Bronchioalveolar stem cells increase after mesenchymal stromal cell treatment in a mouse model of bronchopulmonary dysplasia

Better therapeutic potential of bone marrow-derived mesenchymal stem cells compared with chorionic villi-derived mesenchymal stem cells in airway injury model

Aim: To determine the efficiency of mesenchymal stem cells (MSCs) of different sources on airway epithelial cells regeneration and track where and to what extent transplanted MSCs home to injured tissues. Materials & methods: We performed DiO-labeled human bone marrow-derived MSCs (hBMSCs) or human chorionic villi-derived MSCs transplantation studies using naphthalene-induced airway injury animal models. Results: Compared with human chorionic villi-derived MSCs, hBMSCs facilitated airway epithelium regeneration faster and better from day 5 after transplantation; moreover, more transplanted hBMSCs distributed in injured lung tissues at the early stage of postinjury, which was mediated by C-X-C motif chemokine ligand 12. Conclusion: hBMSCs possessed better potential of migration to the damaged lung and promoting the repair of the injured airway epithelium.

Lung development and emerging roles for type 2 immunity

Lung development is a complex process mediated through the interaction of multiple cell types, factors and mediators. In mice, it starts as early as embryonic day 9 and continues into early adulthood. The process can be separated into five different developmental stages: embryonic, pseudoglandular, canalicular, saccular, and alveolar. Whilst lung bud formation and branching morphogenesis have been studied extensively, the mechanisms of alveolarisation are incompletely understood. Aberrant lung development can lead to deleterious consequences for respiratory health such as bronchopulmonary dysplasia (BPD), a disease primarily affecting preterm neonates, which is characterised by increased pulmonary inflammation and disturbed alveolarisation. While the deleterious effects of type 1-mediated inflammatory responses on lung development have been well established, the role of type 2 responses in postnatal lung development remains poorly understood. Recent studies indicate that type 2-associated immune cells, such as group 2 innate lymphoid cells and alveolar macrophages, are increased in number during postnatal alveolarisation. Here, we present the current state of understanding of the postnatal stages of lung development and the key cell types and mediators known to be involved. We also provide an overview of how stem cells are involved in lung development and regeneration, and the negative influences of respiratory infections. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The effect of mesenchymal stem cell-secreted factors on airway epithelial repair

Aim: This study was aimed to investigate the effect of mesenchymal stem cell (MSC)-secreted factors on airway repair. Materials & methods: An indirect in vitro coculture model of injured airway epithelium explant with MSCs was developed. LC–MS/MS analysis was performed to determine factors secreted by MSCs and their involvement in epithelium repair was evaluated by histopathological assessment. Results: The identification of 54 of MSC proteins of which 44 of them were secretory/extracellular proteins. 43 of the secreted proteins were found to be involved in accelerating airway epithelium repair by stimulating the migratory, proliferative and differentiation abilities of the endogenous repair mechanisms. MSC-secreted proteins also initiated epithelial–mesenchymal transition process during early repair. Conclusion: MSC-secreted factors accelerated airway epithelial repair by stimulating the endogenous reparative and regenerative ability of lung cells.

Use of three-dimensional organoids and lung-on-a-chip methods to study lung development, regeneration and disease

Differences in lung anatomy between mice and humans, as well as frequently disappointing results when using animal models for drug discovery, emphasise the unmet need for in vitro models that can complement animal studies and improve our understanding of human lung physiology, regeneration and disease. Recent papers have highlighted the use of three-dimensional organoids and organs-on-a-chip to mimic tissue morphogenesis and function in vitro Here, we focus on the respiratory system and provide an overview of these in vitro models, which can be derived from primary lung cells and pluripotent stem cells, as well as healthy or diseased lungs. We emphasise their potential application in studies of respiratory development, regeneration and disease modelling.

Effect of mesenchymal stromal (stem) cell (MSC) transplantation in asthmatic animal models: A systematic review and meta-analysis

BACKGROUND

Over the years, mesenchymal stromal (stem) cells (MSCs) have been pre-clinically applied in the treatment of variety kinds of diseases including asthma and chronic lung diseases. Aim of the current study was to systematically review and to conduct meta-analysis on the published studies of MSC treatment in asthma animal models.

METHODS

Publications on the MSC and asthma treatment was thoroughly searched in the electronic databases. Statistical analysis was then performed using the Comprehensive Meta-Analysis software (Version 3). Effect of MSC therapy on asthma model was assessed by Hedges's g with 95% confidence intervals (95% CIs). Random effect model was used due to the heterogeneity between the studies.

RESULTS

Meta-analysis of the 32 included studies showed that MSC transplantation was significantly in favor of attenuating lung injury and remodeling (Hedges's g = -9.104 ± 0.951 with 95% CI: -10.969 ∼ -7.240, P < 0.001) and airway inflammation (Hedges's g = -4.146 ± 0.688 with 95% CI: -5.495 ∼ -2.797, P < 0.001). The mechanism of MSC therapy in asthma seems to be regulating the balance of Th1 cytokine and Th2 cytokines (IFN-γ: Hedges's g = 4.779 ± 1.408 with 95% CI: 1.099-2.725, P < 0.001; IL-4: Hedges's g = -10.781 ± 1.062 with 95% CI: -12.863 ∼ -8.699, P < 0.001; IL-5: Hedges's g = -10.537 ± 1.269 with 95% CI: -13.025 ∼ -8.050, P < 0.001; IL-13: Hedges's g = -6.773 ± 0.788 with 95% CI: -8.318 ∼ -5.229, P < 0.001).

CONCLUSION

Findings of the current systemic review suggested a potential role for MSCs in asthma treatment although it is still challenging in clinical practice. The mechanisms of MSCs in pre-clinical asthma treatment may be associated with attenuating airway inflammation through regulating Th1 and Th2 cytokines.

Therapeutic potential of products derived from mesenchymal stem/stromal cells in pulmonary disease

Multipotent mesenchymal stem/stromal cells (MSCs) possess robust self-renewal characteristics and the ability to differentiate into tissue-specific cells. Their therapeutic potential appears promising as evident from their efficacy in several animal models of pulmonary disorders as well as early-phase clinical trials of acute respiratory distress syndrome (ARDS) and chronic obstructive pulmonary disease (COPD). Such therapeutic efficacy might be attributed to MSC-derived products (the "secretome"), namely conditioned media (CM) and extracellular vesicles (EVs), which have been shown to play pivotal roles in the regenerative function of MSCs. Importantly, the EVs secreted by MSCs can transfer a variety of bioactive factors to modulate the function of recipient cells via various mechanisms, including ligand-receptor interactions, direct membrane fusion, endocytosis, or phagocytosis.Herein, we review the current state-of-the-science of MSC-derived CM and EVs as potential therapeutic agents in lung diseases. We suggest that the MSC-derived secretome might be an appropriate therapeutic agent for treating aggressive pulmonary disorders because of biological and logistical advantages over live cell therapy. Nonetheless, further studies are warranted to elucidate the safety and efficacy of these components in combating pulmonary diseases.

Timing of erythropoietin modified mesenchymal stromal cell transplantation for the treatment of experimental bronchopulmonary dysplasia

The aim of this study is to optimize the timing of erythropoietin gene modified mesenchymal stem cells (EPO‐MSCs) transplantation for bronchopulmonary dysplasia (BPD). Three weeks post‐operation, the results indicated that the damage of airway structure and apoptosis were significantly decreased, the proliferation was increased in three EPO‐MSCs transplantation groups as compared with BPD mice. Moreover, the inflammation cytokines were improvement in early EPO‐MSCs injection mice than in BPD mice, but there was no significant difference between late injection and BPD groups. Furthermore, the protein expression ratio of p‐p38/p38MAPK was down‐regulation in early mice but not in late transplantation mice. Our findings suggest that EPO‐MSCs maybe attenuate BPD injury in early than in late administration by inhibiting inflammation response through down‐regulation of the p38MAPK signalling pathway.

Therapeutic Applications of Extracellular Vesicles: Perspectives from Newborn Medicine

With the advancements in antenatal steroid therapies and surfactant replacement, current clinical practices in neonatal intensive care units allow the survival of infants at very low gestational age. Despite these advances, there continues to be significant morbidity associated with extreme preterm birth that includes both short-term and long-term cardiorespiratory impairment. With no effective single therapy in preventing or treating developmental lung injuries, the need for new tools to treat and reduce risk of complications associated with extreme preterm birth is urgent. Stem cell-based therapies, in particular therapies utilizing mesenchymal stem (stromal) cells (MSCs), have shown promise in a number of animal models of lung pathologies relevant to neonatology. Recent studies in this field have consolidated the concept that the therapeutic mechanism of MSC action is paracrine, and this led to wide acceptance of the concept that the delivery of the MSC secretome rather than live cells may provide an alternative therapeutic approach for many complex diseases. Here, we summarize the significance and application of cell-free based therapies in preclinical models of neonatal lung injury. We emphasize the development of extracellular vesicle (EV)-based therapeutics and focus on the challenges that remain to be addressed before their application to clinical practice.

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.

The Potentials and Caveats of Mesenchymal Stromal Cell-Based Therapies in the Preterm Infant

Preponderance of proinflammatory signals is a characteristic feature of all acute and resulting long-term morbidities of the preterm infant. The proinflammatory actions are best characterized for bronchopulmonary dysplasia (BPD) which is the chronic lung disease of the preterm infant with lifelong restrictions of pulmonary function and severe consequences for psychomotor development and quality of life. Besides BPD, the immature brain, eye, and gut are also exposed to inflammatory injuries provoked by infection, mechanical ventilation, and oxygen toxicity. Despite the tremendous progress in the understanding of disease pathologies, therapeutic interventions with proven efficiency remain restricted to a few drug therapies with restricted therapeutic benefit, partially considerable side effects, and missing option of applicability to the inflamed brain. The therapeutic potential of mesenchymal stromal cells (MSCs)—also known as mesenchymal stem cells—has attracted much attention during the recent years due to their anti-inflammatory activities and their secretion of growth and development-promoting factors. Based on a molecular understanding, this review summarizes the positive actions of exogenous umbilical cord-derived MSCs on the immature lung and brain and the therapeutic potential of reprogramming resident MSCs. The pathomechanistic understanding of MSC actions from the animal model is complemented by the promising results from the first phase I clinical trials testing allogenic MSC transplantation from umbilical cord blood. Despite all the enthusiasm towards this new therapeutic option, the caveats and outstanding issues have to be critically evaluated before a broad introduction of MSC-based therapies.

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.

An Official American Thoracic Society Workshop Report 2015. Stem Cells and Cell Therapies in Lung Biology and Diseases

The University of Vermont College of Medicine, in collaboration with the NHLBI, Alpha-1 Foundation, American Thoracic Society, Cystic Fibrosis Foundation, European Respiratory Society, International Society for Cellular Therapy, and the Pulmonary Fibrosis Foundation, convened a workshop, "Stem Cells and Cell Therapies in Lung Biology and Lung Diseases," held July 27 to 30, 2015, at the University of Vermont. The conference objectives were to review the current understanding of the role of stem and progenitor cells in lung repair after injury and to review the current status of cell therapy and ex vivo bioengineering approaches for lung diseases. These are all rapidly expanding areas of study that both provide further insight into and challenge traditional views of mechanisms of lung repair after injury and pathogenesis of several lung diseases. The goals of the conference were to summarize the current state of the field, discuss and debate current controversies, and identify future research directions and opportunities for both basic and translational research in cell-based therapies for lung diseases. This 10th anniversary conference was a follow up to five previous biennial conferences held at the University of Vermont in 2005, 2007, 2009, 2011, and 2013. Each of those conferences, also sponsored by the National Institutes of Health, American Thoracic Society, and respiratory disease foundations, has been important in helping guide research and funding priorities. The major conference recommendations are summarized at the end of the report and highlight both the significant progress and major challenges in these rapidly progressing fields.

Mesenchymal stem cells in combination with erythropoietin repair hyperoxia-induced alveoli dysplasia injury in neonatal mice via inhibition of TGF-β1 signaling

The aim of the present study is to investigate the protection effects of bone marrow mesenchymal stem cells (MSCs) in combination with EPO against hyperoxia-induced bronchopulmonary dysplasia (BPD) injury in neonatal mice. BPD model was prepared by continuous high oxygen exposure, 1×106 bone marrow MSCs and 5000U/kg recombinant human erythropoietin (EPO) were injected respectively. Results showed that administration of MSCs, EPO especially MSCs+EPO significant attenuated hyperoxia-induced lung damage with a decrease of fibrosis, radical alveolar counts and inhibition of the occurrence of epithelial-mesenchymal transition (EMT). Furthermore, MSCs+EPO co-treatment more significantly suppressed the levels of transforming growth factor-β1(TGF-β1) than MSCs or EPO alone. Collectively, these results suggested that MSCs, EPO in particular MSCs+EPO co-treatment could promote lung repair in hyperoxia-induced alveoli dysplasia injury via inhibition of TGF-β1 signaling pathway to further suppress EMT process and may be a promising therapeutic strategy.

Mesenchymal stem cells in the pathogenesis and treatment of bronchopulmonary dysplasia: a clinical review

Advances in neonatal medicine have led to increased survival of infants born at the limits of viability, resulting in an increased incidence of bronchopulmonary dysplasia (BPD). BPD is a chronic lung disease of premature infants characterized by the arrest of alveolarization, fibroblast activation, and inflammation. BPD leads to significant morbidity and mortality in the neonatal period and is one of the leading causes of chronic lung disease in children. The past decade has brought a surge of trials investigating cellular therapies for the treatment of pulmonary diseases. Mesenchymal stem cells (MSCs) are of particular interest because of their ease of isolation, low immunogenicity, and anti-inflammatory and reparative properties. Clinical trials of MSCs have demonstrated short-term safety and tolerability; however, studies have also shown populations of MSCs with adverse pro-inflammatory and myofibroblastic characteristics. Cell-based therapies may represent the next breakthrough therapy for the treatment of BPD, however, there remain barriers to implementation as well as gaps in knowledge of the role of endogenous MSCs in the pathogenesis of BPD. Concurrent high-quality basic science, translational, and clinical studies investigating the fundamental pathophysiology underlying BPD, therapeutic mechanisms of exogenous MSCs, and logistics of translating cellular therapies will be important areas of future research.

The Therapeutic Potential of Stem Cells for Bronchopulmonary Dysplasia: "It's About Time" or "Not so Fast" ?

OBJECTIVE

While the survival of extremely premature infants has improved over the past decades, the rate of complications - especially for bronchopulmonary dysplasia (BPD) - remains unacceptably high. Over the past 50 years, no safe therapy has had a substantial impact on the incidence and severity of BPD.

METHODS

This may stem from the multifactorial disease pathogenesis and the increasing lung immaturity. Mesenchymal Stromal Cells (MSCs) display pleiotropic effects and show promising results in neonatal rodents in preventing or rescuing lung injury without adverse effects. Early phase clinical trials are now underway to determine the safety and efficacy of this therapy in extremely premature infants.

RESULTS AND CONCLUSION

This review summarizes our current knowledge about MSCs, their mechanism of action and the results of preclinical studies that provide the rationale for early phase clinical trials and discuss remaining gaps in our knowledge.

Mesenchymal Stromal Cell Therapy in Bronchopulmonary Dysplasia: Systematic Review and Meta-Analysis of Preclinical Studies

Extreme prematurity is the leading cause of death among children under 5 years of age. Currently, there is no treatment for bronchopulmonary dysplasia (BPD), the most common complication of extreme prematurity. Experimental studies in animal models of BPD suggest that mesenchymal stromal cells (MSCs) are lung protective. To date, no systematic review and meta-analysis has evaluated the preclinical evidence of this promising therapy. Our protocol was registered with Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies prior to searching MEDLINE (1946 to June 1, 2015), Embase (1947 to 2015 Week 22), Pubmed, Web of Science, and conference proceedings (1990 to present) for controlled comparative studies of neonatal animal models that received MSCs or cell free MSC-derived conditioned media (MSC-CM). Lung alveolarization was the primary outcome. We used random effects models for data analysis and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. We screened 990 citations; 25 met inclusion criteria. All used hyperoxia-exposed neonatal rodents to model BPD. MSCs significantly improved alveolarization (Standardized mean difference of -1.330, 95% confidence interval [CI -1.724, -0.94, I2 69%]), irrespective of timing of treatment, source, dose, or route of administration. MSCs also significantly ameliorated pulmonary hypertension, lung inflammation, fibrosis, angiogenesis, and apoptosis. Similarly, MSC-CM significantly improved alveolarization, angiogenesis, and pulmonary artery remodeling. MSCs, tested exclusively in hyperoxic rodent models of BPD, show significant therapeutic benefit. Unclear risk of bias and incomplete reporting in the primary studies highlights nonadherence to reporting standards. Overall, safety and efficacy in other species/large animal models may provide useful information for guiding the design of clinical trials. Stem Cells Translational Medicine 2017;6:2079-2093.

Human amnion cells reverse acute and chronic pulmonary damage in experimental neonatal lung injury

Background

Despite advances in neonatal care, bronchopulmonary dysplasia (BPD) remains a significant contributor to infant mortality and morbidity. While human amnion epithelial cells (hAECs) have shown promise in small and large animal models of BPD, there is scarce information on long-term benefit and clinically relevant questions surrounding administration strategy remain unanswered. In assessing the therapeutic potential of hAECs, we investigated the impact of cell dosage, administration routes and timing of treatment in a pre-clinical model of BPD.

Methods

Lipopolysaccharide was introduced intra-amniotically at day 16 of pregnancy prior to exposure to 65% oxygen (hyperoxia) at birth. hAECs were administered either 12 hours (early) or 4 days (late) after hyperoxia commenced. Collective lung tissues were subjected to histological analysis, multikine ELISA for inflammatory cytokines, FACS for immune cell populations and 3D lung stem cell culture at neonatal stage (postnatal day 7 and 14). Invasive lung function test and echocardiography were applied at 6 and 10 weeks of age.

Results

hAECs improved the tissue-to-airspace ratio and septal crest density in a dose-dependent manner, regardless of administration route. Early administration of hAECs, coinciding with the commencement of postnatal hyperoxia, was associated with reduced macrophages, dendritic cells and natural killer cells. This was not the case if hAECs were administered when lung injury was established. Fittingly, early hAEC treatment was more efficacious in reducing interleukin-1β, tumour necrosis factor alpha and monocyte chemoattractant protein-1 levels. Early hAEC treatment was also associated with reduced airway hyper-responsiveness and normalisation of pressure–volume loops. Pulmonary hypertension and right ventricle hypertrophy were also prevented in the early hAEC treatment group, and this persisted until 10 weeks of age.

Conclusions

Early hAEC treatment appears to be advantageous over late treatment. There was no difference in efficacy between intravenous and intratracheal administration. The benefits of hAEC administration resulted in long-term improvements in cardiorespiratory function.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0689-9) contains supplementary material, which is available to authorized users.

Fresh Noncultured Endothelial Progenitor Cells Improve Neonatal Lung Hyperoxia-Induced Alveolar Injury

Treatment of preterm human infants with high oxygen can result in disrupted lung alveolar and vascular development. Local or systemic administration of endothelial progenitor cells (EPCs) is reported to remedy such disruption in animal models. In this study, the effects of both fresh (enriched for KDR) and cultured bone marrow (BM)-derived cell populations with EPC characteristics were examined following hyperoxia in neonatal mouse lungs. Intraperitoneal injection of fresh EPCs into five-day-old mice treated with 90% oxygen resulted in full recovery of hyperoxia-induced alveolar disruption by 56 days of age. Partial recovery in septal number following hyperoxia was observed following injection of short-term cultured EPCs, yet aberrant tissue growths appeared following injection of long-term cultured cells. Fresh and long-term cultured cells had no impact on blood vessel development. Short-term cultured cells increased blood vessel number in normoxic and hyperoxic mice by 28 days but had no impact on day 56. Injection of fresh EPCs into normoxic mice significantly reduced alveolarization compared with phosphate buffered saline-injected normoxic controls. These results indicate that fresh BM EPCs have a higher and safer corrective profile in a hyperoxia-induced lung injury model compared with cultured BM EPCs but may be detrimental to the normoxic lung. The appearance of aberrant tissue growths and other side effects following injection of cultured EPCs warrants further investigation. Stem Cells Translational Medicine 2017;6:2094-2105.

Lung organoids: current uses and future promise

Lungs are composed of a system of highly branched tubes that bring air into the alveoli, where gas exchange takes place. The proximal and distal regions of the lung contain epithelial cells specialized for different functions: basal, secretory and ciliated cells in the conducting airways and type II and type I cells lining the alveoli. Basal, secretory and type II cells can be grown in three-dimensional culture, with or without supporting stromal cells, and under these conditions they give rise to self-organizing structures known as organoids. This Review summarizes the different methods for generating organoids from cells isolated from human and mouse lungs, and compares their final structure and cellular composition with that of the airways or alveoli of the adult lung. We also discuss the potential and limitations of organoids for addressing outstanding questions in lung biology and for developing new drugs for disorders such as cystic fibrosis and asthma.

Surfactant effects on the viability and function of human mesenchymal stem cells: in vitro and in vivo assessment

BACKGROUND

Surfactant therapy has become the standard of care for preterm infants with respiratory distress syndrome. Preclinical studies have reported the therapeutic benefits of mesenchymal stem cells (MSCs) in experimental bronchopulmonary dysplasia. This study investigated the effects of a surfactant on the in vitro viability and in vivo function of human MSCs.

METHODS

The viability, phenotype, and mitochondrial membrane potential (MMP) of MSCs were assessed through flow cytometry. The in vivo function was assessed after intratracheal injection of human MSCs (1 × 10⁵ cells) diluted in 30 μl of normal saline (NS), 10 μl of a surfactant diluted in 20 μl of NS, and 10 μl of a surfactant and MSCs (1 × 10⁵ cells) diluted in 20 μl of NS in newborn rats on postnatal day 5. The pups were reared in room air (RA) or an oxygen-enriched atmosphere (85% O₂) from postnatal days 1 to 14; eight study groups were examined: RA + NS, RA + MSCs, RA + surfactant, RA + surfactant + MSCs, O₂ + NS, O₂ + MSCs, O₂ + surfactant, and O₂ + surfactant + MSCs. The lungs were excised for histological and cytokine analysis on postnatal day 14.

RESULTS

Compared with the controls, surfactant-treated MSCs showed significantly reduced viability and MMP after exposure to 1:1 and 1:2 of surfactant:MSCs for 15 and 60 minutes. All human MSC samples exhibited similar percentages of CD markers, regardless of surfactant exposure. The rats reared in hyperoxia and treated with NS exhibited a significantly higher mean linear intercept (MLI) than did those reared in RA and treated with NS, MSCs, surfactant, or surfactant + MSCs. Treatment with MSCs, surfactant, or surfactant + MSCs significantly reduced the hyperoxia-induced increase in MLI. The O₂ + surfactant + MSCs group exhibited a significantly higher MLI than did the O₂ + MSCs group. Furthermore, treatment with MSCs and MSCs + surfactant significantly reduced the hyperoxia-induced increase in apoptotic cells.

CONCLUSIONS

Combination therapy involving a surfactant and MSCs does not exert additive effects on lung development in hyperoxia-induced lung injury.

Intersections of lung progenitor cells, lung disease and lung cancer

The use of stem cell biology approaches to study adult lung progenitor cells and lung cancer has brought a variety of new techniques to the field of lung biology and has elucidated new pathways that may be therapeutic targets in lung cancer. Recent results have begun to identify the ways in which different cell populations interact to regulate progenitor activity, and this has implications for the interventions that are possible in cancer and in a variety of lung diseases. Today's better understanding of the mechanisms that regulate lung progenitor cell self-renewal and differentiation, including understanding how multiple epigenetic factors affect lung injury repair, holds the promise for future better treatments for lung cancer and for optimising the response to therapy in lung cancer. Working between platforms in sophisticated organoid culture techniques, genetically engineered mouse models of injury and cancer, and human cell lines and specimens, lung progenitor cell studies can begin with basic biology, progress to translational research and finally lead to the beginnings of clinical trials.

Stem cell biology has brought new techniques to the lung field and has elucidated possible therapeutic pathwayshttp://ow.ly/h74x30cA6Lo

The roles of drug therapy given via the endotracheal tube to neonates

Many drugs are given to intubated neonates by the inhalation route. The optimum aerosol delivery system, however, has not been identified and there are many challenges in delivering drugs effectively to the lower airways of intubated neonates. The effectiveness of surfactant in prematurely born infants and nitric oxide has been robustly investigated. Other drugs are being used on very limited evidence.

Lkb1 inactivation drives lung cancer lineage switching governed by Polycomb Repressive Complex 2

Adenosquamous lung tumours, which are extremely poor prognosis, may result from cellular plasticity. Here, we demonstrate lineage switching of KRAS+ lung adenocarcinomas (ADC) to squamous cell carcinoma (SCC) through deletion of Lkb1 (Stk11) in autochthonous and transplant models. Chromatin analysis reveals loss of H3K27me3 and gain of H3K27ac and H3K4me3 at squamous lineage genes, including Sox2, ΔNp63 and Ngfr. SCC lesions have higher levels of the H3K27 methyltransferase EZH2 than the ADC lesions, but there is a clear lack of the essential Polycomb Repressive Complex 2 (PRC2) subunit EED in the SCC lesions. The pattern of high EZH2, but low H3K27me3 mark, is also prevalent in human lung SCC and SCC regions within ADSCC tumours. Using FACS-isolated populations, we demonstrate that bronchioalveolar stem cells and club cells are the likely cells-of-origin for SCC transitioned tumours. These findings shed light on the epigenetics and cellular origins of lineage-specific lung tumours.

The mechanisms that govern the transdifferentiation of lung adenocarcinomas (ADC) to squamous cell carcinoma (SCC) are not fully understood. Here, the authors show that EZH2 loss exacerbates the transdifferentiation of ADCs to SCCs as a result of chromatin changes that lead to expression of squamous differentiation genes.

Preclinical evaluation of cell-based strategies to prevent or treat bronchopulmonary dysplasia in animal models: a systematic review

Bronchopulmonary dysplasia (BPD) remains the most common complication of extreme prematurity as no effective treatment is available to date. This calls for the exploration of new therapeutic options like cell therapy, which is already effective for various human (lung) disorders. We systematically searched the MEDLINE, Embase, and Web of Science databases from the earliest date till January 2017 and included original studies on the perinatal use of cell-based therapies (i.e. cells and/or cell-derivatives) to treat BDP in animal models. Fourth publications describing 47 interventions were retrieved. Newborn mice/rats raised in a hyperoxic environment were studied in most interventions. Different cell types - either intact cells or their conditioned medium - were administered, but bone marrow and umbilical cord blood derived mesenchymal stem cells were most prevalent. All studies reported positive effects on outcome parameters including alveolar and vascular morphometry, lung function, and inflammation. Cell homing to the lungs was demonstrated in some studies, but the therapeutic effects seemed to be mostly mediated via paracrine modulation of inflammation, fibrosis and angiogenesis.

CONCLUSION

Multiple rat/mouse studies show promise for cell therapy for BPD. Yet careful study of action mechanisms and side effects in large animal models is imperative before clinical translation can be achieved.

Extracellular superoxide dismutase increased the therapeutic potential of human mesenchymal stromal cells in radiation pulmonary fibrosis

BACKGROUND AIMS

Pulmonary fibrosis induced by irradiation is a significant problem of radiotherapy in cancer patients. Extracellular superoxide dismutase (SOD3) is found to be predominantly and highly expressed in the extracellular matrix of lung and plays a pivotal role against oxidative damage. Early administration of mesenchymal stromal cells (MSCs) has been demonstrated to reduce fibrosis of damaged lung. However, injection of MSCs at a later stage would be involved in fibrosis development. The present study aimed to determine whether injection of human umbilical cord-derived MSCs (UC-MSCs) over-expressing SOD3 at the established fibrosis stage would have beneficial effects in a mice model of radiation pulmonary fibrosis.

METHODS

Herein, pulmonary fibrosis in mice was induced using Cobalt-60 (⁶⁰Co) irradiator with 20 Gy, followed by intravenous injection of UC-MSCs, transduced or not to express SOD3 at 2 h (early delivery) and 60 day (late delivery) post-irradiation, respectively.

RESULTS

Our results demonstrated that the early administration of UC-MSCs could attenuate the microscopic damage, reduce collagen deposition, inhibit (myo)fibroblast proliferation, reduce inflammatory cell infiltration, protect alveolar type II (AE2) cell injury, prevent oxidative stress and increase antioxidant status, and reduce pro-fibrotic cytokine level in serum. Furthermore, the early treatment with SOD3-infected UC-MSCs resulted in better improvement. However, we failed to observe the therapeutic effects of UC-MSCs, transduced to express SOD3, during established fibrosis.

CONCLUSION

Altogether, our results demonstrated that the early treatment with UC-MSCs alone significantly reduced radiation pulmonary fibrosis in mice through paracrine effects, with further improvement by administration of SOD3-infected UC-MSCs, suggesting that SOD3-infected UC-MSCs may be a potential cell-based gene therapy to treat clinical radiation pulmonary fibrosis.

Amnion Epithelial Cells Promote Lung Repair via Lipoxin A4

Human amnion epithelial cells (hAECs) have been shown to possess potent immunomodulatory properties across a number of disease models. Recently, we reported that hAECs influence macrophage polarization and activity, and that this step was dependent on regulatory T cells. In this study, we aimed to assess the effects of hAEC-derived proresolution lipoxin-A₄ (LXA4) on T-cell, macrophage, and neutrophil phenotype and function during the acute phase of bleomycin-induced lung injury. Using C57Bl6 mice, we administered 4 million hAECs intraperitoneally 24 hours after bleomycin challenge. Outcomes were measured at days 3, 5, and 7. hAEC administration resulted in significant changes to T-cell, macrophage, dendritic cell, and monocyte/macrophage infiltration and phenotypes. Endogenous levels of lipoxygenases, LXA4, and the lipoxin receptor FPR2 were elevated in hAEC-treated animals. Furthermore, we showed that the effects of hAECs on macrophage phagocytic activity and T-cell suppression are LXA4 dependent, whereas the inhibition of neutrophil-derived myleoperoxidase by hAECs is independent of LXA4. This study provides the first evidence that lipid-based mediators contribute to the immunomodulatory effects of hAECs and further supports the growing body of evidence that LXA4 is proresolutionary in lung injury. This discovery of LXA4-dependent communication between hAECs, macrophages, T cells, and neutrophils is important to the understanding of hAEC biodynamics and would be expected to inform future clinical applications. Stem Cells Translational Medicine 2017;6:1085-1095.

Human mesenchymal stem cells (MSCs) for treatment towards immune- and inflammation-mediated diseases: review of current clinical trials

Human mesenchymal stem cells (MSCs) are multilineage somatic progenitor/stem cells that have been shown to possess immunomodulatory properties in recent years. Initially met with much skepticism, MSC immunomodulation has now been well reproduced across tissue sources and species to be clinically relevant. This has opened up the use of these versatile cells for application as 3rd party/allogeneic use in cell replacement/tissue regeneration, as well as for immune- and inflammation-mediated disease entities. Most surprisingly, use of MSCs for in immune-/inflammation-mediated diseases appears to yield more efficacy than for regenerative medicine, since engraftment of the exogenous cell does not appear necessary. In this review, we focus on this non-traditional clinical use of a tissue-specific stem cell, and highlight important findings and trends in this exciting area of stem cell therapy.

Cell-based therapies for neonatal lung disease

Preterm birth occurs in approximately 11 % of all births worldwide. Advances in perinatal care have enabled the survival of preterm infants born as early as 23-24 weeks of gestation. However, many are affected by bronchopulmonary dysplasia (BPD)-a common respiratory complication of preterm birth, which has life-long consequences for lung health. Currently, there is no specific treatment for BPD. Recent advances in stem cell research have opened new therapeutic avenues for prevention/repair of lung damage. This review summarizes recent pre-clinical data and early clinical translation of cell-based therapies for BPD.

Organogenesis of adult lung in a dish: Differentiation, disease and therapy

The remarkable regenerative capacity of the lung suggests that stem cells could be of therapeutic importance in diverse lung diseases; however, the successful exploitation of lung stem cell biology has long been hampered by our inability to maintain and expand adult lung stem cells while retaining their multi-lineage potential in vitro. Recently, advances in our understanding of stem cell niches and the role of key signalling modulators in controlling stem cell maintenance and differentiation have fuelled the development of new in vitro three-dimensional (3D) culture technologies that sustain the stem cell-driven formation of near-physiological, self-organizing structures called organoids. Here we review basic approaches to organoid model systems and highlight recent achievements in the generation of organoids from adult stem and progenitor cells of both the murine and human lungs. We evaluate current applications in studying cellular changes in proliferation, differentiation, plasticity, and cell polarity, and cellular and molecular crosstalk of epithelial cells with stroma. Advantages and limitations of organoids for clinical use are also discussed.

Cell Therapy for Bronchopulmonary Dysplasia: Promises and Perils

Despite great achievements in neonatal and perinatal medicine over the past decades, the immature lung remains the most critical organ to care for after premature birth. As a consequence, bronchopulmonary dysplasia (BPD) remains the most common complication of extreme prematurity. BPD impairs normal development and may cause lifelong morbidities. At present, there is no effective treatment for BPD - including preventing premature birth. Recent insights into the biology of stem and progenitor cells have ignited the hope of protecting the immature lung, and even regenerating an already damaged lung by using exogenous stem- or progenitor cells as therapeutics. These therapies are still experimental, and knowledge on the exact mechanisms behind the beneficial effects seen in various animal models of BPD is limited. Nevertheless, early phase clinical trials have started, and encouraging steps towards the therapeutic use of these cells are being made. This review aims to (I) provide an overview of the role of stem/progenitor cells in development and therapy of BPD for the practicing clinician, (II) discuss the potential clinical applications of cell products as therapeutic agents to prevent neonatal lung injury and (III) examine potential obstacles towards the manufacturing of clinical grade cell products for use in the care for premature infants.

Effectiveness of a novel cellular therapy to treat multidrug-resistant tuberculosis

Introduction

We urgently need novel treatments for multidrug-resistant tuberculosis (MDR-TB). Autologous mesenchymal stromal cell (MSC) infusion is one such possibility due to its potential to repair damaged lung tissue and boost immune responses. We aimed to assess the effectiveness of MSC to improve outcomes among MDR-TB patients.

Methods

We analyzed outcomes for 108 Belarussian MDR-TB patients receiving chemotherapy. Thirty-six patients (“cases”) also had MSCs extracted, cultured and re-infused (average time from chemotherapy start to infusion was 49 days); another 36 patients were “study controls”. We identified another control group: 36 patients from the Belarussian surveillance database (“surveillance controls”) 1:1 matched to cases.

Results

Of the cases, 81% had successful outcomes versus 42% of surveillance controls and 39% of study controls. Successful outcome odds were 6.5 (95% Confidence Interval: 1.2–36.2, p = 0.032) times greater for cases than surveillance controls (age-adjusted). Radiological improvement was more likely in cases than study controls. Culture analysis prior to infusion demonstrated a poorer initial prognosis in cases, yet despite this they had better outcomes than the control groups.

Conclusion

MSC treatment could vastly improve outcomes for MDR-TB patients. Our findings could revolutionize therapy options and have strong implications for future directions of MDR-TB therapy research.

Characterization of intercellular communication and mitochondrial donation by mesenchymal stromal cells derived from the human lung

Background

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are capable of repairing wounded lung epithelial cells by donating cytoplasmic material and mitochondria. Recently, we characterized two populations of human lung-derived mesenchymal stromal cells isolated from digested parenchymal lung tissue (LT-MSCs) from healthy individuals or from lung transplant recipients’ bronchoalveolar lavage fluid (BAL-MSCs). The aim of this study was to determine whether LT-MSCs and BAL-MSCs are also capable of donating cytoplasmic content and mitochondria to lung epithelial cells.

Methods

Cytoplasmic and mitochondrial transfer was assessed by co-culturing BEAS2B epithelial cells with Calcein AM or Mitotracker Green FM-labelled MSCs. Transfer was then measured by flow cytometry and validated by fluorescent microscopy. Molecular inhibitors were used to determine the contribution of microtubules/tunnelling nanotubes (TNTs, cytochalasin D), gap junctions (carbenoxolone), connexin-43 (gap26) and microvesicles (dynasore).

Results

F-actin microtubules/TNTs extending from BM-MSCs, LT-MSCs and BAL-MSCs to bronchial epithelial cells formed within 45 minutes of co-culturing cells. Each MSC population transferred a similar volume of cytoplasmic content to epithelial cells. Inhibiting microtubule/TNTs, gap junction formation and microvesicle endocytosis abrogated the transfer of cytoplasmic material from BM-MSCs, LT-MSCs and BAL-MSCs to epithelial cells. In contrast, blocking connexin-43 gap junction formation had no effect on cytoplasmic transfer. All MSC populations donated mitochondria to bronchial epithelial cells with similar efficiency. Mitochondrial transfer was reduced in all co-cultures after microtubule/TNT or endocytosis inhibition. Gap junction formation inhibition reduced mitochondrial transfer in BM-MSC and BAL-MSC co-cultures but had no effect on transfer in LT-MSC co-cultures. Connexin-43 inhibition did not impact mitochondrial transfer. Finally, bronchial epithelial cells were incapable of donating cytoplasmic content or mitochondria to any MSC population.

Conclusion

Similar to their bone marrow counterparts, LT-MSCs and BAL-MSCs can donate cytoplasmic content and mitochondria to bronchial epithelial cells via multiple mechanisms. Given that BM-MSCs utilize these mechanisms to mediate the repair of damaged bronchial epithelial cells, both LT-MSCs and BAL-MSCs will probably function similarly.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-016-0354-8) contains supplementary material, which is available to authorized users.

Mesenchymal Stromal Cells are Readily Recoverable from Lung Tissue, but not the Alveolar Space, in Healthy Humans

Stromal support is critical for lung homeostasis and the maintenance of an effective epithelial barrier. Despite this, previous studies have found a positive association between the number of mesenchymal stromal cells (MSCs) isolated from the alveolar compartment and human lung diseases associated with epithelial dysfunction. We hypothesised that bronchoalveolar lavage derived MSCs (BAL-MSCs) are dysfunctional and distinct from resident lung tissue MSCs (LT-MSCs). In this study, we comprehensively interrogated the phenotype and transcriptome of human BAL-MSCs and LT-MSCs. We found that MSCs were rarely recoverable from the alveolar space in healthy humans, but could be readily isolated from lung transplant recipients by bronchoalveolar lavage. BAL-MSCs exhibited a CD90^Hi , CD73^Hi , CD45^Neg , CD105^Lo immunophenotype and were bipotent, lacking adipogenic potential. In contrast, MSCs were readily recoverable from healthy human lung tissue and were CD90^{Hi or Lo} , CD73^Hi , CD45^Neg , CD105^Int and had full tri-lineage potential. Transcriptional profiling of the two populations confirmed their status as bona fide MSCs and revealed a high degree of similarity between each other and the archetypal bone-marrow MSC. 105 genes were differentially expressed; 76 of which were increased in BAL-MSCs including genes involved in fibroblast activation, extracellular matrix deposition and tissue remodelling. Finally, we found the fibroblast markers collagen 1A1 and α-smooth muscle actin were increased in BAL-MSCs. Our data suggests that in healthy humans, lung MSCs reside within the tissue, but in disease can differentiate to acquire a profibrotic phenotype and migrate from their in-tissue niche into the alveolar space. Stem Cells 2016;34:2548-2558.

Closure of a Recurrent Bronchopleural Fistula Using a Matrix Seeded With Patient-Derived Mesenchymal Stem Cells

This is the first-in-human application of an autologous mesenchymal stem cell (MSC)-seeded matrix graft to repair a multiply recurrent postpneumonectomy bronchopleural fistula (BPF). Adipose-derived MSCs were isolated from patient abdominal adipose tissue, expanded, and seeded onto bio-absorbable mesh, which was surgically implanted at the BPF site. After clinical follow-up of 1.5 years, the patient is clinically asymptomatic without evidence of recurrence or malignant degeneration of MSC populations in situ.

Management of recurrent bronchopleural fistula (BPF) after pneumonectomy remains a challenge. Although a variety of devices and techniques have been described, definitive management usually involves closure of the fistula tract through surgical intervention. Standard surgical approaches for BPF incur significant morbidity and mortality and are not reliably or uniformly successful. We describe the first-in-human application of an autologous mesenchymal stem cell (MSC)-seeded matrix graft to repair a multiply recurrent postpneumonectomy BPF. Adipose-derived MSCs were isolated from patient abdominal adipose tissue, expanded, and seeded onto bio-absorbable mesh, which was surgically implanted at the site of BPF. Clinical follow-up and postprocedural radiological and bronchoscopic imaging were performed to ensure BPF closure, and in vitro stemness characterization of patient-specific MSCs was performed. The patient remained clinically asymptomatic without evidence of recurrence on bronchoscopy at 3 months, computed tomographic imaging at 16 months, and clinical follow-up of 1.5 years. There is no evidence of malignant degeneration of MSC populations in situ, and the patient-derived MSCs were capable of differentiating into adipocytes, chondrocytes, and osteocytes using established protocols. Isolation and expansion of autologous MSCs derived from patients in a malnourished, deconditioned state is possible. Successful closure and safety data for this approach suggest the potential for an expanded study of the role of autologous MSCs in regenerative surgical applications for BPF.

Significance

Bronchopleural fistula is a severe complication of pulmonary resection. Current management is not reliably successful. This work describes the first-in-human application of an autologous mesenchymal stem cell (MSC)-seeded matrix graft to the repair of a large, multiply recurrent postpneumonectomy BPF. Clinical follow-up of 1.5 years without recurrence suggests initial safety and feasibility of this approach. Further assessment of MSC grafts in these difficult clinical scenarios requires expanded study.

Preclinical Studies of Mesenchymal Stem Cell (MSC) Administration in Chronic Obstructive Pulmonary Disease (COPD): A Systematic Review and Meta-Analysis

BACKGROUND

In the last two decades, mesenchymal stem cells (MSCs) have been pre-clinically utilized in the treatment of a variety of kinds of diseases including chronic obstructive pulmonary disease (COPD). The aim of the current study was to systematically review and conduct a meta-analysis on the published pre-clinical studies of MSC administration in the treatment of COPD in animal models.

METHODS AND RESULTS

A systematic search of electronic databases was performed. Statistical analysis was performed using the Comprehensive Meta-Analysis software (Version 3). The pooled Hedges's g with 95% confidence intervals (95% CIs) was adopted to assess the effect size. Random effect model was used due to the heterogeneity between the studies. A total of 20 eligible studies were included in the current systematic review. The overall meta-analysis showed that MSC administration was significantly in favor of attenuating acute lung injury (Hedges's g = -2.325 ± 0.145 with 95% CI: -2.609 ~ -2.040, P < 0.001 for mean linear intercept, MLI; Hedges's g = -3.488 ± 0.504 with 95% CI: -4.476 ~ -2.501, P < 0.001 for TUNEL staining), stimulating lung tissue repair (Hedges's g = 3.249 ± 0.586 with 95% CI: 2.103~ 4.394, P < 0.001) and improving lung function (Hedges's g = 2.053 ± 0.408 with 95% CI: 1.253 ~ 2.854, P< 0.001). The mechanism of MSC therapy in COPD is through ameliorating airway inflammation (Hedges's g = -2.956 ± 0.371 with 95% CI: -3.683 ~ -2.229, P< 0.001) and stimulating cytokine synthesis that involves lung tissue repair (Hedges's g = 3.103 ± 0.734 with 95% CI: 1.664 ~ 4.541, P< 0.001).

CONCLUSION

This systematic review and meta-analysis suggest a promising role for MSCs in COPD treatment. Although the COPD models may not truly mimic COPD patients, these pre-clinical studies demonstrate that MSC hold promise in the treatment of chronic lung diseases including COPD. The mechanisms of MSCs role in preclinical COPD treatment may be associated with attenuating airway inflammation as well as stimulating lung tissue repair.

Protective effects of BMSCs in combination with erythropoietin in bronchopulmonary dysplasia-induced lung injury

Bronchopulmonary dysplasia (BPD) is the most common type of chronic lung disease in infancy, for which no effective therapy is currently available. The aim of the present study was to investigate the effect of treatment with bone marrow mesenchymal stem cells (BMSCs) in combination with recombinant human erythropoietin (rHuEPO) on BPD‑induced mouse lung injury, and discuss the underlying mechanism. The BPD model was established by the exposure of neonatal mice to continuous high oxygen exposure for 14 days, following which 1x106 BMSCs and 5,000 U/kg rHuEPO were injected into the mice 1 h prior to and 7 days following exposure to hyperoxia. The animals received four treatments in total (n=10 in each group). After 14 days, the body weights, airway structure, and levels of matrix metalloproteinase‑9 (MMP‑9) and vascular endothelial growth factor (VEGF) were detected using histological and immunohistochemical analyses. The effect on cell differentiation was observed by examining the presence of platelet endothelial cell adhesion molecule (PECAM) and VEGF using immunofluorescence. Compared with the administration of BMSCs alone, the body weight, airway structure, and the levels of MMP‑9 and VEGF were significantly improved in the BMSCs/rHuEPO group. The results of the present study demonstrated that the intravenous injection of BMSCs significantly improved lung damage in the hyperoxia‑exposed neonatal mouse model. Furthermore, the injection of BMSCs in combination with intraperitoneal injection of rHuEPO had a more marked effect, compared with BMSCs alone, and the mechanism may be mediated by the promoting effects of BMSCs and EPO. The results of the present study provided information, which may assist in future clinical trials.

Therapeutic potential of mesenchymal stem cells for pulmonary complications associated with preterm birth

Preterm infants frequently suffer from pulmonary complications resulting in significant morbidity and mortality. Physiological and structural lung immaturity impairs perinatal lung transition to air breathing resulting in respiratory distress. Mechanical ventilation and oxygen supplementation ensure sufficient oxygen supply but enhance inflammatory processes which might lead to the establishment of a chronic lung disease called bronchopulmonary dysplasia (BPD). Current therapeutic options to prevent or treat BPD are limited and have salient side effects, highlighting the need for new therapeutic approaches. Mesenchymal stem cells (MSCs) have demonstrated therapeutic potential in animal models of BPD. This review focuses on MSC-based therapeutic approaches to treat pulmonary complications and critically compares results obtained in BPD models. Thereby bottlenecks in the translational systems are identified that are preventing progress in combating BPD. Notably, current animal models closely resemble the so-called "old" BPD with profound inflammation and injury, whereas clinical improvements shifted disease pathology towards a "new" BPD in which arrest of lung maturation predominates. Future studies need to evaluate the utility of MSC-based therapies in animal models resembling the "new" BPD though promising in vitro evidence suggests that MSCs do possess the potential to stimulate lung maturation. Furthermore, we address the mode-of-action of MSC-based therapies with regard to lung development and inflammation/fibrosis. Their therapeutic efficacy is mainly attributed to an enhancement of regeneration and immunomodulation due to paracrine effects. In addition, we discuss current improvement strategies by genetic modifications or precondition of MSCs to enhance their therapeutic efficacy which could also prove beneficial for BPD therapies.

Properties of Adult Lung Stem and Progenitor Cells

The last decade has seen significant progress in understanding the organisation of regenerative cells in the adult lung. Cell-lineage tracing and in vitro clonogenic assays have enabled the identification and characterisation of endogenous lung epithelial stem and progenitor cells. Selective lung injury models, and genetically engineered mice have revealed highly conserved gene networks, factors, signalling pathways, and cellular interactions important in maintaining lung homeostasis and regulating lung regeneration and repair following injury. This review describes the current models of lung epithelial stem and progenitor cell organisation in adult mice, and the impediments encountered in translational studies aiming to identify and characterise their human homologs. J. Cell. Physiol. 231: 2582-2589, 2016. © 2016 Wiley Periodicals, Inc.

Immunotherapy for tuberculosis: future prospects

Tuberculosis (TB) is still a major global health problem. A third of the world’s population is infected with Mycobacterium tuberculosis. Only ~10% of infected individuals develop TB but there are 9 million TB cases with 1.5 million deaths annually. The standard prophylactic treatment regimens for latent TB infection take 3–9 months, and new cases of TB require at least 6 months of treatment with multiple drugs. The management of latent TB infection and TB has become more challenging because of the spread of multidrug-resistant and extremely drug-resistant TB. Intensified efforts to find new TB drugs and immunotherapies are needed. Immunotherapies could modulate the immune system in patients with latent TB infection or active disease, enabling better control of M. tuberculosis replication. This review describes several types of potential immunotherapies with a focus on those which have been tested in humans.

Mesenchymal stem cell derived secretome and extracellular vesicles for acute lung injury and other inflammatory lung diseases

INTRODUCTION

Acute respiratory distress syndrome is a major cause of respiratory failure in critically ill patients. Despite extensive research into its pathophysiology, mortality remains high. No effective pharmacotherapy exists. Based largely on numerous preclinical studies, administration of mesenchymal stem or stromal cell (MSC) as a therapeutic for acute lung injury holds great promise, and clinical trials are currently underway. However, concern for the use of stem cells, specifically the risk of iatrogenic tumor formation, remains unresolved. Accumulating evidence now suggest that novel cell-free therapies including MSC-derived conditioned medium and extracellular vesicles released from MSCs might constitute compelling alternatives.

AREAS COVERED

The current review summarizes the preclinical studies testing MSC conditioned medium and/or MSC extracellular vesicles as treatment for acute lung injury and other inflammatory lung diseases.

EXPERT OPINION

While certain logistical obstacles limit the clinical applications of MSC conditioned medium such as the volume required for treatment, the therapeutic application of MSC extracellular vesicles remains promising, primarily due to ability of extracellular vesicles to maintain the functional phenotype of the parent cell. However, utilization of MSC extracellular vesicles will require large-scale production and standardization concerning identification, characterization and quantification.

Stem cell-based therapies for the newborn lung and brain: Possibilities and challenges

There have been substantial advances in neonatal medical care over the past 2 decades that have resulted in the increased survival of very low birth weight infants, survival that in some centers extends to 22 weeks gestational age. Despite these advances, there continues to be significant morbidity associated with extreme preterm birth that includes both short-term and long-term pulmonary and neurologic consequences. No single therapy has proven to be effective in preventing or treating either developmental lung and brain injuries in preterm infants or the hypoxic-ischemic injury that can be inflicted on the full-term brain as a result of in utero or perinatal complications. Stem cell-based therapies are emerging as a potential paradigm-shifting approach for such complex diseases with multifactorial etiologies, but a great deal of work is still required to understand the role of stem/progenitor cells in normal development and in the repair of injured tissue. This review will summarize the biology of the various stem/progenitor cells, their effects on tissue repair in experimental models of lung and brain injury, the recent advances in our understanding of their mechanism of action, and the challenges that remain to be addressed before their eventual application to clinical care.

Human mesenchymal stem cells attenuate experimental bronchopulmonary dysplasia induced by perinatal inflammation and hyperoxia

BACKGROUND

Systemic maternal inflammation and neonatal hyperoxia arrest alveolarization in neonates. The aims were to test whether human mesenchymal stem cells (MSCs) reduce lung inflammation and improve lung development in perinatal inflammation- and hyperoxia-induced experimental bronchopulmonary dysplasia.

METHODS

Pregnant Sprague-Dawley rats were intraperitoneally injected with lipopolysaccharide (LPS, 0.5 mg/kg/day) on Gestational Days 20 and 21. Human MSCs (3×10(5) and 1×10(6) cells) in 0.03 ml normal saline (NS) were administered intratracheally on Postnatal Day 5. Pups were reared in room air (RA) or an oxygen-enriched atmosphere (O2) from Postnatal Days 1 to 14, and six study groups were obtained: LPS+RA+NS, LPS+RA+MSC (3×10(5) cells), LPS+RA+MSC (1×10(6) cells), LPS+O2+NS, LPS+O2+MSC (3×10(5) cells), and LPS+O2+MSC (1×10(6) cells). The lungs were excised for cytokine, vascular endothelial growth factor (VEGF) and connective tissue growth factor (CTGF) expression, and histological analyses on Postnatal Day 14.

RESULTS

Body weight was significantly lower in rats reared in hyperoxia than in those reared in RA. The LPS+O2+NS group exhibited a significantly higher mean linear intercept (MLI) and collagen density and a significantly lower vascular density than the LPS+RA+NS group did. Administering MSC to hyperoxia-exposed rats improved MLI and vascular density and reduced tumor necrosis factor-α and interleukin-6 levels and collagen density to normoxic levels. This improvement in lung development and fibrosis was accompanied by an increase and decrease in lung VEGF and CTGF expression, respectively.

CONCLUSION

Human MSCs attenuated perinatal inflammation- and hyperoxia-induced defective alveolarization and angiogenesis and reduced lung fibrosis, likely through increased VEGF and decreased CTGF expression.

Cellular therapy in tuberculosis

Cellular therapy now offer promise of potential adjunct therapeutic options for treatment of drug-resistant tuberculosis (TB). We review here the role of Mesenchymal stromal cells, (MSCs), as well as other immune effector cells in the therapy of infectious diseases with a focus on TB. MSCs represent a population of tissue-resident non-hematopoietic adult progenitor cells which home into injured tissues increase the proliferative potential of broncho-alveolar stem cells and restore lung epithelium. MSCs have been shown to be immune-modulatory and anti-inflammatory mediated via cell-cell contacts as well as soluble factors. We discuss the functional profile of MSCs and their potential use for adjunct cellular therapy of multi-drug resistant TB, with the aim of limiting tissue damage, and to convert unproductive inflammatory responses into effective anti-pathogen directed immune responses. Adjunct cellular therapy could potentially offer salvage therapy options for patients with drug-resistant TB, increase clinically relevant anti-M.tuberculosis directed immune responses and possibly shorten the duration of anti-TB therapy.

Stem/progenitor cells in endogenous repairing responses: new toolbox for the treatment of acute lung injury

The repair of organs and tissues has stepped into a prospective era of regenerative medicine. However, basic research and clinical practice in the lung regeneration remains crawling. Owing to the complicated three dimensional structures and above 40 types of pulmonary cells, the regeneration of lung tissues becomes a great challenge. Compelling evidence has showed that distinct populations of intrapulmonary and extrapulmonary stem/progenitor cells can regenerate epithelia as well as endothelia in various parts of the respiratory tract. Recently, the discovery of human lung stem cells and their relevant studies has opened the door of hope again, which might put us on the path to repair our injured body parts, lungs on demand. Herein, we emphasized the role of endogenous and exogenous stem/progenitor cells in lungs as well as artificial tissue repair for the injured lungs, which constitute a marvelous toolbox for the treatment of acute lung injury. Finally, we further discussed the potential problems in the pulmonary remodeling and regeneration.