Impact of different frequencies of controlled breath and pressure-support levels during biphasic positive airway pressure ventilation on the lung and diaphragm in experimental mild acute respiratory distress syndrome.

BACKGROUND: We hypothesized that a decrease in frequency of controlled breaths during biphasic positive airway pressure (BIVENT), associated with an increase in spontaneous breaths, whether pressure support (PSV)-assisted or not, would mitigate lung and diaphragm damage in mild experimental acute respiratory distress syndrome (ARDS). MATERIALS AND METHODS: Wistar rats received Escherichia coli lipopolysaccharide intratracheally. After 24 hours, animals were randomly assigned to: 1) BIVENT-100+PSV0%: airway pressure (Phigh) adjusted to VT = 6 mL/kg and frequency of controlled breaths (f) = 100 bpm; 2) BIVENT-50+PSV0%: Phigh adjusted to VT = 6 mL/kg and f = 50 bpm; 3) BIVENT-50+PSV50% (PSV set to half the Phigh reference value, i.e., PSV50%); or 4) BIVENT-50+PSV100% (PSV equal to Phigh reference value, i.e., PSV100%). Positive end-expiratory pressure (Plow) was equal to 5 cmH2O. Nonventilated animals were used for lung and diaphragm histology and molecular biology analysis. RESULTS: BIVENT-50+PSV0%, compared to BIVENT-100+PSV0%, reduced the diffuse alveolar damage (DAD) score, the expression of amphiregulin (marker of alveolar stretch) and muscle atrophy F-box (marker of diaphragm atrophy). In BIVENT-50 groups, the increase in PSV (BIVENT-50+PSV50% versus BIVENT-50+PSV100%) yielded better lung mechanics and less alveolar collapse, interstitial edema, cumulative DAD score, as well as gene expressions associated with lung inflammation, epithelial and endothelial cell damage in lung tissue, and muscle ring finger protein 1 (marker of muscle proteolysis) in diaphragm. Transpulmonary peak pressure (Ppeak,L) and pressure-time product per minute (PTPmin) at Phigh were associated with lung damage, while increased spontaneous breathing at Plow did not promote lung injury. CONCLUSION: In the ARDS model used herein, during BIVENT, the level of PSV and the phase of the respiratory cycle in which the inspiratory effort occurs affected lung and diaphragm damage. Partitioning of inspiratory effort and transpulmonary pressure in spontaneous breaths at Plow and Phigh is required to minimize VILI.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles in Lung Diseases: Current Status and Perspectives.

Extracellular vesicles (EVs) have emerged as a potential therapy for several diseases. These plasma membrane-derived fragments are released constitutively by virtually all cell types-including mesenchymal stromal cells (MSCs)-under stimulation or following cell-to-cell interaction, which leads to activation or inhibition of distinct signaling pathways. Based on their size, intracellular origin, and secretion pathway, EVs have been grouped into three main populations: exosomes, microvesicles (or microparticles), and apoptotic bodies. Several molecules can be found inside MSC-derived EVs, including proteins, lipids, mRNA, microRNAs, DNAs, as well as organelles that can be transferred to damaged recipient cells, thus contributing to the reparative process and promoting relevant anti-inflammatory/resolutive actions. Indeed, the paracrine/endocrine actions induced by MSC-derived EVs have demonstrated therapeutic potential to mitigate or even reverse tissue damage, thus raising interest in the regenerative medicine field, particularly for lung diseases. In this review, we summarize the main features of EVs and the current understanding of the mechanisms of action of MSC-derived EVs in several lung diseases, such as chronic obstructive pulmonary disease (COPD), pulmonary infections [including coronavirus disease 2019 (COVID-19)], asthma, acute respiratory distress syndrome (ARDS), idiopathic pulmonary fibrosis (IPF), and cystic fibrosis (CF), among others. Finally, we list a number of limitations associated with this therapeutic strategy that must be overcome in order to translate effective EV-based therapies into clinical practice.

Iso-Oncotic Albumin Mitigates Brain and Kidney Injury in Experimental Focal Ischemic Stroke.

Background: There is widespread debate regarding the use of albumin in ischemic stroke. We tested the hypothesis that an iso-oncotic solution of albumin (5%), administered earlier after acute ischemic stroke (3 h), could provide neuroprotection without causing kidney damage, compared to a hyper-oncotic albumin (20%) and saline. Objective: To compare the effects of saline, iso-oncotic albumin, and hyper-oncotic albumin, all titrated to similar hemodynamic targets, on the brain and kidney. Methods: Ischemic stroke was induced in anesthetized male Wistar rats (n = 30; weight 437 ± 68 g) by thermocoagulation of pial blood vessels of the primary somatosensory, motor, and sensorimotor cortices. After 3 h, animals were anesthetized and randomly assigned (n = 8) to receive 0.9% NaCl (Saline), iso-oncotic albumin (5% ALB), and hyper-oncotic albumin (20% ALB), aiming to maintain hemodynamic stability (defined as distensibility index of inferior vena cava <25%, mean arterial pressure >80 mmHg). Rats were then ventilated using protective strategies for 2 h. Of these 30 animals, 6 were used as controls (focal ischemic stroke/no fluid). Results: The total fluid volume infused was higher in the Saline group than in the 5% ALB and 20% ALB groups (mean ± SD, 4.3 ± 1.6 vs. 2.7 ± 0.6 and 2.6 ± 0.5 mL, p = 0.03 and p = 0.02, respectively). The total albumin volume infused (g/kg) was higher in the 20% ALB group than in the 5% ALB group (1.4 ± 0.6 vs. 0.4 ± 0.2, p < 0.001). Saline increased neurodegeneration (Fluoro-Jade C staining), brain inflammation in the penumbra (higher tumor necrosis factor-alpha expression), and blood-brain barrier damage (lower gene expressions of claudin-1 and zona occludens-1) compared to both iso-oncotic and hyper-oncotic albumins, whereas it reduced the expression of brain-derived neurotrophic factor (a marker of neuroregeneration) compared only to iso-oncotic albumin. In the kidney, hyper-oncotic albumin led to greater damage as well as higher gene expressions of kidney injury molecule-1 and interleukin-6 than 5% ALB (p < 0.001). Conclusions: In this model of focal ischemic stroke, only iso-oncotic albumin had a protective effect against brain and kidney damage. Fluid therapy thus requires careful analysis of impact not only on the brain but also on the kidney.

Differential effects of the cystic fibrosis lung inflammatory environment on mesenchymal stromal cells.

Growing evidence demonstrates that human mesenchymal stromal cells (MSCs) modify their in vivo anti-inflammatory actions depending on the specific inflammatory environment encountered. Understanding this better is crucial to refine MSC-based cell therapies for lung and other diseases. Using acute exacerbations of cystic fibrosis (CF) lung disease as a model, the effects of ex vivo MSC exposure to clinical bronchoalveolar lavage fluid (BALF) samples, as a surrogate for the in vivo clinical lung environment, on MSC viability, gene expression, secreted cytokines, and mitochondrial function were compared with effects of BALF collected from healthy volunteers. CF BALF samples that cultured positive for Aspergillus sp. (Asp) induced rapid MSC death, usually within several hours of exposure. Further analyses suggested the fungal toxin gliotoxin as a potential mediator contributing to CF BALF-induced MSC death. RNA sequencing analyses of MSCs exposed to either Asp+ or Asp- CF BALF samples identified a number of differentially expressed transcripts, including those involved in interferon signaling, antimicrobial gene expression, and cell death. Toxicity did not correlate with bacterial lung infections. These results suggest that the potential use of MSC-based cell therapies for CF or other lung diseases may not be warranted in the presence of Aspergillus.

Lung inflammatory environments differentially alter mesenchymal stromal cell behavior.

Mesenchymal stromal (stem) cells (MSCs) are increasingly demonstrated to ameliorate experimentally induced lung injuries through disease-specific anti-inflammatory actions, thus suggesting that different in vivo inflammatory environments can influence MSC actions. To determine the effects of different representative inflammatory lung conditions, human bone marrow-derived MSCs (hMSCs) were exposed to in vitro culture conditions from bronchoalveolar lavage fluid (BALF) samples obtained from patients with either the acute respiratory distress syndrome (ARDS) or with other lung diseases including acute respiratory exacerbations of cystic fibrosis (CF) (non-ARDS). hMSCs were subsequently assessed for time- and BALF concentration-dependent effects on mRNA expression of selected pro- and anti-inflammatory mediators, and for overall patterns of gene and mRNA expression. Both common and disease-specific patterns were observed in gene expression of different hMSC mediators, notably interleukin (IL)-6. Conditioned media obtained from non-ARDS BALF-exposed hMSCs was more effective in promoting an anti-inflammatory phenotype in monocytes than was conditioned media from ARDS BALF-exposed hMSCs. Neutralizing IL-6 in the conditioned media promoted generation of anti-inflammatory monocyte phenotype. This proof of concept study suggest that different lung inflammatory environments potentially can alter hMSC behaviors. Further identification of these interactions and the driving mechanisms may influence clinical use of MSCs for treating lung diseases.

Cannabidiol reduces airway inflammation and fibrosis in experimental allergic asthma.

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Asthma remains a major public health problem and, at present, there are no effective interventions capable of reversing airway remodelling. Cannabidiol (CBD) is known to exert immunomodulatory effects through the activation of cannabinoid-1 and - 2 (CB1 and CB2) receptors located in the central nervous system and immune cells, respectively. However, as the role of CBD on airway remodelling and the mechanisms of CB1 and CB2 aren't fully elucidated, this study was designed to evaluate the effects of cannabidiol in this scenario. Allergic asthma was induced in Balb/c mice exposed to ovalbumin, and respiratory mechanics, collagen fibre content in airway and alveolar septa, cytokine levels, and CB1 and CB2 expression were determined. Moreover, expressions of CB1 and CB2 in induced sputum of asthmatic individuals and their correlation with airway inflammation and lung function were also evaluated. CBD treatment, regardless of dosage, decreased airway hyperresponsiveness, whereas static lung elastance only reduced with high dose. These outcomes were accompanied by decreases in collagen fibre content in both airway and alveolar septa and the expression of markers associated with inflammation in the bronchoalveolar lavage fluid and lung homogenate. There was a significant and inverse correlation between CB1 levels and lung function in asthmatic patients. CBD treatment decreased the inflammatory and remodelling processes in the model of allergic asthma. The mechanisms of action appear to be mediated by CB1/CB2 signalling, but these receptors may act differently on lung inflammation and remodelling.

Serum from Asthmatic Mice Potentiates the Therapeutic Effects of Mesenchymal Stromal Cells in Experimental Allergic Asthma.

Asthma is a chronic inflammatory disease characterized by airway inflammation and remodeling, which can lead to progressive decline of lung function. Although mesenchymal stromal cells (MSCs) have shown beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been limited. Mounting evidence suggests that prior exposure of MSCs to specific inflammatory stimuli or environments can enhance their immunomodulatory properties. Therefore, we investigated whether stimulating MSCs with bronchoalveolar lavage fluid (BALF) or serum from asthmatic mice could potentiate their therapeutic properties in experimental asthma. In a house dust mite (HDM) extract asthma model in mice, unstimulated, asthmatic BALF-stimulated, or asthmatic serum-stimulated MSCs were administered intratracheally 24 hours after the final HDM challenge. Lung mechanics and histology; BALF protein, cellularity, and biomarker levels; and lymph-node and bone marrow cellularity were assessed. Compared with unstimulated or BALF-stimulated MSCs, serum-stimulated MSCs further reduced BALF levels of interleukin (IL)-4, IL-13, and eotaxin, total and differential cellularity in BALF, bone marrow and lymph nodes, and collagen fiber content, while increasing BALF IL-10 levels and improving lung function. Serum stimulation led to higher MSC apoptosis, expression of various mediators (transforming growth factor-ß, interferon-γ, IL-10, tumor necrosis factor-α-stimulated gene 6 protein, indoleamine 2,3-dioxygenase-1, and IL-1 receptor antagonist), and polarization of macrophages to M2 phenotype. In conclusion, asthmatic serum may be a novel strategy to potentiate therapeutic effects of MSCs in experimental asthma, leading to further reductions in both inflammation and remodeling than can be achieved with unstimulated MSCs. Stem Cells Translational Medicine 2019;8:301&312.

Mesenchymal stromal cell therapy reduces lung inflammation and vascular remodeling and improves hemodynamics in experimental pulmonary arterial hypertension.

BACKGROUND: Experimental research has reported beneficial effects of mesenchymal stromal cell (MSC) therapy in pulmonary arterial hypertension (PAH). However, these studies either were based on prophylactic protocols or assessed basic remodeling features without evaluating possible mechanisms. We analyzed the effects of MSC therapy on lung vascular remodeling and hemodynamics and its possible mechanisms of action in monocrotaline (MCT)-induced PAH. METHODS: Twenty-eight Wistar rats were randomly divided into two groups. In the PAH group, animals received MCT 60 mg/kg intraperitoneally, while a control group received saline (SAL) instead. On day 14, both groups were further randomized to receive 105 adipose-derived MSCs or SAL intravenously (n = 7/group). On day 28, right ventricular systolic pressure (RVSP) and the gene expression of mediators associated with apoptosis, inflammation, fibrosis, Smad-1 levels, cell proliferation, and endothelial-mesenchymal transition were determined. In addition, lung histology (smooth muscle cell proliferation and plexiform-like injuries), CD68+ and CD163+ macrophages, and plasma levels of vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) were evaluated. RESULTS: In the PAH group, adipose-derived MSCs, compared to SAL, reduced mean RVSP (29 ± 1 vs 39 ± 2 mmHg, p < 0.001), lung tissue collagen fiber content, smooth muscle cell proliferation, CD68+ macrophages, interleukin-6 expression, and the antiapoptotic mediators Bcl-2 and survivin. Conversely, expression of the proapoptotic mediator procaspase-3 and plasma VEGF increased, with no changes in PDGF. In the pulmonary artery, MSCs dampened the endothelial-mesenchymal transition. CONCLUSION: In MCT-induced PAH, MSC therapy reduced lung vascular remodeling, thus improving hemodynamics. These beneficial effects were associated with increased levels of proapoptotic markers, mesenchymal-to-endothelial transition, reduced cell proliferation markers, and inflammation due to a shift away from the M1 phenotype.

Bone Marrow, Adipose, and Lung Tissue-Derived Murine Mesenchymal Stromal Cells Release Different Mediators and Differentially Affect Airway and Lung Parenchyma in Experimental Asthma.

Mesenchymal stromal cells (MSCs) from different sources have differential effects on lung injury. To compare the effects of murine MSCs from bone marrow (BM), adipose tissue (AD), and lung tissue (LUNG) on inflammatory and remodeling processes in experimental allergic asthma, female C57BL/6 mice were sensitized and challenged with ovalbumin (OVA) or saline (C). Twenty-four hours after the last challenge, mice received either saline (50 µl, SAL), BM-MSCs, AD-MSCs, or LUNG-MSCs (105 cells per mouse in 50 µl total volume) intratracheally. At 1 week, BM-MSCs produced significantly greater reductions in resistive and viscoelastic pressures, bronchoconstriction index, collagen fiber content in lung parenchyma (but not airways), eosinophil infiltration, and levels of interleukin (IL)-4, IL-13, transforming growth factor (TGF)-ß, and vascular endothelial growth factor (VEGF) in lung homogenates compared to AD-MSCs and LUNG-MSCs. Only BM-MSCs increased IL-10 and interferon (IFN)-γ in lung tissue. In parallel in vitro experiments, BM-MSCs increased M2 macrophage polarization, whereas AD-MSCs and LUNG-MSCs had higher baseline levels of IL-4, insulin-like growth factor (IGF), and VEGF secretion. Exposure of MSCs to serum specimens obtained from asthmatic mice promoted reductions in secretion of these mediators, particularly in BM-MSCs. Intratracheally administered BM-MSCs, AD-MSCs, and LUNG-MSCs were differentially effective at reducing airway inflammation and remodeling and improving lung function in the current model of allergic asthma. In conclusion, intratracheal administration of MSCs from BM, AD, and LUNG were differentially effective at reducing airway inflammation and remodeling and improving lung function comparably reduced inflammation and fibrogenesis in this asthma model. However, altered lung mechanics and lung remodeling responded better to BM-MSCs than to AD-MSCs or LUNG-MSCs. Moreover, each type of MSC was differentially affected in a surrogate in vitro model of the in vivo lung environment. Stem Cells Translational Medicine 2017;6:1557-1567.

Characterization of a Mouse Model of Emphysema Induced by Multiple Instillations of Low-Dose Elastase.

Many experimental models have been proposed to study the pathophysiological features of emphysema, as well as to search for new therapeutic approaches for acute or chronically injured lung parenchyma. We aimed to characterize an emphysema model induced by multiple instillations of elastase by tracking changes in inflammation, remodeling, and cardiac function after each instillation. Forty-eight C57BL/6 mice were randomly assigned across two groups. Emphysema (ELA) animals received 1, 2, 3, or 4 intratracheal instillations of pancreatic porcine elastase (PPE, 0.2 IU) with a 1-week interval between them. Controls (C) received saline following the same protocol. Before and after implementation of the protocol, animals underwent echocardiographic analysis. After the first instillation of PPE, the percentage of mononuclear cells in the lung parenchyma increased compared to C (p = 0.0001). The second instillation resulted in hyperinflated alveoli, increased mean linear intercept, and reduced elastic fiber content in lung parenchyma compared to C (p = 0.0197). Following the third instillation, neutrophils and collagen fiber content in alveolar septa and airways increased, whereas static lung elastance was reduced compared to C (p = 0.0094). After the fourth instillation, the percentage of M1 macrophages in lungs; levels of interleukin-1ß (IL-1ß), keratinocyte-derived chemokine, hepatocyte growth factor (HGF), and vascular endothelial growth factor (VEGF); and collagen fiber content in the pulmonary vessel wall were increased compared to C (p = 0.0096). At this time point, pulmonary arterial hypertension was apparent, with increased diastolic right ventricular wall thickness. In conclusion, the initial phase of emphysema was characterized by lung inflammation with predominance of mononuclear cells, whereas at the late stage, impairment of pulmonary and cardiovascular functions was observed. This model enables analysis of therapies at different time points during controlled progression of emphysema. Accordingly, early interventions could focus on the inflammatory process, while late interventions should focus on restoring cardiorespiratory function.

Extracellular vesicles derived from mesenchymal stromal cells: a therapeutic option in respiratory diseases?

Extracellular vesicles (EVs) are plasma membrane-bound fragments released from several cell types, including mesenchymal stromal cells (MSCs), constitutively or under stimulation. EVs derived from MSCs and other cell types transfer molecules (such as DNA, proteins/peptides, mRNA, microRNA, and lipids) and/or organelles with reparative and anti-inflammatory properties to recipient cells. The paracrine anti-inflammatory effects promoted by MSC-derived EVs have attracted significant interest in the regenerative medicine field, including for potential use in lung injuries. In the present review, we describe the characteristics, biological activities, and mechanisms of action of MSC-derived EVs. We also review the therapeutic potential of EVs as reported in relevant preclinical models of acute and chronic respiratory diseases, such as pneumonia, acute respiratory distress syndrome, asthma, and pulmonary arterial hypertension. Finally, we discuss possible approaches for potentiating the therapeutic effects of MSC-derived EVs so as to enable use of this therapy in clinical practice.

Therapeutic effects of LASSBio-596 in an elastase-induced mouse model of emphysema.

Emphysema is an intractable pulmonary disease characterized by an inflammatory process of the airways and lung parenchyma and ongoing remodeling process in an attempt to restore lung structure. There is no effective drug therapy that regenerates lung tissue or prevents the progression of emphysema; current treatment is aimed at symptomatic relief. We hypothesized that LASSBio-596, a molecule with potent anti-inflammatory and immunomodulatory effects, might reduce pulmonary inflammation and remodeling and thus improve lung function in experimental emphysema. Emphysema was induced in BALB/c mice by intratracheal administration of porcine pancreatic elastase (0.1 IU) once weekly during 4 weeks. A control group received saline using the same protocol. After the last instillation of saline or elastase, dimethyl sulfoxide, or LASSBio-596 were administered intraperitoneally, once daily for 8 days. After 24 h, in elastase-induced emphysema animals, LASSBio-596 yielded: (1) decreased mean linear intercept, hyperinflation and collagen fiber content, (2) increased elastic fiber content, (3) reduced number of M1 macrophages, (4) decreased tumor necrosis factor-α, interleukin-1ß, interleukin-6, and transforming growth factor-ß protein levels in lung tissue, and increased vascular endothelial growth factor. These changes resulted in increased static lung elastance. In conclusion, LASSBio-596 therapy reduced lung inflammation, airspace enlargement, and small airway wall remodeling, thus improving lung function, in this animal model of elastase-induced emphysema.

Effects of different mesenchymal stromal cell sources and delivery routes in experimental emphysema.

We sought to assess whether the effects of mesenchymal stromal cells (MSC) on lung inflammation and remodeling in experimental emphysema would differ according to MSC source and administration route. Emphysema was induced in C57BL/6 mice by intratracheal (IT) administration of porcine pancreatic elastase (0.1 UI) weekly for 1 month. After the last elastase instillation, saline or MSCs (1×105), isolated from either mouse bone marrow (BM), adipose tissue (AD) or lung tissue (L), were administered intravenously (IV) or IT. After 1 week, mice were euthanized. Regardless of administration route, MSCs from each source yielded: 1) decreased mean linear intercept, neutrophil infiltration, and cell apoptosis; 2) increased elastic fiber content; 3) reduced alveolar epithelial and endothelial cell damage; and 4) decreased keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8) and transforming growth factor-ß levels in lung tissue. In contrast with IV, IT MSC administration further reduced alveolar hyperinflation (BM-MSC) and collagen fiber content (BM-MSC and L-MSC). Intravenous administration of BM- and AD-MSCs reduced the number of M1 macrophages and pulmonary hypertension on echocardiography, while increasing vascular endothelial growth factor. Only BM-MSCs (IV > IT) increased the number of M2 macrophages. In conclusion, different MSC sources and administration routes variably reduced elastase-induced lung damage, but IV administration of BM-MSCs resulted in better cardiovascular function and change of the macrophage phenotype from M1 to M2.

Effects of bone marrow mononuclear cells from healthy or ovalbumin-induced lung inflammation donors on recipient allergic asthma mice.

INTRODUCTION: Asthma is characterized by a chronic inflammatory process which may lead to several changes in bone marrow cell composition. We hypothesized that bone marrow mononuclear cells (BMMCs) obtained from ovalbumin (OVA)-induced lung inflammation mice may promote different effects compared to BMMCs from healthy donors in a model of allergic asthma. METHODS: C57BL/6 mice were randomly assigned to two groups. In the OVA group, mice were sensitized and challenged with ovalbumin, while healthy animals (control group) received saline using the same protocol. BMMCs were analyzed by flow cytometry 24 hours after the last challenge. After BMMC characterization, another group of OVA mice were further randomized into three subgroups to receive intratracheal saline (BMMC-SAL), BMMCs from control or BMMCs from OVA mice (BMMC-Control and BMMC-OVA, respectively; 2x106 cells/mouse), 24 hours after the last challenge. RESULTS: BMMC-OVA exhibited an increased percentage of eosinophils, monocytes and hematopoietic precursors, while mesenchymal stem cells decreased, as compared with BMMC-Control. BMMCs from both donor groups reduced airway resistance, alveolar collapse, bronchoconstriction index, eosinophil infiltration, collagen fiber content in alveolar septa and levels of interleukin (IL)-4, IL-5, IL-13, interferon-γ, transforming growth factor-ß, and vascular endothelial growth factor in lung homogenates. However, the benefits of BMMCs were significantly more pronounced when cells were obtained from control donors. CONCLUSION: Both BMMC-Control and BMMC-OVA reduced the inflammatory and remodeling processes; nevertheless, BMMC-Control led to a greater improvement in lung morphofunction, which may be due to different BMMC composition and/or properties.

DNA nanoparticle-mediated thymulin gene therapy prevents airway remodeling in experimental allergic asthma.

Thymulin has been shown to present anti-inflammatory and anti-fibrotic properties in experimental lung diseases. We hypothesized that a biologically active thymulin analog gene, methionine serum thymus factor, delivered by highly compacted DNA nanoparticles may prevent lung inflammation and remodeling in a mouse model of allergic asthma. The DNA nanoparticles are composed of a single molecule of plasmid DNA compacted with block copolymers of poly-L-lysine and polyethylene glycol (CK30PEG), which have been found safe in a human phase I/II clinical trial. Thymulin plasmids were detected in the lungs of ovalbumin-challenged asthmatic mice up to 27days after administration of DNA nanoparticles carrying thymulin plasmids. A single dose of DNA nanoparticles carrying thymulin plasmids prevented lung inflammation, collagen deposition and smooth muscle hypertrophy in the lungs of a murine model of ovalbumin-challenged allergic asthma, leading to improved lung mechanics. In the present model of chronic allergic asthma, highly compacted DNA nanoparticles using thymulin analog gene modulated the inflammatory and remodeling processes improving lung mechanics.

Repeated administration of bone marrow-derived cells prevents disease progression in experimental silicosis.

BACKGROUND/AIMS: Bone marrow-derived cells (BMDCs) reduced mechanical and histologic changes in the lung in a murine model of silicosis, but these beneficial effects did not persist in the course of lung injury. We hypothesized that repeated administration of BMDCs may decrease lung inflammation and remodeling thus preventing disease progression. METHODS: One hundred and two C57BL/6 mice were randomly divided into SIL (silica, 20 mg intratracheally [IT]) and control (C) groups (saline, IT). C and SIL groups were further randomized to receive BMDCs (2×10(6) cells) or saline IT 15 and 30 days after the start of the protocol. RESULTS: By day 60, BMDCs had decreased the fractional area of granuloma and the number of polymorphonuclear cells, macrophages (total and M1 phenotype), apoptotic cells, the level of transforming growth factor (TGF)-ß' and types I and III collagen fiber content in the granuloma. In the alveolar septa, BMDCs reduced the amount of collagen and elastic fibers, TGF-ß, and the number of M1 and apoptotic cells. Furthermore, interleukin (IL)-1ß, IL-1R1, caspase-3 mRNA levels decreased and the level of IL-1RN mRNA increased. Lung mechanics improved after BMDC therapy. The presence of male donor cells in lung tissue was not observed using detection of Y chromosome DNA. CONCLUSION: repeated administration of BMDCs reduced inflammation, fibrogenesis, and elastogenesis, thus improving lung mechanics through the release of paracrine factors.

Bone marrow-derived mononuclear cells vs. mesenchymal stromal cells in experimental allergic asthma.

We compared the effects of bone marrow-derived mononuclear cells (BMMCs) and mesenchymal stromal cells (MSCs) on airway inflammation and remodeling and lung mechanics in experimental allergic asthma. C57BL/6 mice were sensitized and challenged with ovalbumin (OVA group). A control group received saline using the same protocol. Twenty-four hours after the last challenge, groups were further randomized into subgroups to receive saline, BMMCs (2×10(6)) or MSCs (1×10(5)) intratracheally. BMMC and MSC administration decreased cell infiltration, bronchoconstriction index, alveolar collapse, collagen fiber content in the alveolar septa, and interleukin (IL)-4, IL-13, transforming growth factor (TGF)-ß and vascular endothelial growth factor (VEGF) levels compared to OVA-SAL. Lung function, alveolar collapse, collagen fiber deposition in alveolar septa, and levels of TGF-ß and VEGF improved more after BMMC than MSC therapy. In conclusion, intratracheal BMMC and MSC administration effectively modulated inflammation and fibrogenesis in an experimental model of asthma, but BMMCs was associated with greater benefit in terms of reducing levels of fibrogenesis-related growth factors.

Bone marrow mononuclear cell therapy in experimental allergic asthma: intratracheal versus intravenous administration.

We hypothesized that the route of administration would impact the beneficial effects of bone marrow-derived mononuclear cell (BMDMC) therapy on the remodelling process of asthma. C57BL/6 mice were randomly assigned to two main groups. In the OVA group, mice were sensitized and challenged with ovalbumin, while the control group received saline using the same protocol. Twenty-four hours before the first challenge, control and OVA animals were further randomized into three subgroups to receive saline (SAL), BMDMCs intravenously (2×10(6)), or BMDMCs intratracheally (2×10(6)). The following changes were induced by BMDMC therapy in OVA mice regardless of administration route: reduction in resistive and viscoelastic pressures, static elastance, eosinophil infiltration, collagen fibre content in airways and lung parenchyma; and reduction in the levels of interleukin (IL)-4, IL-13, transforming growth factor-ß and vascular endothelial growth factor. In conclusion, BMDMC modulated inflammatory and remodelling processes regardless of administration route in this experimental model of allergic asthma.

Protective effects of bone marrow mononuclear cell therapy on lung and heart in an elastase-induced emphysema model.

We hypothesized that bone marrow-derived mononuclear cell (BMDMC) therapy protects the lung and consequently the heart in experimental elastase-induced emphysema. Twenty-four female C57BL/6 mice were intratracheally instilled with saline (C group) or porcine pancreatic elastase (E group) once a week during 4 weeks. C and E groups were randomized into subgroups receiving saline (SAL) or male BMDMCs (2 × 10(6), CELL) intravenously 3h after the first saline or elastase instillation. Compared to E-SAL group, E-CELL mice showed, at 5 weeks: lower mean linear intercept, neutrophil infiltration, elastolysis, collagen fiber deposition in alveolar septa and pulmonary vessel wall, lung cell apoptosis, right ventricle wall thickness and area, higher endothelial growth factor and insulin-like growth factor mRNA expressions in lung tissue, and reduced platelet-derived growth factor, transforming growth factor-ß, and caspase-3 expressions. In conclusion, BMDMC therapy was effective at modulating the inflammatory and remodeling processes in the present model of elastase-induced emphysema.

Mechanisms of cellular therapy in respiratory diseases.

PURPOSE: Stem cells present a variety of clinical implications in the lungs. According to their origin, these cells can be divided into embryonic and adult stem cells; however, due to the important ethical and safety limitations that are involved in the embryonic stem cell use, most studies have chosen to focus on adult stem cell therapy. This article aims to present and clarify the recent advances in the field of stem cell biology, as well as to highlight the effects of mesenchymal stem cell (MSC) therapy in the context of acute lung injury/acute respiratory distress syndrome and chronic disorders such as lung fibrosis and chronic obstructive pulmonary disease. METHODS: For this purpose, we performed a critical review of adult stem cell therapies, covering the main clinical and experimental studies published in Pubmed databases in the past 11 years. Different characteristics were extracted from these articles, such as: the experimental model, strain, cellular type and administration route used as well as the positive or negative effects obtained. RESULTS: There is evidence for beneficial effects of MSC on lung development, repair, and remodeling. The engraftment in the injured lung does not occur easily, but several studies report that paracrine factors can be effective in reducing inflammation and promoting tissue repair. MSC releases several growth factors and anti-inflammatory cytokines that regulate endothelial and epithelial permeability and reduce the severity of inflammation. CONCLUSION: A better understanding of the mechanisms that control cell division and differentiation, as well as of their paracrine effects, is required to enable the optimal use of bone marrow-derived stem cell therapy to treat human respiratory diseases.