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

Consecutive intrabronchial administration of Wharton's jelly-derived mesenchymal stromal cells in ECMO-supported pediatric patients with end-stage interstitial lung disease: a safety and feasibility study (CIBA method)

BACKGROUND

Patients ineligible for lung transplant with end-stage Interstitial Lung Disease (ILD) on Extra-Corporeal Membrane Oxygenation (ECMO) face an appalling prognosis with limited therapeutic options. Due to the beneficial effect of Mesenchymal Stromal Cells (MSC) on inflammatory, immunological and infectious diseases, cell therapy has been proposed as an option, but administration is hampered by the ECMO.

METHODS

Cryopreserved Wharton-jelly derived MSC (WJ-MSC) were conveniently diluted and directly applied consecutively on each lobule (5,1 ml = 107 cells) at a continuous slow rate infused over one hour via flexible bronchoscopy (Consecutive IntraBronchial Administration method, CIBA method).

RESULTS

Intrabronchial administration of MSC to a patient on ECMO was well tolerated by the patient even though it did not reverse the patient's ILD. This manuscript presents preliminary evidence from ongoing clinical trials program on Cell Therapy of Inflammatory, Immune and Infectious Diseases and, to our knowledge, is the first report of intrabronchial administration of MSC in a paediatric ECMO patient with ILD. Even more, MSC administered by this method do not reach the systemic circulation and do get blocked on ECMO membrane.

CONCLUSIONS

Direct intrabronchial administration of MSC in a patient on ECMO is feasible and safe, and may be a new avenue to be assayed in ECMO patients with inflammatory, immunological and infectious diseases of the lung.

Management of oxidative stress for cell therapy through combinational approaches of stem cells, antioxidants, and photobiomodulation

Over the recent decades, stem cell-based therapies have been considered as a beneficial approach for the treatment of various diseases. In these types of therapies, the stem cells and their products are used as treating agents. Despite the helpful efficacy of stem cell-based therapies, there may be challenges. Oxidative stress (OS) is one of these challenges that can affect the therapeutic properties of stem cells. Therefore, it seems that employing strategies for the reduction of OS in combination with stem cell therapy can lead to better results of these therapies. Based on the available evidence, antioxidant therapy and photobiomodulation (PBM) are strategies that can regulate the OS in the cells. Antioxidant therapy is a method in which various antioxidants are used in the therapeutic processes. PBM is also the clinical application of light that gained importance in medicine. Antioxidants and PBM can regulate OS by the effect on mitochondria as an important source of OS in the cells. Considering the importance of OS in pathologic pathways and its effect on the treatment outcomes of stem cells, in the present review first the stem cell therapy and effects of OS on this type of therapy are summarized. Then, antioxidant therapy and PBM as approaches for reducing OS with a focus on mitochondrial function are discussed. Also, a novel combination treatment with the hope of achieving better and more stable outcomes in the treatment process of diseases is proposed.

Human macrophage migration inhibitory factor potentiates mesenchymal stromal cell efficacy in a clinically relevant model of allergic asthma

Current asthma therapies focus on reducing symptoms but fail to restore existing structural damage. Mesenchymal stromal cell (MSC) administration can ameliorate airway inflammation and reverse airway remodeling. However, differences in patient disease microenvironments seem to influence MSC therapeutic effects. A polymorphic CATT tetranucleotide repeat at position 794 of the human macrophage migration inhibitory factor (hMIF) gene has been associated with increased susceptibility to and severity of asthma. We investigated the efficacy of human MSCs in high- vs. low-hMIF environments and the impact of MIF pre-licensing of MSCs using humanized MIF mice in a clinically relevant house dust mite (HDM) model of allergic asthma. MSCs significantly attenuated airway inflammation and airway remodeling in high-MIF-expressing CATT7 mice but not in CATT5 or wild-type littermates. Differences in efficacy were correlated with increased MSC retention in the lungs of CATT7 mice. MIF licensing potentiated MSC anti-inflammatory effects at a previously ineffective dose. Mechanistically, MIF binding to CD74 expressed on MSCs leads to upregulation of cyclooxygenase 2 (COX-2) expression. Blockade of CD74 or COX-2 function in MSCs prior to administration attenuated the efficacy of MIF-licensed MSCs in vivo. These findings suggest that MSC administration may be more efficacious in severe asthma patients with high MIF genotypes (CATT6/7/8).

Key Role of Mesenchymal Stromal Cell Interaction with Macrophages in Promoting Repair of Lung Injury

Lung macrophages (Mφs) are essential for pulmonary innate immunity and host defense due to their dynamic polarization and phenotype shifts. Mesenchymal stromal cells (MSCs) have secretory, immunomodulatory, and tissue-reparative properties and have shown promise in acute and chronic inflammatory lung diseases and in COVID-19. Many beneficial effects of MSCs are mediated through their interaction with resident alveolar and pulmonary interstitial Mφs. Bidirectional MSC-Mφ communication is achieved through direct contact, soluble factor secretion/activation, and organelle transfer. The lung microenvironment facilitates MSC secretion of factors that result in Mφ polarization towards an immunosuppressive M2-like phenotype for the restoration of tissue homeostasis. M2-like Mφ in turn can affect the MSC immune regulatory function in MSC engraftment and tissue reparatory effects. This review article highlights the mechanisms of crosstalk between MSCs and Mφs and the potential role of their interaction in lung repair in inflammatory lung diseases.

Proceedings of the ISCT scientific signature series symposium, "Advances in cell and gene therapies for lung diseases and critical illnesses": International Society for Cell & Gene Therapy, Burlington VT, US, July 16, 2021

The ISCT Scientific Signature Series Symposium "Advances in Cell and Gene Therapies for Lung Diseases and Critical Illnesses" was held as an independent symposium in conjunction with the biennial meeting, "Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases," which took place July 12-15, 2021, at the University of Vermont. This is the third Respiratory System-based Signature Series event; the first 2, "Tracheal Bioengineering, the Next Steps" and "Cellular Therapies for Pulmonary Diseases and Critical Illnesses: State of the Art of European Science," took place in 2014 and 2015, respectively. Cell- and gene-based therapies for respiratory diseases and critical illnesses continue to be a source of great promise and opportunity. This reflects ongoing advancements in understanding of the mechanisms by which cell-based therapies, particularly those using mesenchymal stromal cells (MSCs), can mitigate different lung injuries and the increasing sophistication with which preclinical data is translated into clinical investigations. This also reflects continuing evolution in gene transfer vectors, including those designed for in situ gene editing in parallel with those targeting gene or cell replacement. Therefore, this symposium convened global thought leaders in a forum designed to catalyze communication and collaboration to bring the greatest possible innovation and value of cell- and gene-based therapies for patients with respiratory diseases and critical illnesses.

Intranasally Administered Extracellular Vesicles from Adipose Stem Cells Have Immunomodulatory Effects in a Mouse Model of Asthma

Asthma is a chronic eosinophilic airway disease characterized by type 2 helper T cell-driven inflammation. Adipose stem cells (ASCs) and the ASC culture supernatant are known to improve allergic airway inflammation; however, the immunomodulatory effects of ASC-derived extracellular vesicles (EVs) on allergic airway diseases remain unclear. Thus, we assessed the effects of ASC-derived EVs on allergic airway inflammation in a mouse model of asthma. EVs were isolated from the culture supernatant of murine ASCs and characterized. Six-week-old female C57BL/6 mice were sensitized to ovalbumin (OVA) by intraperitoneal injection and challenged intranasally with OVA. Before the OVA challenge, 10 μg/50 μl of ASC-derived EVs was administered intranasally to the experimental group. ASC-derived EVs significantly attenuated airway hyperresponsiveness (AHR) in asthmatic mice (p = 0.023). ASC-derived EVs resulted in a remarkable reduction of the total number of inflammatory cells (p = 0.005) and eosinophils (p = 0.023) in the bronchoalveolar lavage fluid (BALF), the degree of eosinophilic lung inflammation (p < 0.001), and the serum total and OVA-specific immunoglobulin (Ig)E (p = 0.048 and p = 0.001) and total IgG1 (p < 0.001). Interleukin- (IL-) 4 was significantly inhibited with ASC-derived EV pretreatment in the BALF and lung draining lymph nodes (LLNs) (p = 0.040 and p = 0.011). Furthermore, ASC-derived EV administration resulted in a significant increase of the regulatory T cell (Treg) populations in LLNs. ASC-derived EVs alleviated AHR and allergic airway inflammation caused by the induction of Treg expansion in a mouse model of asthma. There seems to be a role for ASC-derived EVs as a modifier in allergic airway disease.

Integrative Studies of Human Cord Blood Derived Mononuclear Cells and Umbilical Cord Derived Mesenchyme Stem Cells in Ameliorating Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a common pulmonary complication observed in preterm infants that is composed of multifactorial pathogenesis. Current strategies, albeit successful in moderately reducing morbidity and mortality of BPD, failed to draw overall satisfactory conclusion. Here, using a typical mouse model mimicking hallmarks of BPD, we revealed that both cord blood-derived mononuclear cells (CB-MNCs) and umbilical cord-derived mesenchymal stem cells (UC-MSCs) are efficient in alleviating BPD. Notably, infusion of CB-MNCs has more prominent effects in preventing alveolar simplification and pulmonary vessel loss, restoring pulmonary respiratory functions and balancing inflammatory responses. To further elucidate the underlying mechanisms within the divergent therapeutic effects of UC-MSC and CB-MNC, we systematically investigated the long noncoding RNA (lncRNA)-microRNA (miRNA)-messenger RNA (mRNA) and circular RNA (circRNA)-miRNA-mRNA networks by whole-transcriptome sequencing. Importantly, pathway analysis integrating Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG)/gene set enrichment analysis (GSEA) method indicates that the competing endogenous RNA (ceRNA) network is mainly related to the regulation of GTPase activity (GO: 0043087), extracellular signal-regulated kinase 1 (ERK1) and ERK2 signal cascade (GO: 0070371), chromosome regulation (GO: 0007059), and cell cycle control (GO: 0044770). Through rigorous selection of the lncRNA/circRNA-based ceRNA network, we demonstrated that the hub genes reside in UC-MSC- and CB-MNC-infused networks directed to the function of cell adhesion, motor transportation (Cdk13, Lrrn2), immune homeostasis balance, and autophagy (Homer3, Prkcd) relatively. Our studies illustrate the first comprehensive mRNA-miRNA-lncRNA and mRNA-miRNA-circRNA networks in stem cell-infused BPD model, which will be valuable in identifying reliable biomarkers or therapeutic targets for BPD pathogenesis and shed new light in the priming and conditioning of UC-MSCs or CB-MNCs in the treatment of neonatal lung injury.

Effects of a novel roflumilast and formoterol fumarate dry powder inhaler formulation in experimental allergic asthma

In this study we aimed to develop a roflumilast (R) and formoterol fumarate (F) dry powder inhaler formulation (DPI) incorporating HPβCD by spray drying and evaluated if it attenuates the inflammatory process and improves lung function in a murine model of ovalbumin induced allergic asthma. The DPI was characterized by powder X-ray diffraction, thermal analysis, scanning electron microscopy, particle size, density, specific surface area and dynamic vapor sorption analyses. In vitro deposition studies were performed using a NGI, while transepithelial permeability and in vivo effects on lung mechanics and inflammation in a model of allergic asthma were also assessed. The R:F formulation was amorphous with high glass transition temperatures, comprised of wrinkled particles, had low bulk and tapped densities, high surface area, suitable particle size for pulmonary delivery and exhibited no recrystallization even at high relative humidities. MMAD were statistically similar of 4.22 ± 0.19 and 4.32 ± 0.13 µm for F and R, respectively. Fine particle fractions (<5 µm) were of more than 50% of the emitted dose. The R:F formulation led to reduced eosinophil infiltration and airway collagen fiber content, yielding decreased airway hyperresponsiveness. In the current asthma model, the R:F formulation combination decreased inflammation and remodeling, thus improving lung mechanics.

Aerosolised Mesenchymal Stem Cells Expressing Angiopoietin-1 Enhances Airway Repair

BACKGROUND

The aim of this study was to investigate the effects of MSCs and MSC-expressing ANGPT1 (MSC-pANGPT1) treatment via aerosolisation in alleviating the asthma-related airway inflammation in the rabbit model.

METHODS

Rabbits were sensitised and challenged with both intraperitoneal injection and inhalation of ovalbumin (Ova). MSCs and MSC-pANGPT1 cells were aerosolised into rabbit lungs using the MicroSprayer® Aerosolizer Model IA-1B 48 h after injury. The post mortem was performed 3 days following cell delivery. Histopathological assessments of the lung tissues and inflammatory response were quantitatively scored following treatments.

RESULT(S)

Administration of aerosolised MSCs and MSC-pANGPT1 were significantly reduced inflammation of the airways (p < 0.001), as reflected by improved of structural changes such as thickness of the basement membrane, epithelium, mucosa and sub-mucosa regions. The airway inflammation score of both treatment groups revealed a significant reduction of inflammation and granulocyte infiltration at the peribronchiale and perivascular regions (p < 0.05). Administration of aerosolised MSCs alone was resulted in significant reduction in the levels of pro-inflammatory genes (IL-4 and TGF-β) while treatment with aerosolised MSC-pANGPT1 led to further reduction of various pro-inflammatory genes to the base-line values (IL4, TNF, MMP9 and TGF-β). Treatment with both aerosolised MSCs and MSC-pANGPT1 cells was also alleviated the number of airway inflammatory cells in the bronchoalveolar lavage (BAL) fluid and goblet cell hyperplasia.

CONCLUSION(S)

Our findings suggest that treatment with MSCs alone attenuated airway inflammation and structural changes of the airway. Treatment with MSC-pANGPT1 provided an additional effect in reducing the expression levels of various pro-inflammatory genes. Both of these treatment enhancing airway repair and therefore may provide a basis for the development of an innovative approach for the treatment and prevention of airway inflammatory diseases.

Autologous bone marrow-derived mononuclear cell therapy in three patients with severe asthma

BACKGROUND

Despite recent advances in understanding its pathophysiology and development of novel therapies, asthma remains a serious public health issue worldwide. Combination therapy with inhaled corticosteroids and long-acting β₂-adrenoceptor agonists results in disease control for many patients, but those who exhibit severe asthma are often unresponsive to conventional treatment, experiencing worse quality of life, frequent exacerbations, and increasing healthcare costs. Bone marrow-derived mononuclear cell (BMMC) transplantation has been shown to reduce airway inflammation and remodeling and improve lung function in experimental models of allergic asthma.

METHODS

This is a case series of three patients who presented severe asthma, unresponsive to conventional therapy and omalizumab. They received a single intravenous dose of autologous BMMCs (2 × 10⁷) and were periodically evaluated for 1 year after the procedure. Endpoint assessments included physical examination, quality of life questionnaires, imaging (computed tomography, single-photon emission computed tomography, and ventilation/perfusion scan), lung function tests, and a 6-min walk test.

RESULTS

All patients completed the follow-up protocol. No serious adverse events attributable to BMMC transplantation were observed during or after the procedure. Lung function remained stable throughout. A slight increase in ventilation of the right lung was observed on day 120 after BMMC transplantation in one patient. All three patients reported improvement in quality of life in the early post-procedure course.

CONCLUSIONS

This paper described for the first time the effects of BMMC therapy in patients with severe asthma, providing a basis for subsequent trials to assess the efficacy of this therapy.

The potential of mesenchymal stem cell therapy for chronic lung disease

Introduction: Mesenchymal stem/stromal cells (MSCs) have been shown to improve lung function and survival in chronic inflammatory lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), pulmonary arterial hypertension (PAH), and silicosis.Areas covered: This review covers rationale for the use of MSC therapy, along with preclinical studies and clinical trials with MSC therapy in chronic lung diseases.Expert opinion: MSC therapy holds promise for the treatment of chronic lung diseases, mainly when administered at early stages. In clinical trials, MSC administration was safe, but associated with limited effects on clinical outcomes. Further studies are required to elucidate unresolved issues, including optimal MSC source and dose, route of administration, and frequency (single vs. multiple-dose regimens). A better understanding of the mechanisms of MSC action, local microenvironment of each disease, and development of strategies to potentiate the beneficial effects of MSCs may improve outcomes.

iPSC- and mesenchymoangioblast-derived mesenchymal stem cells provide greater protection against experimental chronic allergic airways disease compared with a clinically used corticosteroid

The airway remodeling (AWR) associated with chronic allergic airways disease (AAD)/asthma contributes to irreversible airway obstruction. This study compared and combined the antiremodeling and other effects of induced pluripotent stem cell and mesenchymoangioblast-derived mesenchymal stem cells (MCA-MSCs) with the corticosteroid dexamethasone (Dex) in experimental chronic AAD/asthma. Female BALB/c mice subjected to 11 wk of ovalbumin (Ova)-induced chronic AAD were intranasally administered MCA-MSCs (1 × 10⁶ cells/mouse; once weekly on wk 10 and 11), Dex (0.5 mg/ml; once daily for 2 wk), or both combined. MCA-MSC detection and changes in airway inflammation (AI), AWR, and airway hyperresponsiveness (AHR) were measured at the end of wk 11. Mice with chronic AAD had significant AI, goblet cell metaplasia, epithelial damage/thickening, aberrant TGF-β1 levels, subepithelial myofibroblast accumulation, airway/lung fibrosis, and AHR (all P < 0.001 vs. healthy controls). MCA-MSCs were detected in the lungs up to 5-7 d postadministration and demonstrated modest anti-inflammatory but striking antifibrotic effects against Ova-induced AAD, effectively decreasing AHR by 70-75% (all P < 0.05 vs. Ova alone). In comparison, Dex predominantly demonstrated anti-inflammatory effects, decreasing AHR by ∼30%. Combining MCA-MSCs with Dex provided equivalent protection to that offered by either therapy alone. MCA-MSCs reduce chronic AAD-induced AWR and AHR to a greater extent than Dex and may act as a suitable adjunct therapy to corticosteroid treatment of asthma.-Royce, S. G., Mao, W., Lim, R., Kelly, K., Samuel, C. S. iPSC- and mesenchymoangioblast-derived mesenchymal stem cells provide greater protection against experimental chronic allergic airways disease compared with a clinically used corticosteroid.

Simvastatin and bone marrow-derived mesenchymal stem cells (BMSCs) affects serum IgE and lung cytokines levels in sensitized mice

INTRODUCTION

The effects of bone marrow-derived mesenchymal stem cells (BMSCs) and simvastatin combination therapy on serum total and specific IgE levels and lung IL-13 and TGF-β levels in sensitized mouse were examined.

MATERIAL AND METHODS

Control (n = 5), Sensitized (S), (n = 5), S + BMSC (n = 6), S + simvastatin (n = 6) and S + BMSC + simvastatin (n = 4) groups of BALB/c mice were studied. Mice were sensitized by ovalbumin. Sensitized mice were treated with a single intravenous injection of BMSCs (1 × 106) or daily intraperitoneal injection of simvastatin (40 mg/kg) or both BMSCs and simvastatin on the last week of challenge. Serum total and ovalbumin specific IgE levels as well as IL-13 and TGF-β levels in broncho-alveolar lavage (BAL) fluid were evaluated.

RESULTS

Serum total and specific IgE levels as well as lung IL-13 and TGF-β levels were significantly increased in S group compared to control group (P < 0.001 for all cases). Treatment with BMSCs, simvastatin and their combination significantly decreased serum total and specific IgE levels (P < 0.05 to P < 0.01). However, IL-13 and TGF-β levels were significantly decreased by BMSCs and BMSC + simvastatin combination therapy (P < 0.05 for all cases). The effect of simvastatin and BMSCs combination therapy on serum specific IgE levels as well as lung IL-13 and TGF-β levels were significantly higher than the effect of BMSCs and simvastatin alone (P < 0.001 for IL-13 and P < 0.01 for other cases).

CONCLUSIONS

Simvastatin and BMSCs combination therapy affects serum IgE as well as lung IL-13 and TGFβ levels more than BMSC therapy and simvastatin therapy alone which may be due to increased BMSCs migration into the lung tissue.

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 effects of adipose-tissue-derived mesenchymal stromal cells and their extracellular vesicles in experimental silicosis

BACKGROUND

Silicosis is an occupational disease that affects workers who inhale silica particles, leading to extensive lung fibrosis and ultimately causing respiratory failure. Mesenchymal stromal cells (MSCs) have been shown to exert therapeutic effects in lung diseases and represent an alternative treatment for silicosis. Recently, it has been suggested that similar effects can be achieved by the therapeutic use of extracellular vesicles (EVs) obtained from MSCs. The aim of this study was to investigate the effects of adipose-tissue-derived MSCs (AD-MSCs) or their EVs in a model of silicosis.

METHODS

Silicosis was induced by intratracheal instillation of silica in C57BL/6 mice. After the onset of disease, animals received saline, AD-MSCs, or EVs, intratracheally.

RESULTS

At day 30, AD-MSCs and EVs led to a reduction in collagen fiber content, size of granuloma, and in the number of macrophages inside granuloma and in the alveolar septa. In addition, the expression levels of interleukin 1β and transforming growth factor beta in the lungs were decreased. Higher dose of EVs also reduced lung static elastance when compared with the untreated silicosis group.

CONCLUSIONS

Both AD-MSCs and EVs, locally delivered, ameliorated fibrosis and inflammation, but dose-enhanced EVs yielded better therapeutic outcomes in this model of silicosis.

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0669-0) contains supplementary material, which is available to authorized users.

Stem-cell extracellular vesicles and lung repair

Four out of the ten leading causes of morbidity and mortality worldwide are lung diseases. Despite advances in comprehending the pathophysiological mechanisms involved in these disorders, for several respiratory diseases, there is still no effective treatment able to stop their natural history or reverse the morphological and functional damage they cause. In this context, recent research has supported a potential role of cell therapy for lung diseases and critical illness. The anti-inflammatory, antifibrotic, and microbicidal effects of stem cells are mainly attributed to their secretome, which contains proteins, lipids, microRNAs, and mRNAs. These are secreted in the conditioned medium and are also present in extracellular vesicles (EVs). This review will provide a detailed discussion of the role of EVs produced by mesenchymal stromal cells in preclinical experimental models of pulmonary disorders and critical illness, as well as in ongoing clinical trials.

Human adipose tissue mesenchymal stromal cells and their extracellular vesicles act differentially on lung mechanics and inflammation in experimental allergic asthma

Background

Asthma is a chronic inflammatory disease that can be difficult to treat due to its complex pathophysiology. Most current drugs focus on controlling the inflammatory process, but are unable to revert the changes of tissue remodeling. Human mesenchymal stromal cells (MSCs) are effective at reducing inflammation and tissue remodeling; nevertheless, no study has evaluated the therapeutic effects of extracellular vesicles (EVs) obtained from human adipose tissue-derived MSCs (AD-MSC) on established airway remodeling in experimental allergic asthma.

Methods

C57BL/6 female mice were sensitized and challenged with ovalbumin (OVA). Control (CTRL) animals received saline solution using the same protocol. One day after the last challenge, each group received saline, 10⁵ human AD-MSCs, or EVs (released by 10⁵ AD-MSCs). Seven days after treatment, animals were anesthetized for lung function assessment and subsequently euthanized. Bronchoalveolar lavage fluid (BALF), lungs, thymus, and mediastinal lymph nodes were harvested for analysis of inflammation. Collagen fiber content of airways and lung parenchyma were also evaluated.

Results

In OVA animals, AD-MSCs and EVs acted differently on static lung elastance and on BALF regulatory T cells, CD3⁺CD4⁺ T cells, and pro-inflammatory mediators (interleukin [IL]-4, IL-5, IL-13, and eotaxin), but similarly reduced eosinophils in lung tissue, collagen fiber content in airways and lung parenchyma, levels of transforming growth factor-β in lung tissue, and CD3⁺CD4⁺ T cell counts in the thymus. No significant changes were observed in total cell count or percentage of CD3⁺CD4⁺ T cells in the mediastinal lymph nodes.

Conclusions

In this immunocompetent mouse model of allergic asthma, human AD-MSCs and EVs effectively reduced eosinophil counts in lung tissue and BALF and modulated airway remodeling, but their effects on T cells differed in lung and thymus. EVs may hold promise for asthma; however, further studies are required to elucidate the different mechanisms of action of AD-MSCs versus their EVs.

Collection, processing and freezing of equine bone marrow cells

There is no consensus on aspects of equine bone marrow collection and processing. The study aimed to describe the collection of large volumes of bone marrow from horses of advanced age, with emphasis on bone marrow mononuclear cells (BMMCs) recovery and viability after cryopreservation. Fourteen horses, aged 3-24 years, were divided into three experiments. E1 studied the feasibility of collecting 200 mL from the sternums of horses of advanced age; E2 examined the number of cells obtained from the first and last syringe of each puncture; and E3 investigated the influence of heparin concentration on the prevention of cell aggregation, and cell viability after freezing in liquid nitrogen. Bone marrow aspirations were done with syringes pre-filled with Iscove's modified Dulbecco's medium and different concentrations of sodium heparin. BMMCs were counted, cell viability was determined, and samples were frozen. Bone marrow collection from the sternum is safe, even at large volumes and from horses of advanced age, and the number of cells recovered decreases with successive aspirations (p < 0.0001). Heparin concentration influenced cell aggregation, and recovered cells continued to be commercially viable after 150 days in frozen storage.

Contributory Anti-Inflammatory Effects of Mesenchymal Stem Cells, Not Conditioned Media, On Ovalbumin-Induced Asthmatic Changes in Male Rats

Our aim in selecting an appropriate cell fraction and conditioned media (CM) was to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract. Thirty-six rats were classified into healthy and sensitized groups, which were further divided into three subgroups; rats received systemically 50 μl volume of PBS, CM, or 2 × 10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs). Tracheal responsiveness (TR), immunologic responses, and recruitment of rBMMSCs into the lungs were evaluated. A high degree of TR and total WBC and percentages of eosinophils and neutrophils was significantly recorded in all sensitized groups rather than of controls (p < 0.001 to p < 0.05). Concurrently, a significant improvement of TR and eosinophil and neutrophil return toward normal levels was evident in sensitized rats receiving cells as compared to parallel asthmatic animals. Flow cytometric monitoring of lymphocyte subpopulation revealed a decrease in the number of CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p < 0.001 to p < 0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Corroborating our results, the number of CD3⁺CD4⁺ tended to increase (p < 0.05) which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared to other asthmatic groups (p < 0.01 to p < 0.05). Moreover, stem cells could efficiently transmigrate to the lung parenchyma, albeit the dynamic of asthmatic changes stimulated the rate of recruited cells. Our study shed light on superior effects of mesenchymal stem cells, but not CM, in attenuating chronic asthmatic changes in the model of rat.

Effects of human umbilical cord blood mononuclear cells on respiratory system mechanics in a murine model of neonatal lung injury

BACKGROUND

Mononuclear cells (MNCs) have well-documented beneficial effects in a wide range of adult pulmonary diseases. The effects of human umbilical cord blood-derived MNCs on neonatal lung injury, highly relevant for potential autologous application in preterm newborns at risk for bronchopulmonary dysplasia (BPD), remain incompletely established. The aim of this study was to determine the long-term morphologic and functional effects of systemically delivered MNCs in a murine model of neonatal lung injury.

MATERIALS AND METHODS

MNCs from cryopreserved cord blood (1 × 10⁶ cells per pup) were given intravenously to newborn mice exposed to 90% O₂ from birth; controls received cord blood total nucleated cells (TNCs) or granular cells, or equal volume vehicle buffer (sham controls). In order to avoid immune rejection, we used SCID mice as recipients. Lung mechanics (flexiVent™), engraftment, growth, and alveolarization were evaluated eight weeks postinfusion.

RESULTS

Systemic MNC administration to hyperoxia-exposed newborn mice resulted in significant attenuation of methacholine-induced airway hyperreactivity, leading to reduction of central airway resistance to normoxic levels. These bronchial effects were associated with mild improvement of alveolarization, lung compliance, and elastance. TNCs had no effects on alveolar remodeling and were associated with worsened methacholine-induced bronchial hyperreactivity. Granular cell administration resulted in a marked morphologic and functional emphysematous phenotype, associated with high mortality. Pulmonary donor cell engraftment was sporadic in all groups.

CONCLUSIONS

These results suggest that cord blood MNCs may have a cell type-specific role in therapy of pulmonary conditions characterized by increased airway resistance, such as BPD and asthma. Future studies need to determine the active MNC subtype(s), their mechanisms of action, and optimal purification methods to minimize granular cell contamination.

Immunomodulatory oligonucleotide IMT504: Effects on mesenchymal stem cells as a first-in-class immunoprotective/immunoregenerative therapy

The immune responses of humans and animals to insults (i.e., infections, traumas, tumoral transformation and radiation) are based on an intricate network of cells and chemical messengers. Abnormally high inflammation immediately after insult or abnormally prolonged pro-inflammatory stimuli bringing about chronic inflammation can lead to life-threatening or severely debilitating diseases. Mesenchymal stem cell (MSC) transplant has proved to be an effective therapy in preclinical studies which evaluated a vast diversity of inflammatory conditions. MSCs lead to resolution of inflammation, preparation for regeneration and actual regeneration, and then ultimate return to normal baseline or homeostasis. However, in clinical trials of transplanted MSCs, the expectations of great medical benefit have not yet been fulfilled. As a practical alternative to MSC transplant, a synthetic drug with the capacity to boost endogenous MSC expansion and/or activation may also be effective. Regarding this, IMT504, the prototype of a major class of immunomodulatory oligonucleotides, induces in vivo expansion of MSCs, resulting in a marked improvement in preclinical models of neuropathic pain, osteoporosis, diabetes and sepsis. IMT504 is easily manufactured and has an excellent preclinical safety record. In the small number of patients studied thus far, IMT504 has been well-tolerated, even at very high dosage. Further clinical investigation is necessary to demonstrate the utility of IMT504 for resolution of inflammation and regeneration in a broad array of human diseases that would likely benefit from an immunoprotective/immunoregenerative therapy.

Bone marrow mesenchymal stem cells and their conditioned media could potentially ameliorate ovalbumin-induced asthmatic changes

BACKGROUND

The major feature of asthma is governed by chronic airway inflammation. This investigation was proposed to achieve the suitable candidate for ameliorating long-term chronic asthmatic changes of respiratory tract.

METHODS

36 rats were classified into healthy (C) and ovalbumin (OVA)-sensitized animals (S). To sensitize, the rats were exposed to OVA over a course of 32±1days. One day after sensitization, equal six different groups were subjected to experimental procedure (n=6); Rats only received intratracheally 50ml PBS (CPT and SPT groups), 50μl conditioned medium (CM) (CST and SST groups) and 50μl PBS containing 2×10⁶ rat bone marrow-derived mesenchymal stem cells (rBMMSCs) (CCT and SCT groups). Two weeks after treatment, tracheal responsiveness, immunologic responses and recruitment of rBMMSCs into the lung as well as pathological changes were evaluated.

RESULTS

A high degree of tracheal responsiveness, total white blood cell and percentages of eosinophil and neutrophil was significantly recorded in all sensitized groups rather than of controls (p<0.001 to p<0.05). Of interest, all above-mentioned parameters decreased significantly in SST and notably SCT groups as compared to S group (p<0.001 to p<0.05). The results revealed decrease number of blood CD3⁺CD4⁺ and concurrent increase in CD3⁺CD8⁺ in all sensitized rats as compared to control (p<0.001 to p<0.05). Noticeably, no significant modulatory effects of either cell or CM administration were achieved on the CD3⁺CD4⁺ and CD3⁺CD8⁺ populations in non-asthmatic rats. Moreover, the number of CD3⁺CD4⁺ in SST and SCT groups tended to increase, which coincided with a decreased manner of CD3⁺CD8⁺ populations as compared with S group (p<0.001 to p<0.05). However, the CD3⁺CD4⁺ cells in SCT rats were significantly higher than the group SST (p<0.01) whereas CD3⁺CD8⁺ cells diminished simultaneously (p<0.001). Real-time PCR analysis further showed that both CM and particularly MSCs changed the expression of interleukin (IL)-4 and IL-10 in the asthmatic groups to the near level of control rats (p<0.001 to p<0.05). Histopathological analysis revealed a profound reduction of lungs injuries in asthmatic rats when received CM and peculiarly mesenchymal stem cells (p<0.01 to p<0.05).

CONCLUSION

Our study shed light on the superior effects of rBMMSCs, rather than CM, in attenuating of chronic asthmatic changes in the rat model.

Intratracheal Administration of Mesenchymal Stem Cells Modulates Tachykinin System, Suppresses Airway Remodeling and Reduces Airway Hyperresponsiveness in an Animal Model

BACKGROUND

The need for new options for chronic lung diseases promotes the research on stem cells for lung repair. Bone marrow-derived mesenchymal stem cells (MSCs) can modulate lung inflammation, but the data on cellular processes involved in early airway remodeling and the potential involvement of neuropeptides are scarce.

OBJECTIVES

To elucidate the mechanisms by which local administration of MSCs interferes with pathophysiological features of airway hyperresponsiveness in an animal model.

METHODS

GFP-tagged mouse MSCs were intratracheally delivered in the ovalbumin mouse model with subsequent functional tests, the analysis of cytokine levels, neuropeptide expression and histological evaluation of MSCs fate and airway pathology. Additionally, MSCs were exposed to pro-inflammatory factors in vitro.

RESULTS

Functional improvement was observed after MSC administration. Although MSCs did not adopt lung cell phenotypes, cell therapy positively affected airway remodeling reducing the hyperplastic phase of the gain in bronchial smooth muscle mass, decreasing the proliferation of epithelium in which mucus metaplasia was also lowered. Decrease of interleukin-4, interleukin-5, interleukin-13 and increase of interleukin-10 in bronchoalveolar lavage was also observed. Exposed to pro-inflammatory cytokines, MSCs upregulated indoleamine 2,3-dioxygenase. Moreover, asthma-related in vivo upregulation of pro-inflammatory neurokinin 1 and neurokinin 2 receptors was counteracted by MSCs that also determined a partial restoration of VIP, a neuropeptide with anti-inflammatory properties.

CONCLUSION

Intratracheally administered MSCs positively modulate airway remodeling, reduce inflammation and improve function, demonstrating their ability to promote tissue homeostasis in the course of experimental allergic asthma. Because of a limited tissue retention, the functional impact of MSCs may be attributed to their immunomodulatory response combined with the interference of neuropeptide system activation and tissue remodeling.

Intratracheal therapy with autologous bone marrow-derived mononuclear cells reduces airway inflammation in horses with recurrent airway obstruction

This research evaluated the effects of bone marrow-derived mononuclear cells (BMMCs) on the inflammatory process in the equine recurrent airway obstruction (RAO). Eight horses in RAO clinical score were divided into cell therapy group (Gcel) treated with a single intratracheal dose of BMMCs, and dexamethasone group (Gdex) treated with 21days of oral dexamethasone. The horses were clinically revaluated on days 7 and 21, together with cytological evaluation of the BALF, and detection of inflammatory markers (interleukins [IL]-10, -4, and -17, and interferon γ and α). There were decreases in respiratory effort and clinical score on days 7 and 21(p<0.05) for both groups. The percentage of neutrophils decreased and macrophages increased on days 7 and 21 (p<0.005) in both groups. IL-10 levels increased in the Gcel group on day 21 compared to days 0 and 7 (p<0.05), but this was not observed in the Gdex group. The quantification of IL-4, IL-17, IFN-γ, and IFN-α did not change between evaluations in both groups. These preliminary results suggest that BMMCs may ameliorate the inflammatory response of RAO.

Intraperitoneal mesenchymal stem cell administration ameliorates allergic rhinitis in the murine model

Previous studies showed that bone marrow-derived mesenchymal stem cells (BMSCs) could ameliorate a variety of immune-mediated and inflammatory diseases due to their immunomodulatory and anti-inflammatory effects. In this study, we developed a mouse model of ovalbumin (OVA) induced allergic inflammation in the upper airways and evaluated the effects of the intraperitoneal administration of BMSCs on allergic inflammation. Twenty-five BALB/c mice were divided into five groups; group I (control group), group II (sensitized and challenged with OVA and treated with saline-placebo group), group III (sensitized and challenged with OVA and treated with 1 × 10⁶ BMSCs), group IV (sensitized and challenged with OVA and treated with 2 × 10⁶ BMSCs), and group V (sensitized and challenged with phosphate buffered saline (PBS) and treated with 1 × 10⁶ BMSCs). Histopathological features (number of goblet cells, eosinophils and mast cells, basement membrane, epithelium thickness, and subepithelial smooth muscle thickness) of the upper and lower airways and BMSCs migration to nasal and lung tissue were evaluated using light and confocal microscopes. Levels of cytokines in the nasal lavage fluid and lung tissue supernatants were measured using enzyme-linked immunosorbent assay (ELISA). Confocal microscopic analysis showed that there was no significant amount of BMSCs in the nasal and lung tissues of group V. However, significant amount of BMSCs were observed in group III and IV. In OVA-induced AR groups (group II, III, and IV), histopathological findings of chronic asthma, such as elevated subepithelial smooth muscle thickness, epithelium thickness, and number of goblet and mast cells, were determined. Furthermore, the number of nasal goblet and eosinophil cells, histopathological findings of chronic asthma, and IL-4, IL-5, IL-13, and NO levels was significantly lower in both BMSCs-treated groups compared to the placebo group. Our findings indicated that histopathological findings of chronic asthma were also observed in mice upon AR induction. BMSCs migrated to the nasal and lung tissues following intraperitoneal delivery and ameliorated to the airway remodeling and airway inflammation both in the upper and lower airways via the inhibition of T helper (Th) 2 immune response in the murine model of AR.

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.

Cell-Based Therapy for Silicosis

Silicosis is the most common pneumoconiosis globally, with higher prevalence and incidence in developing countries. To date, there is no effective treatment to halt or reverse the disease progression caused by silica-induced lung injury. Significant advances have to be made in order to reduce morbidity and mortality related to silicosis. In this review, we have highlighted the main mechanisms of action that cause lung damage by silica particles and summarized the data concerning the therapeutic promise of cell-based therapy for silicosis.

CD11b+ and Sca-1+ Cells Exert the Main Beneficial Effects of Systemically Administered Bone Marrow-Derived Mononuclear Cells in a Murine Model of Mixed Th2/Th17 Allergic Airway Inflammation

A murine model of severe clinical asthma was used to study which bone marrow-derived mononuclear cells (BMDMCs) are responsible for ameliorating airway hyperresponsiveness and lung inflammation. BMDMCs depleted of either CD11b-positive cells (monocytes, macrophages, dendritic cells) or Sca-1-positive cells (bone marrow-derived mesenchymal stromal cells) were unable to ameliorate these conditions in this model. Depletion of the other cell types did not diminish the ameliorating effects of BMDMC administration.

Systemic administration of bone marrow-derived mononuclear cells (BMDMCs) or bone marrow-derived mesenchymal stromal cells (MSCs) reduces inflammation and airway hyperresponsiveness (AHR) in a murine model of Th2-mediated eosinophilic allergic airway inflammation. However, since BMDMCs are a heterogeneous population that includes MSCs, it is unclear whether the MSCs alone are responsible for the BMDMC effects. To determine which BMDMC population(s) is responsible for ameliorating AHR and lung inflammation in a model of mixed Th2-eosinophilic and Th17-neutrophilic allergic airway inflammation, reminiscent of severe clinical asthma, BMDMCs obtained from normal C57Bl/6 mice were serially depleted of CD45, CD34, CD11b, CD3, CD19, CD31, or Sca-1 positive cells. The different resulting cell populations were then assessed for ability to reduce lung inflammation and AHR in mixed Th2/Th17 allergic airway inflammation induced by mucosal sensitization to and challenge with Aspergillus hyphal extract (AHE) in syngeneic C56Bl/6 mice. BMDMCs depleted of either CD11b-positive (CD11b+) or Sca-1-positive (Sca-1+) cells were unable to ameliorate AHR or lung inflammation in this model. Depletion of the other cell types did not diminish the ameliorating effects of BMDMC administration. In conclusion, in the current model of allergic inflammation, CD11b+ cells (monocytes, macrophages, dendritic cells) and Sca-1+ cells (MSCs) are responsible for the beneficial effects of BMDMCs.

Significance

This study shows that bone marrow-derived mononuclear cells (BMDMCs) are as effective as bone marrow-derived mesenchymal stromal cells (MSCs) in ameliorating experimental asthma. It also demonstrates that not only MSCs present in the pool of BMDMCs are responsible for BMDMCs’ beneficial effects but also monocytes, which are the most important cell population to trigger these effects. All of this is in the setting of a clinically relevant model of severe allergic airways inflammation and thus provides further support for potential clinical use of cell therapy using MSCs, BMDMCs, and also adult cells such as monocytes in patients with severe asthma.

The tyrosine kinase inhibitor dasatinib reduces lung inflammation and remodelling in experimental allergic asthma

BACKGROUND AND PURPOSE

Asthma is characterized by chronic lung inflammation and airway hyperresponsiveness. Despite recent advances in understanding of its pathophysiology, asthma remains a major public health problem, and new therapeutic strategies are urgently needed. In this context, we sought to ascertain whether treatment with the TK inhibitor dasatinib might repair inflammatory and remodelling processes, thus improving lung function, in a murine model of asthma.

EXPERIMENTAL APPROACH

Animals were sensitized and subsequently challenged, with ovalbumin (OVA) or saline. Twenty-four hours after the last challenge, animals were treated with dasatinib, dexamethasone, or saline, every 12 h for 7 consecutive days. Twenty-four hours after the last treatment, the animals were killed, and data were collected. Lung structure and remodelling were evaluated by morphometric analysis, immunohistochemistry, and transmission electron microscopy of lung sections. Inflammation was assessed by cytometric analysis and ELISA, and lung function was evaluated by invasive whole-body plethysmography.

KEY RESULTS

In OVA mice, dasatinib, and dexamethasone led to significant reductions in airway hyperresponsiveness. Dasatinib was also able to attenuate alveolar collapse, contraction index, and collagen fibre deposition, as well as increasing elastic fibre content, in OVA mice. Concerning the inflammatory process, dasatinib reduced inflammatory cell influx to the airway and lung-draining mediastinal lymph nodes, without inducing the thymic atrophy promoted by dexamethasone.

CONCLUSIONS AND IMPLICATIONS

In this model of allergic asthma, dasatinib effectively blunted the inflammatory and remodelling processes in asthmatic lungs, enhancing airway repair and thus improving lung mechanics.

Functional Role of FcγRIIB in the Regulation of Mesenchymal Stem Cell Function

Mesenchymal stem cells (MSCs) derived from bone marrow are plural-potent stem cells with immune regulatory functions. We aimed to evaluate role of FcγRIIB in the regulation of bone marrow-derived MSC function. MSCs were prepared from mouse bone marrow derived from wild-type (WT) or FcγRIIB-deficient (FcγRIIB-/-) mice. MSCs were co-cultured with bone marrow-derived dendritic cells (BMDCs), and BMDC maturation and function were evaluated by flow cytometric analysis and carboxyfluorescein succinimidyl ester-labeled OT-II T-cell addition. An acute asthma model was established by aeresol ovalbumin challenge in mice. Mice received WT or FcγRIIB-/- MSC therapy. Lung function was evaluated by histological examination and cytokine production measurement. mRNA and protein expression levels of target genes were examined by real-time quantitative polymerase chain reactionor western blotting. We found that MSCs derived from bone marrow exhibit a high level of FcγRIIB expression. FcγRIIB deficiency impaired the suppressive function of MSCs, as FcγRIIB deficiency efficiently reversed the inhibitory effect of MSCs on BMDC maturation and function. Additionally, FcγRIIB-/-MSCs were less potent at suppressing asthma in model mice, possibly through reduced expression of Smad2, Smad3, Cox-2, and prostaglandin E2 in FcγRIIB-/-MSCs. FcγRIIB might play an essential role in regulating the inhibitory effects of MSCs derived from bone marrow.

An official American Thoracic Society workshop report: stem cells and cell therapies in lung biology and diseases

The University of Vermont College of Medicine and the Vermont Lung Center, in collaboration with the NHLBI, Alpha-1 Foundation, American Thoracic Society, European Respiratory Society, International Society for Cell Therapy, and the Pulmonary Fibrosis Foundation, convened a workshop, "Stem Cells and Cell Therapies in Lung Biology and Lung Diseases," held July 29 to August 1, 2013 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 conference was a follow-up to four previous biennial conferences held at the University of Vermont in 2005, 2007, 2009, and 2011. 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 stromal cell therapy attenuated lung and kidney injury but not brain damage in experimental cerebral malaria

Introduction

Malaria is the most relevant parasitic disease worldwide, and still accounts for 1 million deaths each year. Since current antimalarial drugs are unable to prevent death in severe cases, new therapeutic strategies have been developed. Mesenchymal stromal cells (MSC) confer host resistance against malaria; however, thus far, no study has evaluated the therapeutic effects of MSC therapy on brain and distal organ damage in experimental cerebral malaria.

Methods

Forty C57BL/6 mice were injected intraperitoneally with 5 × 10⁶Plasmodium berghei-infected erythrocytes or saline. After 24 h, mice received saline or bone marrow (BM)-derived MSC (1x10⁵) intravenously and were housed individually in metabolic cages. After 4 days, lung and kidney morphofunction; cerebrum, spleen, and liver histology; and markers associated with inflammation, fibrogenesis, and epithelial and endothelial cell damage in lung tissue were analyzed.

Results

In P. berghei-infected mice, BM-MSCs: 1) reduced parasitemia and mortality; 2) increased phagocytic neutrophil content in brain, even though BM-MSCs did not affect the inflammatory process; 3) decreased malaria pigment detection in spleen, liver, and kidney; 4) reduced hepatocyte derangement, with an increased number of Kupffer cells; 5) decreased kidney damage, without effecting significant changes in serum creatinine levels or urinary flow; and 6) reduced neutrophil infiltration, interstitial edema, number of myofibroblasts within interstitial tissue, and collagen deposition in lungs, resulting in decreased lung static elastance. These morphological and functional changes were not associated with changes in levels of tumor necrosis factor-α, keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8), or interferon-γ, which remained increased and similar to those of P. berghei animals treated with saline. BM-MSCs increased hepatocyte growth factor but decreased VEGF in the P. berghei group.

Conclusions

BM-MSC treatment increased survival and reduced parasitemia and malaria pigment accumulation in spleen, liver, kidney, and lung, but not in brain. The two main organs associated with worse prognosis in malaria, lung and kidney, sustained less histological damage after BM-MSC therapy, with a more pronounced improvement in lung function.

Stem cells in animal asthma models: a systematic review

BACKGROUND AIMS

Asthma control frequently falls short of the goals set in international guidelines. Treatment options for patients with poorly controlled asthma despite inhaled corticosteroids and long-acting β-agonists are limited, and new therapeutic options are needed. Stem cell therapy is promising for a variety of disorders but there has been no human clinical trial of stem cell therapy for asthma. We aimed to systematically review the literature regarding the potential benefits of stem cell therapy in animal models of asthma to determine whether a human trial is warranted.

METHODS

The MEDLINE and Embase databases were searched for original studies of stem cell therapy in animal asthma models.

RESULTS

Nineteen studies were selected. They were found to be heterogeneous in their design. Mesenchymal stromal cells were used before sensitization with an allergen, before challenge with the allergen and after challenge, most frequently with ovalbumin, and mainly in BALB/c mice. Stem cell therapy resulted in a reduction of bronchoalveolar lavage fluid inflammation and eosinophilia as well as Th2 cytokines such as interleukin-4 and interleukin-5. Improvement in histopathology such as peribronchial and perivascular inflammation, epithelial thickness, goblet cell hyperplasia and smooth muscle layer thickening was universal. Several studies showed a reduction in airway hyper-responsiveness.

CONCLUSIONS

Stem cell therapy decreases eosinophilic and Th2 inflammation and is effective in several phases of the allergic response in animal asthma models. Further study is warranted, up to human clinical trials.

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-β, 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.

Sustained effect of bone marrow mononuclear cell therapy in axonal regeneration in a model of optic nerve crush

In adult mammals, the regeneration of the optic nerve is very limited and at the moment there are several groups trying different approaches to increase retinal ganglion cell (RGC) survival and axonal outgrowth. One promising approach is cell therapy. In previous work, we performed intravitreal transplantation of bone-marrow mononuclear cells (BMMCs) after optic nerve crush in adult rats and we demonstrated an increase in RGC survival and axon outgrowth 14 days after injury. In the present work, we investigated if these results could be sustained for a longer period of time. Optic nerve crush was performed in Lister-hooded adult rats and BMMC or saline injections were performed shortly after injury. Neuronal survival and regeneration were evaluated in rats׳ retina and optic nerve after 28 days. We demonstrated an increase of 5.2 fold in the axon outgrowth 28 days after lesion, but the BMMCs had no effect on RGC survival. In an attempt to prolong RGC survival, we established a new protocol with two BMMC injections, the second one 7 days after the injury. Untreated animals received two injections of saline. We observed that although the axonal outgrowth was still increased after the second BMMC injection, the RGC survival was not significantly different from untreated animals. These results demonstrate that BMMCs transplantation promotes neuroregeneration at least until 28 days after injury. However, the effects on RGC survival previously observed by us at 14 days were not sustained at 28 days and could not be prolonged with a second dose of BMMC.

Human mesenchymal stem cells resolve airway inflammation, hyperreactivity, and histopathology in a mouse model of occupational asthma

Occupational asthma (OA) is characterized by allergic airway inflammation and hyperresponsiveness, leading to progressive airway remodeling and a concomitant decline in lung function. The management of OA remains suboptimal in clinical practice. Thus, establishing effective therapies might overcome the natural history of the disease. We evaluated the ability of human adipose-tissue-derived mesenchymal stem cells (hASCs), either unmodified or engineered to secrete the IL-33 decoy receptor sST2, to attenuate the inflammatory and respiratory symptoms in a previously validated mouse model of OA to ammonium persulfate (AP). Twenty-four hours after a dermal AP sensitization and intranasal challenge regimen, the animals received intravenously 1 × 10(6) cells (either hASCs or hASCs overexpressing sST2) or saline and were analyzed at 1, 3, and 6 days after treatment. The infused hASCs induced an anti-inflammatory and restorative program upon reaching the AP-injured, asthmatic lungs, leading to early reduction of neutrophilic inflammation and total IgE production, preserved alveolar architecture with nearly absent lymphoplasmacytic infiltrates, negligible smooth muscle hyperplasia/hypertrophy in the peribronchiolar areas, and baseline airway hyperreactivity (AHR) to methacholine. Local sST2 overexpression barely increased the substantial efficacy displayed by unmodified hASCs. Thus, hASCs may represent a viable multiaction therapeutic capable to adequately respond to the AP-injured lung environment by resolving inflammation, tissue remodeling, and bronchial hyperresponsiveness typical of OA.

Mesenchymal stem cell therapy in lung disorders: pathogenesis of lung diseases and mechanism of action of mesenchymal stem cell

Lung disorders such as asthma, acute respiratory distress syndrome (ARDS), chronic obstructive lung disease (COPD), and interstitial lung disease (ILD) show a few common threads of pathogenic mechanisms: inflammation, aberrant immune activity, infection, and fibrosis. Currently no modes of effective treatment are available for ILD or emphysema. Being anti-inflammatory, immunomodulatory, and regenerative in nature, the administration of mesenchymal stem cells (MSCs) has shown the capacity to control immune dysfunction and inflammation in the lung. The intravenous infusion of MSCs, the common mode of delivery, is followed by their entrapment in lung vasculature before MSCs reach to other organ systems thus indicating the feasible and promising approach of MSCs therapy for lung diseases. In this review, we discuss the mechanistic basis for MSCs therapy for asthma, ARDS, COPD, and ILD.