Effect of mesenchymal stromal cell infusions on lung function in COPD patients with high CRP levels

Failure to launch commercially-approved mesenchymal stromal cell therapies: what's the path forward? Proceedings of the International Society for Cell & Gene Therapy (ISCT) Annual Meeting Roundtable held in May 2023, Palais des Congrès de Paris, Organized by the ISCT MSC Scientific Committee

Mesenchymal stromal cells (MSCs) are promising cell therapy candidates, but their debated efficacy in clinical trials still limits successful adoption. Here, we discuss proceedings from a roundtable session titled "Failure to Launch Mesenchymal Stromal Cells 10 Years Later: What's on the Horizon?" held at the International Society for Cell & Gene Therapy 2023 Annual Meeting. Panelists discussed recent progress toward developing patient-stratification approaches for MSC treatments, highlighting the role of baseline levels of inflammation in mediating MSC treatment efficacy. In addition, MSC critical quality attributes (CQAs) are beginning to be elucidated and applied to investigational MSC products, including immunomodulatory functional assays and other potency markers that will help to ensure product consistency and quality. Lastly, next-generation MSC products, such as culture-priming strategies, were discussed as a promising strategy to augment MSC basal fitness and therapeutic potency. Key variables that will need to be considered alongside investigations of patient stratification approaches, CQAs and next-generation MSC products include the specific disease target being evaluated, route of administration of the cells and cell manufacturing parameters; these factors will have to be matched with postulated mechanisms of action towards treatment efficacy. Taken together, patient stratification metrics paired with the selection of therapeutically potent MSCs (using rigorous CQAs and/or engineered MSC products) represent a path forward to improve clinical successes and regulatory endorsements.

Viral airway injury promotes cell engraftment in an in vitro model of cystic fibrosis cell therapy

Cell therapy is a potential treatment for cystic fibrosis (CF). However, cell engraftment into the airway epithelium is challenging. Here, we model cell engraftment in vitro using the air-liquid interface (ALI) culture system by injuring well-differentiated CF ALI cultures and delivering non-CF cells at the time of peak injury. Engraftment efficiency was quantified by measuring chimerism by droplet digital PCR and functional ion transport in Ussing chambers. Using this model, we found that human bronchial epithelial cells (HBECs) engraft more efficiently when they are cultured by conditionally reprogrammed cell (CRC) culture methods. Cell engraftment into the airway epithelium requires airway injury, but the extent of injury needed is unknown. We compared three injury models and determined that severe injury with partial epithelial denudation facilitates long-term cell engraftment and functional CFTR recovery up to 20% of wildtype function. The airway epithelium promptly regenerates in response to injury, creating competition for space and posing a barrier to effective engraftment. We examined competition dynamics by time-lapse confocal imaging and found that delivered cells accelerate airway regeneration by incorporating into the epithelium. Irradiating the repairing epithelium granted engrafting cells a competitive advantage by diminishing resident stem cell proliferation. Intentionally, causing severe injury to the lungs of people with CF would be dangerous. However, naturally occurring events like viral infection can induce similar epithelial damage with patches of denuded epithelium. We found that viral preconditioning promoted effective engraftment of cells primed for viral resistance.NEW & NOTEWORTHY Cell therapy is a potential treatment for cystic fibrosis (CF). Here, we model cell engraftment by injuring CF air-liquid interface cultures and delivering non-CF cells. Successful engraftment required severe epithelial injury. Intentionally injuring the lungs to this extent would be dangerous. However, naturally occurring events like viral infection induce similar epithelial damage. We found that viral preconditioning promoted the engraftment of cells primed for viral resistance leading to CFTR functional recovery to 20% of the wildtype.

The impact of the immune system on lung injury and regeneration in COPD

COPD is a devastating respiratory condition that manifests via persistent inflammation, emphysema development and small airway remodelling. Lung regeneration is defined as the ability of the lung to repair itself after injury by the proliferation and differentiation of progenitor cell populations, and becomes impaired in the COPD lung as a consequence of cell intrinsic epithelial stem cell defects and signals from the micro-environment. Although the loss of structural integrity and lung regenerative capacity are critical for disease progression, our understanding of the cellular players and molecular pathways that hamper regeneration in COPD remains limited. Intriguingly, despite being a key driver of COPD pathogenesis, the role of the immune system in regulating lung regenerative mechanisms is understudied. In this review, we summarise recent evidence on the contribution of immune cells to lung injury and regeneration. We focus on four main axes: 1) the mechanisms via which myeloid cells cause alveolar degradation; 2) the formation of tertiary lymphoid structures and the production of autoreactive antibodies; 3) the consequences of inefficient apoptotic cell removal; and 4) the effects of innate and adaptive immune cell signalling on alveolar epithelial proliferation and differentiation. We finally provide insight on how recent technological advances in omics technologies and human ex vivo lung models can delineate immune cell-epithelium cross-talk and expedite precision pro-regenerative approaches toward reprogramming the alveolar immune niche to treat COPD.

Application of mesenchymal stem cells for anti-senescence and clinical challenges

Senescence is a hot topic nowadays, which shows the accumulation of senescent cells and inflammatory factors, leading to the occurrence of various senescence-related diseases. Although some methods have been identified to partly delay senescence, such as strengthening exercise, restricting diet, and some drugs, these only slow down the process of senescence and cannot fundamentally delay or even reverse senescence. Stem cell-based therapy is expected to be a potential effective way to alleviate or cure senescence-related disorders in the coming future. Mesenchymal stromal cells (MSCs) are the most widely used cell type in treating various diseases due to their potentials of self-replication and multidirectional differentiation, paracrine action, and immunoregulatory effects. Some biological characteristics of MSCs can be well targeted at the pathological features of aging. Therefore, MSC-based therapy is also a promising strategy to combat senescence-related diseases. Here we review the recent progresses of MSC-based therapies in the research of age-related diseases and the challenges in clinical application, proving further insight and reference for broad application prospects of MSCs in effectively combating senesce in the future.

Effects of secretome supplementation on interleukin-6, tumor necrosis factor-α, procalcitonin, and the length of stay in acute exacerbation COPD patients

Acute exacerbation chronic obstructive pulmonary disease (AECOPD) is associated with significant poor survival. Mesenchymal stem cells (MSC) therapy has been a promising treatment for COPD; therefore, it has the potential to be an additional therapy for AECOPD. Its potential is associated with its secretome since it has anti-inflammatory and immunomodulator activities. The aim of this study was to determine the effect of the secretome as an adjuvant therapy in reducing the levels of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), procalcitonin, and the length of stay in AECOPD patients. A clinical control trial study was conducted among 28 moderate and severe AECOPD patients who were hospitalized from January to February 2023. The control group (n=14) received standard therapy of AECOPD while the treatment group (n=14) received standard therapy plus secretome 1 ml twice daily for three days. The levels of IL-6, TNF-α, and procalcitonin were measured at admission and on the fourth day of treatment. The length of stay was calculated from the time the patient was admitted until the patient was discharged from hospital. The data were compared using a paired Student t-test, chi-squared test and Mann-Whitney test as appropriate. In the treatment group, the levels of IL-6, TNF-α and procalcitonin after the treatment reduced 13.09 pg/mL, 5.00 pg/mL and 751.26 pg/mL, respectively compared to pre-treatment. In contrast, the levels of IL-6, TNF-α and procalcitonin increased 48.56 pg/mL, 44.48 pg/mL and 346.96 pg/mL, respectively after four days of treatment. There was a significant reduction of IL-6, TNF-α and procalcitonin in treatment group compared to the control group with p=0.022, p=0.009 and p=0.001, respectively. However, there was no significant reduction of the length of stay (p=0.072). In conclusion, administration of secretome to AECOPD patients could reduce the levels of IL-6, TNF-α and procalcitonin.

Mesenchymal Stem Cells from COPD Patients Are Capable of Restoring Elastase-Induced Emphysema in a Murine Experimental Model

COPD is a chronic lung disease that affects millions of people, declining their lung function and impairing their life quality. Despite years of research and drug approvals, we are still not capable of halting progression or restoring normal lung function. Mesenchymal stem cells (MSC) are cells with extraordinary repair capacity, and MSC-based therapy brings future hope for COPD treatment, although the best source and route of administration are unclear. MSC from adipose tissue (AD-MSC) represents an option for autologous treatment; however, they could be less effective than donor MSC. We compared in vitro behavior of AD-MSC from COPD and non-COPD individuals by migration/proliferation assay, and tested their therapeutic potential in an elastase mouse model. In addition, we tested intravenous versus intratracheal routes, inoculating umbilical cord (UC) MSC and analyzed molecular changes by protein array. Although COPD AD-MSC have impaired migratory response to VEGF and cigarette smoke, they were as efficient as non-COPD in reducing elastase-induced lung emphysema. UC-MSC reduced lung emphysema regardless of the administration route and modified the inflammatory profile in elastase-treated mice. Our data demonstrate equal therapeutic potential of AD-MSC from COPD and non-COPD subjects in the pre-clinical model, thus supporting their autologous use in disease.

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

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

What is the need and why is it time for innovative models for understanding lung repair and regeneration?

Advances in tissue engineering continue at a rapid pace and have provided novel methodologies and insights into normal cell and tissue homeostasis, disease pathogenesis, and new potential therapeutic strategies. The evolution of new techniques has particularly invigorated the field and span a range from novel organ and organoid technologies to increasingly sophisticated imaging modalities. This is particularly relevant for the field of lung biology and diseases as many lung diseases, including chronic obstructive pulmonary disease (COPD) and idiopathic fibrosis (IPF), among others, remain incurable with significant morbidity and mortality. Advances in lung regenerative medicine and engineering also offer new potential avenues for critical illnesses such as the acute respiratory distress syndrome (ARDS) which also continue to have significant morbidity and mortality. In this review, an overview of lung regenerative medicine with focus on current status of both structural and functional repair will be presented. This will serve as a platform for surveying innovative models and techniques for study, highlighting the need and timeliness for these approaches.

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.

Extracellular Vesicles and Cellular Ageing

Ageing is a complex process characterized by deteriorated performance at multiple levels, starting from cellular dysfunction to organ degeneration. Stem cell-based therapies aim to administrate stem cells that eventually migrate to the injured site to replenish the damaged tissue and recover tissue functionality. Stem cells can be easily obtained and cultured in vitro, and display several qualities such as self-renewal, differentiation, and immunomodulation that make them suitable candidates for stem cell-based therapies. Current animal studies and clinical trials are being performed to assess the safety and beneficial effects of stem cell engraftments for regenerative medicine in ageing and age-related diseases.Since alterations in cell-cell communication have been associated with the development of pathophysiological processes, new research is focusing on the modulation of the microenvironment. Recent research has highlighted the important role of some microenvironment components that modulate cell-cell communication, thus spreading signals from damaged ageing cells to neighbor healthy cells, thereby promoting systemic ageing. Extracellular vesicles (EVs) are small-rounded vesicles released by almost every cell type. EVs cargo includes several bioactive molecules, such as lipids, proteins, and genetic material. Once internalized by target cells, their specific cargo can induce epigenetic modifications and alter the fate of the recipient cells. Also, EV's content is dependent on the releasing cells, thus, EVs can be used as biomarkers for several diseases. Moreover, EVs have been proposed to be used as cell-free therapies that focus on their administration to slow or even reverse some hallmarks of physiological ageing. It is not surprising that EVs are also under study as next-generation therapies for age-related diseases.

Mapping global trends in research of stem cell therapy for COVID-19: A bibliometric analysis

Over the past 2 years, the world has witnessed the devastating effects of the COVID-19 pandemic on humanity. Fortunately, stem cell therapy is widely used in clinical practice for the treatment of COVID-19 and has saved the lives of many critically ill patients. A bibliometric analysis of this field can analyze research hotspots and predict the research trends. This research analyzed documents from Web of Science between the years 2020-2022. The bibliometrics software bibliometrix, VOSviewer, and CiteSpace were used to complete the visual analysis of publications, authors, countries, documents, organizations, collaborative networks, and keywords clustering. 896 publications on COVID-19 stem cell therapy were included in the analysis, including 451 articles and 445 review articles. The field grew at the average growth rate of 103.17% between 2020 and 2021. The United States had the highest number of publications and citations. Many developing countries had also contributed significantly to the field. The journal with the most articles was Stem Cell Research and Therapy. The most cited journal was Stem Cell Reviews and Reports. The published documents were focused on five themes: "Cell Biology", "Medicine Research Experimental", "Cell Tissue Engineering", "Immunology", and "Pharmacology Pharmacy". The bibliometric analysis revealed that current clinical trials had validated stem cell therapy's remarkable potential in treating COVID-19 and its complications. It is foreseeable that future research in this area will continue to increase. With the help of bibliometric analysis, researchers can identify the current state of research and potential research hotspots.

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.

Liver-directed SERPINA1 gene therapy attenuates progression of spontaneous and tobacco smoke-induced emphysema in α1-antitrypsin null mice

α₁-antitrypsin deficiency is a rare genetic condition that can cause liver and/or lung disease. There is currently no cure for this disorder, although repeated infusions of plasma-purified protein may slow down emphysema progression. Gene therapy in which a single recombinant adeno-associated viral vector (rAAV) administration would lead to sustained protein expression could therefore similarly affect disease progression, and provide the added benefits of reducing treatment burden and thereby improving the patient’s quality of life. The study presented here tests whether treating the Serpina1a-e knockout mouse model of α₁-antitrypsin-deficiency lung disease with gene therapy would have an impact on the disease course, either on spontaneous disease caused by aging or on accelerated disease caused by exposure to cigarette smoke. Liver-directed gene therapy led to dose-dependent levels of biologically active human α₁-antitrypsin protein. Furthermore, decreased lung compliance and increased elastic recoil indicate that treated mice had largely preserved lung tissue elasticity and alveolar wall integrity compared with untreated mice. rAAV-mediated gene augmentation is therefore able to compensate for the loss of function and restore a beneficial lung protease-antiprotease balance. This work constitutes a preclinical study report of a disease-modifying treatment in the Serpina1a-e knockout mouse model using a liver-specific rAAV serotype 8 capsid.

The Inflammatory Lung Microenvironment; a Key Mediator in MSC Licensing

Recent clinical trials of mesenchymal stromal cell (MSC) therapy for various inflammatory conditions have highlighted the significant benefit to patients who respond to MSC administration. Thus, there is strong interest in investigating MSC therapy in acute inflammatory lung conditions, such as acute respiratory distress syndrome (ARDS). Unfortunately, not all patients respond, and evidence now suggests that the differential disease microenvironment present across patients and sub-phenotypes of disease or across disease severities influences MSC licensing, function and therapeutic efficacy. Here, we discuss the importance of licensing MSCs and the need to better understand how the disease microenvironment influences MSC activation and therapeutic actions, in addition to the need for a patient-stratification approach.

Paracrine Regulation of Alveolar Epithelial Damage and Repair Responses by Human Lung-Resident Mesenchymal Stromal Cells

COPD is characterized by irreversible lung tissue damage. We hypothesized that lung-derived mesenchymal stromal cells (LMSCs) reduce alveolar epithelial damage via paracrine processes, and may thus be suitable for cell-based strategies in COPD. We aimed to assess whether COPD-derived LMSCs display abnormalities. LMSCs were isolated from lung tissue of severe COPD patients and non-COPD controls. Effects of LMSC conditioned-medium (CM) on H₂O₂-induced, electric field- and scratch-injury were studied in A549 and NCI-H441 epithelial cells. In organoid models, LMSCs were co-cultured with NCI-H441 or primary lung cells. Organoid number, size and expression of alveolar type II markers were assessed. Pre-treatment with LMSC-CM significantly attenuated oxidative stress-induced necrosis and accelerated wound repair in A549. Co-culture with LMSCs supported organoid formation in NCI-H441 and primary epithelial cells, resulting in significantly larger organoids with lower type II-marker positivity in the presence of COPD-derived versus control LMSCs. Similar abnormalities developed in organoids from COPD compared to control-derived lung cells, with significantly larger organoids. Collectively, this indicates that LMSCs' secretome attenuates alveolar epithelial injury and supports epithelial repair. Additionally, LMSCs promote generation of alveolar organoids, with abnormalities in the supportive effects of COPD-derived LMCS, reflective of impaired regenerative responses of COPD distal lung cells.

Transcriptional profiling of circulating mononuclear cells from patients with chronic obstructive pulmonary disease receiving mesenchymal stromal cell infusions

Chronic obstructive pulmonary disease (COPD) is an inflammatory airways disease with limited therapeutic options. We have previously shown that mesenchymal stromal cell (MSC) infusions are well tolerated in patients with COPD and reduce circulatory biomarkers associated with systemic inflammation and oxidative stress. This study aimed to delineate the underlying mechanisms further by characterizing the transcriptional networks in these patients and to explore the role of MSC‐derived paracrine factors in regulating these pathways. Allogeneic, bone marrow‐derived MSCs were systemically administered into patients with stable COPD (n = 9). Gene expression profiles from peripheral blood mononuclear cells (PBMCs) were analyzed across the first week after infusion. Paracrine mechanisms associated with these transcriptional changes were explored further by culturing patient PBMCs with MSC‐conditioned medium (MSC‐CM) or post‐MSC infusion (PI) plasma to measure the regulatory effects of soluble factors that may be derived from MSCs. MSC‐CM and PI‐plasma were characterized further to identify potential immunoregulatory candidates. MSC infusion elicited a strong but transient transcriptional response in patient PBMCs that was sustained up to 7 days. MSC infusion strongly downregulated transcriptional pathways related to interleukin (IL)‐8 and IL‐1β, which were also significantly inhibited in vitro following co‐culture of PBMCs with MSC‐CM and PI‐plasma. MSC‐derived soluble tumor necrosis factor receptor‐1, transforming growth factor‐β1, and extracellular vesicle‐associated microRNAs were identified as potential mechanisms promoting these changes, but depletion of these individual candidates revealed inconsistent results. MSC‐derived paracrine factors modulate important inflammatory pathways that are relevant to COPD pathogenesis. These data strengthen the hypothesis that therapies using MSCs and their secreted products may be beneficial to patients with COPD.