Mesenchymal stem cells: a promising therapy for the acute respiratory distress syndrome

11β hydroxysteroid dehydrogenase type 1 transgenic mesenchymal stem cells attenuate inflammation in models of sepsis

Background

Human bone marrow mesenchymal stem cell (MSC) administration reduces inflammation in pre-clinical models of sepsis and sepsis-related lung injury, however clinical efficacy in patients has not yet been demonstrated. We previously showed that Alveolar Macrophage (AM) 11β-hydroxysteroid dehydrogenase type-1 (HSD-1) autocrine signalling is impaired in critically ill sepsis patients, which promotes inflammatory injury. Administration of transgenic MSCs (tMSCs) which overexpress HSD-1 may enhance the anti-inflammatory effects of local glucocorticoids and be more effective at reducing inflammation in sepsis than cellular therapy alone.

Methods

MSCs were transfected using a recombinant lentiviral vector containing the HSD-1 and GPF transgenes under the control of a tetracycline promoter. Thin layer chromatography assessed HSD-1 reductase activity in tMSCs. Mesenchymal stem cell phenotype was assessed by flow cytometry and bi-lineage differentiation. HSD-1 tMSCs were co-cultured with LPS-stimulated monocyte-derived macrophages (MDMs) from healthy volunteers prior to assessment of pro-inflammatory cytokine release. HSD-1 tMSCs were administered intravenously to mice undergoing caecal ligation and puncture (CLP).

Results

MSCs were transfected with an efficiency of 91.1%, and maintained an MSC phenotype. Functional HSD-1 activity was demonstrated in tMSCs, with predominant reductase cortisol activation (peak 8.23 pM/hour/100,000 cells). HSD-1 tMSC co-culture with LPS-stimulated MDMs suppressed TNFα and IL-6 release. Administration of transgene activated HSD-1 tMSCs in a murine model of CLP attenuated neutrophilic inflammation more effectively than transgene inactive tMSCs (medians 0.403 v 1.36 × 106/ml, p = 0.033).

Conclusion

The synergistic impact of HSD-1 transgene expression and MSC therapy attenuated neutrophilic inflammation in a mouse model of peritoneal sepsis more effectively than MSC therapy alone. Future studies investigating the anti-inflammatory capacity of HSD-1 tMSCs in models of sepsis-related direct lung injury and inflammatory diseases are required.

Investigational pharmacological agents for the treatment of ARDS

INTRODUCTION

Acute Respiratory Distress Syndrome (ARDS) is a heterogeneous form of lung injury with severe hypoxemia and bilateral infiltrates after an inciting event that results in diffuse lung inflammation with a high mortality rate. While research in COVID-related ARDS has resulted in several pharmacotherapeutic agents that have undergone successful investigation, non-COVID ARDS studies have not resulted in many widely accepted pharmacotherapeutic agents despite exhaustive research.

AREAS COVERED

The aim of this review is to discuss adjuvant pharmacotherapies targeting non-COVID Acute Lung Injury (ALI)/ARDS and novel therapeutics in COVID associated ALI/ARDS. In ARDS, variable data may support selective use of neuromuscular blocking agents, corticosteroids and neutrophil elastase inhibitors, but are not yet universally used. COVID-ALI/ARDS has data supporting the use of IL-6 monoclonal antibodies, corticosteroids, and JAK inhibitor therapy.

EXPERT OPINION

Although ALI/ARDS modifying pharmacological agents have been identified in COVID-related disease, the data in non-COVID ALI/ARDS has been less compelling. The increased use of more specific molecular phenotyping based on physiologic parameters and biomarkers, will ensure equipoise between groups, and will likely allow more precision in confirming pharmacological agent efficacy in future studies.

[Mesenchymal stem cells: Therapeutic option in ARDS, COPD, and COVID-19 patients]

Acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD) and COVID-19 have as a common characteristic the inflammatory lesion of the lung epithelium. The therapeutic options are associated with opportunistic infections, a hyperglycemic state, and adrenal involvement. Therefore, the search for new treatment strategies that reduce inflammation, and promote re-epithelialization of damaged tissue is very important. This work describes the relevant pathophysiological characteristics of these diseases and evaluates recent findings on the immunomodulatory, anti-inflammatory and regenerative effect of mesenchymal stem cells (MSC) and their therapeutic use. In Pubmed we selected the most relevant studies on the subject, published between 2003 and 2022 following the PRISMA guide. We conclude that MSCs are an important therapeutic option for regenerative treatment in COPD, ARDS, and COVID-19, because of their ability to differentiate into type II pneumocytes and maintain the size and function of lung tissue by replacing dead or damaged cells.

Overexpression of FoxM1 Enhanced the Protective Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Lipopolysaccharide-Induced Acute Lung Injury through the Activation of Wnt/β-Catenin Signaling

BACKGROUND

Mesenchymal stem cell- (MSC-) based cell and gene therapies have made remarkable progress in alleviating acute lung injury/acute respiratory distress syndrome (ALI/ARDS). However, the benefits of Forkhead box protein M1 (FoxM1) gene-modified MSCs in the treatment of ALI have not been studied.

METHODS

We evaluated the therapeutic effects of FoxM1-modified MSCs in ALI mice induced by lipopolysaccharide (LPS) by quantifying the survival rate, lung weight ratio (wet/dry), and contents of bronchoalveolar lavage fluid. In addition, microcomputed tomography, histopathology, Evans Blue assay, and quantification of apoptosis were performed. We also explored the underlying mechanism by assessing Wnt/β-catenin signaling following the treatment of mice with FoxM1-modified MSCs utilizing the Wnt/β-catenin inhibitor XAV-939.

RESULTS

Compared with unmodified MSCs, transplantation of FoxM1-modified MSCs improved survival and vascular permeability; reduced total cell counts, leukocyte counts, total protein concentrations, and inflammatory cytokines in BALF; attenuated lung pathological impairments and fibrosis; and inhibited apoptosis in LPS-induced ALI/ARDS mice. Furthermore, FoxM1-modified MSCs maintained vascular integrity during ALI/ARDS by upregulating Wnt/β-catenin signaling, which was partly reversed via a pathway inhibitor.

CONCLUSION

Overexpression of FoxM1 optimizes the treatment action of MSCs on ALI/ARDS by inhibiting inflammation and apoptosis and restoring vascular integrity partially through Wnt/β-catenin signaling pathway stimulation.

Mesenchymal Stem Cell Therapy for ALI/ARDS: Therapeutic Potential and Challenges

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a serious clinical common disease, which may be caused by a variety of pathological factors and can induce a series of serious complications. There is still no specific and effective method for the treatment of ALI/ARDS. Mesenchymal stem cells (MSCs) have been one of the treatment methods for ALI, which can regulate related signal pathways such as PI3K/AKT, Wnt, and NF-κB to reduce inflammation. MSCs exist in a variety of tissues and have the ability of self-renewal and differentiation, which can be activated by specific substances or environments and home to the site of tissue damage, where they differentiate into new tissue cells and repair the damage. Both exosomes and cytokines involving the paracrine mechanism of MSCs have benefits on the treatment of ALI. Lung organoids produced by 3D culture technology can simulate the characteristics of the lung and help to research the pathophysiological process of ALI. This review summarizes the mechanisms by which MSCs treat ALI/ARDS and expects to use 3D models for future challenges in this field.

Mesenchymal stem cell transfusion: Possible beneficial effects in COVID-19 patients

SARS-CoV-2 attaches to the angiotensin-converting enzyme 2 (ACE-2) receptor on human cells. The virus causes hypercytokinemia, capillary leak, pulmonary edema, acute respiratory distress syndrome, acute cardiac injury, and leads to death. Mesenchymal stem cells (MSCs) are ACE-2 negative cells; therefore, can escape from SARS-CoV-2. MSCs prevent hypercytokinemia and help the resolution of the pulmonary edema and other damages occurred during the course of COVID-19. In addition, MSCs enhance the regeneration of the lung and other tissues affected by SARS-CoV-2. The case series reported beneficial effect of MSCs in COVID-19 treatment. However, there are some concerns about the safety of MSCs, particularly referring to the increased risk of disseminated intravascular coagulation, and thromboembolism due to the expression of TF/CD142. Prospective, randomized, large scale studies are needed to reveal the optimum dose, administration way, time, efficacy, and safety of MSCs in the COVID-19 treatment.

Gene engineered mesenchymal stem cells: greater transgene expression and efficacy with minicircle vs. plasmid DNA vectors in a mouse model of acute lung injury

BACKGROUND

Acute lung injury (ALI) and in its severe form, acute respiratory distress syndrome (ARDS), results in increased pulmonary vascular inflammation and permeability and is a major cause of mortality in many critically ill patients. Although cell-based therapies have shown promise in experimental ALI, strategies are needed to enhance the potency of mesenchymal stem cells (MSCs) to develop more effective treatments. Genetic modification of MSCs has been demonstrated to significantly improve the therapeutic benefits of these cells; however, the optimal vector for gene transfer is not clear. Given the acute nature of ARDS, transient transfection is desirable to avoid off-target effects of long-term transgene expression, as well as the potential adverse consequences of genomic integration.

METHODS

Here, we explored whether a minicircle DNA (MC) vector containing human angiopoietin 1 (MC-ANGPT1) can provide a more effective platform for gene-enhanced MSC therapy of ALI/ARDS.

RESULTS

At 24 h after transfection, nuclear-targeted electroporation using an MC-ANGPT1 vector resulted in a 3.7-fold greater increase in human ANGPT1 protein in MSC conditioned media compared to the use of a plasmid ANGPT1 (pANGPT1) vector (2048 ± 567 pg/mL vs. 552.1 ± 33.5 pg/mL). In the lipopolysaccharide (LPS)-induced ALI model, administration of pANGPT1 transfected MSCs significantly reduced bronchoalveolar lavage (BAL) neutrophil counts by 57%, while MC-ANGPT1 transfected MSCs reduced it by 71% (p < 0.001) by Holm-Sidak's multiple comparison test. Moreover, compared to pANGPT1, the MC-ANGPT1 transfected MSCs significantly reduced pulmonary inflammation, as observed in decreased levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-2 (MIP-2). pANGPT1-transfected MSCs significantly reduced BAL albumin levels by 71%, while MC-ANGPT1-transfected MSCs reduced it by 85%.

CONCLUSIONS

Overall, using a minicircle vector, we demonstrated an efficient and sustained expression of the ANGPT1 transgene in MSCs and enhanced the therapeutic effect on the ALI model compared to plasmid. These results support the potential benefits of MC-ANGPT1 gene enhancement of MSC therapy to treat ARDS.

Overexpression of TGFβ1 in murine mesenchymal stem cells improves lung inflammation by impacting the Th17/Treg balance in LPS-induced ARDS mice

Background

T helper 17 cells (Th17)/regulatory T cells (Treg), as subtypes of CD4⁺ T cells, play an important role in the inflammatory response of acute respiratory distress syndrome (ARDS). However, there is still a lack of effective methods to regulate the differentiation balance of Th17/Treg. It was proven that mesenchymal stem cells (MSCs) could regulate the differentiation of CD4⁺ T cells, but the mechanism is still unclear. TGFβ1, a paracrine cytokine of MSCs, could also regulate the differentiation of Th17/Treg but is lowly expressed in MSCs. Therefore, mouse MSCs (mMSCs) overexpressing TGFβ1 were constructed by lentivirus transduction and intratracheally transplanted into LPS-induced ARDS mice in our study. The aim of this study was to evaluate the therapeutic effects of mMSCs overexpressing TGFβ1 on inflammation and immunoregulation by impacting the Th17/Treg balance in LPS-induced ARDS mice.

Methods

mMSCs overexpressing TGFβ1 were constructed using lentiviral vectors. Then, mouse bone-marrow-derived MSCs (mBM-MSC) and mBM-MSC-TGFβ1 (mBM-MSC overexpressing TGFβ1) were transplanted intratracheally into ARDS mice induced by lipopolysaccharide. At 3 and 7 days after transplantation, the mice were sacrificed, and the homing of the mMSCs was assayed by ex vivo optical imaging. The relative numbers of Th17 and Treg in the lungs and spleens of mice were detected by FCM. IL-17A and IL-10 levels in the lungs of mice were analysed by western blot. Permeability and inflammatory cytokines were evaluated by analysing the protein concentration of BALF using ELISA. Histopathology of the lungs was assessed by haematoxylin and eosin staining and lung injury scoring. Alveolar lung fibrosis was assessed by Masson’s trichrome staining and Ashcroft scoring. The mortality of ARDS mice was followed until 7 days after transplantation.

Results

The transduction efficiencies mediated by the lentiviral vectors ranged from 82.3 to 88.6%. Overexpressing TGFβ1 inhibited the proliferation of mMSCs during days 5–7 (p < 0.05) but had no effect on mMSC differentiation or migration (p > 0.05). Compared to that in the LPS + mBM-MSC-NC group mice, engraftment of mMSCs overexpressing TGFβ1 led to much more differentiation of T cells into Th17 or Treg (p < 0.05), improved permeability of injured lungs (p < 0.05) and ameliorative histopathology of lung tissue in ARDS mice (p < 0.05). Moreover, IL-17A content was also decreased while IL-10 content was increased in the LPS + mBM-MSC-TGFβ1 group compared with those in the LPS + mBM-MSC-NC group (p < 0.05). Finally, mMSCs overexpressing TGFβ1 did not aggravate lung fibrosis in ARDS mice (p > 0.05).

Conclusion

MSCs overexpressing TGFβ1 could regulate lung inflammation and attenuate lung injuries by modulating the imbalance of Th17/Treg in the lungs of ARDS mice.

Mesenchymal Stem Cells: A new front emerge in COVID19 treatment

Currently, treating coronavirus disease 2019 (COVID-19) patients, particularly those afflicted with severe pneumonia, is challenging, as no effective pharmacotherapy for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exists. Severe pneumonia is recognized as a clinical syndrome characterized by hyper-induction of pro-inflammatory cytokine production, which can induce organ damage, followed by edema, dysfunction of air exchange, acute respiratory distress syndrome, acute cardiac injury, secondary infection and increased mortality. Owing to the immunoregulatory and differentiation potential of mesenchymal stem cells (MSCs), we aimed to outline current insights into the clinical application of MSCs in COVID-19 patients. Based on results from preliminary clinical investigations, it can be predicted that MSC therapy for patients infected with SARS-CoV-2 is safe and effective, although multiple clinical trials with a protracted follow-up will be necessary to determine the long-term effects of the treatment on COVID-19 patients.

Genetically modified mesenchymal stem cell therapy for acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a devastating hypoxemic respiratory failure, characterized by disruption of the alveolar-capillary membrane barrier. Current management for ARDS remains supportive, including lung-protective ventilation and a conservative fluid strategy. Mesenchymal stem cells (MSCs) have emerged as a potentially attractive candidate for the management of ARDS through facilitating lung tissue regeneration and repair by releasing paracrine soluble factors. Over the last decade, a variety of strategies have emerged to optimize MSC-based therapy. Among these, the strategy using genetically modified MSCs has received increased attention recently due to its distinct advantage, in conferring incremental migratory capacity and, enhancing the anti-inflammatory, immunomodulatory, angiogenic, and antifibrotic effects of these cells in numerous preclinical ARDS models, which may in turn provide additional benefits in the management of ARDS. Here, we provide an overview of recent studies testing the efficacy of genetically modified MSCs using preclinical models of ARDS.

Lung-derived exosomes in phosgene-induced acute lung injury regulate the functions of mesenchymal stem cells partially via miR-28-5p

Accidental phosgene exposure can result in acute lung injury (ALI). Mesenchymal stem cells (MSCs) have been found to alleviate phosgene-induced ALI. However, the mechanism of MSCs underlying such protective effect remains largely unexplored. Exosomes, important components of microenvironment, are closely associated with intercellular information transfer. In the present study, we isolated lung exosomes in rats after phosgene exposure by ultracentrifugation and explored their effects on MSCs in vitro. ALI exosomes were elliptical in shape and 50-200 nm in size. ALI exosomes could promote proliferation and migration of MSCs. Moreover, ALI exosomes increased the secretion of IL-10, leading to enhanced immunoregulatory properties of MSCs. The paracrine factors, VEGF, HGF, LL-37 and Ang-1, were also augmented by ALI exosomes. However, ALI exosomes had no effect on differentiation of MSCs towards lung alveolar cells. To identify the effective miRNAs in ALI exosomes, we performed miRNA profile analysis. MiR-28-5p was considered as a possible effective molecule. We further studied the effect of miR-28-5p on MSCs. MiR-28-5p mimic promoted proliferation, migration, immunomodulation of MSCs. MiR-28-5p mimic promoted the paracrine of VEGF, HGF, LL-37 and Ang-1. Besides, we explored molecular mechanism of miR-28-5p in MSCs. PI3K/Akt signaling pathway was found significantly augmented by miR-28-5p mimic, indicating the activation in this process. Taken together, our findings could help identify the effects of lung-derived exosomes on MSCs, and the effective molecule in exosomes, miR-28-5p, activated MSCs through PI3K/Akt signaling pathway.

Lats2-Underexpressing Bone Marrow-Derived Mesenchymal Stem Cells Ameliorate LPS-Induced Acute Lung Injury in Mice

The pathophysiology of the acute lung injury (ALI) is characterized by the damage of alveolar epithelial cells, which can be repaired by exogenous bone marrow-derived mesenchymal stem cells (BMSCs). However, the migration and differentiation abilities of BMSCs are not sufficient for the purpose, and a new approach that could strengthen the repair effects of BMSCs in ALI still needs to be clarified. We have previously proved that in vitro large tumor suppressor kinase 2- (Lats2-) underexpressing BMSCs may enhance their tissue repair effects in ALI; thus, in the present study, we tried to explore whether Lats2-underexpressing BMSCs could rescue lipopolysaccharide- (LPS-) induced ALI in vivo. BMSCs from C57BL/6 mice transfected with Lats2-interfering lentivirus vector or lentivirus blank controls were transplanted intratracheally into LPS-induced ALI mice. The retention and differentiation of BMSCs in the lung were evaluated by in vivo imaging, immunofluorescence staining, and Western blotting. The lung edema and permeability were assessed by lung wet weight/body weight ratio (LWW/BW) and measurements of proteins in bronchoalveolar lavage fluid (BALF) using ELISA. Acute lung inflammation was measured by the cytokines in the lung homogenate and BALF using RT-qPCR and ELISA, respectively. Lung injury was evaluated by HE staining and lung injury scoring. Pulmonary fibrosis was evaluated by Picrosirius red staining, immunohistochemistry for α-SMA and TGF-β1, and hydroxyproline assay and RT-qPCR for Col1α1 and Col3α1. Lats2-mediated inhibition of the Hippo pathway increased the retention of BMSCs and their differentiation toward type II alveolar epithelial cells in the lung. Furthermore, Lats2-underexpressing BMSCs improved lung edema, permeability of the lung epithelium, and lung inflammation. Finally, Lats2-underexpressing BMSCs alleviated lung injury and early pulmonary fibrosis. Our studies suggest that underexpression of Lats2 could further enhance the repair effects of BMSCs against epithelial impair and the therapeutic potential of BMSCs in ALI mice.

Mesenchymal stem cells for sensorineural hearing loss: protocol for a systematic review of preclinical studies

BACKGROUND

Sensorineural hearing loss (SNHL) is the most common form of hearing impairment and is characterized by a loss of receptor hair cells and/or spiral ganglion neurons. Regenerative stem cell therapy could potentially restore normal hearing and slow the progression of hearing loss in patients. Preclinical animal studies have demonstrated that mesenchymal stem cells (MSCs) could be a promising new therapy for this condition. These findings have prompted investigators to begin human clinical trials to assess the safety and efficacy of MSCs for the treatment of SNHL. The objective of the proposed systematic review is to examine the efficacy of MSCs as a therapy for SNHL in animal models.

METHODS

We will include preclinical animal studies of SNHL in which MSCs are administered, and outcomes are compared against MSC-naïve controls. The primary outcome will include audiologic tests that are routinely used in experimental studies of hearing loss, such as auditory brainstem response (ABR) and distortion product otoacoustic emissions testing (DPOAE). Secondary outcomes will include histology, microscopy, gene protein expression, and behavioral responses of animals. Electronic searches of MEDLINE via PubMed, Scopus, ScienceDirect, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) will be performed. Search results will be screened independently and in duplicate. Data from eligible studies will be extracted, pooled, and analyzed using random effects models. Risk of bias and publication bias will be assessed using the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) risk of bias tool and Funnel Plots/Egger's regression tests, respectively.

DISCUSSION

This systematic review will provide a summary of the efficacy of MSC therapy in animal models of SNHL, utilizing functional hearing assessment as a primary outcome. Findings from this review are important because they can elucidate research gaps that should be addressed in future preclinical studies and in turn can be translated into clinical studies.

SYSTEMATIC REVIEW REGISTRATION

CAMARADES ( http://www.dcn.ed.ac.uk/camarades/ ).

Mesenchymal Stem Cell-Based Therapy of Inflammatory Lung Diseases: Current Understanding and Future Perspectives

During acute or chronic lung injury, inappropriate immune response and/or aberrant repair process causes irreversible damage in lung tissue and most usually results in the development of fibrosis followed by decline in lung function. Inhaled corticosteroids and other anti-inflammatory drugs are very effective in patients with inflammatory lung disorders, but their long-term use is associated with severe side effects. Accordingly, new therapeutic agents that will attenuate ongoing inflammation and, at the same time, promote regeneration of injured alveolar epithelial cells are urgently needed. Mesenchymal stem cells (MSCs) are able to modulate proliferation, activation, and effector function of all immune cells that play an important role in the pathogenesis of acute and chronic inflammatory lung diseases. In addition to the suppression of lung-infiltrated immune cells, MSCs have potential to differentiate into alveolar epithelial cells in vitro and, accordingly, represent new players in cell-based therapy of inflammatory lung disorders. In this review article, we described molecular mechanisms involved in MSC-based therapy of acute and chronic pulmonary diseases and emphasized current knowledge and future perspectives related to the therapeutic application of MSCs in patients suffering from acute respiratory distress syndrome, pneumonia, asthma, chronic obstructive pulmonary diseases, and idiopathic pulmonary fibrosis.

Mesenchymal Stem Cells Deliver Exogenous MicroRNA-let7c via Exosomes to Attenuate Renal Fibrosis

The advancement of microRNA (miRNA) therapies has been hampered by difficulties in delivering miRNA to the injured kidney in a robust and sustainable manner. Using bioluminescence imaging in mice with unilateral ureteral obstruction (UUO), we report that mesenchymal stem cells (MSCs), engineered to overexpress miRNA-let7c (miR-let7c-MSCs), selectively homed to damaged kidneys and upregulated miR-let7c gene expression, compared with nontargeting control (NTC)-MSCs. miR-let7c-MSC therapy attenuated kidney injury and significantly downregulated collagen IVα1, metalloproteinase-9, transforming growth factor (TGF)-β1, and TGF-β type 1 receptor (TGF-βR1) in UUO kidneys, compared with controls. In vitro analysis confirmed that the transfer of miR-let7c from miR-let7c-MSCs occurred via secreted exosomal uptake, visualized in NRK52E cells using cyc3-labeled pre-miRNA-transfected MSCs with/without the exosomal inhibitor, GW4869. The upregulated expression of fibrotic genes in NRK52E cells induced by TGF-β1 was repressed following the addition of isolated exosomes or indirect coculture of miR-let7c-MSCs, compared with NTC-MSCs. Furthermore, the cotransfection of NRK52E cells using the 3'UTR of TGF-βR1 confirmed that miR-let7c attenuates TGF-β1-driven TGF-βR1 gene expression. Taken together, the effective antifibrotic function of engineered MSCs is able to selectively transfer miR-let7c to damaged kidney cells and will pave the way for the use of MSCs for therapeutic delivery of miRNA targeted at kidney disease.

Autologous Peripheral Blood Mononuclear Cells as Treatment in Refractory Acute Respiratory Distress Syndrome

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a devastating disorder. Despite enormous efforts in clinical research, effective treatment options are lacking, and mortality rates remain unacceptably high.

OBJECTIVES

A male patient with severe ARDS showed no clinical improvement with conventional therapies. Hence, an emergent experimental intervention was performed.

METHODS

We performed intratracheal administration of autologous peripheral blood-derived mononuclear cells (PBMCs) and erythropoietin (EPO).

RESULTS

We found that after 2 days of initial PBMC/EPO application, lung function improved and extracorporeal membrane oxygenation (ECMO) support was reduced. Bronchoscopy and serum inflammatory markers revealed reduced inflammation. Additionally, serum concentration of miR-449a, b, c and miR-34a, a transient upregulation of E-cadherin and associated chromatin marks in PBMCs indicated airway epithelial differentiation. Extracellular vesicles from PBMCs demonstrated anti-inflammatory capacity in a TNF-α-mediated nuclear factor-x03BA;B in vitro assay. Despite improving respiratory function, the patient died of multisystem organ failure on day 38 of ECMO treatment.

CONCLUSIONS

This case report provides initial encouraging evidence to use locally instilled PBMC/EPO for treatment of severe refractory ARDS. The observed clinical improvement may partially be due to the anti-inflammatory effects of PBMC/EPO to promote tissue regeneration. Further studies are needed for more in-depth understanding of the underlying mechanisms of in vivo regeneration.

The use of human amniotic fluid stem cells as an adjunct to promote pulmonary development in a rabbit model for congenital diaphragmatic hernia

OBJECTIVE

This study aimed to evaluate the potential benefit of intra-tracheal injection of human amniotic fluid stem cells (hAFSC) on pulmonary development combined with TO in a rabbit model for CDH.

METHODS

In time-mated pregnant does a left diaphragmatic defect was created at d23 (term = 31). At d28, previously operated fetuses were assigned to either TO and injection with 70 μL of phosphate buffered saline (PBS) or 1.0 × 10(6) c-Kit positive hAFSC expressing LacZ or were left untouched (CDH). Harvesting was done at d31 to obtain their lung-to-body weight ratio (LBWR), airway and vascular lung morphometry, X-gal staining and immunohistochemistry for Ki67 and surfactant protein-B (SP-B).

RESULTS

CDH-induced pulmonary hypoplasia is countered by TO + PBS, this reverses LBWR, mean terminal bronchiole density (MTBD) and medial thickness to normal. The additional injection of hAFSC decreases MTBD and results in a non-significant decrease in muscularization of intra-acinary vessels. There were no inflammatory changes and LacZ positive hAFSC were dispersed throughout the lung parenchyma 4 days after injection.

CONCLUSION

HAFSC exert an additional effect on TO leading to a decrease in MTBD, a measure of alveolar number surrounding the terminal bronchioles, without signs of toxicity. © 2015 John Wiley & Sons, Ltd.

Interferon Gamma-treated Dental Pulp Stem Cells Promote Human Mesenchymal Stem Cell Migration In Vitro

INTRODUCTION

Chronic inflammation disrupts dental pulp regeneration by disintegrating the recruitment process of progenitors for repair. Bone marrow-derived mesenchymal stem cells (BM-MSCs) share the common features with dental pulp stem cells (DPSCs). The aim of the study was to investigate the migration of BM-MSCs toward DPSCs in response to inflammatory chemoattractants. Additionally, our studies also delineated the signaling mechanisms from BM-MSCs in mediating the proliferation and differentiation of DPSCs in vitro.

METHODS

Human DPSCs and BM-MSCs between passages 2 and 4 were used and were grown in odontogenic differentiation medium. Mineralization was determined by alizarin red staining analysis. Migration was assessed using crystal violet staining in cells grown in Boyden chamber Transwell inserts (Corning Inc Foundation, Tewksbury, MA). The mineralization potential of DPSCs was evaluated using alkaline phosphatase activity assay. Real-time polymerase chain reaction analysis was performed to assess the gene expression profile of chemokine (C-X-C motif) ligand (Cxcl) 3, 5, 6, 10, 11, 12, 14, and 16; stromal cell-derived factor (SDF) α; vascular endothelial growth factor; and fibroblast growth factor.

RESULTS

Interferon gamma (FN-γ) treatment significantly abrogated the differentiation potential of DPSCs as shown by using alizarin red and alkaline phosphatase activity analysis. An increase in the migration of BM-MSCs was documented when cocultured with IFN-γ-treated DPSCs. RNA expression studies showed an increase in the levels of Cxcl6 and Cxcl12 in BM-MSCs when cocultured with IFN-γ-treated DPSCs. Additionally, an up-regulation of proangiogenic factors vascular endothelial growth factor and fibroblast growth factor were observed in DPSCs exposed to IFN-γ.

CONCLUSIONS

Our findings indicate that inflamed IFN-γ-treated DPSCs release factors (presumably Cxcl6 and 12) that contribute to the homing of MSCs. This model might provide a potential research tool for studying MSC-DPSC cross talk and for future studies involving the recruitment and sustainability of progenitor stem cells sustaining the inflammatory cascade to treat pulp inflammation.

Advances in understanding of the pathogenesis of acute respiratory distress syndrome

The clinical syndrome of acute lung injury (ALI) occurs as a result of an initial acute systemic inflammatory response. This can be consequent to a plethora of insults, either direct to the lung or indirect. The insult results in increased epithelial permeability, leading to alveolar flooding with a protein-rich oedema fluid. The resulting loss of gas exchange leads to acute respiratory failure and typically catastrophic illness, termed acute respiratory distress syndrome (ARDS), requiring ventilatory and critical care support. There remains a significant disease burden, with some estimates showing 200,000 cases each year in the USA with a mortality approaching 50%. In addition, there is a significant burden of morbidity in survivors. There are currently no disease-modifying therapies available, and the most effective advances in caring for these patients have been in changes to ventilator strategy as a result of the ARDS network studies nearly 15 years ago. Here, we will give an overview of more recent advances in the understanding of the cellular biology of ALI and highlight areas that may prove fertile for future disease-modifying therapies.

Therapeutic Effects of Bone Marrow-Derived Mesenchymal Stem Cells in Models of Pulmonary and Extrapulmonary Acute Lung Injury

Bone marrow-derived mesenchymal stem cells (MSCs) offer a promising therapy for acute lung injury (ALI). However, whether the same MSC treatments possess similar potential for different ALI models is not fully clear. The present study evaluated the distribution and therapeutic effects of intravenous MSC administration for the treatment of intratracheal lipopolysaccharide (LPS)-induced intrapulmonary ALI and intravenous LPS/zymosan-induced extrapulmonary ALI, matched with lung injury severity, at 30 min and 1, 3, and 7 days. We found that MSC transplantation attenuated lung injury and inhibited lung inflammation in both ALI models. The benefits of MSCs were more significant in the intrapulmonary ALI mice. In vivo and ex vivo fluorescence imaging showed that MSCs primarily homed into the lung. However, more MSCs were recruited into the lungs of the intrapulmonary ALI mice than those of the extrapulmonary ALI mice over the time course. A few MSCs were also detected in the liver and spleen at days 3 and 7. In addition, the two ALI models showed different extrapulmonary organ dysfunction. A lower percentage of cell apoptosis and SDF-1α levels was found in the liver and spleen of the intrapulmonary ALI mice than in those of the extrapulmonary ALI mice. These results suggested that the two ALI models were accompanied with different degrees of extrapulmonary organ damage, which resulted in differences in the trafficking and accumulation of MSCs to the injured lung and consequently accounted for different therapeutic effects of MSCs for lung repair in the two ALI models. These data suggest that intravenous administration of MSCs has a greater potential for the treatment of intrapulmonary ALI than extrapulmonary ALI matched with lung injury severity; these differences were due to more recruitment of MSCs in the lungs of intrapulmonary ALI mice than those of extrapulmonary ALI mice. This finding may contribute to the clinical use of MSCs for the treatment of ALI.

Bone marrow mesenchymal stem cells protect alveolar macrophages from lipopolysaccharide-induced apoptosis partially by inhibiting the Wnt/β-catenin pathway

Apoptosis of alveolar macrophages (AMs) plays a pathogenic role in acute lung injury (ALI) and its severe type, acute respiratory distress syndrome (ARDS). Mesenchymal stem cells (MSCs) are promising therapeutic cells for preventing apoptosis and eliminating cellular injury. We investigated the effects of rat bone marrow mesenchymal stem cells (BMSCs) on lipopolysaccharide (LPS)-induced apoptosis in AMs using transwell experiments, and examined the underlying mechanisms LPS induced AMs apoptosis in a dose- and time-dependent fashion, whereas BMSCs reduced AMs apoptosis when co-cultured at appropriate ratios. BMSCs decreased expression of cleaved caspase-3 and the pro-apoptotic protein, Bax, whilst increased levels of the anti-apoptotic protein, Bcl-2, prolonging the lifespan of AMs in vitro. Promotion of AMs survival by BMSCs required down-regulation of p-GSK-3β and β-catenin in AMs. The anti-apoptosis action of BMSCs was reversed by SB216763, a specific inhibitor of GSK-3β that also activates Wnt/β-catenin signaling. In conclusion, BMSCs can attenuate AM apoptosis partially by suppressing the Wnt/β-catenin pathway.

Aging mesenchymal stem cells fail to protect because of impaired migration and antiinflammatory response

RATIONALE

Aging is characterized by functional impairment and reduced capacity to respond appropriately to environmental stimuli and injury. With age, there is an increase in the incidence and severity of chronic and acute lung diseases. However, the relationship between age and the lung's reduced ability to repair is far from established and necessitates further research in the field.

OBJECTIVES

Little is currently known about age-related phenomena in mesenchymal stem cells (MSCs). On account of their ability to protect the endothelium and the alveolar epithelium through multiple paracrine mechanisms, we looked for adverse effects that aging might cause in MSC biology. Such age-related changes might partly account for the increased susceptibility of the aging lung to injury.

MEASUREMENTS AND MAIN RESULTS

We demonstrated that old mice have more inflammation in response to acute lung injury. To investigate the causes, we compared the global gene expression of aged and young bone marrow-derived MSCs (B-MSCs). Our results revealed that the expression levels of inflammatory response genes depended on the age of the B-MSCs. We demonstrated that the age-dependent decrease in expression of several cytokine and chemokine receptors is important for the migration and activation of B-MSCs. Finally, we showed by adoptive transfer of aged B-MSCs to young endotoxemic mice that aged cells lacked the antiinflammatory protective effect of their young counterparts.

CONCLUSIONS

Taken together, the decreased expression of cytokine and chemokine receptors in aged B-MSCs compromises their protective role by perturbing the potential of B-MSCs to become activated and mobilize to the site of injury.

Treatment of acute respiratory distress syndrome with allogeneic adipose-derived mesenchymal stem cells: a randomized, placebo-controlled pilot study

Background

Recent studies have demonstrated that mesenchymal stem cells (MSCs) modulate the immune response and reduce lung injury in animal models. Currently, no clinical studies of the effects of MSCs in acute respiratory distress syndrome (ARDS) exist. The objectives of this study were first to examine the possible adverse events after systemic administration of allogeneic adipose-derived MSCs in ARDS patients and second to determine potential efficacy of MSCs on ARDS.

Methods

Twelve adult patients meeting the Berlin definition of acute respiratory distress syndrome with a PaO₂/FiO₂ ratio of < 200 were randomized to receive allogeneic adipose-derived MSCs or placebo in a 1:1 fashion. Patients received one intravenous dose of 1 × 10⁶ cells/kg of body weight or saline. Possible side effects were monitored after treatment. Acute lung injury biomarkers, including IL-6, IL-8 and surfactant protein D (SP-D), were examined to determine the effects of MSCs on lung injury and inflammation.

Results

There were no infusion toxicities or serious adverse events related to MSCs administration and there were no significant differences in the overall number of adverse events between the two groups. Length of hospital stay, ventilator-free days and ICU-free days at day 28 after treatment were similar. There were no changes in biomarkers examined in the placebo group. In the MSCs group, serum SP-D levels at day 5 were significantly lower than those at day 0 (p = 0.027) while the changes in IL-8 levels were not significant. The IL-6 levels at day 5 showed a trend towards lower levels as compared with day 0, but this trend was not statistically significant (p = 0.06).

Conclusions

Administration of allogeneic adipose-derived MSCs appears to be safe and feasible in the treatment of ARDS. However, the clinical effect with the doses of MSCs used is weak, and further optimization of this strategy will probably be required to reach the goal of reduced alveolar epithelial injury in ARDS.

Trial registration

Clinical trials.gov, NCT01902082

Human adult bone marrow-derived stem cells decrease severity of lipopolysaccharide-induced acute respiratory distress syndrome in sheep

INTRODUCTION

Acute respiratory distress syndrome (ARDS) is the most common cause of respiratory failure among critically ill subjects, sepsis and severe bacterial pneumonia being its most common causes. The only interventions that have proven beneficial are protective ventilation strategies and fluid conservation approaches. New therapies are needed to address this common clinical problem. Others and we have previously shown the beneficial effect of infusion of exogenous adult stem cells in different pre-clinical models of ARDS.

METHODS

In the present study endotoxin was infused intravenously into 14 sheep from which 6 received different doses of adult stem cells by intrabronchial delivery to evaluate the effect of stem cell therapy.

RESULTS

After administration of endotoxin, there was a rapid decline in oxygenation to hypoxemic values, indicative of severe-to-moderate ARDS. None of the animals treated with saline solution recovered to normal baseline values during the 6 hours that the animals were followed. In contrast, sheep treated with a dose of 40 million adult stem cells returned their levels of oxygen in their blood to baseline two hours after the cells were infused. Similarly, improvements in carbon dioxide (CO2) clearance, pulmonary vascular pressures and inflammation were observed and confirmed by histology and by the decrease in lung edema.

CONCLUSIONS

We concluded that instillation of adult non-hematopoietic stem cells can diminish the impact of endotoxin and accelerate recovery of oxygenation, CO2 removal and inflammation in the ovine model, making the use of adult stem cells a real alternative for future therapies for ARDS.

Human mesenchymal stem cells overexpressing the IL-33 antagonist soluble IL-1 receptor-like-1 attenuate endotoxin-induced acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are characterized by pulmonary edema attributable to alveolar epithelial-interstitial-endothelial injury, associated with profound inflammation and respiratory dysfunction. The IL-33/IL-1 receptor-like-1 (ST2) axis plays a key role in the development of immune-inflammatory responses in the lung. Cell-based therapy has been recently proposed as an effective alternative for the treatment of ALI and ARDS. Here, we engineered human adipose tissue-derived mesenchymal stem cells (hASCs) overexpressing soluble IL-1 receptor-like-1 (sST2), a decoy receptor for IL-33, in order to enhance their immunoregulatory and anti-inflammatory properties when applied in a murine ALI model. We administered both hASCs and hASC-sST2 systemically at 6 hours after intranasal LPS instillation, when pathological changes had already occurred. Bioluminescence imaging, immunohistochemistry, and focused transcriptional profiling confirmed the increased presence of hASCs in the injured lungs and the activation of an immunoregulatory program (CXCR-4, tumor necrosis factor-stimulated gene 6 protein, and indoleamine 2,3-dioxygenase up-regulation) in these cells, 48 hours after endotoxin challenge. A comparative evaluation of hASCs and the actions of hASC-sST2 revealed that local sST2 overproduction by hASC-sST2 further prevented IL-33, Toll-like receptor-4, IL-1β, and IFN-γ induction, but increased IL-10 expression in the injured lungs. This synergy caused a substantial decrease in lung airspace inflammation and vascular leakage, characterized by significant reductions in protein content, differential neutrophil counts, and proinflammatory cytokine (TNF-α, IL-6, and macrophage inflammatory protein 2) concentrations in bronchoalveolar lavage fluid. In addition, hASC-sST2-treated ALI lungs showed preserved alveolar architecture, an absence of apoptosis, and minimal inflammatory cell infiltration. These results suggest that hASCs genetically engineered to produce sST2 could become a promising therapeutic strategy for ALI/ARDS management.

Lipopolysaccharide impaired the functional activity of endothelial colony-forming cells

BACKGROUND

Recent studies have shown that endothelial progenitor cells (EPCs) contribute to lung repair after lipopolysaccharide (LPS)-induced lung injury and infusion of LPS decreased early EPCs in human peripheral blood. However, the effects of LPS on endothelial colony-forming cells (ECFCs) remain to be determined.

OBJECTIVE

To investigate possible effects of LPS on the functional activity of ECFCs.

METHODS

ECFCs were isolated from human umbilical cord blood and characterized. ECFCs at passages 3-5 were treated for 24 h with either LPS or vehicle control. Their viability, migration and in vitro vasculogenesis activity were assayed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, modified Boyden chamber and in vitro angiogenesis assays, respectively. ECFC adhesion was assessed by replating cells on fibronectin-coated dishes and subsequent counting of adherent cells.

RESULTS

Incubation with LPS dose-dependently inhibited the viable, migratory, adhesive and in vitro vasculogenesis capacity of ECFCs.

CONCLUSION

LPS impaired the functional activity of ECFCs.

Update in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by permeability pulmonary edema and refractory hypoxemia. Recently, the new definition of ARDS has been published, and this definition suggested severity-oriented respiratory treatment by introducing three levels of severity according to PaO₂/FiO₂ and positive end-expiratory pressure. Lung-protective ventilation is still the key of better outcome in ARDS. Through randomized trials, short-term use of neuromuscular blockade at initial stage of mechanical ventilation, prone ventilation in severe ARDS, and extracorporeal membrane oxygenation in ARDS with influenza pneumonia showed beneficial efficacy. However, ARDS mortality still remains high. Therefore, early recognition of ARDS modified risk factors and the avoidance of aggravating factors during the patient's hospital stay can help decrease its development. In addition, efficient antifibrotic strategies in late-stage ARDS should be developed to improve the outcome.

Tropism of avian influenza A (H5N1) virus to mesenchymal stem cells and CD34+ hematopoietic stem cells

The presence of abnormal hematologic findings such as lymphopenia, thrombocytopenia, and pancytopenia were diagnosed in severe cases of avian influenza A H5N1. Whether direct viral dissemination to bone marrow (BM) cells causes this phenomenon remains elusive. We explore the susceptibility of the two stem cell types; hematopoietic stem cells (HSCs) and mesenchymal stromal cells (MSCs) isolated from human BM cells or cord blood, to infection with avian H5N1 viruses. For the first time, we demonstrated that the H5N1 virus could productively infect and induce cell death in both human stem cell types. In contrast, these activities were not observed upon human influenza virus infection. We also determined whether infection affects the immunomodulatory function of MSCs. We noted a consequent dysregulation of MSC-mediated immune modulation as observed by high cytokine and chemokine production in H5N1 infected MSCs and monocytes cocultures. These findings provide a better understanding of H5N1 pathogenesis in terms of broad tissue tropism and systemic spread.

Novel and emerging therapies safeguarding health of humans and their companion animals: a review

Modern medicine has helped to a great extent to eradicate and cure several diseases of mankind and animals. But the existence of incurable diseases like cancer, Acquired Immunodeficiency Syndrome (AIDS), diabetes or rheumatoid arthritis, side effects of allopathic medicine, increasing trend of antibiotic resistance and chemicals and biopesticides causing dietary risk have made the situation more critical than ever before. Thus, it has become a matter of concern for the scientists and researchers to develop novel therapies. Bacteriophage therapy to treat pathogenic bacterial infections, virophage therapy for conservation of global system and avian egg yolk antibody therapy for designing prophylactic strategies against Gastrointestinal (GI) diseases are interesting approaches. Others include the use of cytokines as adjunctive immunomodulators, gene therapy focusing on diseases caused by single gene defects, RNAi technology to suppress specific gene of interest and apoptins for cancer treatment. Stem cell therapy against several diseases and ailments has also been discussed. The use of nanoparticles for better drug delivery, even though costly, has been given equal importance. Nevertheless, immunomodulation, be it through physiological, chemical or microbial products, or through essential micronutrients, probiotics, herbs or cow therapy prove to be cost-effective, causing minimum adverse reactions when compared to allopathy. Development in the field of molecular biology has created an enormous impact on vaccine development. The present review deals with all these novel and emerging therapies essential to safeguard the health of humans and companion animals.