Stem Cell-Based Therapy in Idiopathic Pulmonary Fibrosis

Unlocking the Future: Pluripotent Stem Cell-Based Lung Repair

The human respiratory system is susceptible to a variety of diseases, ranging from chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis to acute respiratory distress syndrome (ARDS). Today, lung diseases represent one of the major challenges to the health care sector and represent one of the leading causes of death worldwide. Current treatment options often focus on managing symptoms rather than addressing the underlying cause of the disease. The limitations of conventional therapies highlight the urgent clinical need for innovative solutions capable of repairing damaged lung tissue at a fundamental level. Pluripotent stem cell technologies have now reached clinical maturity and hold immense potential to revolutionize the landscape of lung repair and regenerative medicine. Meanwhile, human embryonic (HESCs) and human-induced pluripotent stem cells (hiPSCs) can be coaxed to differentiate into lung-specific cell types such as bronchial and alveolar epithelial cells, or pulmonary endothelial cells. This holds the promise of regenerating damaged lung tissue and restoring normal respiratory function. While methods for targeted genetic engineering of hPSCs and lung cell differentiation have substantially advanced, the required GMP-grade clinical-scale production technologies as well as the development of suitable preclinical animal models and cell application strategies are less advanced. This review provides an overview of current perspectives on PSC-based therapies for lung repair, explores key advances, and envisions future directions in this dynamic field.

Scarring and Skin Fibrosis Reversal with Regenerative Surgery and Stem Cell Therapy

Skin scarring and fibrosis affect millions of people worldwide, representing a serious clinical problem causing physical and psychological challenges for patients. Stem cell therapy and regenerative surgery represent a new area of treatment focused on promoting the body's natural ability to repair damaged tissue. Adipose-derived stem cells (ASCs) represent an optimal choice for practical regenerative medicine due to their abundance, autologous tissue origin, non-immunogenicity, and ease of access with minimal morbidity for patients. This review of the literature explores the current body of evidence around the use of ASCs-based regenerative strategies for the treatment of scarring and skin fibrosis, exploring the different surgical approaches and their application in multiple fibrotic skin conditions. Human, animal, and in vitro studies demonstrate that ASCs present potentialities in modifying scar tissue and fibrosis by suppressing extracellular matrix (ECM) synthesis and promoting the degradation of their constituents. Through softening skin fibrosis, function and overall quality of life may be considerably enhanced in different patient cohorts presenting with scar-related symptoms. The use of stem cell therapies for skin scar repair and regeneration represents a paradigm shift, offering potential alternative therapeutic avenues for fibrosis, a condition that currently lacks a cure.

Antler stem cell exosomes alleviate pulmonary fibrosis via inhibiting recruitment of monocyte macrophage, rather than polarization of M2 macrophages in mice

Pulmonary fibrosis (PF), a chronic interstitial lung disease, is characterized by over-abundant deposition of extracellular matrix consisting mainly of collagen I. In previous studies, we demonstrated that deer antler stem cells (AnSCs), a novel type of adult stem cell, are capable of significantly down-regulating collagen formation in different organs and tissues and speculated that they could effectively treat PF via reducing collagen deposition in the lung tissue. In the present study, we found that administration of AnSCs improved the survival rate of PF mice and reduced lung fibrosis, collagen deposition and myofibroblast differentiation. The effects of AnSC treatment were significantly better than the positive control (adipose-derived stem cells). Interestingly, AnSC-Exos were almost equally effective as AnSCs in treating PF, suggesting that the effects of AnSCs on reduction of PF may be mainly through a paracrine mechanism. Further, AnSC-Exos reduced the number of M2 macrophages, a type of macrophage that secrets pro-fibrotic factors to accelerate fibrotic progression, in the lung tissues. In vitro experiments showed that the effects of AnSC-Exos on macrophage modulation were likely achieved via inhibition of the recruitment of circulating monocyte-derived macrophages (reducing the number of macrophages), rather than via inhibition of M2 polarization of macrophages. Inhibition of macrophage recruitment by AnSCs may be achieved indirectly via inhibiting CCL7 expression in fibroblasts; both let-7b and let-7a were highly enriched in AnSC-Exos and may play a critical role in the inhibition of CCL7 expression of fibroblasts. Collectively, the use of antler stem cells or their exosomes opens up a novel strategy for PF treatment in the clinical setting.

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

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

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

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

Promises and Challenges of Cell-Based Therapies to Promote Lung Regeneration in Idiopathic Pulmonary Fibrosis

The lung epithelium is constantly exposed to harmful agents present in the air that we breathe making it highly susceptible to damage. However, in instances of injury to the lung, it exhibits a remarkable capacity to regenerate injured tissue thanks to the presence of distinct stem and progenitor cell populations along the airway and alveolar epithelium. Mechanisms of repair are affected in chronic lung diseases such as idiopathic pulmonary fibrosis (IPF), a progressive life-threatening disorder characterized by the loss of alveolar structures, wherein excessive deposition of extracellular matrix components cause the distortion of tissue architecture that limits lung function and impairs tissue repair. Here, we review the most recent findings of a study of epithelial cells with progenitor behavior that contribute to tissue repair as well as the mechanisms involved in mouse and human lung regeneration. In addition, we describe therapeutic strategies to promote or induce lung regeneration and the cell-based strategies tested in clinical trials for the treatment of IPF. Finally, we discuss the challenges, concerns and limitations of applying these therapies of cell transplantation in IPF patients. Further research is still required to develop successful strategies focused on cell-based therapies to promote lung regeneration to restore lung architecture and function.

Mesenchymal Stem Cell-Derived Extracellular Vesicles as Idiopathic Pulmonary Fibrosis Microenvironment Targeted Delivery

Idiopathic pulmonary fibrosis (IPF) affects an increasing number of people globally, yet treatment options remain limited. At present, conventional treatments depending on drug therapy do not show an ideal effect in reversing the lung damage or extending the lives of IPF patients. In recent years, more and more attention has focused on extracellular vesicles (EVs) which show extraordinary therapeutic effects in inflammation, fibrosis disease, and tissue damage repair in many kinds of disease therapy. More importantly, EVs can be modified or used as a drug or cytokine delivery tool, targeting injury sites to enhance treatment efficiency. In light of this, the treatment strategy of mesenchymal stem cell-extracellular vesicles (MSC-EVs) targeting the pulmonary microenvironment for IPF provides a new idea for the treatment of IPF. In this review, we summarized the inflammation, immune dysregulation, and extracellular matrix microenvironment (ECM) disorders in the IPF microenvironment in order to reveal the treatment strategy of MSC-EVs targeting the pulmonary microenvironment for IPF.

Mesenchymal stem cells: A new therapeutic tool for chronic kidney disease

Chronic kidney disease (CKD) has a major impact on public health, which could progress to end-stage kidney disease (ESRD) and consume many medical resources. Currently, the treatment for CKD has many flaws, so more effective treatment tools are urgently required for CKD. Mesenchymal stem cells (MSCs) are primitive cells with self-renewal and proliferation capacity and differentiation potential. Extensive preclinical and clinical data has shown that cell-based therapies using MSCs can modulate immunity, inhibit inflammatory factors, and improve renal function in CKD, suggesting that MSCs have the potential to be a new, effective therapeutic tool for CKD. In this review, we will describe different kinds of MSCs and MSCs products for the treatment of CKD in experimental models and clinical trials, potential signaling pathways, therapeutic efficacy, and critical issues that need to be addressed before therapeutic application in humans.

pH-Triggered Aggregation of Gold Nanoparticles for Enhanced Labeling and Long-Term CT Imaging Tracking of Stem Cells in Pulmonary Fibrosis Treatment

Gold nanoparticles (AuNPs) pose a great challenge in the development of nanotracers that can self-adaptively alter their properties in response to certain cellular environments for long-term stem cell tracking. Herein, pH-sensitive Au nanotracers (CPP-PSD@Au) are fabricated by sequential coupling of AuNPs with sulfonamide-based polymer (PSD) and cell-penetrating peptide (CPP), which can be efficiently internalized by mesenchymal stem cells (MSCs) and undergo pH-induced self-assembly in endosomes, facilitating long-term computed tomography (CT) imaging tracking MSCs in a murine model of idiopathic pulmonary fibrosis (IPF). Using the CPP-PSD@Au, the transplanted MSCs for the first time can be monitored with CT imaging for up to 35 days after transplantation into the lung of IPF mice, clearly elucidating the migration process of MSCs in vivo. Moreover, we preliminarily explored the mechanism of the CPP-PSD@Au labeled MSCs in the alleviation of IPF, including recovery of alveolar integrity, decrease of collagen deposition, as well as down-regulation of relevant cytokine level. This work facilitates our understanding of the behavior and effect of MSCs in the therapy of IPF, thereby providing an important insight into the stem cell-based treatment of lung diseases.

Adipose Stromal Cell-Secretome Counteracts Profibrotic Signals From IPF Lung Matrices

Introduction: Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease characterized by excess deposition and altered structure of extracellular matrix (ECM) in the lungs. The fibrotic ECM is paramount in directing resident cells toward a profibrotic phenotype. Collagens, an important part of the fibrotic ECM, have been shown to be structurally different in IPF. To further understand the disease to develop better treatments, the signals from the ECM that drive fibrosis need to be identified. Adipose tissue-derived stromal cell conditioned medium (ASC-CM) has demonstrated antifibrotic effects in animal studies but has not been tested in human samples yet. In this study, the collagen structural integrity in (fibrotic) lung tissue, its interactions with fibroblasts and effects of ASC-CM treatment hereon were studied. Methods: Native and decellularized lung tissue from patients with IPF and controls were stained for denatured collagen using a collagen hybridizing peptide. Primary lung fibroblasts were seeded into decellularized matrices from IPF and control subjects and cultured for 7 days in the presence or absence of ASC-CM. Reseeded matrices were fixed, stained and analyzed for total tissue deposition and specific protein expression. Results: In both native and decellularized lung tissue, more denatured collagen was observed in IPF tissue compared to control tissue. Upon recellularization with fibroblasts, the presence of denatured collagen was equalized in IPF and control matrices, whereas total ECM was higher in IPF matrices than in the control. Treatment with ASC-CM resulted in less ECM deposition, but did not alter the levels of denatured collagen. Discussion: Our data showed that ASC-CM can inhibit fibrotic ECM-induced profibrotic behavior of fibroblasts. This process was independent of collagen structural integrity. Our findings open up new avenues for ASC-CM to be explored as treatment for IPF.

Dissecting the Role of Mesenchymal Stem Cells in Idiopathic Pulmonary Fibrosis: Cause or Solution

Idiopathic pulmonary fibrosis (IPF) is one of the most aggressive forms of idiopathic interstitial pneumonias, characterized by chronic and progressive fibrosis subverting the lung's architecture, pulmonary functional decline, progressive respiratory failure, and high mortality (median survival 3 years after diagnosis). Among the mechanisms associated with disease onset and progression, it has been hypothesized that IPF lungs might be affected either by a regenerative deficit of the alveolar epithelium or by a dysregulation of repair mechanisms in response to alveolar and vascular damage. This latter might be related to the progressive dysfunction and exhaustion of the resident stem cells together with a process of cellular and tissue senescence. The role of endogenous mesenchymal stromal/stem cells (MSCs) resident in the lung in the homeostasis of these mechanisms is still a matter of debate. Although endogenous MSCs may play a critical role in lung repair, they are also involved in cellular senescence and tissue ageing processes with loss of lung regenerative potential. In addition, MSCs have immunomodulatory properties and can secrete anti-fibrotic factors. Thus, MSCs obtained from other sources administered systemically or directly into the lung have been investigated for lung epithelial repair and have been explored as a potential therapy for the treatment of lung diseases including IPF. Given these multiple potential roles of MSCs, this review aims both at elucidating the role of resident lung MSCs in IPF pathogenesis and the role of administered MSCs from other sources for potential IPF therapies.

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.

Extracellular vesicles derived from umbilical cord mesenchymal stromal cells alleviate pulmonary fibrosis by means of transforming growth factor-β signaling inhibition

Background

Pulmonary fibrosis (PF), the end point of interstitial lung diseases, is characterized by myofibroblast over differentiation and excessive extracellular matrix accumulation, leading to progressive organ dysfunction and usually a terminal outcome. Studies have shown that umbilical cord-derived mesenchymal stromal cells (uMSCs) could alleviate PF; however, the underlying mechanism remains to be elucidated.

Methods

The therapeutic effects of uMSC-derived extracellular vesicles (uMSC-EVs) on PF were evaluated using bleomycin (BLM)-induced mouse models. Then, the role and mechanism of uMSC-EVs in inhibiting myofibroblast differentiation were investigated in vivo and in vitro.

Results

Treatment with uMSC-EVs alleviated the PF and enhanced the proliferation of alveolar epithelial cells in BLM-induced mice, thus improved the life quality, including the survival rate, body weight, fibrosis degree, and myofibroblast over differentiation of lung tissue. Moreover, these effects of uMSC-EVs on PF are likely achieved by inhibiting the transforming growth factor-β (TGF-β) signaling pathway, evidenced by decreased expression levels of TGF-β2 and TGF-βR2. Using mimics of uMSC-EV-specific miRNAs, we found that miR-21 and miR-23, which are highly enriched in uMSC-EVs, played a critical role in inhibiting TGF-β2 and TGF-βR2, respectively.

Conclusion

The effects of uMSCs on PF alleviation are likely achieved via EVs, which reveals a new role of uMSC-EV-derived miRNAs, opening a novel strategy for PF treatment in the clinical setting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02296-8.

Targeted Dual Small Interfering Ribonucleic Acid Delivery via Non-Viral Polymeric Vectors for Pulmonary Fibrosis Therapy

Inhibiting the myofibroblast differentiation of lung-resident mesenchymal stem cells (LR-MSCs) is a promising yet challenging approach for pulmonary fibrosis (PF) therapy. Here, micelles formed by a graft copolymer of multiple PEGs modified branched polyethylenimine are used for delivering runt-related transcription factor-1 (RUNX1) small interfering RNA (siRNA) (siRUNX1) to the lung, aiming to inhibit the myofibroblast differentiation of LR-MSCs. LR-MSC targeting is achieved by functionalizing the micelle surface with an anti-stem-cell antigen-1 antibody fragment (Fab'). Consequently, therapeutic benefits are obtained by successful suppression of myofibroblast differentiation of LR-MSCs in bleomycin-induced PF model mice treated with siRUNX1-loaded micelles. Furthermore, an excellent synergistic effect of PF therapy is achieved for this micelle system loaded siRUNX1 and glioma-associated oncogene homolog-1 (Gli1) small interfering RNA (siGli1), a traditional anti-PF siRNA of glioma-associated oncogene homolog-1. Hence, this work not only provides RUNX1 as a novel PF therapeutic target, but also as a promising dual siRNA-loaded nanocarrier system for the therapy of PF.

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

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

Hydrogen Peroxide Preconditioning Promotes Protective Effects of Umbilical Cord Vein Mesenchymal Stem Cells in Experimental Pulmonary Fibrosis

Purpose: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disorder with few available treatments. Mesenchymal stem cell therapy (MSCT), an innovative approach, has high therapeutic potential when used to treat IPF. According to recent data, preconditioning of MSCs can improve their therapeutic effects. Our research focuses on investigating the anti-inflammatory and antifibrotic effects of H2 O2 -preconditioned MSCs (p-MSCs) on mice with bleomycin-induced pulmonary fibrosis (PF). Methods: Eight-week-old male C57BL/6 mice were induced with PF by intratracheal (IT) instillation of bleomycin (4 U/kg). Human umbilical cord vein-derived MSCs (hUCV-MSCs) were isolated and exposed to a sub-lethal concentration (15 μM for 24 h) of H2 O2 in vitro. One week following the injection of bleomycin, 2×105 MSCs or p-MSCs were injected (IT) into the experimental PF. The survival rate and weight of mice were recorded, and 14 days after MSCs injection, all mice were sacrificed. Lung tissue was removed from these mice to examine the myeloperoxidase (MPO) activity, histopathological changes (hematoxylin-eosin and Masson's trichrome) and expression of transforming growth factor beta 1 (TGF-β1) and alpha-smooth muscle actin (α-SMA) through immunohistochemistry (IHC) staining. Results: Compared to the PF+MSC group, p-MSCs transplantation results in significantly decreased connective tissue (P<0.05) and collagen deposition. Additionally, it is determined that lung tissue in the PF+pMSC group has increased alveolar space (P<0.05) and diminished expression of TGF-β1 and α-SMA. Conclusion: The results demonstrate that MSCT using p-MSCs decreases inflammatory and fibrotic factors in bleomycin-induced PF, while also able to increase the therapeutic potency of MSCT in IPF.

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.

Optimization of the adipose-derived mesenchymal stem cell delivery time for radiation-induced lung fibrosis treatment in rats

The present study attempts to identify the optimal time duration for the administration of Ad-MSCs, in order to maximize its therapeutic benefits, and compare the degree of fibrosis among three different administration time points using the RILF rat model system. Ad-MSCs were delivered to Sprague-Dawley rats through the tail vein at the following different time points after thorax irradiation: two hours, seven days, and two hours + seven days. Post Ad-MSCs transplantation and the histopathological analysis of the lungs were performed along with analysis of inflammatory cytokine levels, including interleukin (IL)-1, IL-2, IL-6, IL-10 and tumor necrosis factor-α (TNF-α). In particular, pro-fibrotic factors (TGF-β1 and α-SMA) were also evaluated in serum and lung tissues. In addition, it was also determined whether Ad-MSCs had any role in inhibiting the transition of type II alveolar epithelial cells into fibroblasts in the lungs of injured rats. The present results demonstrated that the intravenous delivery of Ad-MSCs twice at the 2-hour and 7-day (R + MSC_2h+7d group) was effective in reducing lung fibrosis for long term durations, when compared with single delivery either at the two-hour or 7-day time points. In addition, a marked anti-inflammatory effect was also observed in RILF rats in the R + MSC_2h+7d group, as indicated by the reduced serum levels of pro-inflammatory cytokines (TNF-α, IL-1 and IL-6) and increased levels of anti-inflammatory cytokines IL-10 and IL-2. Rats that were delivered twice with Ad-MSCs (R + MSC_2h+7d group) exhibited significantly reduced TGF-β1 and α-SMA levels, in contrast to rats in the R + MSC_7d or R + MSC_2h groups, after four weeks. Furthermore, it was also noted that after four weeks, Ad-MSCs increased the number of lung epithelial cells (SP-C) and inhibited the lung fibroblastic cells (α-SMA) of rats in the R + MSC_2h and R + MSC_2h+7d groups. The present study concluded that two injections of Ad-MSCs (R + MSC_2h+7d group) appear to be optimal for therapeutic efficacy and safety during RILF.

Endothelial Colony-Forming Cells Do Not Participate to Fibrogenesis in a Bleomycin-Induced Pulmonary Fibrosis Model in Nude Mice

Idiopathic pulmonary fibrosis (IPF) is a devastating lung disease characterized by fibroblast proliferation, extracellular matrix deposition, destruction of pulmonary alveolar architecture and vascular remodeling. Apart pirfenidone or nintendanib that only slow down the fibrotic process, there is no curative treatment other than lung transplantation. Because cell therapy approaches have been proposed in IPF, we hypothesized that injection of endothelial colony-forming cells (ECFCs), the vasculogenic subtype of endothelial progenitor cells, could modulate fibrosis in a Nude mouse model of bleomycin induced-pulmonary fibrosis. Mice were injected with ECFCs isolated from cord blood and from peripheral blood of adult IPF patients at two time-points: during the development of the fibrosis or once the fibrosis was constituted. We assessed morbidity, weight variation, collagen deposition, lung imaging by microCT, Fulton score and microvascular density. Neither ECFCs isolated from cord blood nor from IPF patients were able to modulate fibrosis or vascular density during fibrogenesis or when fibrosis was constituted. These findings indicate that human ECFCs do not promote an adaptive regenerative response in the lung upon fibrosis or angiogenic process in the setting of bleomycin-induced pulmonary fibrosis in Nude mice.

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.

Transplantation of adipose-derived mesenchymal stem cells attenuates pulmonary fibrosis of silicosis via anti-inflammatory and anti-apoptosis effects in rats

Background

Silicosis has been topping the list of high-incidence occupational diseases in developing countries and cannot be completely cured. Recent advances in stem cell research have made possible the treatment of various diseases including lung fibrosis. The application of stem cell therapy in occupational diseases, in particular the use of adipose-derived mesenchymal stem cells (AD-MSCs) in treatment of silicosis, has not yet been reported. The aim of the study is to explore the intervening effect of silica-induced lung fibrosis in rats.

Methods

In this study, we investigated the anti-pulmonary fibrosis effects of the transplantation of AD-MSCs in rats in which lung fibrosis was induced by oral tracheal intubation with silica suspension. Twenty rats were divided into four groups: control group (n = 5), exposure group (n = 5), vehicle group (n = 5) and treatment group (n = 5). AD-MSCs were given to rats after exposure to silica for 24 h. Twenty-eight days after AD-MSC transplantation, we examined the organ coefficient, inflammatory cytokines, apoptosis, pathological and fibrotic changes in lung tissue.

Results

Results showed that exposure to silica for 28 days induced an increase of the lung coefficient with significant pulmonary fibrosis. Treatment with AD-MSC transplantation led to a remissive effect on pulmonary fibrosis. We found that after AD-MSC transplantation the inflammatory response decreased and Caspase-3 protein expression significantly decreased with a significant increase of the Bcl-2/Bax ratio.

Conclusions

Anti-inflammatory and anti-apoptosis of AD-MSCs may play important roles in their anti-pulmonary fibrosis effect. Our data suggest that transplantation of AD-MSCs holds promise for potential interference in the formation of silicosis through regulating inflammatory and apoptotic processes.

Gap Junctions Are Involved in the Rescue of CFTR-Dependent Chloride Efflux by Amniotic Mesenchymal Stem Cells in Coculture with Cystic Fibrosis CFBE41o- Cells

We previously found that human amniotic mesenchymal stem cells (hAMSCs) in coculture with CF immortalised airway epithelial cells (CFBE41o- line, CFBE) on Transwell® filters acquired an epithelial phenotype and led to the expression of a mature and functional CFTR protein. In order to explore the role of gap junction- (GJ-) mediated intercellular communication (GJIC) in this rescue, cocultures (hAMSC : CFBE, 1 : 5 ratio) were studied for the formation of GJIC, before and after silencing connexin 43 (Cx43), a major component of GJs. Functional GJs in cocultures were inhibited when the expression of the Cx43 protein was downregulated. Transfection of cocultures with siRNA against Cx43 resulted in the absence of specific CFTR signal on the apical membrane and reduction in the mature form of CFTR (band C), and in parallel, the CFTR-dependent chloride channel activity was significantly decreased. Cx43 downregulation determined also a decrease in transepithelial resistance and an increase in paracellular permeability as compared with control cocultures, implying that GJIC may regulate CFTR expression and function that in turn modulate airway epithelium tightness. These results indicate that GJIC is involved in the correction of CFTR chloride channel activity upon the acquisition of an epithelial phenotype by hAMSCs in coculture with CF cells.

Human placental mesenchymal stem cells of fetal origins-alleviated inflammation and fibrosis by attenuating MyD88 signaling in bleomycin-induced pulmonary fibrosis mice

Pulmonary fibrosis is a progressive lung disease that its pathogenic mechanism currently is incompletely understood. Toll-like receptor (TLR) signaling has recently been identified as a regulator of inflammation and pulmonary fibrosis. In addition, mesenchymal stem cells (MSCs) of different origins offer a great promise in treatment of idiopathic pulmonary fibrosis (IPF). However mechanisms of pathogenic roles of TLR signaling and therapeutic effects of MSCs in the IPF remain elusive. In present study, the involvement of TLR signaling and the therapeutic role of MSCs were interrogated in MyD88-deficient mice using human placental MSCs of fetal origins (hfPMSCs). The results showed an alleviated pulmonary inflammation and fibrosis in myeloid differentiation primary response gene 88 (MyD88)-deficient mice treated with bleomycin (BLM), accompanied with a reduced TGF-β signaling and production of pro-fibrotic cytokines, including TNF-α, IL-1β. An exposure of HLF1 lung fibroblasts, A549 epithelial cells and RAW264.7 macrophages to BLM led an increased expression of key components of MyD88 and TGF-β signaling cascades. Of interest, enforced expression and inhibition of MyD88 protein resulted in an enhanced and a reduced TGF-β signaling in above cells in the presence of BLM, respectively. However, the addition of TGF-β1 showed a marginally inhibitory effect on MyD88 signaling in these cells in the absence of BLM. Importantly, the administration of hfPMSCs could significantly attenuate BLM-induced pulmonary fibrosis in mice, along with a reduced hydroxyproline (HYP) deposition, MyD88 and TGF-β signaling activation, and production of pro-fibrotic cytokines. These results may suggest an importance of MyD88/TGF-β signaling axis in the tissue homeostasis and functional integrity of lung in response to injury, which may offer a novel target for treatment of pulmonary fibrosis.

Adipose-derived mesenchymal stem cells therapy for acute kidney injury induced by ischemia-reperfusion in a rat model

Acute kidney injury (AKI) represents a group of complicated syndromes with a high mortality rate. The administration of adipose-derived mesenchymal stem cells (ADMSCs) has been tested as a possible treatment method for AKI. The long-term evaluation of AKI induced by ischemia/reperfusion (IR) and the probable renal protection of ADMSCs are limited. In this study we have established a rat AKI model induced by IR and investigated the possible protective effects of ADMSCs. Adult Sprague-Dawley (SD) rats were divided into three groups (n = 6/each group). The MOCK group was as the normal control. Rats in the IR-AKI and IR-AKI+ADMSCs groups were subjected to IR injury by clamping both renal pedicles for 40 minutes. Rats in the MOCK and IR-AKI groups were injected with PBS via the tail vein as negative treatment controls. Rats in the IR-AKI+ADMSCs group received ADMSCs therapy (2 × 10⁶ cells were injected into the rats via the tail vein). We found that ADMSC transplantation restored the pathologic morphology induced by IR-AKI to normal compared with the MOCK group, suggesting the reparative function of ADMSCs in kidney tissues. Compared with IR-induced AKI alone, ADMSC treatment significantly decreased the number of apoptotic cells, the level of total urinary protein and serum creatinine, the expression of pro-inflammatory cytokines (IL-6, TNF-α, IL-1β, IFN-γ, TNF-α, IFN-γ, and TGF-β), and the inflammation-associated proteins (HGF and SDF1), but increased the expression of the anti-inflammatory cytokine, IL-10, and the anti-apoptotic regulator, Bcl-2. Our data have indicated that ADMSC transplantation may protect against IR-induced AKI by anti-apoptotic and anti-inflammatory effects.

TNF-α-induced NF-κB activation promotes myofibroblast differentiation of LR-MSCs and exacerbates bleomycin-induced pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible lung disease of unknown cause. It has been reported that both lung resident mesenchymal stem cells (LR-MSCs) and tumor necrosis factor-α (TNF-α) play important roles in the development of pulmonary fibrosis. However, the underlying connections between LR-MSCs and TNF-α in the pathogenesis of pulmonary fibrosis are still elusive. In this study, we found that the pro-inflammatory cytokine TNF-α and the transcription factor nuclear factor kappa B (NF-κB) p65 subunit were both upregulated in bleomycin-induced fibrotic lung tissue. In addition, we discovered that TNF-α promotes myofibroblast differentiation of LR-MSCs through activating NF-κB signaling. Interestingly, we also found that TNF-α promotes the expression of β-catenin. Moreover, we demonstrated that suppression of the NF-κB signaling could attenuate myofibroblast differentiation of LR-MSCs and bleomycin-induced pulmonary fibrosis which were accompanied with decreased expression of β-catenin. Our data implicates that inhibition of the NF-κB signaling pathway may provide a therapeutic strategy for pulmonary fibrosis, a disease that warrants more effective treatment approaches.

Optimal Dose and Timing of Umbilical Stem Cells Treatment in Pulmonary Arterial Hypertensive Rats

PURPOSE

Pulmonary arterial hypertension (PAH) is a fatal disease which is characterized by an increase in pulmonary arterial pressure leading to increases in right ventricular afterload. Human umbilical cord blood derived-mesenchymal stem cells (hUCB-MSCs) administered via the jugular vein have been previously shown to improve PAH by reversal treatment. However, the effect of low dosage and transfusion timing of hUCB-MSCs on PAH has not yet been clearly established. Obviously, low dosage treatment can lead to a reduction in costs. This is the first study on early transfusion effect.

MATERIALS AND METHODS

This study was divided into two parts. The first part is an investigation of dose-dependent effect. hUCB-MSCs were administered into 3 groups of rats (UA: 3×10⁶ cells, UB: 1.5×10⁶ cells, UC: 3×10⁵ cells) via the external jugular vein at week 1 after monocrotaline (MCT) injection. The second part is a search for optimal treatment timing in 3×10⁵ cells dose of hUCB-MSCs administered at day 1 for UD group (low dose of hUCB-MSCs at day 1), at day 1 and week 1 for the UE group (dual transfusion of low dose of hUCB-MSCs at day 1 and week 1) and at 1 week for the UF group (reversal treatment of low dose hUCB-MSC at week 1) after MCT injection.

RESULTS

The administration of 3×10⁵ hUCB-MSCs was as effective as the 3×10⁶ dose in decreasing mean right ventricle (RV) pressure and pulmonary pathological changes. Early treatment with hUCB-MSCs improved mean RV pressure, pulmonary pathological changes and heart collagen 3 protein expression levels in PAH.

CONCLUSION

Low-dose early treatment of hUCB-MSCs is as effective as a high dose treatment of hUCB-MSCs in improving PAH although dual or reversal treatment is still more effective.

Placental stem cells: The promise of curing diseases before birth

Regenerative medicine is a rapidly expanding and promising field for many diseases and injuries. Stem cells for regenerative therapies have originally been obtained from bone marrow, but are now readily extracted from a variety of adult tissues. Fetal tissue has recently garnered interest for its ease of differentiation into a variety of phenotypes and its relative abundance of pluripotent-linked transcription factors. However, much ethical concern surrounds the methods of obtaining fetal cells. The placenta has emerged as a potential source of fetal derived cells due to its favorable technical and ethical characteristics, as well as its promising therapeutic properties. This preview focuses on providing on overview on the derivation and characteristics of placental derived stem cells as well as delving into their various clinical applications and potential future directions.

miR-877-3p targets Smad7 and is associated with myofibroblast differentiation and bleomycin-induced lung fibrosis

Myofibroblast differentiation of lung resident mesenchymal stem cells (LR-MSC) plays an important role in idiopathic pulmonary fibrosis. By comparing the expression profiles of miRNAs before and after myofibroblast differentiation of LR-MSC, we identified miR-877-3p as a fibrosis-related miRNA. We found that miR-877-3p sequestration inhibited the myofibroblast differentiation of LR-MSC and attenuates bleomycin-induced lung fibrosis by targeting Smad7. Smad7, as an inhibitory smad in the TGF-β1 signaling pathway, was decreased in the myofibroblast differentiation of LR-MSC and up-regulation of Smad7 could inhibit the differentiation process. Our data implicates a potential application of miR-877-3p as a fibrosis suppressor for pulmonary fibrosis therapy and also as a fibrosis marker for predicting prognosis.

Cell-based therapies for the treatment of idiopathic pulmonary fibrosis (IPF) disease

INTRODUCTION

During the last few decades, cell-based therapies have shown great potential to treat patients with lung diseases. It has been proposed that the administration of cells into an injured lung could be considered as a therapeutic method to repair and replace lost lung tissue. Using this method, transplanted cells with the ability to proliferate and differentiate into alveolar cells, have been suggested as a therapeutic strategy for IPF treatment.

AREAS COVERED

In this review, the latest investigations using various types of cells for IPF therapy have been presented. The cells studied for cell-based therapies in IPF are lung alveolar epithelial cells, lung resident stem cells and exogenous adult stem cells such as MSCs.

EXPERT OPINION

After many years of investigation, the use of cell-based therapies to treat IPF is still at the experimental phase. Problems include bioethical issues, safety of cell transplantation, routes of delivery and the dose and timing of administration. Further investigations are necessary to establish the best strategy for using cell-based therapies effectively for the treatment of IPF.

Biomaterials as carrier, barrier and reactor for cell-based regenerative medicine

Cell therapy has achieved tremendous success in regenerative medicine in the past several decades. However, challenges such as cell loss, death and immune-rejection after transplantation still persist. Biomaterials have been designed as carriers to deliver cells to desirable region for local tissue regeneration; as barriers to protect transplanted cells from host immune attack; or as reactors to stimulate host cell recruitment, homing and differentiation. With the assistance of biomaterials, improvement in treatment efficiency has been demonstrated in numerous animal models of degenerative diseases compared with routine free cell-based therapy. Emerging clinical applications of biomaterial assisted cell therapies further highlight their great promise in regenerative therapy and even cure for complex diseases, which have been failed to realize by conventional therapeutic approaches.