and ATII cell dysfunction in emphysema. Here, we discuss the current understanding of alveolar re-epithelialization and altered reparative responses in the pathophysiology of this disease. Current therapeutics and emerging treatments, including cell therapies in clinical trials, are addressed as well.

Chronic obstructive pulmonary disease and asthma: mesenchymal stem cells and their extracellular vesicles as potential therapeutic tools

Chronic lung diseases, such as chronic obstructive pulmonary disease (COPD) and asthma, are one of the most frequent causes of morbidity and mortality in the global. COPD is characterized by progressive loss of lung function through inflammation, apoptosis, and oxidative stress caused by chronic exposure to harmful environmental pollutants. Airway inflammation and epithelial remodeling are also two main characteristics of asthma. In spite of extensive efforts from researchers, there is still a great need for novel therapeutic approaches for treatment of these conditions. Accumulating evidence suggests the potential role of mesenchymal stem cells (MSCs) in treatment of many lung injuries due to their beneficial features including immunomodulation and tissue regeneration. Besides, the therapeutic advantages of MSCs are chiefly related to their paracrine functions such as releasing extracellular vesicles (EVs). EVs comprising exosomes and microvesicles are heterogeneous bilayer membrane structures loaded with various lipids, nucleic acids and proteins. Due to their lower immunogenicity, tumorigenicity, and easier management, EVs have appeared as favorable alternatives to stem cell therapies. Therefore, in this review, we provided an overview on the current understanding of the importance of MSCs and MSC-derived EVs from different sources reported in preclinical and clinical COPD and asthmatic models.

How to Make Sense out of 75,000 Mesenchymal Stromal Cell Publications?

Mesenchymal stromal cells have been the subject of an expanding number of studies over the past decades. Today, over 75,000 publications are available that shine light on the biological properties and therapeutic effects of these versatile cells in numerous pre-clinical models and early-phase clinical trials. The massive number of papers makes it hard for researchers to comprehend the whole field, and furthermore, they give the impression that mesenchymal stromal cells are wonder cells that are curative for any condition. It is becoming increasingly difficult to dissect how and for what conditions mesenchymal stromal cells exhibit true and reproducible therapeutic effects. This article tries to address the question how to make sense of 75,000, and still counting, publications on mesenchymal stromal cells.

CD26 Inhibition Potentiates the Therapeutic Effects of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells by Delaying Cellular Senescence

Mesenchymal stem cells (MSCs) are recognized as potential treatments for multiple degenerative and inflammatory disorders as a number of animal and human studies have indicated their therapeutic effects. There are also several clinically approved medicinal products that are manufactured using these cells. For such large-scale manufacturing requirements, the in vitro expansion of harvested MSCs is essential. Multiple subculturing of MSCs, however, provokes cellular senescence processes which is known to deteriorate the therapeutic efficacy of the cells. Strategies to rejuvenate or selectively remove senescent MSCs are therefore highly desirable for fostering future clinical applications of these cells. In this present study, we investigated gene expression changes related to cellular senescence of MSCs derived from umbilical cord blood and found that CD26, also known as DPP4, is significantly upregulated upon cellular aging. We further observed that the inhibition of CD26 by genetic or pharmacologic means delayed the cellular aging of MSCs with their multiple passaging in culture. Moreover, the sorting and exclusion of CD26-positive MSCs from heterogenous cell population enhanced in vitro cell attachment and reduced senescence-associated cytokine secretion. CD26-negative MSCs also showed superior therapeutic efficacy in mouse lung emphysema model. Our present results collectively suggest CD26 is a potential novel target for the rejuvenation of senescent MSCs for their use in manufacturing MSC-based applications.

Mitochondria in Focus: From Function to Therapeutic Strategies in Chronic Lung Diseases

Mitochondria are essential organelles for cell metabolism, growth, and function. Mitochondria in lung cells have important roles in regulating surfactant production, mucociliary function, mucus secretion, senescence, immunologic defense, and regeneration. Disruption in mitochondrial physiology can be the central point in several pathophysiologic pathways of chronic lung diseases such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and asthma. In this review, we summarize how mitochondria morphology, dynamics, redox signaling, mitophagy, and interaction with the endoplasmic reticulum are involved in chronic lung diseases and highlight strategies focused on mitochondrial therapy (mito-therapy) that could be tested as a potential therapeutic target for lung diseases.

Roles of Mesenchymal Cells in the Lung: From Lung Development to Chronic Obstructive Pulmonary Disease

Mesenchymal cells are an essential cell type because of their role in tissue support, their multilineage differentiation capacities and their potential clinical applications. They play a crucial role during lung development by interacting with airway epithelium, and also during lung regeneration and remodeling after injury. However, much less is known about their function in lung disease. In this review, we discuss the origins of mesenchymal cells during lung development, their crosstalk with the epithelium, and their role in lung diseases, particularly in chronic obstructive pulmonary disease.

Human Adipose-Derived Mesenchymal Stem Cells Ameliorate Elastase-Induced Emphysema in Mice by Mesenchymal-Epithelial Transition

Purpose

Chronic obstructive pulmonary disease (COPD) is a worldwide problem because of its high prevalence and mortality. However, there is no fundamental treatment to ameliorate their pathological change in COPD lung. Recently, adipose-derived mesenchymal stem cells (ADSCs) have attracted attention in the field of regenerative medicine to repair damaged organs. Moreover, their utility in treating respiratory diseases has been reported in some animal models. However, the detailed mechanism by which ADSCs improve chronic respiratory diseases, including COPD, remains to be elucidated. We examined whether human ADSCs (hADSCs) ameliorated elastase-induced emphysema and whether hADSCs differentiated into alveolar epithelial cells in a murine model of COPD.

Methods

Female SCID-beige mice (6 weeks old) were divided into the following four groups according to whether they received an intratracheal injection of phosphate-buffered saline or porcine pancreatic elastase, and whether they received an intravenous injection of saline or hADSCs 3 days after intratracheal injection; Control group, hADSC group, Elastase group, and Elastase-hADSC group. We evaluated the lung function, assessed histological changes, and compared gene expression between hADSCs isolated from the lung of Elastase-hADSC group and naïve hADSCs 28 days after saline or elastase administration.

Results

hADSCs improved the pathogenesis of COPD, including the mean linear intercept and forced expiratory volume, in an elastase-induced emphysema model in mice. Furthermore, hADSCs were observed in the lungs of elastase-treated mice at 25 days after administration. These cells expressed genes related to mesenchymal–epithelial transition and surface markers of alveolar epithelial cells, such as TTF-1, β-catenin, and E-cadherin.

Conclusion

hADSCs have the potential to improve the pathogenesis of COPD by differentiating into alveolar epithelial cells by mesenchymal–epithelial transition.

Mechanisms, Pathophysiology and Currently Proposed Treatments of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is one of the leading global causes of morbidity and mortality. A hallmark of COPD is progressive airflow obstruction primarily caused by cigarette smoke (CS). CS exposure causes an imbalance favoring pro- over antioxidants (oxidative stress), leading to transcription factor activation and increased expression of inflammatory mediators and proteases. Different cell types, including macrophages, epithelial cells, neutrophils, and T lymphocytes, contribute to COPD pathophysiology. Alteration in cell functions results in the generation of an oxidative and inflammatory microenvironment, which contributes to disease progression. Current treatments include inhaled corticosteroids and bronchodilator therapy. However, these therapies do not effectively halt disease progression. Due to the complexity of its pathophysiology, and the risk of exacerbating symptoms with existing therapies, other specific and effective treatment options are required. Therapies directly or indirectly targeting the oxidative imbalance may be promising alternatives. This review briefly discusses COPD pathophysiology, and provides an update on the development and clinical testing of novel COPD treatments.

Exosomal lncRNA TCONS_00064356 derived from injured alveolar epithelial type II cells affects the biological characteristics of mesenchymal stem cells

Chronic obstructive pulmonary disease (COPD) is a prevalent respiratory disease, and a leading cause of morbidity and mortality worldwide. There is still a lack of effective treatment to improve pulmonary structural abnormality and reverse the progression of COPD. Mesenchymal stem cell (MSC)-based therapies have attracted much attention and show promising clinical application prospects in COPD treatment. Understanding the communication between injured alveolar cells and MSCs will help us improve the efficiency of MSC-based therapies. Here, we showed that exosomes secreted by injured alveolar epithelial type II (AEC-II) cells could promote the proliferation and migration of MSCs, accompanied with increased expression levels of genes related to mitochondrial synthesis and transfer. Moreover, we identified 21 significantly dysregulated exosomal lncRNAs (16 upregulated and 5 downregulated) using lncRNA sequencing. In addition, we found that lncRNA TCONS_00064356-overexpressing MSCs showed increased proliferation and migration capacities and upregulated expression levels of the genes related to mitochondrial synthesis and transfer. Together, our study uncovers a new potential exosome-mediated communication pathway between injured AEC-II cells and MSCs and provides new targets and ideas for improving the efficiency of MSC-based therapies for COPD.

Study of Mesenchymal Stem Cell-Mediated Mitochondrial Transfer in In Vitro Models of Oxidant-Mediated Airway Epithelial and Smooth Muscle Cell Injury

Mesenchymal stem cells (MSCs) have emerged as an attractive candidate for cell-based therapy. In the past decade, many animal and pilot clinical studies have demonstrated that MSCs are therapeutically beneficial for the treatment of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease (COPD). However, due to the scarcity of adult human MSCs, human-induced pluripotent stem cells mesenchymal stem cells (iPSCs) are now increasingly used as a source of MSCs. iPSCs are derived by reprogramming somatic cells from a wide variety of tissues such as skin biopsies and then differentiating them into iPSC-MSCs. One of the mechanisms through which MSCs exert their protective effects is mitochondrial transfer. Specifically, transfer of mitochondria from iPSC-MSCs to lung cells was shown to protect lung cells against oxidative stress-induced mitochondrial dysfunction and apoptosis and to reduce lung injury and inflammation in in vivo models of lung disease. In this chapter, we detail our methods to visualize and quantify iPSC-MSC-mediated mitochondrial transfer and to study its effects on oxidant-induced airway epithelial and smooth muscle cell models of acute airway cell injury.

Characterization of an elastase-induced emphysema model in immune-deficient rats

OBJECTIVES

Emphysema affects millions of patients worldwide. Cell transplantation and tissue engineering are promising approaches for the regeneration of gas exchange tissue in vivo. A reproducible and resource-efficient animal model with relevant pathological and physiological features is critical to assess efficacy of novel therapies. Here, we share a method for rapid development of emphysema in an adaptive immune-deficient rat with <5% mortality, which is ideal for high-throughput human cell-based experimentation.

METHODS

Porcine pancreatic elastase (PPE) was intratracheally administered to male RNU rats. Rats were monitored for 21 days after which subjects underwent lung computed tomography (CT) scans. Rats were then weighed, intubated and mechanically ventilated to measure dynamic compliance. After sacrifice, lungs were fixed, and histological sections were quantitatively assessed for emphysematous changes.

RESULTS

A single instillation of elastase was enough to produce anatomic and physiological evidence of emphysema. Weight change for doses of 16 and 32 units PPE/100 g were significantly lower than controls (P = 0.028 and P = 0.043, respectively). Compliance values for doses of 16 and 32 units PPE/100 g were significantly higher than controls (P = 0.037 and P = 0.006, respectively). Lung hyperlucency was confirmed by CT with mean Hounsfield units for a dose of 32 units PPE/100 g being significantly lower than controls (P < 0.001). The mean linear intersect for doses of 16 and 32 units PPE/100 g were significantly higher than controls (both P < 0.001). All reported P-values are one-sided.

CONCLUSIONS

We present an efficient method for emphysema development in immune-deficient rats as a tool to evaluate human biological therapeutics. Changes in dynamic compliance, histology and cross-sectional imaging recapitulate human emphysema.

All Trans Retinoic Acid (ATRA) progresses alveolar epithelium regeneration by involving diverse signalling pathways in emphysematous rat

INTRODUCTION

Pulmonary emphysema is characterized by destruction of alveoli leading to inadequate oxygenation, disability and frequently death. This destruction was understood so far as irreversible. Published data has shown that ATRA (All Trans Retinoic Acid) reverses elastase-induced emphysema in rats. However, the molecular mechanisms governing regeneration process are so far unknown.

OBJECTIVE

To examine the therapeutic potential of ATRA on various molecular pathways and their coordination towards governance of alveolar epithelial regeneration in emphysematous rats.

METHODS

Emphysema was induced by elastase versus saline in Sprague-Dawley rats. On days 26-37, rats received daily intraperitoneal injections with ATRA (500 μg/kg b.w.) versus olive-oil. Lungs were removed at day 38 for histopathology and investigation of relative mRNA and protein expressions.

RESULTS

Histopathological analysis has shown that losses of alveoli were recovered in therapy (EA) group. Moreover, expressions of markers genes for alveolar cell proliferation, differentiation and EMT events at mRNA and protein levels were significantly increased in EA group than emphysema group (ES). Upon validation at genomics level, expressions of components of Notch, Hedgehog, Wnt, BMP and TGFβ pathways were significantly attenuated in EA group when compared with ES and were well comparable with the healthy group.

CONCLUSION

Therapeutic supplementation of ATRA rectifies the deregulated Notch, Hedgehog, Wnt, BMP and TGFβ pathways in emphysema condition, resulting in alveolar epithelium regeneration. Hence, ATRA may prove to be a potential drug in the treatment of emphysema. Nevertheless, elaborated studies are to be conducted.

The Coronavirus Pandemic (SARS-CoV-2): New Problems Demand New Solutions, the Alternative of Mesenchymal (Stem) Stromal Cells

Mesenchymal (stem) stromal cells (MSC) can be a therapeutic alternative for COVID-19 considering their anti-inflammatory, regenerative, angiogenic, and even antimicrobial capacity. Preliminary data point to therapeutic interest of MSC for patients with COVID-19, and their effect seems based on the MSC's ability to curb the cytokine storm caused by COVID-19. In fact, promising clinical studies using MSC to treat COVID-19, are currently underway. For this reason, now is the time to firmly consider new approaches to MSC research that addresses key issues, like selecting the most optimal type of MSC for each indication, assuming the heterogeneity of the donor-dependent MSC and the biological niche where MSC are located.

Regulation of alveolar type 2 stem/progenitor cells in lung injury and regeneration

The renewal of lung epithelial cells is normally slow unless the lung is injured. The resident epithelial stem cells rapidly proliferate and differentiate to maintain lung structure and function when the lung is damaged. The alveolar epithelium is characterized by alveolar type 1 (AT1) and alveolar type 2 (AT2) cells. AT2 cells are the stem cells for alveoli, as they can both self-renew and generate AT1 cells. Abnormal proliferation and regulation of AT2 cells will lead to serious lung diseases including cancers. In this review, we focused on the alveolar stem/progenitor cells, the key physiological function of AT2 cells in lung homeostasis and the complicated regulation of AT2 cells in the repairing processes after lung injury.

Mesenchymal Stromal Cell Secretome for Severe COVID-19 Infections: Premises for the Therapeutic Use

From the end of 2019, the world population has been faced the spread of the novel coronavirus SARS-CoV-2 responsible for COVID-19 infection. In approximately 14% of the patients affected by the novel coronavirus, the infection progresses with the development of pneumonia that requires mechanical ventilation. At the moment, there is no specific antiviral treatment recommended for the COVID-19 pandemic and the therapeutic strategies to deal with the infection are only supportive. In our opinion, mesenchymal stem cell secretome could offer a new therapeutic approach in treating COVID-19 pneumonia, due to the broad pharmacological effects it shows, including anti-inflammatory, immunomodulatory, regenerative, pro-angiogenic and anti-fibrotic properties.

Molecular and Cellular Mechanisms Responsible for Beneficial Effects of Mesenchymal Stem Cell-Derived Product "Exo-d-MAPPS" in Attenuation of Chronic Airway Inflammation

Mesenchymal stem cells (MSCs), due to their potential for differentiation into alveolar epithelial cells and their immunosuppressive characteristics, are considered a new therapeutic agent in cell-based therapy of inflammatory lung disorders, including chronic obstructive pulmonary disease (COPD). Since most of the MSC-mediated beneficent effects were the consequence of their paracrine action, herewith, we investigated the effects of a newly designed MSC-derived product "Exosome-derived Multiple Allogeneic Protein Paracrine Signaling (Exo-d-MAPPS)" in the attenuation of chronic airway inflammation by using an animal model of COPD (induced by chronic exposure to cigarette smoke (CS)) and clinical data obtained from Exo-d-MAPPS-treated COPD patients. Exo-d-MAPPS contains a high concentration of immunomodulatory factors which are capable of attenuating chronic airway inflammation, including soluble TNF receptors I and II, IL-1 receptor antagonist, and soluble receptor for advanced glycation end products. Accordingly, Exo-d-MAPPS significantly improved respiratory function, downregulated serum levels of inflammatory cytokines (TNF-α, IL-1β, IL-12, and IFN-γ), increased serum concentration of immunosuppressive IL-10, and attenuated chronic airway inflammation in CS-exposed mice. The cellular makeup of the lungs revealed that Exo-d-MAPPS treatment attenuated the production of inflammatory cytokines in lung-infiltrated macrophages, neutrophils, and natural killer and natural killer T cells and alleviated the antigen-presenting properties of lung-infiltrated macrophages and dendritic cells (DCs). Additionally, Exo-d-MAPPS promoted the expansion of immunosuppressive IL-10-producing alternatively activated macrophages, regulatory DCs, and CD4+FoxP3+T regulatory cells in inflamed lungs which resulted in the attenuation of chronic airway inflammation. In a similar manner, as it was observed in an animal model, Exo-d-MAPPS treatment significantly improved the pulmonary status and quality of life of COPD patients. Importantly, Exo-d-MAPPS was well tolerated since none of the 30 COPD patients reported any adverse effects after Exo-d-MAPPS administration. In summing up, we believe that Exo-d-MAPPS could be considered a potentially new therapeutic agent in the treatment of chronic inflammatory lung diseases whose efficacy should be further explored in large clinical trials.

Rat bone mesenchymal stem cells exert antiproliferative effects on nicotine‑exposed T cells via iNOS production

Adoptive transfer of bone marrow‑derived mesenchymal stem cells (BMSCs) significantly alleviates smoking‑induced chronic obstructive pulmonary disease (COPD) in rats. Considering the critical roles of T cells during COPD development, the present study aimed to further identify the molecular mechanisms underlying the antiproliferative effect of BMSCs on splenic T cells isolated from rats following chronic exposure to nicotine. Splenic T cells were co‑cultured with rat BMSCs at various ratios and subsequently, T‑cell proliferation was measured using the Cell Counting Kit‑8 assay. The effects of the inducible nitric oxide synthase (iNOS) inhibitor N‑nitro‑L‑arginine methylester (L‑NAME) and short hairpin (sh)RNA‑lentivirus‑mediated knockdown of iNOS in BMSCs on T‑cell proliferation were evaluated. The expression levels of iNOS and STAT5 phosphorylation in BMSCs and T cells, respectively, were assessed by reverse transcription‑quantitative PCR and western blotting. A higher ratio of BMSCs to T cells resulted in increased inhibition of T‑cell proliferation; therefore, the ratio of 1:20 was selected for further in vitro experiments. At a dose of 5 µM, L‑NAME displayed the strongest ability to reverse the antiproliferative effects of BMSCs in the co‑culture system. Both L‑NAME treatment and shRNA‑mediated knockdown of iNOS expression significantly decreased the suppressive effects of BMSCs, downregulated iNOS expression at the mRNA and protein levels in BMSCs, and enhanced STAT5 phosphorylation in T cells. BMSCs inhibited the proliferation of nicotine‑exposed T cells, which was associated with iNOS expression in BMSCs and decreased STAT5 phosphorylation in T cells. The present study indicated the potential mechanisms underlying the beneficial effects of BMSC infusion in patients with chronic smoking‑induced COPD and emphysema.

The Potential of Mesenchymal Stem Cells to Treat Systemic Inflammation in Horses

One hallmark of mesenchymal stem cells (MSCs) is the ability to differentiate into multiple tissue types which assists in tissue regeneration. Another hallmark of MSCs is their potent anti-inflammatory and immunomodulatory properties and the potential to treat inflammatory, immune-mediated, and ischemic conditions. In equine practice, MSCs have shown efficacy in the treatment of musculoskeletal disorders such as tendinopathy, meniscal tears and cartilage injury. However, there are many equine disease processes and conditions that may benefit from the immunomodulatory properties of MSCs. Examples include conditions associated with overwhelming acute inflammatory response such as systemic inflammatory response syndrome to chronic diseases characterized by a prolonged low level of inflammation such as equine asthma and recurrent uveitis. For the acute inflammatory response processes, there is often high morbidity and mortality with no effective immunomodulatory treatment to prevent the overwhelming synthesis of proinflammatory mediators. For chronic inflammatory disease processes, frequently long-term corticosteroid treatment is the therapeutic mainstay, with serious potential complications. Thus, there is an unmet need for alternative anti-inflammatory treatments for both acute and chronic illnesses in horses. While MSCs show promise for such conditions, much research is needed before a clinically safe and effective treatment will be available. Optimal MSC tissue source, patient vs. donor source (autologous vs. allogeneic) and cell growth conditions need to be determined for each problem. For immediate use, allogeneic MSC treatments is preferable, but immune tolerance and adequate safety require further study. MSC collection and cryopreservation from horses before they are injured or ill, whether from umbilical cord tissue, bone marrow or adipose might become more widespread. Once these fundamental approaches to treating specific diseases with MSCs are determined, the route of administration, dose and timing of administration also need to be studied. To provide a framework for development of MSC immunomodulatory treatments, this article reviews the current understanding of equine MSC anti-inflammatory and immunomodulatory properties and proposes how MSC therapy may be further developed to treat acute onset systemic inflammatory processes and chronic inflammatory diseases.

Allogeneic mesenchymal stromal cells: Novel therapeutic option for mutated FLNA-associated respiratory failure in the pediatric setting

BACKGROUND

Mesenchymal stromal cell (MSC)-mediated therapeutic effects have been observed in the treatment of lung diseases. For the first time, this treatment was used as rescue therapy in a pediatric patient with a life-threatening respiratory syndrome associated with the filamin A (FLNA) gene mutation.

METHODS

A child with a new pathogenic variant of the FLNA gene c.7391_7403del (p.Val2464AlafsTer5), at the age of 18 months, due to serious and irreversible chronic respiratory failure, was treated with repeated intravenous infusions of allogeneic bone marrow (BM)-MSCs. The child's respiratory condition was monitored. Immunologic studies before each MSC treatment were performed.

RESULTS

No acute adverse events related to the MSC infusions were observed. After the second infusion, the child's respiratory condition progressively improved, with reduced necessity for mechanical ventilation support. A thorax computed tomography (CT) scan showed bilateral recovery of the basal parenchyma, anatomical-functional alignment and aerial penetration improvement. After the first MSC administration, an increase in Th17 and FoxP3⁺ T percentages in the peripheral blood was observed. After the second MSC infusion, a significant rise in the Treg/Th17 ratio was noted, as well as an increased percentage of CD20⁺ /CD19⁺ B lymphocytes and augmented PHA-induced proliferation.

DISCUSSION

MSC infusions are a promising therapeutic modality for patients in respiratory failure, as observed in this pediatric patient with an FLNA mutation. MSCs may have an immunomodulatory effect and thus mitigate lung injury; although in this case, MSC antimicrobial effects may have synergistically impacted the clinical improvements. Further investigations are planned to establish the safety and efficacy of this treatment option for interstitial lung diseases in children.

Immune-Modulation in Chronic Obstructive Pulmonary Disease: Current Concepts and Future Strategies

Chronic obstructive pulmonary disease (COPD) is caused by the chronic inhalation of toxic particles and gases that are primarily but not exclusively derived from cigarette smoke that may be either actively or passively inhaled, which initiates a persistent innate and adaptive immune response in the lung. This immune response is associated with an aberrant tissue repair and remodeling process that results in varying degrees of chronic inflammation with excess production of mucus in the central airways and permanent destruction of the smaller conducting airways and gas exchanging surface in the peripheral lung. Currently, the primary aims of treatment in COPD are bronchodilation (inhaled short- and long-acting β-agonist and antimuscarinic therapies), to control symptoms and nonspecific broad-acting anti-inflammatory agents (inhaled and oral corticosteroids, phosphor-di-esterase inhibitors, and macrolides). That provide symptomatic relief but have little or no impact on either disease progression or mortality. As our understanding of the immune pathogenesis of the COPD improves, available immune modulation therapies have the potential to alter or interfere with damaging immune pathways, thereby slowing relentless progression of lung tissue destruction. The purpose of this brief review is to discuss our current understanding of the immune pathogenesis of both the airways and parenchymal injury as well as the dysfunctional tissue repair process to propose immune modulating interventions in an attempt to stabilize or return these pathological changes to their normal state. The ultimate goal of the immune modulation therapy is to improve both morbidity and mortality associated with COPD.

Mesenchymal stem/stromal cell secretome for lung regeneration: The long way through "pharmaceuticalization" for the best formulation

Pulmonary acute and chronic diseases, such as chronic obstructive pulmonary disease, pulmonary fibrosis and pulmonary hypertension, are considered to be major health issues worldwide. Cellular therapies with Mesenchymal Stem Cells (MSCs) offer a new therapeutic approach for chronic and acute lung diseases related to their anti-inflammatory, immunomodulatory, regenerative, pro-angiogenic and anti-fibrotic properties. Such therapeutic effects can be attributed to MSC-secretome, made of free soluble proteins and extracellular vesicles (EVs). This review summarizes the recent findings related to the efficacy and safety of MSC-derived products in pre-clinical models of lung diseases, pointing out the biologically active substances contained into MSC-secretome and their mechanisms involved in tissue regeneration. A perspective view is then provided about the missing steps required for the secretome "pharmaceuticalization" into a high quality, safe and effective medicinal product, as well as the formulation strategies required for EV non-invasive route of administration, such as inhalation.

Predifferentiated amniotic fluid mesenchymal stem cells enhance lung alveolar epithelium regeneration and reverse elastase-induced pulmonary emphysema

INTRODUCTION

Pulmonary emphysema is a major component of chronic obstructive pulmonary disease (COPD). Emphysema progression attributed not only to alveolar structure loss and pulmonary regeneration impairment, but also to excessive inflammatory response, proteolytic and anti-proteolytic activity imbalance, lung epithelial cells apoptosis, and abnormal lung remodeling. To ameliorate lung damage with higher efficiency in lung tissue engineering and cell therapy, pre-differentiating graft cells into more restricted cell types before transplantation could enhance their ability to anatomically and functionally integrate into damaged lung. In this study, we aimed to evaluate the regenerative and repair ability of lung alveolar epithelium in emphysema model by using lung epithelial progenitors which pre-differentiated from amniotic fluid mesenchymal stem cells (AFMSCs).

METHODS

Pre-differentiation of eGFP-expressing AFMSCs to lung epithelial progenitor-like cells (LEPLCs) was established under a modified small airway growth media (mSAGM) for 7-day induction. Pre-differentiated AFMSCs were intratracheally injected into porcine pancreatic elastase (PPE)-induced emphysema mice at day 14, and then inflammatory-, fibrotic-, and emphysema-related indices and pathological changes were assessed at 6 weeks after PPE administration.

RESULTS

An optimal LEPLCs pre-differentiation condition has been achieved, which resulted in a yield of approximately 20% lung epithelial progenitors-like cells from AFMSCs in a 7-day period. In PPE-induced emphysema mice, transplantation of LEPLCs significantly improved regeneration of lung tissues through integrating into the lung alveolar structure, relieved airway inflammation, increased expression of growth factors such as vascular endothelial growth factor (VEGF), and reduced matrix metalloproteinases and lung remodeling factors when compared with mice injected with AFMSCs. Histopathologic examination observed a significant amelioration in DNA damage in alveolar cells, detected by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL), the mean linear intercept, and the collagen deposition in the LEPLC-transplanted groups.

CONCLUSION

Transplantation of predifferentiated AFMSCs through intratracheal injection showed better alveolar regeneration and reverse elastase-induced pulmonary emphysema in PPE-induced pulmonary emphysema mice.

Mesenchymal Stem Cell-Based Therapy of Inflammatory Lung Diseases: Current Understanding and Future Perspectives

During acute or chronic lung injury, inappropriate immune response and/or aberrant repair process causes irreversible damage in lung tissue and most usually results in the development of fibrosis followed by decline in lung function. Inhaled corticosteroids and other anti-inflammatory drugs are very effective in patients with inflammatory lung disorders, but their long-term use is associated with severe side effects. Accordingly, new therapeutic agents that will attenuate ongoing inflammation and, at the same time, promote regeneration of injured alveolar epithelial cells are urgently needed. Mesenchymal stem cells (MSCs) are able to modulate proliferation, activation, and effector function of all immune cells that play an important role in the pathogenesis of acute and chronic inflammatory lung diseases. In addition to the suppression of lung-infiltrated immune cells, MSCs have potential to differentiate into alveolar epithelial cells in vitro and, accordingly, represent new players in cell-based therapy of inflammatory lung disorders. In this review article, we described molecular mechanisms involved in MSC-based therapy of acute and chronic pulmonary diseases and emphasized current knowledge and future perspectives related to the therapeutic application of MSCs in patients suffering from acute respiratory distress syndrome, pneumonia, asthma, chronic obstructive pulmonary diseases, and idiopathic pulmonary fibrosis.

Clinical Application of Stem/Stromal Cells in COPD

Chronic obstructive pulmonary disease (COPD) is a progressive life-threatening disease that is significantly increasing in prevalence and is predicted to become the third leading cause of death worldwide by 2030. At present, there are no true curative treatments that can stop the progression of the disease, and new therapeutic strategies are desperately needed. Advances in cell-based therapies provide a platform for the development of new therapeutic approaches in severe lung diseases such as COPD. At present, a lot of focus is on mesenchymal stem (stromal) cell (MSC)-based therapies, mainly due to their immunomodulatory properties. Despite increasing number of preclinical studies demonstrating that systemic MSC administration can prevent or treat experimental COPD and emphysema, clinical studies have not been able to reproduce the preclinical results and to date no efficacy or significantly improved lung function or quality of life has been observed in COPD patients. Importantly, the completed appropriately conducted clinical trials uniformly demonstrate that MSC treatment in COPD patients is well tolerated and no toxicities have been observed. All clinical trials performed so far, have been phase I/II studies, underpowered for the detection of potential efficacy. There are several challenges ahead for this field such as standardized isolation and culture procedures to obtain a cell product with high quality and reproducibility, administration strategies, improvement of methods to measure outcomes, and development of potency assays. Moreover, COPD is a complex pathology with a diverse spectrum of clinical phenotypes, and therefore it is essential to develop methods to select the subpopulation of patients that is most likely to potentially respond to MSC administration. In this chapter, we will discuss the current state of the art of MSC-based cell therapy for COPD and the hurdles that need to be overcome.

Impact of one versus two doses of mesenchymal stromal cells on lung and cardiovascular repair in experimental emphysema

Background

A single administration of mesenchymal stromal cells (MSCs) has been shown to reduce lung inflammation in experimental elastase-induced emphysema; however, effects were limited in terms of lung-tissue repair and cardiac function improvement. We hypothesized that two doses of MSCs could induce further lung and cardiovascular repair by mitigating inflammation and remodeling in a model of emphysema induced by multiple elastase instillations. We aimed to comparatively investigate the effects of one versus two doses of MSCs, administered 1 week apart, in a murine model of elastase-induced emphysema.

Methods

C57BL/6 mice were randomly divided into control (CTRL) and emphysema (E) groups. Mice in the E group received porcine pancreatic elastase (0.2 IU, 50 μL) intratracheally once weekly for four consecutive weeks; the CTRL animals received sterile saline (50 μL) using the same protocol. Three hours after the last instillation, the E group was further randomized to receive either saline (SAL) or murine MSCs (10⁵ cells) intratracheally, in one or two doses (1 week apart). Fourteen days later, mice were euthanized, and all data analyzed.

Results

Both one and two doses of MSCs improved lung mechanics, reducing keratinocyte-derived chemokine and transforming growth factor-β levels in lung homogenates, total cell and macrophage counts in bronchoalveolar lavage fluid (BALF), and collagen fiber content in airways and blood vessels, as well as increasing vascular endothelial growth factor in lung homogenates and elastic fiber content in lung parenchyma. However, only the two-dose group exhibited reductions in tumor necrosis factor-α in lung tissue, BALF neutrophil and lymphocyte count, thymus weight, and total cellularity, as well as CD8⁺ cell counts and cervical lymph node CD4⁺ and CD8⁺ T cell counts, as well as further increased elastic fiber content in the lung parenchyma and reduced severity of pulmonary arterial hypertension.

Conclusions

Two doses of MSCs enhanced lung repair and improvement in cardiac function, while inducing T cell immunosuppression, mainly of CD8⁺ cells, in elastase-induced emphysema.

Clinical Application of Mesenchymal Stem Cell-Derived Extracellular Vesicle-Based Therapeutics for Inflammatory Lung Diseases

It is currently thought that extracellular vesicles (EVs), such as exosomes and microvesicles, play an important autocrine/paracrine role in intercellular communication. EVs package proteins, mRNA and microRNA (miRNA), which have the ability to transfer biological information to recipient cells in the lungs. Depending on their origin, EVs fulfil different functions. EVs derived from mesenchymal stem cells (MSCs) have been found to promote therapeutic activities that are comparable to MSCs themselves. Recent animal model-based studies suggest that MSC-derived EVs have significant potential as a novel alternative to whole-cell therapies. Compared to their parent cells, EVs may have a superior safety profile and can be stored without losing function. It has been observed that MSC-derived EVs suppress pro-inflammatory processes and reduce oxidative stress, pulmonary fibrosis and remodeling in a variety of in vivo inflammatory lung disease models by transferring their components. However, there remain significant challenges to translate this therapy to the clinic. From this view point, we will summarize recent studies on EVs produced by MSCs in preclinical experimental models of inflammatory lung diseases. We will also discuss the most relevant issues in bringing MSC-derived EV-based therapeutics to the clinic for the treatment of inflammatory lung diseases.

Mesenchymal stromal cells: a novel therapy for the treatment of chronic obstructive pulmonary disease?

COPD is characterised by tissue destruction and inflammation. Given the lack of curative treatments and the progressive nature of the disease, new treatments for COPD are highly relevant. In vitro cell culture and animal studies have demonstrated that mesenchymal stromal cells (MSCs) have the capacity to modify immune responses and to enhance tissue repair. These properties of MSCs provided a rationale to investigate their potential for treatment of a variety of diseases, including COPD. Preclinical models support the hypothesis that MSCs may have clinical efficacy in COPD. However, although clinical trials have demonstrated the safety of MSC treatment, thus far they have not provided evidence for MSC efficacy in the treatment of COPD. In this review, we discuss the rationale for MSC-based cell therapy in COPD, the main findings from in vitro and in vivo preclinical COPD model studies, clinical trials in patients with COPD and directions for further research.