Alveolar epithelial cell therapy with human cord blood-derived hematopoietic progenitor cells

Umbilical cord blood-derived therapy for preterm lung injury: a systematic review and meta-analysis

INTRODUCTION

Lung injuries, such as bronchopulmonary dysplasia (BPD), remain a major complication of preterm birth, with limited therapeutic options. One potential emerging therapy is umbilical cord blood (UCB)-derived therapy.

OBJECTIVES

To systematically assess the safety and efficacy of UCB-derived therapy for preterm lung injury in preclinical and clinical studies.

METHODS

A systematic search of MEDLINE, Embase, CENTRAL, ClinicalTrials.gov, and WHO International Trials Registry Platform was performed. A meta-analysis was conducted with Review Manager (5.4.1) using a random effects model. Data was expressed as standardized mean difference (SMD) for preclinical data and pooled relative risk (RR) for clinical data, with 95% confidence intervals (CI). Potential effect modifiers were investigated via subgroup analysis. Certainty of evidence was assessed using the GRADE system.

RESULTS

Twenty-three preclinical studies and six clinical studies met eligibility criteria. Statistically significant improvements were seen across several preclinical outcomes, including alveolarization (SMD, 1.32, 95%CI [0.99, 1.65]), angiogenesis (SMD, 1.53, 95%CI [0.87, 2.18]), and anti-inflammatory cytokines (SMD, 1.68, 95%CI [1.03, 2.34]). In clinical studies, 103 preterm infants have received UCB-derived therapy for preterm lung injury and no significant difference was observed in the development of BPD (RR, 0.93, 95%CI [0.73, 1.18]). Across both preclinical and clinical studies, administration of UCB-derived therapy appeared safe. Certainty of evidence was assessed as "low."

CONCLUSIONS

Administration of UCB-derived therapy was associated with statistically significant improvements across several lung injury markers in preclinical studies. Early clinical studies demonstrated the administration of UCB-derived therapy as safe and feasible but lacked data regarding efficacy.

Progress on Electro-Enhancement of Cell Manufacturing

With the long persistence of complex, chronic diseases in society, there is increasing motivation to develop cells as living medicine to treat diseases ranging from cancer to wounds. While cell therapies can significantly impact healthcare, the shortage of starter cells meant that considerable raw materials must be channeled solely for cell expansion, leading to expensive products with long manufacturing time which can prevent accessibility by patients who either cannot afford the treatment or have highly aggressive diseases and cannot wait that long. Over the last three decades, there has been increasing knowledge on the effects of electrical modulation on proliferation, but to the best of the knowledge, none of these studies went beyond how electro-control of cell proliferation may be extended to enhance industrial scale cell manufacturing. Here, this review is started by discussing the importance of maximizing cell yield during manufacturing before comparing strategies spanning biomolecular/chemical/physical to modulate cell proliferation. Next, the authors describe how factors governing invasive and non-invasive electrical stimulation (ES) including capacitive coupling electric field may be modified to boost cell manufacturing. This review concludes by describing what needs to be urgently performed to bridge the gap between academic investigation of ES to industrial applications.

Human-Immune-System (HIS) humanized mouse model (DRAGA: HLA-A2.HLA-DR4.Rag1KO.IL-2RγcKO.NOD) for COVID-19

We report a Human Immune System (HIS)-humanized mouse model ("DRAGA": HLA-A2.HLA-DR4.Rag1KO.IL-2 RγcKO.NOD) for COVID-19 research. DRAGA mice express transgenically HLA-class I and class-II molecules in the mouse thymus to promote human T cell development and human B cell Ig-class switching. When infused with human hematopoietic stem cells from cord blood reconstitute a functional human immune system, as well as human epi/endothelial cells in lung and upper respiratory airways expressing the human ACE2 receptor for SARS-CoV-2. The DRAGA mice were able to sustain SARS-CoV-2 infection for at least 25 days. Infected mice showed replicating virus in the lungs, deteriorating clinical condition, and human-like lung immunopathology including human lymphocyte infiltrates, microthrombi and pulmonary sequelae. Among the intra-alveolar and peri-bronchiolar lymphocyte infiltrates, human lung-resident (CD103+) CD8+ and CD4+ T cells were sequestered in epithelial (CD326+) lung niches and secreted granzyme B and perforin, suggesting anti-viral cytotoxic activity. Infected mice also mounted human IgG antibody responses to SARS-CoV-2 viral proteins. Hence, HIS-DRAGA mice showed unique advantages as a surrogate in vivo human model for studying SARS-CoV-2 immunopathological mechanisms and testing the safety and efficacy of candidate vaccines and therapeutics.

Biodistribution studies for cell therapy products: Current status and issues

Information on the biodistribution (BD) of cell therapy products (CTPs) is essential for prediction and assessment of their efficacy and toxicity profiles in non-clinical and clinical studies. To conduct BD studies, it is necessary to understand regulatory requirements, implementation status, and analytical methods. This review aimed at surveying international and Japanese trends concerning the BD study for CTPs and the following subjects were investigated, which were considered particularly important: 1) comparison of guidelines to understand the regulatory status of BD studies in a global setting; 2) case studies of the BD study using databases to understand its current status in cell therapy; 3) case studies on quantitative polymerase chain reaction (qPCR) used primarily in non-clinical BD studies for CTPs; and 4) survey of imaging methods used for non-clinical and clinical BD studies. The results in this review will be a useful resource for implementing BD studies.

Application of Mesenchymal Stem Cells in Inflammatory and Fibrotic Diseases

Mesenchymal stem cells (MSCs) are multipotent stem cells that can be isolated from various tissues in the adult body. MSCs should be characterized by three criteria for regenerative medicine. MSCs must (1) adhere to plastic surfaces, (2) express specific surface antigens, and (3) differentiate into mesodermal lineages, including chondrocytes, osteoblasts, and adipocytes, in vitro. Interestingly, MSCs have immunomodulatory features and secrete trophic factors and immune receptors that regulate the microenvironment in host tissue. These specific and unique therapeutic properties make MSCs ideal as therapeutic agents in vivo. Specifically, pre-clinical and clinical investigators generated inflammatory and fibrotic diseases models, and then transplantation of MSCs into diseases models for therapeutic effects investigation. In this review, we characterize MSCs from various tissues and describe their applications for treating various inflammation and fibrotic diseases.

Stromal cell-derived factor-1 (SDF-1) expression in very preterm human lungs: potential relevance for stem cell therapy for bronchopulmonary dysplasia

Background: The axis formed by CXC chemokine receptor 4 (CXCR4), expressed on mesenchymal stromal cells (MSCs), and stromal cell-derived factor-1 (SDF-1), expressed in recipient organs, is a critical mediator of MSC migration in non-pulmonary injury models. The role and regulation of SDF-1 expression in preterm lungs, of potential relevance for MSC-based cell therapy for bronchopulmonary dysplasia (BPD), is unknown. The aim of this study was to determine the spatiotemporal pattern of CXCR4/SDF-1 expression in lungs of extremely preterm infants at risk for BPD.Methods: Postmortem lung samples were collected from ventilated extremely preterm infants who died between 23 and 29 wks ("short-term ventilated") or between 36 and 39 wks ("long-term ventilated") corrected postmenstrual age. Results were compared with age-matched infants who had lived <12 h or stillborn infants ("early" and "late" controls). CXCR4 and SDF-1 expression was studied by immunohistochemistry, immunofluorescence/confocal microscopy, and qRT-PCR analysis.Results: Compared with age-matched controls without antenatal infection, lungs of early control infants with evidence of intrauterine infection/inflammation showed significant upregulation of SDF-1 expression, localized to the respiratory epithelium, and of CXCR4 expression, localized to stromal cells. Similarly, pulmonary SDF-1 mRNA levels were significantly higher in long-term ventilated ex-premature infants with established BPD than in age-matched controls. The pulmonary vasculature was devoid of SDF-1 expression at all time points. Endogenous CXCR4-positive stromal cells were preferentially localized along the basal aspect of SDF-1-positive bronchial and respiratory epithelial cells, suggestive of functionality of the CXCR4/SDF-1 axis.Conclusions: Incipient and established neonatal lung injury is associated with upregulation of SDF-1 expression, restricted to the respiratory epithelium. Knowledge of the clinical associations, time-course and localization of pulmonary SDF-1 expression may guide decisions about the optimal timing and delivery route of MSC-based cell therapy for BPD.

Use of Autologous Cord Blood Mononuclear Cells Infusion for the Prevention of Bronchopulmonary Dysplasia in Extremely Preterm Neonates: A Study Protocol for a Placebo-Controlled Randomized Multicenter Trial [NCT03053076]

Background: Despite the rapid advance of neonatal care, bronchopulmonary dysplasia (BPD) remains a significant burden for the preterm population, and there is a lack of effective intervention. Stem cell depletion because of preterm birth is regarded as one of the underlying pathological mechanisms for the arrest of alveolar and vascular development. Preclinical and small-sample clinical studies have proven the efficacy and safety of stem cells in treating and preventing lung injury. However, there are currently no randomized clinical trials (RCTs) investigating the use of autologous cord blood mononuclear cells (ACBMNC) for the prevention of BPD in premature infants. The purpose of this study is to investigate the effects of infusion of ACBMNC for the prevention of BPD in preterm neonates <28 weeks. Methods: In this prospective, randomized controlled double-blind multi-center clinical trial, 200 preterm neonates <28 weeks gestation will be randomly assigned to receive intravenous ACBMNC infusion (5 × 107 cells/kg) or placebo (normal saline) within 24 h after birth in a 1:1 ratio using a central randomization system. The primary outcome will be survival without BPD at 36 weeks of postmenstrual age or at discharge, whichever comes first. The secondary outcomes will include the mortality rate, other common preterm complication rates, respiratory support duration, length, and cost of hospitalization, and long-term outcomes after a 2-year follow-up. Conclusion: This will be the first randomized, controlled, blinded trial to evaluate the efficacy of ACBMNC infusion as a prevention therapy for BPD. The results of this trial will provide valuable clinical evidence for recommendations on the management of BPD in extremely preterm infants. Clinical Trial Registration: ClinicalTrials.gov, NCT03053076, registered 02/14/2017, retrospectively registered, https://register.clinicaltrials.gov/prs/app/action/SelectProtocol?sid=S0006WN4&selectaction=Edit&uid=U0002PLA&ts=2&cx=9y23d4 (Additional File 2).

Umbilical Cord Blood Cells Do Not Reduce Ventilation-Induced Lung Injury in Preterm Lambs

Background

Preterm infants often have immature lungs and, consequently, many require respiratory support at birth. However, respiratory support causes lung inflammation and injury, termed ventilation-induced lung injury (VILI). Umbilical cord blood (UCB) contains five cell types that have been shown to reduce inflammation and injury. The aim of this study was to determine whether UCB cells can reduce VILI in preterm lambs.

Methods

We assessed lung inflammation and injury, with and without UCB cell administration. Fetal lambs at 125 ± 1 days gestation underwent sterile surgery and were randomly allocated to one of four groups; unoperated controls (UNOP), sham controls (SHAM), injuriously ventilated lambs (VILI), and injuriously ventilated lambs that received UCB cells via the jugular vein 1 h after ventilation (VILI_CELLS). Ventilated lambs received an injurious ventilation strategy for 15 min, before they were returned to the uterus and the lamb and ewe recovered for 24 h. After 24 h, lambs were delivered via caesarean section and euthanized and the lungs were collected for histological and molecular assessment of inflammation and injury.

Results

VILI led to increased immune cell infiltration, increased cellular proliferation, increased tissue wall thickness, and significantly reduced alveolar septation compared to controls. Further, extracellular matrix proteins collagen and elastin had abnormal deposition following VILI compared to control groups. Administration of UCB cells did not reduce any of these indices.

Conclusion

Administration of UCB cells 1 h after ventilation onset did not reduce VILI in preterm lambs.

Pathology of Neonatal Non- albicans Candidiasis: Autopsy Study and Literature Review

INTRODUCTION/OBJECTIVES

Non- albicans Candida species such as Candida parapsilosis and Candida glabrata have emerged as prevalent pathogens in premature infants. The aim of this study was to systematically delineate the histopathologic findings in neonatal non- albicans candidiasis.

METHODS

We performed a retrospective clinicopathologic analysis of extremely premature (23-28 weeks' gestation) infants diagnosed with invasive candidiasis. Archival autopsy tissues were subjected to periodic acid-Schiff, methenamine-silver and anti- Candida (immuno)histochemical stains, as well as dual anti- Candida and anti-cytokeratin or anti-CD31 immunofluorescence assays. In addition, we studied the prevalence of intestinal Candida colonization in a consecutive autopsy series of extremely premature infants.

RESULTS

Based on positive postmortem blood and/or lung cultures, invasive candidiasis (3 non- albicans and 11 Candida albicans) was diagnosed in 14 of the 187 extremely premature infants examined between 1995 and 2017. In contrast to the well-known inflammatory and tissue-destructive phenotype of congenital C. albicans infection, invasive non- albicans candidiasis/candidemia caused by C. parapsilosis and C. glabrata was inconspicuous by routine hematoxylin-eosin-based histopathologic analysis despite a heavy fungal presence detected in intestines, lungs, and blood by targeted (immuno)histochemical assays. Intestinal colonization by Candida species was identified in 16 of the 26 (61%) extremely premature neonates who had lived for at least 1 week, as assessed by anti- Candida immunostaining.

CONCLUSION

Invasive neonatal non- albicans candidiasis/candidemia appears to have no distinct histopathologic signature. Based on the notoriously low sensitivity of fungal blood cultures and the observed high frequency of Candida intestinal colonization (>50%), it is likely that non- albicans candidiasis/candidemia may be underdiagnosed in (deceased) preterm infants. Routine inclusion of targeted (immuno)histochemical fungal detection strategies in the perinatal autopsy may lead to deeper insight into the prevalence and clinical relevance of neonatal non- albicans candidiasis.

Mesenchymal stem cells for therapeutic applications in pulmonary medicine

INTRODUCTION

Mesenchymal stem cells (MSCs) of different biological sources are in Phase 1 clinical trials and are being considered for Phase 2 therapy of lung disorders, and lung (progenitor) cells derived from pluripotent stem cells (SCs) are under development in preclinical animal models.

SOURCES OF DATA

PubMed.gov and ClinicalTrials.gov.

AREAS OF AGREEMENT

There is consensus about the therapeutic potential of transplanted SCs, mainly MSCs, primarily involves paracrine 'bystander' effects that confer protection of the epithelial and endothelial linings of the lung caused by inflammation and/or fibrosis and lead to increased survival in animal models. Clinical trials of Phase 1 indicate safety and suggest that the efficacy of SC therapy in patients with various lung diseases will require a higher dosage than previously evaluated.

AREAS OF CONTROVERSY

A growing interest in the re-epithelialization and re-endothelialization of damaged lung tissue involves the putative pulmonary differentiation of exogenous MSCs. Currently, it is not clear whether or not the observed regeneration of distal airways/vasculature is derived from lung-resident and/or transplanted SCs.

GROWING POINTS

Important topics under investigation include optimization of the cell source with a decrease in cell population heterogeneity characterized by defined markers, route of delivery for effective treatment, potential dose and therapeutic protocol of SC application, development of quantitative assays and biomarkers of lung disease and repair, and the potential use of tissue engineered lung.

AREAS TIMELY FOR DEVELOPING RESEARCH

Ability of MSCs to differentiate into epithelial cells of the lung, use of autologous induced pluripotent SCs (iPSCs) derived from the patients, complete biochemical characterization of the secretome of SCs used for therapy, and the incorporation of simultaneous and/or subsequent treatment with drugs which also aid in lung repair and regeneration.

CAUTIONARY NOTE

Although safety of MSC-based cell therapy was proved in Phase 1, efficacy, long-term survival and preservation of lung respiratory function need to be further evaluated, cautioning against hastily translating SCs therapy from animal models of lung injury to clinical trials of patients with lung disorders.

Human peripheral blood CD34+ cells attenuate oleic acid-induced acute lung injury in rats

BACKGROUND AIMS

Adult stem cell-based therapy is a promising novel approach for treatment of acute lung injury (ALI). In this study, we evaluated the therapeutic effect of isolated human peripheral blood CD34+ progenitor cells in an ALI rat model, induced by oleic acid (OA) injection.

METHODS

Seventy-five adult female rats were used in this study. Group A, control without treatment, and group B, control injected with phosphate-buffered saline, comprised 15 rats each; the remaining 45 rats were injected with OA to induce ALI and were further subdivided into 3 groups: group C (ALI group, 15 rats), group D (ALI and fibroblast group, 15 rats) and group E (ALI and CD34+ cell group, 15 rats).

RESULTS

CD34+ cells transplantation in rats with OA-induced lung injury improves the arterial PaO(2) and wet/dry ratio, reduces infiltration of inflammatory cells and decreases lung vascular permeability as determined by reduced intra-alveolar and interstitial patchy congestion and hemorrhage as well as decreased interstitial edema. Additionally, lung inflammation determined by expression of the pro-inflammatory mediators intercellular adhesion molecule 1 and tumor necrosis factor-α was attenuated in CD34+ cell-treated rats at 6, 24 and 48 h post-OA challenge compared with non-treated rats. Moreover, the expression of anti-inflammatory molecule interleukin-10 was up-regulated in the lung of OA-induced ALI rats after administration of CD34+ cells. The important finding was that human TNF-α-induced protein 6 (TSG-6) gene expression was significantly up-regulated in rats treated with CD34+ cells.

CONCLUSIONS

The freshly isolated human peripheral blood-derived CD34+ cells may be used as an important source of stem cells that improve ALI. The anti-inflammatory properties of CD34+ cells in the lung are explained, at least in part, by activation of CD34+ cells to express TSG-6.

Intranasal versus intraperitoneal delivery of human umbilical cord tissue-derived cultured mesenchymal stromal cells in a murine model of neonatal lung injury

Clinical trials investigating mesenchymal stromal cell (MSC) therapy for bronchopulmonary dysplasia have been initiated; however, the optimal delivery route and functional effects of MSC therapy in newborns remain incompletely established. We studied the morphologic and functional effects of intranasal versus i.p. MSC administration in a rodent model of neonatal lung injury. Cultured human cord tissue MSCs (0.1, 0.5, or 1 × 10(6) cell per pup) were given intranasally or i.p. to newborn severe combined immunodeficiency-beige mice exposed to 90% O2 from birth; sham controls received an equal volume of phosphate-buffered saline. Lung mechanics, engraftment, lung growth, and alveolarization were evaluated 8 weeks after transplantation. High-dose i.p. MSC administration to newborn mice exposed to 90% O2 resulted in the restoration of normal lung compliance, elastance, and pressure-volume loops (tissue recoil). Histologically, high-dose i.p. MSC administration was associated with alveolar septal widening, suggestive of interstitial matrix modification. Intranasal MSC or lower-dose i.p. administration had no significant effects on lung function or alveolar remodeling. Pulmonary engraftment was rare in all the groups. These findings suggest that high-dose systemic administration of human cultured MSCs can restore normal compliance in neonatally injured lungs, possibly by paracrine modulation of the interstitial matrix. Intranasal delivery had no obvious pulmonary effects.

Concise review: current status of stem cells and regenerative medicine in lung biology and diseases

Lung diseases remain a significant and devastating cause of morbidity and mortality worldwide. In contrast to many other major diseases, lung diseases notably chronic obstructive pulmonary diseases (COPDs), including both asthma and emphysema, are increasing in prevalence and COPD is expected to become the third leading cause of disease mortality worldwide by 2020. New therapeutic options are desperately needed. A rapidly growing number of investigations of stem cells and cell therapies in lung biology and diseases as well as in ex vivo lung bioengineering have offered exciting new avenues for advancing knowledge of lung biology as well as providing novel potential therapeutic approaches for lung diseases. These initial observations have led to a growing exploration of endothelial progenitor cells and mesenchymal stem (stromal) cells in clinical trials of pulmonary hypertension and COPD with other clinical investigations planned. Ex vivo bioengineering of the trachea, larynx, diaphragm, and the lung itself with both biosynthetic constructs as well as decellularized tissues have been used to explore engineering both airway and vascular systems of the lung. Lung is thus a ripe organ for a variety of cell therapy and regenerative medicine approaches. Current state-of-the-art progress for each of the above areas will be presented as will discussion of current considerations for cell therapy-based clinical trials in lung diseases.

Stem cells, cell therapies, and bioengineering in lung biology and diseases. Comprehensive review of the recent literature 2010-2012

A conference, "Stem Cells and Cell Therapies in Lung Biology and Lung Diseases," was held July 25 to 28, 2011 at the University of Vermont 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 rapidly expanding areas of study that 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, to discuss and debate current controversies, and to identify future research directions and opportunities for basic and translational research in cell-based therapies for lung diseases. The goal of this article, which accompanies the formal conference report, is to provide a comprehensive review of the published literature in lung regenerative medicine from the last conference report through December 2012.

Strategies for whole lung tissue engineering

Recent work has demonstrated the feasibility of using decellularized lung extracellular matrix scaffolds to support the engineering of functional lung tissue in vitro. Rendered acellular through the use of detergents and other reagents, the scaffolds are mounted in organ-specific bioreactors where cells in the scaffold are provided with nutrients and appropriate mechanical stimuli such as ventilation and perfusion. Though initial studies are encouraging, a great deal remains to be done to advance the field and transition from rodent lungs to whole human tissue engineered lungs. To do so, a variety of hurdles must be overcome. In particular, a reliable source of human-sized scaffolds, as well as a method of terminal sterilization of scaffolds, must be identified. Continued research in lung cell and developmental biology will hopefully help identify the number and types of cells that will be required to regenerate functional lung tissue. Finally, bioreactor designs must be improved in order to provide more precise ventilation stimuli and vascular perfusion in order to avoid injury to or death of the cells cultivated within the scaffold. Ultimately, the success of efforts to engineer a functional lung in vitro will critically depend on the ability to create a fully endothelialized vascular network that provides sufficient barrier function and alveolar-capillary surface area to exchange gas at rates compatible with healthy lung function.

Human CD34+ progenitor cells freshly isolated from umbilical cord blood attenuate inflammatory lung injury following LPS challenge

Adult stem cell-based therapy is a promising novel approach for treatment of acute lung injury. Here we investigated the therapeutic potential of freshly isolated human umbilical cord blood CD34⁺ progenitor cells (fCB-CD34⁺ cells) in a mouse model of acute lung injury. At 3 h post-lipopolysaccharide (LPS) challenge, fCB-CD34⁺ cells were transplanted i.v. to mice while CD34⁻ cells or PBS were administered as controls in separate cohorts of mice. We observed that fCB-CD34⁺ cell treatment inhibited lung vascular injury evident by decreased lung vascular permeability. In contrast, CD34⁻ cells had no effects on lung vascular injury. Lung inflammation determined by myeloperoxidase activity, neutrophil sequestration and expression of pro-inflammatory mediators was attenuated in fCB-CD34⁺ cell-treated mice at 26 h post-LPS challenge compared to PBS or CD34⁻ cell-treated controls. Importantly, lung inflammation in fCB-CD34⁺ cell-treated mice was returned to normal levels as seen in basal mice at 52 h post-LPS challenge whereas PBS or CD34⁻ cell-treated control mice exhibited persistent lung inflammation. Accordingly, fCB-CD34⁺ cell-treated mice exhibited a marked increase of survival rate. Employing in vivo 5-bromo-2′-deoxyuridine incorporation assay, we found a drastic induction of lung endothelial proliferation in fCB-CD34⁺ cell-treated mice at 52 h post-LPS compared to PBS or CD34⁻ cell-treated controls, which contributed to restoration of vascular integrity and thereby inhibition of lung inflammation. Taken together, these data have demonstrated the protective effects of fCB-CD34⁺ cell on acute lung injury induced by LPS challenge, suggesting fCB-CD34⁺ cells are an important source of stem cells for the treatment of acute lung injury.

Stem cell experiments moves into clinic: new hope for children with bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease with long-term complications that affects mainly preterm born children with low birth weights, especially those treated with mechanical ventilation and oxygen therapy. Successful treatment of BPD could reduce the incidence of other diseases of prematurity such as periventricular leukomalacia and retinopathy. The effects of current therapies are unsatisfactory; thus, searching for novel therapeutic is underway. One promising approach seems administration of mesenchymal stem cells (MSC). Preclinical data strongly support the role of progenitor cells in the preservation of lung structure. MSC can be found more often in pre-term than term umbilical cord and its isolation from Wharton's jelly carries a potential in treating diseases of prematurity. Several questions concerning the use of MSC in BPD remain to be answered, including the amount of transferred cells, intervals between infusions, the best route for administration and the timing. MSC can be administered as a treatment or prophylaxis. However, having in mind that not all prematurely born children are at risk of developing bronchopulmonary dysplasia, a search for laboratory markers identifying potential patients should be conducted. This review summarizes the latest achievements in MSC therapy in the context of BPD.

Induced pluripotent stem cells without c-Myc reduce airway responsiveness and allergic reaction in sensitized mice

BACKGROUND

Allergic disorders have increased substantially in recent years. Asthma is characterized by airway damage and remodeling. Reprogramming induced pluripotent stem cells (iPSCs) from adult somatic cells transfected by Oct-4/Sox-2/Klf-4, but not c-Myc, has shown the potential of embryonic-like cells. These cells have potential for multilineage differentiation and provide a resource for stem cell-based utility. However, the therapeutic potential of iPSCs without c-Myc (iPSC-w/o-c-Myc) in allergic diseases and airway hyperresponsiveness has not been investigated. The aim of this study was to evaluate the therapeutic effect of iPSC-w/o-c-Myc transplantation in a murine asthma model.

METHODS

BALB/c mice were sensitized with alum-adsorbed ovalbumin (OVA) and then challenged with aerosolized OVA. Phosphate-buffered saline or iPSC-w/o-c-Myc was then intravenously injected after inhalation. Serum allergen-specific antibody levels, airway hyperresponsiveness, cytokine levels in spleen cells and bronchoalveolar lavage fluid (BALF), and cellular distribution in BALF were then examined.

RESULTS

Treatment with iPSC-w/o-c-Myc effectively suppressed both Th1 and Th2 antibody responses, which was characterized by reduction in serum allergen-specific IgE, IgG, IgG1, and IgG2a levels as well as in interleukin-5 and interferon-γ levels in BALF and in OVA-incubated splenocytes. Meanwhile, regulatory cytokine, interleukin-10, was enhanced. Transplantation of iPSC-w/o-c-Myc also significantly attenuated cellular infiltration in BALF and allergic airway hyperresponsiveness. However, no tumor formation was observed 6 months after transplantation.

CONCLUSIONS

Administration of iPSC-w/o-c-Myc not only inhibited Th1 inflammatory responses but also had therapeutic effects on systemic allergic responses and airway hyperresponsiveness. iPSC-w/o-c-Myc transplantation may be a potential modality for treating allergic reactions and bronchial asthma.

Ex vivo expanded human cord blood-derived hematopoietic progenitor cells induce lung growth and alveolarization in injured newborn lungs

BACKGROUND

We investigated the capacity of expanded cord blood-derived CD34+ hematopoietic progenitor cells to undergo respiratory epithelial differentiation ex vivo, and to engraft and attenuate alveolar disruption in injured newborn murine lungs in vivo.

METHODS

Respiratory epithelial differentiation was studied in CD34+ cells expanded in the presence of growth factors and cytokines ("basic" medium), in one group supplemented with dexamethasone ("DEX"). Expanded or freshly isolated CD34+ cells were inoculated intranasally in newborn mice with apoptosis-induced lung injury. Pulmonary engraftment, lung growth and alveolarization were studied at 8 weeks post-inoculation.

RESULTS

SP-C mRNA expression was seen in 2/7 CD34+ cell isolates expanded in basic media and in 6/7 isolates expanded in DEX, associated with cytoplasmic SP-C immunoreactivity and ultrastructural features suggestive of type II cell-like differentiation. Administration of expanding CD34+ cells was associated with increased lung growth and, in animals treated with DEX-exposed cells, enhanced alveolar septation. Freshly isolated CD34+ cells had no effect of lung growth or remodeling. Lungs of animals treated with expanded CD34+ cells contained intraalveolar aggregates of replicating alu-FISH-positive mononuclear cells, whereas epithelial engraftment was extremely rare.

CONCLUSION

Expanded cord blood CD34+ cells can induce lung growth and alveolarization in injured newborn lungs. These growth-promoting effects may be linked to paracrine or immunomodulatory effects of persistent cord blood-derived mononuclear cells, as expanded cells showed limited respiratory epithelial transdifferentiation.

Lung injury in preterm neonates: the role and therapeutic potential of stem cells

Continuous improvements in perinatal care have allowed the survival of ever more premature infants, making the task of protecting the extremely immature lung from injury increasingly challenging. Premature infants at risk of developing chronic lung disease or bronchopulmonary dysplasia (BPD) are now born at the late canalicular stage of lung development, just when the airways become juxtaposed to the lung vasculature and when gas-exchange becomes possible. Readily available strategies, including improved antenatal management (education, regionalization, steroids, and antibiotics), together with exogenous surfactant and exclusive/early noninvasive ventilatory support, will likely decrease the incidence/severity of BPD over the next few years. Nonetheless, because of the extreme immaturity of the developing lung, the extent to which disruption of lung growth after prematurity and neonatal management lead to an earlier or more aggravated decline in respiratory function in later life is a matter of concern. Consequently, much more needs to be learned about the mechanisms of lung development, injury, and repair. Recent insight into stem cell biology has sparked interest for stem cells to repair damaged organs. This review summarizes the exciting potential of stem cell-based therapies for lung diseases in general and BPD in particular.

Glycochenodeoxycholate induces rat alveolar epithelial type II cell death and inhibits surfactant secretion in vitro

Bile acid-induced lung injury has become an important topic for neonatologists after the discovery of a high incidence of infant respiratory distress syndrome complicated from maternal intrahepatic cholestasis. To explore the molecular pathway of bile acid-induced lung injury, we investigated the cytotoxicity of the glycochenodeoxycholate (GCDC) to alveolar epithelial type II cells (AECII), as the main component of bile acid. The results demonstrated that glycochenodeoxycholate induced oxidative stress, mitochondrial damage, and increased caspase activity in the primary cultured AECII. Moreover, ROS scavengers and caspase inhibitors could rescue cell death induced by GCDC in rat AECII. Our results also indicated that GCDC inhibited AECII surfactant secretion. In conclusion, this study suggested that cell death prevention and cell therapy should be considered as therapeutic strategies for infant respiratory distress syndrome complicated from maternal intrahepatic cholestasis.

Resilience of the human fetal lung following stillbirth: potential relevance for pulmonary regenerative medicine

Recent advances in pulmonary regenerative medicine have increased the demand for alveolar epithelial progenitor cells. Fetal lung tissues from spontaneous pregnancy losses may represent a neglected, yet ethically and societally acceptable source of alveolar epithelial cells. The aim of this study was to determine the regenerative capacity of fetal lungs obtained from second trimester stillbirths. Lung tissues were harvested from 11 stillborn fetuses (13 to 22 weeks' gestation) at postdelivery intervals ranging from 10 to 41 hours and grafted to the renal subcapsular space of immune-suppressed rats to provide optimal growth conditions. Histology, epithelial and alveolar type II cell proliferation, and surfactant protein-C mRNA expression were studied in preimplantation lung tissues and in xenografts at posttransplantation week 2. All xenografts displayed advanced architectural maturation compared with their respective preimplantation tissues, regardless of gestational age and postdelivery interval. The proliferative activity of the grafts was significantly higher than that of the preimplantation tissues (mean Ki-67 labeling index 26.7%±7.7% versus 14.7%±10.5%; P<.01). The proliferative activity of grafts obtained after a long (>36 hours) postdelivery interval was significantly higher than that of the corresponding preimplantation tissue, and equivalent to that of grafts obtained after a short postdelivery interval (<14 hours). The regenerative capacity of fetal lung tissue was greater at younger (13 to 17 weeks) than at older (19 to 22 weeks) gestational ages. The presence of inflammation/chorioamnionitis did not appear to affect graft regeneration. All grafts studied displayed robust surfactant protein-C mRNA expression. In conclusion, fetal lung tissues from second trimester stillbirths can regain their inherent high regenerative potential following short-term culture, even if harvested more than 36 hours after delivery.