Aerosolised Mesenchymal Stem Cells Expressing Angiopoietin-1 Enhances Airway Repair

Indoleamine 2, 3-dioxygenase-transfected bone marrow-derived mesenchymal stem cells promote corneal allograft survival by inhibiting T cell proliferation: A rat study

PURPOSE

Allograft rejection is still the main cause of corneal transplantation failure. Therefore, we investigated the role of indoleamine 2,3-dioxygenase (IDO)-transfected bone marrow-derived mesenchymal stem cells (IDO-BMSCs) in corneal allograft rejection in rats.

METHODS

IDO-BMSCs were constructed and co-cultured with CD4+CD24- T cells to detect their effects on the proliferation of CD4+CD25-T cells in vitro. A corneal allograft rat model was used to confirm our in vitro and in vivo observations. Therefore, IDO-BMSCs were injected directly into the recipient's conjunctiva on the day of corneal transplantation and on day 5 after operation. Corneal graft rejection indices, including corneal neovascularization, opacity, and edema, were measured for up to 14 days after transplantation. The recipients' cervical lymph nodes and peripheral blood were collected to test the role of IDO-BMSCs in immune cells using flow cytometry.

RESULTS

The lentivirus-mediated IDO gene was successfully transfected into BMSCs, which stably secreted the IDO protein. The proliferation of CD4+CD25-T cells was significantly inhibited after their co-culture with IDO-BMSCs. Subconjunctival injection of IDO-BMSCs into corneal allografts of rats effectively reduced graft neovascularization, promoted allograft survival, and induced immune tolerance. Both CD4+ and CD8+ T cells in the local lymph nodes and peripheral blood, along with CD4+CD25-T cells in the local lymph nodes, were significantly reduced after transplantation.

CONCLUSION

Our results suggest that IDO-BMSC treatment enhances the direct immunomodulatory effect of corneal allograft transplants in rats, promoting corneal allograft survival by inhibiting the proliferation of CD4+, CD8+, and CD4+CD25-T cells. Therefore, modification of BMSCs by lentivirus-mediated IDO gene transfection may provide a novel strategy for controlling corneal allograft rejection.

sFgl2 gene-modified MSCs regulate the differentiation of CD4+ T cells in the treatment of autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is a T-cell-mediated autoimmune liver disease that can lead to liver injury and has a poor long-term prognosis. Mesenchymal stromal cells (MSCs) have immunosuppressive effects and can treat AIH. CD4+ T cells express the unique inhibitory Fcγ receptor (FcγRIIB), which is the only receptor for the immunosuppressive factor soluble fibrinogen-like protein 2 (sFgl2). This study aimed to examine the therapeutic effect of sFgl2 gene-modified MSCs (sFgl2-MSCs) on AIH.

METHODS

MSCs were obtained from the inguinal fat of mice and cocultured with CD4+ T cells sorted from mouse spleens. FcγRIIB expression on CD4+ T cells was determined by flow cytometry. sFgl2 expression in MSCs transfected with lentiviral vectors carrying the Fgl2 gene and a green fluorescent protein-encoding sequence was determined by enzyme-linked immunosorbent assay. The percentages of Th1 cells Th17 cells and regulatory T cells (Tregs) were determined by flow cytometry And the levels of p-SHP2 and p-SMAD2/3 were detected by Western blotting after the cells were cocultured with MSCs for 72 h. After locating MSCs by in vivo imaging Con A-induced experimental AIH mice were randomly divided into 4 groups and administered different treatments. After 24 h histopathological scores liver function and cytokine levels were examined and the proportions of CD4+ T cells CD8+ T cells Tregs Th17 cells and Th1 cells in the spleen and liver were determined by flow cytometry. In addition immunohistochemical staining was used to detect the liver infiltration of T-bet-, Foxp3- and RORγ-positive cells.

RESULTS

FcγRIIB expression on CD4+ T cells was upregulated after coculture with MSCs. After coculture with sFgl2-MSCs, the proportion of Tregs among CD4+ T cells increased, the proportion of Th17 and Th1 cells decreased, and the levels of p-SHP2 and p-SMAD2/3 increased. In vivo, sFgl2-MSCs significantly improved liver function, decreased liver necrosis area, decreased tumor necrosis factor-α, interleukin (IL)-1β and IL-6 expression, increased IL-10 expression, reduced liver infiltration of CD4+ T and CD8+ T cells, increased the proportion of Tregs and reduced the proportions of Th17 and Th1 cells in mice.

CONCLUSION

By promoting Tregs differentiation and inhibiting Th17 and Th1 cell differentiation, sFgl2 gene-modified MSCs have a more powerful therapeutic effect on Con A-induced experimental AIH and may represent a strategy for the clinical treatment of AIH.

Asthma: The Use of Animal Models and Their Translational Utility

Asthma is characterized by chronic lower airway inflammation that results in airway remodeling, which can lead to a permanent decrease in lung function. The pathophysiology driving the development of asthma is complex and heterogenous. Animal models have been and continue to be essential for the discovery of molecular pathways driving the pathophysiology of asthma and novel therapeutic approaches. Animal models of asthma may be induced or naturally occurring. Species used to study asthma include mouse, rat, guinea pig, cat, dog, sheep, horse, and nonhuman primate. Some of the aspects to consider when evaluating any of these asthma models are cost, labor, reagent availability, regulatory burden, relevance to natural disease in humans, type of lower airway inflammation, biological samples available for testing, and ultimately whether the model can answer the research question(s). This review aims to discuss the animal models most available for asthma investigation, with an emphasis on describing the inciting antigen/allergen, inflammatory response induced, and its translation to human asthma.

Imaging drug delivery to the lungs: Methods and applications in oncology

Direct delivery to the lung via inhalation is arguably one of the most logical approaches to treat lung cancer using drugs. However, despite significant efforts and investment in this area, this strategy has not progressed in clinical trials. Imaging drug delivery is a powerful tool to understand and develop novel drug delivery strategies. In this review we focus on imaging studies of drug delivery by the inhalation route, to provide a broad overview of the field to date and attempt to better understand the complexities of this route of administration and the significant barriers that it faces, as well as its advantages. We start with a discussion of the specific challenges for drug delivery to the lung via inhalation. We focus on the barriers that have prevented progress of this approach in oncology, as well as the most recent developments in this area. This is followed by a comprehensive overview of the different imaging modalities that are relevant to lung drug delivery, including nuclear imaging, X-ray imaging, magnetic resonance imaging, optical imaging and mass spectrometry imaging. For each of these modalities, examples from the literature where these techniques have been explored are provided. Finally the different applications of these technologies in oncology are discussed, focusing separately on small molecules and nanomedicines. We hope that this comprehensive review will be informative to the field and will guide the future preclinical and clinical development of this promising drug delivery strategy to maximise its therapeutic potential.

Effervescent Atomizer as Novel Cell Spray Technology to Decrease the Gas-to-Liquid Ratio

Cell spraying has become a feasible application method for cell therapy and tissue engineering approaches. Different devices have been used with varying success. Often, twin-fluid atomizers are used, which require a high gas velocity for optimal aerosolization characteristics. To decrease the amount and velocity of required air, a custom-made atomizer was designed based on the effervescent principle. Different designs were evaluated regarding spray characteristics and their influence on human adipose-derived mesenchymal stromal cells. The arithmetic mean diameters of the droplets were 15.4−33.5 µm with decreasing diameters for increasing gas-to-liquid ratios. The survival rate was >90% of the control for the lowest gas-to-liquid ratio. For higher ratios, cell survival decreased to approximately 50%. Further experiments were performed with the design, which had shown the highest survival rates. After seven days, no significant differences in metabolic activity were observed. The apoptosis rates were not influenced by aerosolization, while high gas-to-liquid ratios caused increased necrosis levels. Tri-lineage differentiation potential into adipocytes, chondrocytes, and osteoblasts was not negatively influenced by aerosolization. Thus, the effervescent aerosolization principle was proven suitable for cell applications requiring reduced amounts of supplied air. This is the first time an effervescent atomizer was used for cell processing.

Mesenchymal Stromal Cells: an Antimicrobial and Host-Directed Therapy for Complex Infectious Diseases

There is an urgent need for new antimicrobial strategies for treating complex infections and emerging pathogens. Human mesenchymal stromal cells (MSCs) are adult multipotent cells with antimicrobial properties, mediated through direct bactericidal activity and modulation of host innate and adaptive immune cells. More than 30 in vivo studies have reported on the use of human MSCs for the treatment of infectious diseases, with many more studies of animal MSCs in same-species models of infection. MSCs demonstrate potent antimicrobial effects against the major classes of human pathogens (bacteria, viruses, fungi, and parasites) across a wide range of infection models. Mechanistic studies have yielded important insight into their immunomodulatory and bactericidal activity, which can be enhanced through various forms of preconditioning. MSCs are being investigated in over 80 clinical trials for difficult-to-treat infectious diseases, including sepsis and pulmonary, intra-abdominal, cutaneous, and viral infections. Completed trials consistently report MSCs to be safe and well tolerated, with signals of efficacy against some infectious diseases. Although significant obstacles must be overcome to produce a standardized, affordable, clinical-grade cell therapy, these studies suggest that MSCs may have particular potential as an adjunct therapy in complex or resistant infections.

Targeting the Angiopoietin/Tie Pathway: Prospects for Treatment of Retinal and Respiratory Disorders

Anti-angiogenic approaches have significantly advanced the treatment of vascular-related pathologies. The ephemeral outcome and known side effects of the current vascular endothelial growth factor (VEGF)-based anti-angiogenic treatments have intensified research on other growth factors. The angiopoietin/Tie (Ang/Tie) family has an established role in vascular physiology and regulates angiogenesis, vascular permeability, and inflammatory responses. The Ang/Tie family consists of angiopoietins 1-4, their receptors, tie1 and 2 and the vascular endothelial-protein tyrosine phosphatase (VE-PTP). Modulation of Tie2 activation has provided a promising outcome in preclinical models and has led to clinical trials of Ang/Tie-targeting drug candidates for retinal disorders. Although less is known about the role of Ang/Tie in pulmonary disorders, several studies have revealed great potential of the Ang/Tie family members as drug targets for pulmonary vascular disorders as well. In this review, we summarize the functions of the Ang/Tie pathway in retinal and pulmonary vascular physiology and relevant disorders and highlight promising drug candidates targeting this pathway currently being or expected to be under clinical evaluation for retinal and pulmonary vascular disorders.

Evolution of Diploid Progenitor Lung Cell Applications: From Optimized Biotechnological Substrates to Potential Active Pharmaceutical Ingredients in Respiratory Tract Regenerative Medicine

The objective of this review is to describe the evolution of lung tissue-derived diploid progenitor cell applications, ranging from historical biotechnological substrate functions for vaccine production and testing to current investigations around potential therapeutic use in respiratory tract regenerative medicine. Such cell types (e.g., MRC-5 or WI-38 sources) were extensively studied since the 1960s and have been continuously used over five decades as safe and sustainable industrial vaccine substrates. Recent research and development efforts around diploid progenitor lung cells (e.g., FE002-Lu or Walvax-2 sources) consist in qualification for potential use as optimal and renewed vaccine production substrates and, alternatively, for potential therapeutic applications in respiratory tract regenerative medicine. Potentially effective, safe, and sustainable cell therapy approaches for the management of inflammatory lung diseases or affections and related symptoms (e.g., COVID-19 patients and burn patient severe inhalation syndrome) using local homologous allogeneic cell-based or cell-derived product administrations are considered. Overall, lung tissue-derived progenitor cells isolated and produced under good manufacturing practices (GMP) may be used with high versatility. They can either act as key industrial platforms optimally conforming to specific pharmacopoeial requirements or as active pharmaceutical ingredients (API) for potentially effective promotion of lung tissue repair or regeneration.

Cellular Therapy for the Treatment of Paediatric Respiratory Disease

Respiratory disease is the leading cause of death in children under the age of 5 years old. Currently available treatments for paediatric respiratory diseases including bronchopulmonary dysplasia, asthma, cystic fibrosis and interstitial lung disease may ameliorate symptoms but do not offer a cure. Cellular therapy may offer a potential cure for these diseases, preventing disease progression into adulthood. Induced pluripotent stem cells, mesenchymal stromal cells and their secretome have shown great potential in preclinical models of lung disease, targeting the major pathological features of the disease. Current research and clinical trials are focused on the adult population. For cellular therapies to progress from preclinical studies to use in the clinic, optimal cell type dosage and delivery methods need to be established and confirmed. Direct delivery of these therapies to the lung as aerosols would allow for lower doses with a higher target efficiency whilst avoiding potential effect of systemic delivery. There is a clear need for research to progress into the clinic for the treatment of paediatric respiratory disease. Whilst research in the adult population forms a basis for the paediatric population, varying disease pathology and anatomical differences in paediatric patients means a paediatric-centric approach must be taken.

Therapeutic Potential of Adipose-Derived Stem Cells in the Treatment of Pulmonary Diseases

Stem cells derived from adipose tissues (ADSCs) have emerged as an ideal candidate for various models of respiratory diseases, including asthma, chronic obstructive pulmonary disease (COPD), and acute respiratory distress syndrome. ADSCs have qualities that may make them better suited for treating inflammatory lung diseases than other MSCs. ADSCs show a lower senescence ratio, higher proliferative capacity and stability in terms of their genetic and morphology during long-term culture over bone marrow-derived mesenchymal stem cells (BMMSCs). With advanced research techniques, the advantageous effects of ADSCs seem limited to their ability to engraft, differentiate, and be related to their secretion of trophic factors. These trophic factors regulate the therapeutic and regenerative outcomes in various lung inflammatory diseases. Taken together, these particular qualities of ADSCs make them significantly relevant for clinical applications. This article discusses a recent advance of ADSCs biology and their translational application emphasizing their anti-inflammatory, immunomodulatory and regenerative properties particularly on lung inflammatory diseases. Besides, the relevant advancements made in the field, the regulatory aspects, and other challenges and obstacles will be highlighted.

Emerging Cell-Based Therapies in Chronic Lung Diseases: What About Asthma?

Asthma is a widespread disease characterized by chronic airway inflammation. It causes substantial disability, impaired quality of life, and avoidable deaths around the world. The main treatment for asthmatic patients is the administration of corticosteroids, which improves the quality of life; however, prolonged use of corticosteroids interferes with extracellular matrix elements. Therefore, cell-based therapies are emerging as a novel therapeutic contribution to tissue regeneration for lung diseases. This study aimed to summarize the advancements in cell therapy involving mesenchymal stromal cells, extracellular vesicles, and immune cells such as T-cells in asthma. Our findings provide evidence that the use of mesenchymal stem cells, their derivatives, and immune cells such as T-cells are an initial milestone to understand how emergent cell-based therapies are effective to face the challenges in the development, progression, and management of asthma, thus improving the quality of life.

Treatment of Cystic Fibrosis: From Gene- to Cell-Based Therapies

Prognosis of patients with cystic fibrosis (CF) varies extensively despite recent advances in targeted therapies that improve CF transmembrane conductance regulator (CFTR) function. Despite being a multi-organ disease, extensive lung tissue destruction remains the major cause of morbidity and mortality. Progress towards a curative treatment strategy that implements a CFTR gene addition-technology to the patients’ lungs has been slow and not yet developed beyond clinical trials. Improved delivery vectors are needed to overcome the body’s defense system and ensure an efficient and consistent clinical response before gene therapy is suitable for clinical care. Cell-based therapy–which relies on functional modification of allogenic or autologous cells ex vivo, prior to transplantation into the patient–is now a therapeutic reality for various diseases. For CF, pioneering research has demonstrated proof-of-principle for allogenic transplantation of cultured human airway stem cells into mouse airways. However, applying a cell-based therapy to the human airways has distinct challenges. We review CF gene therapies using viral and non-viral delivery strategies and discuss current advances towards autologous cell-based therapies. Progress towards identification, correction, and expansion of a suitable regenerative cell, as well as refinement of pre-cell transplant lung conditioning protocols is discussed.

Therapeutic Potential of Mesenchymal Stem Cells and Their Products in Lung Diseases-Intravenous Administration versus Inhalation

The number of publications studying the therapeutic use of stem cells has steadily increased since 2000. Compared to other applications, there has been little interest in the evaluation of mesenchymal stem cells (MSCs) and MSC-derived products (mostly extracellular vesicles) for the treatment of respiratory diseases. Due to the lack of efficient treatments for acute respiratory distress syndrome caused by infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the action of MSCs has also been studied. This review describes mode of action and use of MSCs and MSC-derived products in the treatment of lung diseases including the respective advantages and limitations of the products. Further, issues related to standardized production are addressed. Administration by inhalation of MSCs, compared to intravenous injection, could decrease cell damage by shear stress, eliminate the barrier to reach target cells in the alveoli, prevent thrombus formation in the pulmonary vasculature and retention in filter for extracorporeal membrane oxygenation. There is more feasible to deliver extracellular vesicles than MSCs with inhalers, offering the advantage of non-invasive and repeated administration by the patient. Major obstacles for comparison of results are heterogeneity of the products, differences in the treatment protocols and small study cohorts.

Endoscopic atomization of mesenchymal stromal cells: in vitro study for local cell therapy of the lungs

BACKGROUND AIMS

Cell-based therapies of pulmonary diseases with mesenchymal stromal cells (MSCs) are increasingly under experimental investigation. In most of these, MSCs are administered intravenously or by direct intratracheal instillation. A parallel approach is to administer the cells into the lung by endoscopic atomization (spraying). In a previous study, the authors developed a flexible endoscopic atomization device that allows administration of respiratory epithelial cells in the lungs with high survival.

METHODS

In this study, the authors evaluated the feasibility of spraying MSCs with two different endoscopic atomization devices (air and pressure atomization). Following atomization, cell viability was evaluated with live/dead staining. Subsequent effects on cytotoxicity, trilineage differentiation and expression of MSC-specific markers as well as on MSC metabolic activity and morphology were analyzed for up to 7 days.

RESULTS

MSC viability immediately after spraying and subsequent metabolic activity for 7 days was not influenced by either of the devices. Slightly higher cytotoxicity rates could be observed for pressure-atomized compared with control and air-atomized MSCs over 7 days. Flow cytometry revealed no changes in characteristic MSC cell surface marker expression, and morphology remained unchanged. Standard differentiation into osteocytes, chondrocytes and adipocytes was inducible after atomization.

CONCLUSIONS

In the literature, a minimal survival of 50% was previously defined as the cutoff value for successful cell atomization. This is easily met with both of the authors' devices, with more than 90% survival. Thus, there is a potential role for atomization in intrapulmonary MSC-based cell therapies, as it is a feasible and easily utilizable approach based on clinically available equipment.

Acute Lung Injury: Disease Modelling and the Therapeutic Potential of Stem Cells

Acute lung injury (ALI) is a severe clinical condition with high morbidity and mortality that usually results in the development of multiple organ dysfunction. The complex pathophysiology of ALI seems to provide a wide range of targets that offer numerous therapeutic options. However, despite extensive studies of ALI pathophysiology and treatment, no effective pharmacotherapy is available. Increasing evidence from both preclinical and clinical studies supports the preventive and therapeutic effects of mesenchymal stem cells (MSCs) for treating ALI. As cell-based therapy poses the risk of occlusion in microvasculature or unregulated growth, MSC-derived extracellular vesicles (MSC-EVs) have been extensively studied as a new therapeutic strategy for non-cell based therapy. It is widely accepted that the therapeutic properties of MSCs are derived from soluble factors with paracrine or endocrine effects, and EVs are among the most important paracrine or endocrine vehicles that can deliver various soluble factors with a similar phenotype as the parent cell. Therapeutic effects of MSCs have been reported for various delivery approaches, diverse doses, multiple origins, and different times of administration, and MSC-EVs treatment may include but is not limited to these choices. The mechanisms by which MSCs and MSC-EVs may contribute to ALI treatment remain elusive and need further exploration. This review provides an overview of preclinical studies that support the application of MSC-EVs for treating ALI, and it discusses emerging opportunities and their associated challenges.

An Assessment on Impact of COVID-19 Infection in a Gender Specific Manner

Coronavirus disease 2019 (COVID-19) is caused by novel coronavirus Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was first time reported in December 2019 in Wuhan, China and thereafter quickly spread across the globe. Till September 19, 2020, COVID-19 has spread to 216 countries and territories. Severe infection of SARS-CoV-2 cause extreme increase in inflammatory chemokines and cytokines that may lead to multi-organ damage and respiratory failure. Currently, no specific treatment and authorized vaccines are available for its treatment. Renin angiotensin system holds a promising role in human physiological system specifically in regulation of blood pressure and electrolyte and fluid balance. SARS-CoV-2 interacts with Renin angiotensin system by utilizing angiotensin-converting enzyme 2 (ACE2) as a receptor for its cellular entry. This interaction hampers the protective action of ACE2 in the cells and causes injuries to organs due to persistent angiotensin II (Ang-II) level. Patients with certain comorbidities like hypertension, diabetes, and cardiovascular disease are under the high risk of COVID-19 infection and mortality. Moreover, evidence obtained from several reports also suggests higher susceptibility of male patients for COVID-19 mortality and other acute viral infections compared to females. Analysis of severe acute respiratory syndrome coronavirus (SARS) and Middle East respiratory syndrome coronavirus (MERS) epidemiological data also indicate a gender-based preference in disease consequences. The current review addresses the possible mechanisms responsible for higher COVID-19 mortality among male patients. The major underlying aspects that was looked into includes smoking, genetic factors, and the impact of reproductive hormones on immune systems and inflammatory responses. Detailed investigations of this gender disparity could provide insight into the development of patient tailored therapeutic approach which would be helpful in improving the poor outcomes of COVID-19. Graphical abstract.

Defining a Regulatory Strategy for ATMP/Aerosol Delivery Device Combinations in the Treatment of Respiratory Disease

Advanced Therapeutic Medicinal Products (ATMP) are a heterogenous group of investigational medicinal products at the forefront of innovative therapies with direct applicability in respiratory diseases. ATMPs include, but are not limited to, stem cells, their secretome, or extracellular vesicles, and each have shown some potential when delivered topically within the lung. This review focuses on that subset of ATMPs. One key mode of delivery that has enabling potential in ATMP validation is aerosol-mediated delivery. The selection of the most appropriate aerosol generator technology is influenced by several key factors, including formulation, patient type, patient intervention, and healthcare economics. The aerosol-mediated delivery of ATMPs has shown promise for the treatment of both chronic and acute respiratory disease in pre-clinical and clinical trials; however, in order for these ATMP device combinations to translate from the bench through to commercialization, they must meet the requirements set out by the various global regulatory bodies. In this review, we detail the potential for ATMP utility in the lungs and propose the nebulization of ATMPs as a viable route of administration in certain circumstances. Further, we provide insight to the current regulatory guidance for nascent ATMP device combination product development within the EU and US.

Stem Cells Secretome from Oral Tissue Could Represent a Promising Therapeutic Approach in COVID-19-Disease?

At present, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has quickly become a health emergency because no specifics vaccines or drugs, at this moment, are available. Recent studies have shown that the transplantation of mesenchymal stem cells (MSCs) into Coronavirus Disease 2019 (COVID-19) patients could represent a promising strategy for the development of new therapeutic methods. We speculate and suggest that the secretome of human Oral Tissue Stem Cells (hOTSCs), for their immunomodulatory and anti-inflammatory specific properties, could exert beneficial effects on the COVID-19 patients through an innovative aerosolisation technique. This non-invasive technique can offer multiple advantages in prophylaxis, as well as the prevention and treatment of severe epidemic respiratory syndrome with minimum risk and optimal therapeutic effects. This has the potential to create a novel pathway towards immunomodulatory therapy for the treatment of COVID-19 positive patients.

State of the Art Review of Cell Therapy in the Treatment of Lung Disease, and the Potential for Aerosol Delivery

Respiratory and pulmonary diseases are among the leading causes of death globally. Despite tremendous advancements, there are no effective pharmacological therapies capable of curing diseases such as COPD (chronic obstructive pulmonary disease), ARDS (acute respiratory distress syndrome), and COVID-19. Novel and innovative therapies such as advanced therapy medicinal products (ATMPs) are still in early development. However, they have exhibited significant potential preclinically and clinically. There are several longitudinal studies published, primarily focusing on the use of cell therapies for respiratory diseases due to their anti-inflammatory and reparative properties, thereby hinting that they have the capability of reducing mortality and improving the quality of life for patients. The primary objective of this paper is to set out a state of the art review on the use of aerosolized MSCs and their potential to treat these incurable diseases. This review will examine selected respiratory and pulmonary diseases, present an overview of the therapeutic potential of cell therapy and finally provide insight into potential routes of administration, with a focus on aerosol-mediated ATMP delivery.

Mesenchymal stem cells transfected with sFgl2 inhibit the acute rejection of heart transplantation in mice by regulating macrophage activation

Background

Mesenchymal stem cells (MSCs) have become a promising candidate for cell-based immune therapy for acute rejection (AR) after heart transplantation due to possessing immunomodulatory properties. In this study, we evaluated the efficacy of soluble fibronectin-like protein 2 (sFgl2) overexpressing mesenchymal stem cells (sFgl2-MSCs) in inhibiting AR of heart transplantation in mice by regulating immune tolerance through inducing M2 phenotype macrophage polarization.

Methods and results

The sFgl2, a novel immunomodulatory factor secreted by regulatory T cells, was transfected into MSCs to enhance their immunosuppressive functions. After being co-cultured for 72 h, the sFgl2-MSCs inhibited M1 polarization whereas promoted M2 of polarization macrophages through STAT1 and NF-κB pathways in vitro. Besides, the sFgl2-MSCs significantly enhanced the migration and phagocytosis ability of macrophages stimulated with interferon-γ (IFN-γ) and lipopolysaccharide (LPS). Further, the application potential of sFgl2-MSCs in AR treatment was demonstrated by heterotopic cardiac transplantation in mice. The tissue damage and macrophage infiltration were evaluated by H&E and immunohistochemistry staining, and the secretion of inflammatory cytokines was analyzed by ELISA. The results showed that sFgl2-MSCs injected intravenously were able to locate in the graft, promote the M2 polarization of macrophages in vivo, regulate the local and systemic immune response, significantly protect tissues from damaging, and finally prolonged the survival time of mice heart grafts.

Conclusion

sFgl2-MSCs ameliorate AR of heart transplantation by regulating macrophages, which provides a new idea for the development of anti-AR treatment methods after heart transplantation.

Mesenchymal stem cells in allergic diseases: Current status

Allergic diseases, which include asthma, allergic skin diseases, allergic rhinitis and allergic conjunctivitis, have already garnered worldwide public health attention over recent decades. Mesenchymal stem cells (MSCs) have gradually emerged as a potential method for treating allergic diseases due to their immunosuppressive characteristics, tissue repair ability and secretion of various biological factors. This potential of MSC-based therapy has been confirmed in clinical and preclinical studies, which report the therapeutic benefits of MSCs for various allergic diseases and explore the antiallergic mechanisms. In this review, we focus on the discoveries and biological mechanisms of MSCs as a therapeutic tool in allergic diseases. We discuss the challenges of conducting MSC studies as well as future directions.

Regulation and Directing Stem Cell Fate by Tissue Engineering Functional Microenvironments: Scaffold Physical and Chemical Cues

It is well known that stem cells reside within tissue engineering functional microenvironments that physically localize them and direct their stem cell fate. Recent efforts in the development of more complex and engineered scaffold technologies, together with new understanding of stem cell behavior in vitro, have provided a new impetus to study regulation and directing stem cell fate. A variety of tissue engineering technologies have been developed to regulate the fate of stem cells. Traditional methods to change the fate of stem cells are adding growth factors or some signaling pathways. In recent years, many studies have revealed that the geometrical microenvironment played an essential role in regulating the fate of stem cells, and the physical factors of scaffolds including mechanical properties, pore sizes, porosity, surface stiffness, three-dimensional structures, and mechanical stimulation may affect the fate of stem cells. Chemical factors such as cell-adhesive ligands and exogenous growth factors would also regulate the fate of stem cells. Understanding how these physical and chemical cues affect the fate of stem cells is essential for building more complex and controlled scaffolds for directing stem cell fate.

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

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