Mesenchymal Stem Cells and Idiopathic Pulmonary Fibrosis. Potential for Clinical Testing

Enzyme-like nanoparticle-engineered mesenchymal stem cell secreting HGF promotes visualized therapy for idiopathic pulmonary fibrosis in vivo

Stem cell therapy is being explored as a potential treatment for idiopathic pulmonary fibrosis (IPF), but its effectiveness is hindered by factors like reactive oxygen species (ROS) and inflammation in fibrotic lungs. Moreover, the distribution, migration, and survival of transplanted stem cells are still unclear, impeding the clinical advancement of stem cell therapy. To tackle these challenges, we fabricate AuPtCoPS trimetallic-based nanocarriers (TBNCs), with enzyme-like activity and plasmid loading capabilities, aiming to efficiently eradicate ROS, facilitate delivery of therapeutic genes, and ultimately improve the therapeutic efficacy. TBNCs also function as a computed tomography contrast agent for tracking mesenchymal stem cells (MSCs) during therapy. Accordingly, we enhanced the antioxidant stress and anti-inflammatory capabilities of engineered MSCs and successfully visualized their biological behavior in IPF mice in vivo. Overall, this study provides an efficient and forward-looking treatment approach for IPF and establishes a framework for a stem cell-based therapeutic system aimed at addressing lung disease.

Human umbilical cord-derived mesenchymal stem cell transplantation improves the long COVID

No effective treatments can ameliorate symptoms of long COVID patients. Our study assessed the safety and efficacy of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) in the treatment of long COVID patients. Ten long COVID patients were enrolled and received intravenous infusions of UC-MSCs on Days 0, 7, and 14. Adverse events and clinical symptoms were recorded, and chest-high-resolution CT (HRCT) images and laboratory parameters were analyzed. During UC-MSCs treatment and follow-up, we did not observe serious adverse events, the symptoms of long COVID patients were significantly relieved in a short time, especially sleep difficulty, depression or anxiety, memory issues, and so forth, and the lung lesions were also repaired. The routine laboratory parameters did not exhibit any significant abnormalities following UC-MSCs transplantation (UMSCT). The proportion of regulatory T cells gradually increased, but it was not statistically significant until 12 months. The proportion of naive B cells was elevated, while memory B cells, class-switched B-cells, and nonswitched B-cells decreased at 1 month after infusion. Additionally, we observed a transient elevation in circulating interleukin (IL)-6 after UMSCT, while tumor necrosis factor (TNF)-α, IL-17A, and IL-10 showed no significant changes. The levels of circulating immunoglobulin (Ig) M increased significantly at month 2, while IgA increased significantly at month 6. Furthermore, the SARS-CoV-2 IgG levels remained consistently high in all patients at Month 6, and there was no significant decrease during the subsequent 12-month follow-up. UMSCT was safe and tolerable in long COVID patients. It showed potential in alleviating long COVID symptoms and improving interstitial lung lesions.

Therapeutic utility of human umbilical cord-derived mesenchymal stem cells-based approaches in pulmonary diseases: Recent advancements and prospects

Pulmonary diseases across all ages threaten millions of people and have emerged as one of the major public health issues worldwide. For diverse disease conditions, the currently available approaches are focused on alleviating clinical symptoms and delaying disease progression but have not shown significant therapeutic effects in patients with lung diseases. Human umbilical cord-derived mesenchymal stem cells (UC-MSCs) isolated from the human UC have the capacity for self-renewal and multilineage differentiation. Moreover, in recent years, these cells have been demonstrated to have unique advantages in the treatment of lung diseases. We searched the Public Clinical Trial Database and found 55 clinical trials involving UC-MSC therapy for pulmonary diseases, including coronavirus disease 2019, acute respiratory distress syndrome, bronchopulmonary dysplasia, chronic obstructive pulmonary disease, and pulmonary fibrosis. In this review, we summarize the characteristics of these registered clinical trials and relevant published results and explore in depth the challenges and opportunitiesfaced in clinical application. Moreover, the underlying molecular mechanisms involved in UC-MSC-based therapy for pulmonary diseases are also analyzed in depth. In brief, this comprehensive review and detailed analysis of these clinical trials can be expected to provide a scientific reference for future large-scale clinical application.

Inhaled nanoparticles for treating idiopathic pulmonary fibrosis by inhibiting honeycomb cyst and alveoli interstitium remodeling

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with high mortality. The Food and Drug Administration-approved drugs, nintedanib and pirfenidone, could delay progressive fibrosis by inhibiting the overactivation of fibroblast, however, there was no significant improvement in patient survival due to low levels of drug accumulation and remodeling of honeycomb cyst and interstitium surrounding the alveoli. Herein, we constructed a dual drug (verteporfin and pirfenidone)-loaded nanoparticle (Lip@VP) with the function of inhibiting airway epithelium fluidization and fibroblast overactivation to prevent honeycomb cyst and interstitium remodeling. Specifically, Lip@VP extensively accumulated in lung tissues via atomized inhalation. Released verteporfin inhibited the fluidization of airway epithelium and the formation of honeycomb cyst, and pirfenidone inhibited fibroblast overactivation and reduced cytokine secretion that promoted the fluidization of airway epithelium. Our results indicated that Lip@VP successfully rescued lung function through inhibiting honeycomb cyst and interstitium remodeling. This study provided a promising strategy to improve the therapeutic efficacy for IPF.

Olfactory mucosa mesenchymal stem cells alleviate pulmonary fibrosis via the immunomodulation and reduction of inflammation

BACKGROUND

Pulmonary fibrosis (PF) is a progressive fibrosing interstitial pneumonia that leads to respiratory failure and other complications, which is ultimately fatal. Mesenchymal stem cells (MSCs) transplant is a promising strategy to solve this problem, while the procurement of MSCs from the patient for autotransplant remains a challenge.

METHODS

Here, we presented olfactory mucosa mesenchymal stem cells (OM-MSCs) from mouse turbinate and determined the preventing efficacy of allotransplant for PF. We demonstrated the antiinflammation and immunomodulatory effects of OM-MSCs. Flow cytometric analysis was used to verify the effect of OM-MSCs on monocyte-derived macrophage populations in the lung.

RESULTS

Administration of OM-MSCs reduces inflammation, attenuates the matrix metallopeptidase 13 (MMP13) expression level and restores the bleomycin (BLM)-induced pulmonary fibrosis by assessing the architecture of lung, collagen type I; (COL1A1), actin alpha 2, smooth muscle, aorta (ACTA2/α-SMA) and hydroxyproline. This therapeutic effect of OM-MSCs was related to the increase in the ratio of nonclassical monocytes to proinflammatory monocytes in the lung.

CONCLUSIONS

This study suggests that transplant of OM-MSCs represents an effective and safe treatment for PF.

Nanoengineered mesenchymal stem cell therapy for pulmonary fibrosis in young and aged mice

Pulmonary fibrosis (PF) is an age-related interstitial lung disease that results in notable morbidity and mortality. The Food and Drug Administration-approved drugs can decelerate the progression of PF; however, curing aged patients with severe fibrosis is ineffective because of insufficient accumulation of these drugs and wide necrocytosis of type II alveolar epithelial cells (AEC IIs). Here, we constructed a mesenchymal stem cell (MSC)-based nanoengineered platform via the bioconjugation of MSCs and type I collagenase-modified liposomes loaded with nintedanib (MSCs-Lip@NCAF) for treating severe fibrosis. Specifically, MSCs-Lip@NCAF migrated to fibrotic lungs because of the homing characteristic of MSCs and then Lip@NCAF was sensitively released. Subsequently, Lip@NCAF ablated collagen fibers, delivered nintedanib into fibroblasts, and inhibited fibroblast overactivation. MSCs differentiated into AEC IIs to repair alveolar structure and ultimately promote the regeneration of damaged lungs in aged mice. Our findings indicated that MSCs-Lip@NCAF could be used as a promising therapeutic candidate for PF therapy, especially in aged patients.

Pulmonary fibrosis: A short- or long-term sequelae of severe COVID-19?

The pandemic of coronavirus disease 2019 (COVID‑19), caused by a novel severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2), has caused an enormous impact on the global healthcare. SARS-CoV-2 infection primarily targets the respiratory system. Although most individuals testing positive for SARS-CoV-2 present mild or no upper respiratory tract symptoms, patients with severe COVID-19 can rapidly progress to acute respiratory distress syndrome (ARDS). ARDS-related pulmonary fibrosis is a recognized sequelae of COVID-19. Whether post-COVID-19 lung fibrosis is resolvable, persistent, or even becomes progressive as seen in human idiopathic pulmonary fibrosis (IPF) is currently not known and remains a matter of debate. With the emergence of effective vaccines and treatments against COVID-19, it is now important to build our understanding of the long-term sequela of SARS-CoV-2 infection, to identify COVID-19 survivors who are at risk of developing chronic pulmonary fibrosis, and to develop effective anti-fibrotic therapies. The current review aims to summarize the pathogenesis of COVID-19 in the respiratory system and highlights ARDS-related lung fibrosis in severe COVID-19 and the potential mechanisms. It envisions the long-term fibrotic lung complication in COVID-19 survivors, in particular in the aged population. The early identification of patients at risk of developing chronic lung fibrosis and the development of anti-fibrotic therapies are discussed.

Advances in cellular senescence in idiopathic pulmonary fibrosis (Review)

Idiopathic pulmonary fibrosis (IPF) is a progressive, irreversible and fatal interstitial lung disease of unknown cause, with a median survival of 2-3 years. Its pathogenesis is unclear and there is currently no effective treatment for IPF. Approximately two-thirds of patients with IPF are >60 years old, with a mean age of 66 years, suggesting a link between aging and IPF. However, the mechanism by which aging promotes development of PF remains unclear. Senescence of alveolar epithelial cells and lung fibroblasts (LFs) and their senescence-associated secretion phenotype (SASP) may be involved in the occurrence and development of IPF. The present review focus on senescence of LFs and epithelial and stem cells, as well as SASP, the activation of profibrotic signaling pathways and potential treatments for pathogenesis of IPF.

Perspectives of PDE inhibitor on treating idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) without an identifiable cause. If not treated after diagnosis, the average life expectancy is 3-5 years. Currently approved drugs for the treatment of IPF are Pirfenidone and Nintedanib, as antifibrotic drugs, which can reduce the decline rate of forced vital capacity (FVC) and reduce the risk of acute exacerbation of IPF. However these drugs can not relieve the symptoms associated with IPF, nor improve the overall survival rate of IPF patients. We need to develop new, safe and effective drugs to treat pulmonary fibrosis. Previous studies have shown that cyclic nucleotides participate in the pathway and play an essential role in the process of pulmonary fibrosis. Phosphodiesterase (PDEs) is involved in cyclic nucleotide metabolism, so PDE inhibitors are candidates for pulmonary fibrosis. This paper reviews the research progress of PDE inhibitors related to pulmonary fibrosis, so as to provide ideas for the development of anti-pulmonary fibrosis drugs.

Stem cells, cell therapies, and bioengineering in lung biology and disease 2021

The 9th biennial conference titled "Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases" was hosted virtually, due to the ongoing COVID-19 pandemic, in collaboration with the University of Vermont Larner College of Medicine, the National Heart, Lung, and Blood Institute, the Alpha-1 Foundation, the Cystic Fibrosis Foundation, and the International Society for Cell & Gene Therapy. The event was held from July 12th through 15th, 2021 with a pre-conference workshop held on July 9th. As in previous years, the objectives remained to review and discuss the status of active research areas involving stem cells (SCs), cellular therapeutics, and bioengineering as they relate to the human lung. Topics included 1) technological advancements in the in situ analysis of lung tissues, 2) new insights into stem cell signaling and plasticity in lung remodeling and regeneration, 3) the impact of extracellular matrix in stem cell regulation and airway engineering in lung regeneration, 4) differentiating and delivering stem cell therapeutics to the lung, 5) regeneration in response to viral infection, and 6) ethical development of cell-based treatments for lung diseases. This selection of topics represents some of the most dynamic and current research areas in lung biology. The virtual workshop included active discussion on state-of-the-art methods relating to the core features of the 2021 conference, including in situ proteomics, lung-on-chip, induced pluripotent stem cell (iPSC)-airway differentiation, and light sheet microscopy. The conference concluded with an open discussion to suggest funding priorities and recommendations for future research directions in basic and translational lung biology.

Effects of transplanted mesenchymal stem cells on repair of the lung tissue of rats with experimental pulmonary fibrosis

Pulmonary fibrosis is one of the commonest forms of interstitial lung diseases with poorly studied methods of its treatment in both human and veterinary medicines. Therefore, this paper focused on seeking alternative methods of its diagnostics and treatment. The article provides the results of the study of bronchoalveolar lavage fluid of rats with experimental lung fibrosis and influence of transplanted allogeneic mesenchymal stem cells of the bone marrow on stimulation of regenerative processes in damaged lung tissues. The studies were conducted on female Wistar rats with pulmonary fibrosis modeled using single transthoracic injection of solution of bleomycin hydrochloride. For the purpose of treatment, we used allogeneic mesenchymal stem cells introduced by various methods and the traditional treatment. We determined that best normalization of the parameters of the studied brochoalveolar lavage occurred in animals that received mesenchymal stem cells. The most active repair processes were in the experimental group that received the mesenchymal stem cells directly to the lung tissue. The animals that received intravenous injection of mesenchymal stemm cells were observed to have lower clinical parameters of the brochoalveolar lavage, but still better than such in the group treated traditionally. The lowest parameters were in animals that received the traditional treatment; they were greater than the phisological parameters, but significantly exceeded them in animals of the control group, indicating presence of inflammatory process in the lung tissue. The conducted cytological assays of the samples of the brochoalveolar lavage revealed that experimental animals with experimental pulmonary fibrosis had development of macrophage and lymphocytic reactions under the influence of transplanted mesenchymal stemm cells. We observed no atypical cells in all the experimental groups. This allows us to draw a conclusion that using stem cells by various methods of transplantation does not stimulate the onset of negative reactons (formation of atypical cells, metastatic processes, etc). Thus, the results of the study of the influence of transplanted mesenchymal stem cells demonstrate that in the conditions of experimental pulmonary fibrosis, the activity of regenerative processes in pathologically altered lung tissue may be an effective method of treatment of animals with this kind of pathology.

Mesenchymal stem cell-based treatments for COVID-19: status and future perspectives for clinical applications

As a result of cross-species transmission in December 2019, the coronavirus disease 2019 (COVID-19) became a serious endangerment to human health and the causal agent of a global pandemic. Although the number of infected people has decreased due to effective management, novel methods to treat critical COVID-19 patients are still urgently required. This review describes the origins, pathogenesis, and clinical features of COVID-19 and the potential uses of mesenchymal stem cells (MSCs) in therapeutic treatments for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-infected patients. MSCs have previously been shown to have positive effects in the treatment of lung diseases, such as acute lung injury, idiopathic pulmonary fibrosis, acute respiratory distress syndrome, lung cancer, asthma, and chronic obstructive pulmonary disease. MSC mechanisms of action involve differentiation potentials, immune regulation, secretion of anti-inflammatory factors, migration and homing, anti-apoptotic properties, antiviral effects, and extracellular vesicles. Currently, 74 clinical trials are investigating the use of MSCs (predominately from the umbilical cord, bone marrow, and adipose tissue) to treat COVID-19. Although most of these trials are still in their early stages, the preliminary data are promising. However, long-term safety evaluations are still lacking, and large-scale and controlled trials are required for more conclusive judgments regarding MSC-based therapies. The main challenges and prospective directions for the use of MSCs in clinical applications are discussed herein. In summary, while the clinical use of MSCs to treat COVID-19 is still in the preliminary stages of investigation, promising results indicate that they could potentially be utilized in future treatments.

Effect of 2D and 3D Culture Microenvironments on Mesenchymal Stem Cell-Derived Extracellular Vesicles Potencies

Therapeutic benefits of mesenchymal stem cells (MSCs) are now widely believed to come from their paracrine signalling, i.e. secreted factors such as cytokines, chemokines, and extracellular vesicles (EVs). Cell-free therapy using EVs is an active and emerging field in regenerative medicine. Typical 2D cultures on tissue culture plastic is far removed from the physiological environment of MSCs. The application of 3D cell culture allows MSCs to adapt to their cellular environment which, in turn, influences their paracrine signalling activity. In this study we evaluated the impact of 3D MSCs culture on EVs secretion, cargo proteome composition, and functional assessment in immunomodulatory, anti-inflammatory and anti-fibrotic properties.

MSC-EVs from 2D and 3D cultures expressed classical EV markers CD81, CD63, and CD9 with particle diameter of <100 nm. There were distinct changes in immunomodulatory potencies where 3D cultures exhibited reduced indoleamine 2,3-dioxygenase (IDO) activity and significantly reduced macrophage phagocytosis. Administration of 2D and 3D EVs following double dose bleomycin challenge in aged mice showed a marked increase of bodyweight loss in 3D group throughout days 7–28. Histopathological observations of lung tissues in 3D group showed increased collagen deposition, myofibroblast differentiation and leukocytes infiltrations. Assessment of lung mechanics showed 3D group did not improve lung function and instead exhibited increased resistance and tissue damping. Proteome profiling of MSC-EV composition revealed molecular enrichment of EV markers (compared to parental cells) and differential proteome between EVs from 2D and 3D culture condition associated with immune-based and fibrosis/extracellular matrix/membrane organization associated function.

This study provides insight into distinct variation in EV protein composition dependent on the cellular microenvironment of the parental cells, which could have implications in their therapeutic effect and potency. Overall, this work suggests that EVs produced from 3D MSC cultures did not enhance typical MSC-EV properties expected from 2D cultures (immunomodulation, anti-fibrotic, anti-inflammatory). The outcome highlights critical differences between MSC-EVs obtained from different culture microenvironments, which should be considered when scaling up MSC culture for clinical manufacturing.

Idiopathic pulmonary fibrosis: Current and future treatment

Objectives

Idiopathic pulmonary fibrosis (IPF) is a chronic fibrotic lung disease characterized by dry cough, fatigue, and progressive exertional dyspnea. Lung parenchyma and architecture is destroyed, compliance is lost, and gas exchange is compromised in this debilitating condition that leads inexorably to respiratory failure and death within 3–5 years of diagnosis. This review discusses treatment approaches to IPF in current use and those that appear promising for future development.

Data Source

The data were obtained from the Randomized Controlled Trials and scientific studies published in English literature. We used search terms related to IPF, antifibrotic treatment, lung transplant, and management.

Results

Etiopathogenesis of IPF is not fully understood, and treatment options are limited. Pathological features of IPF include extracellular matrix remodeling, fibroblast activation and proliferation, immune dysregulation, cell senescence, and presence of aberrant basaloid cells. The mainstay therapies are the oral antifibrotic drugs pirfenidone and nintedanib, which can improve quality of life, attenuate symptoms, and slow disease progression. Unilateral or bilateral lung transplantation is the only treatment for IPF shown to increase life expectancy.

Conclusion

Clearly, there is an unmet need for accelerated research into IPF mechanisms so that progress can be made in therapeutics toward the goals of increasing life expectancy, alleviating symptoms, and improving well‐being.

Mesenchymal stromal cells attenuate alveolar type 2 cells senescence through regulating NAMPT-mediated NAD metabolism

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive deadly fibrotic lung disease with high prevalence and mortality worldwide. The therapeutic potential of mesenchymal stem cells (MSCs) in pulmonary fibrosis may be attributed to the strong paracrine, anti-inflammatory, anti-apoptosis and immunoregulatory effects. However, the mechanisms underlying the therapeutic effects of MSCs in IPF, especially in terms of alveolar type 2 (AT2) cells senescence, are not well understood. The purpose of this study was to evaluate the role of MSCs in NAD metabolism and senescence of AT2 cells in vitro and in vivo.

Methods

MSCs were isolated from human bone marrow. The protective effects of MSCs injection in pulmonary fibrosis were assessed via bleomycin mouse models. The senescence of AT2 cells co-cultured with MSCs was evaluated by SA-β-galactosidase assay, immunofluorescence staining and Western blotting. NAD+ level and NAMPT expression in AT2 cells affected by MSCs were determined in vitro and in vivo. FK866 and NAMPT shRNA vectors were used to determine the role of NAMPT in MSCs inhibiting AT2 cells senescence.

Results

We proved that MSCs attenuate bleomycin-induced pulmonary fibrosis in mice. Senescence of AT2 cells was alleviated in MSCs-treated pulmonary fibrosis mice and when co-cultured with MSCs in vitro. Mechanistic studies showed that NAD+ and NAMPT levels were rescued in AT2 cells co-cultured with MSCs and MSCs could suppress AT2 cells senescence mainly via suppressing lysosome-mediated NAMPT degradation.

Conclusions

MSCs attenuate AT2 cells senescence by upregulating NAMPT expression and NAD+ levels, thus exerting protective effects in pulmonary fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02688-w.

Fibrotic Idiopathic Interstitial Lung Disease: The Molecular and Cellular Key Players

Interstitial lung diseases (ILDs) that are known as diffuse parenchymal lung diseases (DPLDs) lead to the damage of alveolar epithelium and lung parenchyma, culminating in inflammation and widespread fibrosis. ILDs that account for more than 200 different pathologies can be divided into two groups: ILDs that have a known cause and those where the cause is unknown, classified as idiopathic interstitial pneumonia (IIP). IIPs include idiopathic pulmonary fibrosis (IPF), non-specific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP) known also as bronchiolitis obliterans organizing pneumonia (BOOP), acute interstitial pneumonia (AIP), desquamative interstitial pneumonia (DIP), respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), and lymphocytic interstitial pneumonia (LIP). In this review, our aim is to describe the pathogenic mechanisms that lead to the onset and progression of the different IIPs, starting from IPF as the most studied, in order to find both the common and standalone molecular and cellular key players among them. Finally, a deeper molecular and cellular characterization of different interstitial lung diseases without a known cause would contribute to giving a more accurate diagnosis to the patients, which would translate to a more effective treatment decision.

Human bronchial epithelial cell-derived extracellular vesicle therapy for pulmonary fibrosis via inhibition of TGF-β-WNT crosstalk

Idiopathic pulmonary fibrosis (IPF) is characterized by devastating and progressive lung parenchymal fibrosis, resulting in poor patient prognosis. An aberrant recapitulation of developmental lung gene expression, including genes for transforming growth factor (TGF)-β and WNT, has been widely implicated in the pathogenic IPF wound healing process that results from repetitive alveolar epithelial injury. Extracellular vesicles (EVs) have been shown to carry bioactive molecules and to be involved in various physiological and pathological processes. Here, we demonstrate that, by attenuating WNT signalling, human bronchial epithelial cell-derived EVs (HBEC EVs) inhibit TGF-β mediated induction of both myofibroblast differentiation and lung epithelial cellular senescence. This effect of HBEC EVs is more pronounced than that observed with mesenchymal stem cell-derived EVs. Mechanistically, the HBEC EV microRNA (miRNA) cargo is primarily responsible for attenuating both myofibroblast differentiation and cellular senescence. This attenuation occurs via inhibition of canonical and non-canonical WNT signalling pathways. Among enriched miRNA species present in HBEC EVs, miR-16, miR-26a, miR-26b, miR-141, miR-148a, and miR-200a are mechanistically involved in reducing WNT5A and WNT10B expression in LFs, and in reducing WNT3A, WNT5A, and WNT10B expression in HBECs. Mouse models utilizing intratracheal administration of EVs demonstrate efficient attenuation of bleomycin-induced lung fibrosis development accompanied by reduced expression of both β-catenin and markers of cellular senescence. These findings indicate that EVs derived from normal resident lung HBECs may possess anti-fibrotic properties. They further suggest that, via miRNA-mediated inhibition of TGF-β-WNT crosstalk, HBEC EVs administration can be a promising anti-fibrotic modality of treatment for IPF.

Idiopathic pulmonary fibrosis: Disease mechanisms and drug development

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disease of unknown cause characterized by relentless scarring of the lung parenchyma leading to reduced quality of life and earlier mortality. IPF is an age-related disorder, and with the population aging worldwide, the economic burden of IPF is expected to steadily increase in the future. The mechanisms of fibrosis in IPF remain elusive, with favored concepts of disease pathogenesis involving recurrent microinjuries to a genetically predisposed alveolar epithelium, followed by an aberrant reparative response characterized by excessive collagen deposition. Pirfenidone and nintedanib are approved for treatment of IPF based on their ability to slow functional decline and disease progression; however, they do not offer a cure and are associated with tolerability issues. In this review, we critically discuss how cutting-edge research in disease pathogenesis may translate into identification of new therapeutic targets, thus facilitate drug discovery. There is a growing portfolio of treatment options for IPF. However, targeting the multitude of profibrotic cytokines and growth factors involved in disease pathogenesis may require a combination of therapeutic strategies with different mechanisms of action.

Mesenchymal Stromal Cell Secretome for Post-COVID-19 Pulmonary Fibrosis: A New Therapy to Treat the Long-Term Lung Sequelae?

To date, more than 100 million people worldwide have recovered from COVID-19. Unfortunately, although the virus is eradicated in such patients, fibrotic irreversible interstitial lung disease (pulmonary fibrosis, PF) is clinically evident. Given the vast numbers of individuals affected, it is urgent to design a strategy to prevent a second wave of late mortality associated with COVID-19 PF as a long-term consequence of such a devastating pandemic. Available antifibrotic therapies, namely nintedanib and pirfenidone, might have a role in attenuating profibrotic pathways in SARS-CoV-2 infection but are not economically sustainable by national health systems and have critical adverse effects. It is our opinion that the mesenchymal stem cell secretome could offer a new therapeutic approach in treating COVID-19 fibrotic lungs through its anti-inflammatory and antifibrotic factors.

Inhibition of miR-199a-5p rejuvenates aged mesenchymal stem cells derived from patients with idiopathic pulmonary fibrosis and improves their therapeutic efficacy in experimental pulmonary fibrosis

Background

Idiopathic pulmonary fibrosis (IPF) is an age-related disease with no cure. Mesenchymal stem cell (MSC)-based therapy has emerged as a novel strategy for IPF treatment. Nevertheless, MSCs derived from patients with IPF (IPF-MSCs) become senescent, thereby reducing their beneficial effects in IPF. MicroRNAs (miRNAs) mediate the senescence of MSCs, but the underlying mechanisms are not fully understood. We investigated the mechanisms by which miR-199a-5p regulates IPF-MSC senescence and whether its inhibition could rejuvenate IPF-MSCs and enhance their therapeutic efficacy.

Methods

Control-MSCs and IPF-MSCs were isolated from the adipose tissue of age-matched healthy and IPF donors, respectively. Cell senescence was examined by senescence-associated β-galactosidase (SA-β-gal) staining. The level of miR-199a-5p was measured by RT-PCR. Autophagy was determined using a transmission electron microscope (TEM). The therapeutic efficacy of anti-miR-199a-5p-IPF-MSCs was assessed using a mouse model of bleomycin-induced lung fibrosis.

Results

Despite similar surface makers, IPF-MSCs exhibited increased cellular senescence and decreased proliferative capacity compared with control-MSCs. The expression of miR-199a-5p was significantly enhanced in the serum of IPF patients and IPF-MSCs compared with that of healthy donors and control-MSCs. The upregulation of miR-199a-5p induced senescence of control-MSCs, whereas the downregulation rescued IPF-MSC senescence. Mechanistically, miR-155-5p suppressed autophagy of MSCs via the AMPK signaling pathway by downregulating the expression of Sirtuin 1(Sirt1), resulting in cellular senescence. Accordingly, miR-155-5p inhibition promoted autophagy and ameliorated IPF-MSC senescence by activating the Sirt1/AMPK signaling pathway. Compared with IPF-MSCs, the transplantation of anti-miR-199a-5p-IPF-MSCs increased the ability to prevent progression of pulmonary fibrosis in bleomycin-treated mice.

Conclusions

Our study shows that miR-199a-5p regulates MSC senescence in patients with IPF by regulating the Sirt1/AMPK signaling pathway and miR-199a-5p is a novel target to rejuvenate IPF-MSCs and enhance their beneficial effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02215-x.

CT/NIRF dual-modal imaging tracking and therapeutic efficacy of transplanted mesenchymal stem cells labeled with Au nanoparticles in silica-induced pulmonary fibrosis

Mesenchymal stem cells (MSCs) have shown promising therapeutic effects in cell-based therapies and regenerative medicine. Efficient tracking of MSCs is an urgent clinical need that will help us to understand their behavior after transplantation and allow adjustment of therapeutic strategies. However, no clinically approved tracers are currently available, which limits the clinical translation of stem cell therapy. In this study, a nanoparticle (NP) for computed tomography (CT)/fluorescence dual-modal imaging, Au@Albumin@ICG@PLL (AA@ICG@PLL), was developed to track bone marrow-derived mesenchymal stem cells (BMSCs) that were administered intratracheally into mice with silica-induced pulmonary fibrosis, which facilitated understanding of the therapeutic effect and the possible molecular mechanism of stem cell therapy. The AuNPs were first formed in bovine serum albumin (BSA) solution and modified with indocyanine green (ICG), and subsequently coated with a poly-l-lysine (PLL) layer to enhance intracellular uptake and biocompatibility. BMSCs were labeled with AA@ICG@PLL NPs with high efficiency without an effect on biological function or therapeutic capacity. The injected AA@ICG@PLL-labeled BMSCs could be tracked via CT and near-infrared fluorescence (NIRF) imaging for up to 21 days after transplantation. Using these NPs, the molecular anti-inflammatory mechanism of transplanted BMSCs was revealed, which included the downregulation of proinflammatory cytokines, suppression of macrophage activation, and delay of the fibrosis process. This study suggests a promising role for imaging-guided MSC-based therapy for pulmonary fibrosis, such as idiopathic pulmonary fibrosis (IPF) and pneumoconiosis.

How the Pathological Microenvironment Affects the Behavior of Mesenchymal Stem Cells in the Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by fibroblasts activation, ECM accumulation, and diffused alveolar inflammation. The role of inflammation in IPF is still controversial and its involvement may follow nontraditional mechanisms. It is seen that a pathological microenvironment may affect cells, in particular mesenchymal stem cells (MSCs) that may be able to sustain the inflamed microenvironment and influence the surrounding cells. Here MSCs have been isolated from fibrotic (IPF-MSCs) and control (C-MSCs) lung tissue; first cells were characterized and compared by the expression of molecules related to ECM, inflammation, and other interdependent pathways such as hypoxia and oxidative stress. Subsequently, MSCs were co-cultured between them and with NHLF to test the effects of the cellular crosstalk. Results showed that pathological microenvironment modified the features of MSCs: IPF-MSCs, compared to C-MSCs, express higher level of molecules related to ECM, inflammation, oxidative stress, and hypoxia; notably, when co-cultured with C-MSCs and NHLF, IPF-MSCs are able to induce a pathological phenotype on the surrounding cell types. In conclusion, in IPF the pathological microenvironment affects MSCs that in turn can modulate the behavior of other cell types favoring the progression of IPF.

AntagomiR-199a Enhances the Liver Protective Effect of Hypoxia-Preconditioned BM-MSCs in a Rat Model of Reduced-Size Liver Transplantation

BACKGROUND

Reduced-size liver transplantation (LT) was invented to overcome the shortage of donor livers; however, it has proven to be more susceptible to ischemia-reperfusion injury. Bone marrow-derived mesenchymal stem cell infusion has been shown to be protective following LT. Optimization of MSC infusion has been performed, among which hypoxia preconditioning and miRNA modulation have shown promise. MiR-199a inhibition was reported to induce angioneogenesis; however, whether mir-199a inhibition enhances the protective effect of Bone marrow-derived mesenchymal stem cells in LT remains unknown. In this study, we combined antagomiR-199a with hypoxia-preconditioned MSC (H-MSC) infusion to discuss their effect and mechanism in a rat model of reduced-size LT.

METHODS

A reduced-size LT model was constructed and H-MSCs were intraportally injected during operation. AgomiR-199a and antagomir-199a were injected through the caudal vein once a day after LT. The level of apoptosis and proinflammatory cytokines were measured. An anti-vascular endothelial growth factor (VEGF) antibody was injected to further explore the underlying mechanism.

RESULTS

AntagomiR-199a plus H-MSC not only significantly decreased ALT and AST 72 h after LT but also ameliorated the level of apoptosis and inhibited inflammatory reactions. On the contrary, agomir-199a reduced the protective effect of the H-MSC infusion. In terms of mechanism, the liver protective effect of miR-199a inhibition was abolished by treatment with a VEGF-neutralizing antibody.

CONCLUSIONS

AntagomiR-199a enhanced the protective effect of H-MSCs infusion via activation of the hypoxia induction factor 1α/VEGF axis.

Monocyte-derived multipotent cell delivered programmed therapeutics to reverse idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a highly heterogeneous and fatal disease. However, IPF treatment has been limited by the low drug delivery efficiency to lungs and dysfunctional "injured" type II alveolar epithelial cell (AEC II). Here, we present surface-engineered nanoparticles (PER NPs) loading astaxanthin (AST) and trametinib (TRA) adhered to monocyte-derived multipotent cell (MOMC) forming programmed therapeutics (MOMC/PER). Specifically, the cell surface is designed to backpack plenty of PER NPs that reach directly to the lungs due to the homing characteristic of the MOMC and released PER NPs retarget injured AEC II after responding to the matrix metalloproteinase-2 (MMP-2) in IPF tissues. Then, released AST can enhance synergetic effect of TRA for inhibiting myofibroblast activation, and MOMC can also repair injured AEC II to promote damaged lung regeneration. Our findings provide proof of concept for developing a strategy for cell-mediated lung-targeted delivery platform carrying dual combined therapies to reverse IPF.

Periostin plays a critical role in the cell cycle in lung fibroblasts

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a devastating disease with a median survival of only three to 5 years. Fibroblast proliferation is a hallmark of IPF as is secretion of extracellular matrix proteins from fibroblasts. However, it is still uncertain how IPF fibroblasts acquire the ability to progressively proliferate. Periostin is a matricellular protein highly expressed in the lung tissues of IPF patients, playing a critical role in the pathogenesis of pulmonary fibrosis. However, it remains undetermined whether periostin affects lung fibroblast proliferation.

METHODS

In this study, we first aimed at identifying periostin-dependently expressed genes in lung fibroblasts using DNA microarrays. We then examined whether expression of cyclins and CDKs controlling cell cycle progression occur in a periostin-dependent manner. We next examined whether downregulation of cell proliferation-promoting genes by knockdown of periostin or integrin, a periostin receptor, using siRNA, is reflected in the cell proliferation of lung fibroblasts. We then looked at whether lung fibroblasts derived from IPF patients also require periostin for maximum proliferation. We finally investigated whether CP4715, a potent inhibitor against integrin α_Vβ₃ (a periostin receptor), which we have recently found blocks TGF-β signaling, followed by reduced BLM-induced pulmonary fibrosis in mice, can block proliferation of lung fibroblasts derived from IPF patients.

RESULTS

Many cell-cycle-related genes are involved in the upregulated or downregulated genes by periostin knockdown. We confirmed that in lung fibroblasts, periostin silencing downregulates expression of several cell-cycle-related molecules, including the cyclin, CDK, and, E2F families, as well as transcription factors such as B-MYB and FOXM1. Periostin or integrin silencing slowed proliferation of lung fibroblasts and periostin silencing increased the distribution of the G0/G1 phase, whereas the distribution of the G2/M phase was decreased. Lung fibroblasts derived from IPF patients also required periostin for maximum proliferation. Moreover, CP4715 downregulated proliferation along with expression of cell-cycle-related genes in IPF lung fibroblasts as well as in normal lung fibroblasts.

CONCLUSIONS

Periostin plays a critical role in the proliferation of lung fibroblasts and the present results provide us a solid basis for considering inhibitors of the periostin/integrin α_Vβ₃ interaction for the treatment of IPF patients.

Near-infrared-persistent luminescence/bioluminescence imaging tracking of transplanted mesenchymal stem cells in pulmonary fibrosis

A dual-labeling strategy integrating near-infrared-persistent luminescence and RfLuc-based bioluminescence imaging techniques has been developed to track the transplanted stem cells, deepening the understanding of the role played by stem cells in PF treatment.

Mesenchymal stromal cell exosomes prevent and revert experimental pulmonary fibrosis through modulation of monocyte phenotypes

Mesenchymal stromal/stem cell (MSC) therapy has shown promise in experimental models of idiopathic pulmonary fibrosis (IPF). The aim of this study was to test the therapeutic effects of extracellular vesicles produced by human BM MSCs (MEx) in a bleomycin-induced pulmonary fibrosis model and investigate mechanisms of action. Adult C57BL/6 mice were challenged with endotracheal instillation of bleomycin and treated with MEx concurrently, or for reversal models, at day 7 or 21. Experimental groups were assessed at day 7, 14, or 28. Bleomycin-challenged mice presented with severe septal thickening and prominent fibrosis, and this was effectively prevented or reversed by MEx treatment. MEx modulated lung macrophage phenotypes, shifting the proportions of lung proinflammatory/classical and nonclassical monocytes and alveolar macrophages toward the monocyte/macrophage profiles of control mice. A parallel immunomodulatory effect was demonstrated in the BM. Notably, transplantation of MEx-preconditioned BM-derived monocytes alleviated core features of pulmonary fibrosis and lung inflammation. Proteomic analysis revealed that MEx therapy promotes an immunoregulatory, antiinflammatory monocyte phenotype. We conclude that MEx prevent and revert core features of bleomycin-induced pulmonary fibrosis and that the beneficial actions of MEx may be mediated via systemic modulation of monocyte phenotypes.

First-in-human high-cumulative-dose stem cell therapy in idiopathic pulmonary fibrosis with rapid lung function decline

Previous phase I studies demonstrated safety and some beneficial effects of mesenchymal stem cells (MSCs) in patients with mild to moderate idiopathic pulmonary fibrosis (IPF). The aim of our study was to evaluate the safety, tolerability, and efficacy of a high cumulative dose of bone marrow MSCs in patients with rapid progressive course of severe to moderate IPF. Twenty patients with forced ventilation capacity (FVC) ≥40% and diffusing capacity of the lung for carbon monoxide (DLCO) ≥20% with a decline of both >10% over the previous 12 months were randomized into two groups: one group received two intravenous doses of allogeneic MSCs (2 × 10⁸ cells) every 3 months, and the second group received a placebo. A total amount of 1.6 × 10⁹ MSCs had been administered to each patient after the study completion. There were no significant adverse effects after administration of MSCs in any patients. In the group of MSC therapy, we observed significantly better improvement for the 6‐minute walk distance in 13 weeks, for DLCO in 26 weeks, and for FVC in 39 weeks compared with placebo. FVC for 12 months in the MSCs therapy group increased by 7.8% from baseline, whereas it declined by 5.9% in the placebo group. We did not find differences between the groups in mortality (two patients died in each group) or any changes in the high‐resolution computed tomography fibrosis score. In patients with IPF and a rapid pulmonary function decline, therapy with high doses of allogeneic MSCs is a safe and promising method to reduce disease progression.

Cell-based therapy for idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is an example of interstitial lung diseases that is characterized by chronic, progressive, and fibrotic lung injuries. During lung fibrosis, normal healthy lung tissues are replaced by remarkably destroyed alveolar architecture and altered extracellular cell matrix. These changes eventually cause severe disruption of the tightly-controlled gas exchange process and reduction of lung compliance that ultimately lead to both respiratory failure and death. In the last decade, progress has been made toward understanding the pathogenesis of pulmonary fibrosis, and two novel disease-modifying therapies were approved. However, finding more effective treatments for pulmonary fibrosis is still a challenge, with its incidence continues to increase globally, which is associated with significantly high mortality, morbidity and economical healthcare burden. Different stem cell types have recently emerged as a promising therapy for human diseases, including lung fibrosis, with numerous studies on the identification, characterization, proliferation and differentiation of stem cells. A large body of both basic and pre-clinical research on stem cells has been recently translated to patient care worldwide. Herein, we review recent advances in our understanding of the pathophysiology of IPF, and types of cells used in IPF cell-based therapies, including alveolar and mixed lung epithelial cells, different stem cell types (MSCs, ADSCs, IPSCs…etc.), endogenous lung tissue-specific stem cells, and circulating endothelial progenitors (EPCs). We also discuss recent studies on the applications of these cells in IPF therapy and their delivery routes, effective doses for cell therapy, and timing of delivery. Finally, we discuss attractive recent and current clinical trials conducted on cell-based therapy for IPF.

SPIO nanoparticle-labeled bone marrow mesenchymal stem cells inhibit pulmonary EndoMT induced by SiO2

Endothelial-mesenchymal transition (EndoMT) is a key step during lung fibrosis. Studies have shown that bone marrow mesenchymal stem cells (BMSCs) may act as therapeutic candidates for lung fibrosis. However, the effects of BMSCs on EndoMT induced by SiO₂ have not been elucidated, and means to label and track grafted cells have been lacking. The current study explored whether BMSCs prevented pulmonary fibrosis by targeting EndoMT, as well as analyzed the distribution of BMSCs labeled with superparamagnetic iron oxide (SPIO) nanoparticles during treatment. TIE2-GFP mice, human umbilical vein endothelial cells (HUVECs), and BMSCs labeled with SPIO nanoparticles were used to explore the distributions and therapeutic effects of BMSCs in vivo and in vitro. We found that BMSCs reversed lung fibrosis by targeting EndoMT in vivo. Furthermore, we show that BMSCs labeled with SPIO nanoparticles could be used to track stem cells reliably in the lungs for 14 days. Conditioned medium from BMSCs attenuated the increased functional changes and reversed the SiO₂-induced upregulation of ER stress and autophagy markers irrespective of whether they were nanoparticle labeled or not. Our findings identify novel methods to track labeled BMSCs with therapeutic potential.

Fibrosis in tissue engineering and regenerative medicine: treat or trigger?

Fibrosis is a life-threatening pathological condition resulting from a dysfunctional tissue repair process. There is no efficient treatment and organ transplantation is in many cases the only therapeutic option. Here we review tissue engineering and regenerative medicine (TERM) approaches to address fibrosis in the cardiovascular system, the kidney, the lung and the liver. These strategies have great potential to achieve repair or replacement of diseased organs by cell- and material-based therapies. However, paradoxically, they might also trigger fibrosis. Cases of TERM interventions with adverse outcome are also included in this review. Furthermore, we emphasize the fact that, although organ engineering is still in its infancy, the advances in the field are leading to biomedically relevant in vitro models with tremendous potential for disease recapitulation and development of therapies. These human tissue models might have increased predictive power for human drug responses thereby reducing the need for animal testing.

Human Adipose-Derived Mesenchymal Stem Cells Modify Lung Immunity and Improve Antibacterial Defense in Pneumosepsis Caused by Klebsiella pneumoniae

Adult mesenchymal stem cells exert immunomodulatory effects that might improve the host response during sepsis. Knowledge on the effect of adipose-derived mesenchymal stem cells (ASCs) in sepsis is limited. Klebsiella (K.) pneumoniae is a common cause of gram-negative pneumonia and sepsis. This study sought to determine the effect of human ASCs on the host response during pneumosepsis in mice. Mice were infected with K. pneumoniae via the airways to induce a gradually evolving infection in the lung culminating pneumosepsis. One or 6 hours after infection, mice were infused intravenously with ASCs or vehicle, and euthanized after 16 hours or 48 hours, respectively. The effects of freshly cultured and cryopreserved ASCs were compared, the latter formulation being more clinically relevant. Intravenously administered ASCs were visualized in lung tissue by immunostaining at 1 and 3 hours, but not at 15 hours after infusion. Although early after infection, ASCs did not or only modestly influence bacterial loads, they reduced bacterial burdens in lungs and distant organs at 48 hours. ASCs reduced the lung levels of pro-inflammatory cytokines and attenuated lung pathology, but did not influence distant organ injury. ASCs strongly modified the lung transcriptome in uninfected mice and especially mice with pneumosepsis. Cryopreserved and cultured ASCs induced largely similar effects on the lung transcriptome. These data indicate that human ASCs induce profound immune modulatory effects in the lungs, resulting in reduced bacterial burdens and lung inflammation during pneumosepsis caused by a common human pathogen, suggesting that ASCs may be an adjunctive therapeutic in this condition. Stem Cells Translational Medicine 2019;8:785&796.

Comparative study of the effects of mesenchymal stem cells with different delivery methods in an experimental model of lung fibrosis

Background: Transplantation of mesenchymal stem cells (MSCs) is one of the most promising directions in the treatment of idiopathic pulmonary fibrosis. In experimental small animal studies, intravenous and endobronchial (installation) techniques are used for the cell preparation delivery, while in humans inhalation of drugs is the simplest and most available method. Aim: The aim of the study was to determine the optimal type of a nebulizer for viability of MSCs during nebulization, followed by a comparison of the effects of inhalation and intravenous delivery methods in a standard model of bleomycin pulmonary fibrosis in rabbits. Methods: At the first stage, the survival of MSCs was assessed ex vivo after 10 minutes of compressor, ultrasound and mesh nebulization. Subsequently we used a nebulizer, which showed the best result in the cells, viability. At the next stage аfter bronchoscopic installation of bleomycin, 5 rabbits received intravenous transplantation of 2×106 allogeneic BMMSCs, other 5 rabbits — 2×107 MSCs inhaled via a compressor nebulizer; the control healthy and bleomycin groups included 5 animals each. Results: The highest degree of viability of MSC was maintained after passing via the compressor nebulizer (72%), a significantly lower survival rate was observed in ultrasonic nebulization (20%) and no live cells were detected after mesh nebulization. Both groups treated with MSC had a significantly lower fibrosis index on the Ashcroft morphometric scale than the control group of bleomycin fibrosis. Collagen expression in the lung tissue was significantly higher in all the groups with bleomycin injury, but in animals which underwent MSC inhalation, it was significantly different (0.51 point) from the bleomycin group without treatment (2.1 points). The level of neutrophils in the BAL fluid was significantly lower in animals which received the intravenous MSC therapy. The levels of TNF-α and TGF-β1 in the BAL fluids tended to decrease in the treatment groups, but did not differ significantly from control. Conclusions: The highest survival rate of MSCs is observed when using a compressor nebulizer, which apparently should be considered as the best way for delivering cells to the respiratory tract. Both inhalation and intravenous administration of MSCs cause similar effects of inhibiting the development of bleomycin-induced pulmonary fibrosis, which indicates the possibility of using both ways of cell delivery without loss of effectiveness.

Interrupted reprogramming of alveolar type II cells induces progenitor-like cells that ameliorate pulmonary fibrosis

We describe here an interrupted reprogramming strategy to generate “induced progenitor-like (iPL) cells” from alveolar epithelial type II (AEC-II) cells. A carefully defined period of transient expression of reprogramming factors (Oct4, Sox2, Klf4, and c-Myc (OSKM)) is able to rescue the limited in vitro clonogenic capacity of AEC-II cells, potentially by activation of a bipotential progenitor-like state. Importantly, our results demonstrate that interrupted reprogramming results in controlled expansion of cell numbers yet preservation of the differentiation pathway to the alveolar epithelial lineage. When transplanted to the injured lungs, AEC-II-iPL cells are retained in the lung and ameliorate bleomycin-induced pulmonary fibrosis. Interrupted reprogramming can be used as an alternative approach to produce highly specified functional therapeutic cell populations and may lead to significant advances in regenerative medicine.

A modified reprogramming strategy helps expand populations of surfactant-producing lung cells in a dish without altering their cellular function. A team led by Thomas Waddell and Andras Nagy from the University of Toronto, Canada isolated alveolar type II cells from the lungs of mice. They transiently induced expression of four reprogramming factors in these cells for a defined period of time. Before this “interrupted” reprogramming, the lung cells had limited ability to continue replicating themselves. Afterwards, the cells could expand their numbers dramatically without entering a pluripotent state. Rather, the cells maintained their original function while also expressing genes associated with lung precursor cells, which could explain their proliferative ability. The cells, when transplanted into the injured lungs, helped ameliorate pulmonary fibrosis in a mouse model, suggesting that a similar cell-based therapy may be useful in people.

Production via good manufacturing practice of exofucosylated human mesenchymal stromal cells for clinical applications

BACKGROUND

The regenerative and immunomodulatory properties of human mesenchymal stromal cells (hMSCs) have raised great hope for their use in cell therapy. However, when intravenously infused, hMSCs fail to reach sites of tissue injury. Fucose addition in α(1,3)-linkage to terminal sialyllactosamines on CD44 creates the molecule known as hematopoietic cell E-/L-selectin ligand (HCELL), programming hMSC binding to E-selectin that is expressed on microvascular endothelial cells of bone marrow (BM), skin and at all sites of inflammation. Here we describe how this modification on BM-derived hMSCs (BM-hMSCs) can be adapted to good manufacturing practice (GMP) standards.

METHODS

BM-hMSCs were expanded using xenogenic-free media and exofucosylated using α(1,3)-fucosyltransferases VI (FTVI) or VII (FTVII). Enforced fucosylation converted CD44 into HCELL, and HCELL formation was assessed using Western blot, flow cytometry and cell-binding assays. Untreated (unfucosylated), buffer-treated and exofucosylated BM-hMSCs were each analyzed for cell viability, immunophenotype and differentiation potential, and E-selectin binding stability was assessed at room temperature, at 4°C, and after cryopreservation. Cell product safety was evaluated using microbiological testing, karyotype analysis, and c-Myc messenger RNA (mRNA) expression, and potential effects on genetic reprogramming and in cell signaling were analyzed using gene expression microarrays and receptor tyrosine kinase (RTK) phosphorylation arrays.

RESULTS

Our protocol efficiently generates HCELL on clinical-scale batches of BM-hMSCs. Exofucosylation yields stable HCELL expression for 48 h at 4°C, with retained expression after cell cryopreservation. Cell viability and identity are unaffected by exofucosylation, without changes in gene expression or RTK phosphorylation.

DISCUSSION

The described exofucosylation protocol using xenogenic-free reagents enforces HCELL expression on hMSCs endowing potent E-selectin binding without affecting cell viability or native phenotype. This described protocol is readily scalable for GMP-compliant clinical production.

Mesenchymal Stem Cells for the Treatment of Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is an inexorably progressive lung disease of unknown origin. Prognosis is poor, with limited treatment options available, and the median survival remains just 3-5 years. Despite the use of pirfenidone and nintedanib for the treatment of IPF, curative therapies remain elusive and mortality remains high. Regenerative medicine and the use of cell-based therapies has recently emerged as a potential option for various diseases. Promising results of preclinical studies using mesenchymal stem cells (MSCs) suggest that they may represent a potential therapeutic option for the treatment of chronic lung diseases including IPF. Encouraging results of Phase 1 studies of MSCs various have reduced safety concerns. Nonetheless, there is still a pressing need for exploratory biomarkers and interval end-points in the context of MSCs investigation. This review intends to summarize the current state of knowledge for stem cells in the experimental and clinical setting of IPF, present important safety and efficacy issues, highlight future challenges and address the need for large, multicenter clinical trials coupled with realistic end-points, including biomarkers, to assess treatment efficacy.

Stem cells in lung repair and regeneration: Current applications and future promise

Lung diseases are major cause of morbidity and mortality worldwide. The progress in regenerative medicine and stem cell research in the lung are currently a fast-growing research topic that can provide solutions to these major health problems. Under normal conditions, the rate of cellular proliferation is relatively low in the lung in vivo, compared to other major organ systems. Lung injury leads to the activation of stem/progenitor cell populations that re-enter the cell cycle. Yet, little is known about stem cells in the lung, despite common thoughts that these cells could play a critical role in the repair of lung injuries. Nor do we fully understand the cellular and architectural complexity of the respiratory tract, and the diverse stem/progenitor cells that are involved in the lung repair and regeneration. In this review, we discuss the conceptual framework of lung stem/progenitor cell biology, and describe lung diseases, in which stem cell manipulations may be physiologically significant. In addition, we highlight the challenges of lung stem cell-based therapy.

Mesenchymal stromal cells prevent bleomycin-induced lung and skin fibrosis in aged mice and restore wound healing

Fibrosis can develop in nearly any tissue leading to a wide range of chronic fibrotic diseases. However, current treatment options are limited. In this study, we utilized an established aged mouse model of bleomycin-induced lung fibrosis (BLM) to test our hypothesis that fibrosis may develop simultaneously in multiple organs by evaluating skin fibrosis and wound healing. Fibrosis was induced in lung in aged (18-22-month-old) C57BL/6 male mice by intratracheal BLM administration. Allogeneic adipose-derived mesenchymal stromal cells (ASCs) or saline were injected intravenously 24 hr after BLM administration. Full thickness 8-mm punch wounds were performed 7 days later to study potential systemic anti-fibrotic and wound healing effects of intravenously delivered ASCs. Mice developed lung and skin fibrosis as well as delayed wound closure. Moreover, we observed similar changes in the expression of known pro-fibrotic factors in both lung and skin wound tissue, including miR-199 and protein expression of its corresponding target, caveolin-1, as well as phosphorylation of protein kinase B. Importantly, ASC-treated mice exhibited attenuation of BLM-induced lung and skin fibrosis and accelerated wound healing, suggesting that ASCs may prime injured tissues and prevent end-organ fibrosis.

Sirtuin1 Protects against Systemic Sclerosis-related Pulmonary Fibrosis by Decreasing Proinflammatory and Profibrotic Processes

Pulmonary fibrosis is the leading cause of death in systemic sclerosis (SSc). Sirtuin1 (SIRT1) is a deacetylase with known antiinflammatory and antifibrotic activity in the liver, kidney, and skin. The role of SIRT1 in SSc-related pulmonary fibrosis is unknown. In the present work, we determined that the expression of SIRT1 in peripheral blood mononuclear cells of patients with SSc with pulmonary fibrosis is lower than that in patients with SSc without pulmonary fibrosis. In in vivo studies of bleomycin-induced lung fibrosis in mice, SIRT1 activation with resveratrol reduced collagen production when it was administered either prophylactically during the inflammatory stage or after the development of fibrosis. Furthermore, SIRT1 activation or overexpression inhibited tumor necrosis factor-α-induced inflammatory responses in vitro in human fetal lung fibroblasts, depletion of SIRT1 in fibroblasts enhanced inflammation, and these effects were related to changes in the acetylation of NF-κB. In addition, SIRT1 activation or exogenous overexpression inhibited collagen production in vitro, and these manipulations also inhibited fibrosis via inactivation of transforming growth factor-β/mothers against decapentaplegic homolog and mammalian target of rapamycin signaling. Taken together, our results show that a loss of SIRT1 may participate in the pathogenesis of SSc-related pulmonary fibrosis, and that SIRT1 activation is an effective treatment for both the early (inflammatory) and late (fibrotic) stages of pulmonary fibrosis. Thus, SIRT1 may be a promising therapeutic target in the management of SSc-related pulmonary fibrosis.

Clinical applications of mesenchymal stem cells in chronic lung diseases

Mesenchymal stem (stromal) cells (MSCs) are multipotent stromal cells that have the ability to modulate immune response to tissue injury and promote repair in vivo. The therapeutic potential of ex vivo expanded MSCs are currently under investigation for a variety of chronic and acute lung diseases. This review summarizes the encouraging results regarding the safety of MSCs administration from recent and current clinical trials for idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and chronic obstructive pulmonary disease. It also reviews the early preliminary data extracted by the same trials regarding the efficacy of MSCs in the aforementioned lung diseases.

Paracrine Mechanisms of Mesenchymal Stem Cells in Tissue Repair

Tissue regeneration from transplanted mesenchymal stromal cells (MSC) either through transdifferentiation or cell fusion was originally proposed as the principal mechanism underlying their therapeutic action. However, several studies have now shown that both these mechanisms are very inefficient. The low MSC engraftment rate documented in injured areas also refutes the hypothesis that MSC repair tissue damage by replacing cell loss with newly differentiated cells. Indeed, despite evidence of preferential homing of MSC to the site of myocardial ischemia, exogenously administered MSC show poor survival and do not persist in the infarcted area. Therefore, it has been proposed that the functional benefits observed after MSC transplantation in experimental models of tissue injury might be related to the secretion of soluble factors acting in a paracrine fashion. This hypothesis is supported by pre-clinical studies demonstrating equal or even improved organ function upon infusion of MSC-derived conditioned medium (MSC-CM) compared with MSC transplantation. Identifying key MSC-secreted factors and their functional role seems a reasonable approach for a rational design of nextgeneration MSC-based therapeutics. Here, we summarize the major findings regarding both different MSC-mediated paracrine actions and the identification of paracrine mediators.

Application of the allogenic mesenchymal stem cells in the therapy of the bladder tuberculosis

Urogenital tuberculosis (TB) often leads to contraction of the bladder, a reduction of the urinary reservoir capacity, and, in the latest stage, to real microcystitis up to full obliteration. Bladder TB Stage 4 is unsuitable for conservative therapy, and cystectomy with subsequent enteroplasty is indicated. In this study, using a model of bladder TB in New Zealand rabbits, the therapeutic efficacy of the interstitial injection of autologous bone-derived mesenchymal stem cells (MSCs) combined with standard anti-TB treatment in the restoration of the bladder function was demonstrated. For analysis of the MSC distribution in tissues, the latter were labelled with superparamagnetic iron oxide nanoparticles. In vitro studies demonstrated the high intracellular incorporation of nanoparticles and the absence of cytotoxicity on MSC viability and proliferation. A single-dose administration of MSCs into the bladder mucosal layer significantly reduced the wall deformation and inflammation and hindered the development of fibrosis, which was proven by the subsequent histological assay. Confocal microscopy studies of the bladder cryosections confirmed the presence of superparamagnetic iron oxide nanoparticle-labelled MSCs in different bladder layers of the treated animals, thus indicating the role of stem cells in bladder regeneration.

Involvement of ER stress, PI3K/AKT activation, and lung fibroblast proliferation in bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is characterized by fibroblast proliferation and extracellular matrix remodelling, leading to respiratory insufficiency. The mechanisms underlying this progressive and devastating disease remain unclear. Conditions that can impair the function of the endoplasmic reticulum (ER) cause accumulation of unfolded or misfolded proteins, resulting in ER stress and activation of the unfolded protein response (UPR). ER stress has been implicated in many conditions including cancer, diabetes, obesity, and inflammation. It is also involved in lung fibrosis, through myofibroblastic differentiation of fibroblasts; however, the precise role of ER stress in lung fibrosis is unknown. The current study aimed to investigate the underlying mechanisms of ER stress inhibitors in the treatment of bleomycin-induced lung fibrosis. We demonstrated that bleomycin can activate ER stress associated proteins, including GRP78, CHOP, and ATF-4, both in vitro and in vivo. PI3K/AKT acts upstream of ER stress to affect lung fibroblast proliferation, resulting in bleomycin-induced pulmonary fibrosis. Treatment with ER stress inhibitors or a PI3K inhibitor caused a reduction in fibroblast proliferation and improved pulmonary function. The relationship between PI3K/AKT/mTOR and ER stress in pulmonary fibrosis, and the application of PI3K inhibitors and ER stress inhibitors in the treatment of pulmonary fibrosis require further investigation.

The Processes and Mechanisms of Cardiac and Pulmonary Fibrosis

Fibrosis is the formation of fibrous connective tissue in response to injury. It is characterized by the accumulation of extracellular matrix components, particularly collagen, at the site of injury. Fibrosis is an adaptive response that is a vital component of wound healing and tissue repair. However, its continued activation is highly detrimental and a common final pathway of numerous disease states including cardiovascular and respiratory disease. Worldwide, fibrotic diseases cause over 800,000 deaths per year, accounting for ~45% of total deaths. With an aging population, the incidence of fibrotic disease and subsequently the number of fibrosis-related deaths will rise further. Although, fibrosis is a well-recognized cause of morbidity and mortality in a range of disease states, there are currently no viable therapies to reverse the effects of chronic fibrosis. Numerous predisposing factors contribute to the development of fibrosis. Biological aging in particular, interferes with repair of damaged tissue, accelerating the transition to pathological remodeling, rather than a process of resolution and regeneration. When fibrosis progresses in an uncontrolled manner, it results in the irreversible stiffening of the affected tissue, which can lead to organ malfunction and death. Further investigation into the mechanisms of fibrosis is necessary to elucidate novel, much needed, therapeutic targets. Fibrosis of the heart and lung make up a significant proportion of fibrosis-related deaths. It has long been established that the heart and lung are functionally and geographically linked when it comes to health and disease, and thus exploring the processes and mechanisms that contribute to fibrosis of each organ, the focus of this review, may help to highlight potential avenues of therapeutic investigation.

Safety and Efficacy of Allogeneic Lung Spheroid Cells in a Mismatched Rat Model of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a devastating interstitial lung disease characterized by the relentless deposition of extracellular matrix causing lung distortions and dysfunctions. The prognosis after detection is merely 3-5 years and the only two Food and Drug Administration-approved drugs treat the symptoms, not the disease, and have numerous side effects. Stem cell therapy is a promising treatment strategy for pulmonary fibrosis. Current animal and clinical studies focus on the use of adipose or bone marrow-derived mesenchymal stem cells. We, instead, have established adult lung spheroid cells (LSCs) as an intrinsic source of therapeutic lung stem cells. In the present study, we compared the efficacy and safety of syngeneic and allogeneic LSCs in immuno-competent rats with bleomycin-induced pulmonary inflammation in an effort to mitigate fibrosis development. We found that infusion of allogeneic LSCs reduces the progression of inflammation and fibrotic manifestation and preserves epithelial and endothelial health without eliciting significant immune rejection. Our study sheds light on potential future developments of LSCs as an allogeneic cell therapy for humans with pulmonary fibrosis. Stem Cells Translational Medicine 2017;9:1905-1916.