The transcriptome of nitrofen-induced pulmonary hypoplasia in the rat model of congenital diaphragmatic hernia

Fetal hypoplastic lungs have multilineage inflammation that is reversed by amniotic fluid stem cell extracellular vesicle treatment

Antenatal administration of extracellular vesicles from amniotic fluid stem cells (AFSC-EVs) reverses features of pulmonary hypoplasia in models of congenital diaphragmatic hernia (CDH). However, it remains unknown which lung cellular compartments and biological pathways are affected by AFSC-EV therapy. Herein, we conducted single-nucleus RNA sequencing (snRNA-seq) on rat fetal CDH lungs treated with vehicle or AFSC-EVs. We identified that intra-amniotically injected AFSC-EVs reach the fetal lung in rats with CDH, where they promote lung branching morphogenesis and epithelial cell differentiation. Moreover, snRNA-seq revealed that rat fetal CDH lungs have a multilineage inflammatory signature with macrophage enrichment, which is reversed by AFSC-EV treatment. Macrophage enrichment in CDH fetal rat lungs was confirmed by immunofluorescence, flow cytometry, and inhibition studies with GW2580. Moreover, we validated macrophage enrichment in human fetal CDH lung autopsy samples. Together, this study advances knowledge on the pathogenesis of pulmonary hypoplasia and further evidence on the value of an EV-based therapy for CDH fetuses.

Extracellular matrix and cyclic stretch alter fetal cardiomyocyte proliferation and maturation in a rodent model of heart hypoplasia

Introduction

Birth defects, particularly those that affect development of the heart, are a leading cause of morbidity and mortality in infants and young children. Babies born with heart hypoplasia (heart hypoplasia) disorders often have a poor prognosis. It remains unclear whether cardiomyocytes from hypoplastic hearts retain the potential to recover growth, although this knowledge would be beneficial for developing therapies for heart hypoplasia disorders. The objective of this study was to determine the proliferation and maturation potential of cardiomyocytes from hypoplastic hearts and whether these behaviors are influenced by biochemical signaling from the extracellular matrix (ECM) and cyclic mechanical stretch.

Method

Congenital diaphragmatic hernia (CDH)-associated heart hypoplasia was induced in rat fetuses by maternal exposure to nitrofen. Hearts were isolated from embryonic day 21 nitrofen-treated fetuses positive for CDH (CDH+) and from fetuses without nitrofen administration during gestation.

Results and discussion

CDH+ hearts were smaller and had decreased myocardial proliferation, along with evidence of decreased maturity compared to healthy hearts. In culture, CDH+ cardiomyocytes remained immature and demonstrated increased proliferative capacity compared to their healthy counterparts. Culture on ECM derived from CDH+ hearts led to a significant reduction in proliferation for both CDH+ and healthy cardiomyocytes. Healthy cardiomyocytes were dosed with exogenous nitrofen to examine whether nitrofen may have an aberrant effect on the proliferative ability of cardiomyocyte, yet no significant change in proliferation was observed. When subjected to stretch, CDH+ cardiomyocytes underwent lengthening of sarcomeres while healthy cardiomyocyte sarcomeres were unaffected. Taken together, our results suggest that alterations to environmental cues such as ECM and stretch may be important factors in the pathological progression of heart hypoplasia.

Malarial PI4K inhibitor induced diaphragmatic hernias in rat: Potential link with mammalian kinase inhibition

Background

MMV390048 is an aminopyridine plasmodial PI4K inhibitor, selected as a Plasmodium blood‐stage schizonticide for a next generation of malaria treatments to overcome resistance to current therapies. MMV390048 showed an acceptable preclinical safety profile and progressed up to Phase 2a clinical trials. However, embryofetal studies revealed adverse developmental toxicity signals, including diaphragmatic hernias and cardiovascular malformations in rats but not rabbits.

Methods

In vivo exposures of free plasma concentrations of compound in rats were assessed in relation to in vitro human kinase inhibition by MMV390048, using the ADP‐Glo™ Kinase Assay.

Results

We demonstrate a potential link between the malformations seen in the embryofetal developmental (EFD) studies and inhibition of the mammalian PI4Kβ paralogue, as well as inhibition of the off‐target kinases MAP4K4 and MINK1. PI3Kγ may also play a role in the embryofetal toxicity as its in vitro inhibition is covered by in vivo exposure. The exposures in the rabbit embryofetal development studies did not reach concentrations likely to cause PI4K inhibition. Overall, we hypothesize that the in vivo malformations observed could be due to inhibition of the PI4K target in combination with the off‐targets, MAP4K4 and MINK1. However, these relationships are by association and not mechanistically proven.

Conclusions

Deciphering if the EFD effects are dependent on PI4K inhibition, and/or via inhibition of other off‐target kinases will require the generation of novel, more potent, and more specific PI4K inhibitors.

Fetal lung regeneration using stem cell-derived extracellular vesicles: A new frontier for pulmonary hypoplasia secondary to congenital diaphragmatic hernia

The poor outcomes of babies with congenital diaphragmatic hernia (CDH) are directly related to pulmonary hypoplasia, a cosndition characterized by impaired lung development. Although the pathogenesis of pulmonary hypoplasia is not fully elucidated, there is now evidence that CDH patients have missing or dysregulated microRNAs (miRNAs) that regulate lung development. A prenatal therapy that supplements these missing/dysregulated miRNAs could be a strategy to rescue normal lung development. Extracellular vesicles (EVs), also known as exosomes when of small dimensions, are lipid-bound nanoparticles that can transfer their heterogeneous cargo (proteins, lipids, small RNAs) to target cells to induce biological responses. Herein, we review all studies that show evidence for stem cell-derived EVs as a regenerative therapy to rescue normal development in CDH fetal lungs. Particularly, we report studies showing that administration of EVs derived from amniotic fluid stem cells (AFSC-EVs) to models of pulmonary hypoplasia promotes fetal lung growth and maturation via transfer of miRNAs that are known to regulate lung developmental processes. We also describe that stem cell-derived EVs exert effects on vascular remodeling, thus possibly preventing postnatal pulmonary hypertension. Finally, we discuss future perspectives and challenges to translate this promising stem cell EV-based therapy to clinical practice. This article is protected by copyright. All rights reserved.

Fetal lung underdevelopment is rescued by administration of amniotic fluid stem cell extracellular vesicles in rodents

Fetal lung underdevelopment, also known as pulmonary hypoplasia, is characterized by decreased lung growth and maturation. The most common birth defect found in babies with pulmonary hypoplasia is congenital diaphragmatic hernia (CDH). Despite research and clinical advances, babies with CDH still have high morbidity and mortality rates, which are directly related to the severity of lung underdevelopment. To date, there is no effective treatment that promotes fetal lung growth and maturation. Here, we describe a stem cell-based approach in rodents that enhances fetal lung development via the administration of extracellular vesicles (EVs) derived from amniotic fluid stem cells (AFSCs). Using fetal rodent models of pulmonary hypoplasia (primary epithelial cells, organoids, explants, and in vivo), we demonstrated that AFSC-EV administration promoted branching morphogenesis and alveolarization, rescued tissue homeostasis, and stimulated epithelial cell and fibroblast differentiation. We confirmed this regenerative ability in in vitro models of lung injury using human material, where human AFSC-EVs obtained following good manufacturing practices restored pulmonary epithelial homeostasis. Investigating EV mechanism of action, we found that AFSC-EV beneficial effects were exerted via the release of RNA cargo. MicroRNAs regulating the expression of genes involved in lung development, such as the miR17-92 cluster and its paralogs, were highly enriched in AFSC-EVs and were increased in AFSC-EV-treated primary lung epithelial cells compared to untreated cells. Our findings suggest that AFSC-EVs hold regenerative ability for underdeveloped fetal lungs, demonstrating potential for therapeutic application in patients with pulmonary hypoplasia.

Basic and translational science advances in congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is a birth defect that is characterized by lung hypoplasia, pulmonary hypertension and a diaphragmatic defect that allows herniation of abdominal organs into the thoracic cavity. Although widely unknown to the public, it occurs as frequently as cystic fibrosis (1:2500). There is no monogenetic cause, but different animal models revealed various biological processes and epigenetic factors involved in the pathogenesis. However, the pathobiology of CDH is not sufficiently understood and its mortality still ranges between 30 and 50%. Future collaborative initiatives are required to improve our basic knowledge and advance novel strategies to (prenatally) treat the abnormal lung development. This review focusses on the genetic, epigenetic and protein background and the latest advances in basic and translational aspects of CDH research.

Absolute quantification of infecting viral particles by chip-based digital polymerase chain reaction

In silico and empirical quantification of viruses is paramount for obtaining information on viral populations that have a major impact on biogeochemical cycles. The uncultured Pelagibacter virus vSAG 37-F6 discovered via single-virus genomics is one of the most abundant and cosmopolitan marine viruses; however, little is understood about its temporal variation. Here, we estimated the absolute number of infecting 37-F6 viruses in coastal bacterioplankton from the Mediterranean Sea by using a novel, feasible SYBR Green I chip-based digital PCR (SYBR dPCR) technique, not implemented before for enumerating (uncultured) microbes. Quantitative SYBR dPCR estimated 450-3480 genome copies of virus 37-F6 in cells/mL (i.e. infecting viruses) and a total of ≈10-400 putative infected cells/mL with a potential C release of 0.12-4.9 pg/ml in the analysed samples. Considering that virus 37-F6 is ubiquitous and abundant in all Tara samples, an enormous amount of C could be transformed by this virus through the 'viral shunt'. Thus, this SYBR dPCR technique has enabled the absolute quantification of an ecologically relevant uncultured virus in nature and the estimation of its potential contribution on biogeochemical cycles. Overall, our study also shows that this approach has a broad applicability for quantifying any other target loci in Microbiology and Virology.

Tandem mass tag (TMT) proteomic analysis of fetal lungs revealed differential expression of tight junction proteins in a rat model of congenital diaphragmatic hernia

OBJECTIVE

Congenital diaphragmatic hernia (CDH) is a common and often lethal birth defect characterized by congenital lung malformation, which severely affects neonate prognosis and mortality. This study aimed to investigate differences in protein expression in order to elucidate the mechanism of CDH-associated pulmonary hypoplasia during the early stage of lung development using tandem mass tag (TMT) quantitative proteomics.

METHODS

Nitrofen was administered orally to establish a rat CDH model, and pathological changes were evaluated through hematoxylin-eosin (H&E), PCNA, and Ki67 staining at the pseudoglandular stage. Fetal lungs were then collected, pooled before TMT labeling, and subjected to mass spectrometry. Immunohistochemistry (IHC), Western blotting, and Q-PCR were used to further validate the candidate proteins.

RESULTS

A total of 79 differentially expressed proteins (DEPs) were identified when CDH and control lungs were compared, and further bioinformatics analysis showed that these proteins play important roles in tight-junctions, phospholipase D signaling, and the HIF-1 signaling pathway. Three differentially expressed proteins, Cldn3, Magi1, and Myh9 are involved in the tight-junction pathway (P < 0.05), and their differential expressions were confirmed by IHC, Western blotting, and Q-PCR.

CONCLUSION

These findings indicate that alterations of tight-junction protein expression may play an important role in the pathogenesis of abnormal lung development in CDH. Further studies are warranted to verify the mechanism by which these tight-junction proteins influence the pathogenesis of CDH-associated pulmonary hypoplasia.

Retinoic Acid Induces Differentiation of Mouse F9 Embryonic Carcinoma Cell by Modulating the miR-485 Targeting of Abhd2

Retinoic acid (RA) plays a key role in pluripotent cell differentiation. In F9 embryonic carcinoma cells, RA can induce differentiation towards somatic lineages via the Ras-extracellular signal-regulated kinase (Ras/Erk) pathway, but the mechanism through which it induces the Erk1/2 phosphorylation is unclear. Here, we show that miR-485 is a positive regulator that targets α/β-hydrolase domain-containing protein 2 (Abhd2), which can result in Erk1/2 phosphorylation and triggers differentiation. RA up-regulates miR-485 and concurrently down-regulates Abhd2. We verified that Abhd2 is targeted by miR-485 and they both can influence the phosphorylation of Erk1/2. In summary, RA can mediate cell differentiation by phosphorylating Erk1/2 via miR-485 and Abhd2.

MIF inhibition enhances pulmonary angiogenesis and lung development in congenital diaphragmatic hernia

BACKGROUND

Congenital diaphragmatic hernia (CDH) is a complex birth anomaly with significant mortality and morbidity. Lung hypoplasia and persistent pulmonary hypertension (PPHN) limit survival in CDH. Macrophage migration inhibitory factor (MIF), a key regulator of innate immunity, is involved in hypoxia-induced vascular remodeling and PPHN. We hypothesized that antenatal inhibition of MIF in CDH fetuses, would reduce vascular remodeling, and improve angiogenesis and lung development.

METHODS

Pregnant rats were randomized into three groups: Control, nitrofen, and nitrofen + ISO-92. Lung volumes of pups were measured by CT scanning. Right ventricular systolic pressure (RVSP) and vascular wall thickness (VWT) were measured together with MIF concentration, angiogenesis markers, lung morphometry, and histology.

RESULTS

Prenatal treatment with ISO-92, an MIF inhibitor, improved normalization of static lung volume, lung volume-to-body weight ratio, decreased alveolar septal thickness, RVSP and VWT and improved radial alveolar count as compared to the non-treated group. Expression of MIF was unaffected by ISO-92; however, ISO-92 increased p-eNOS and VEGF activities and reduced arginase 1, 2 and Sflt-1.

CONCLUSION

Prenatal inhibition of MIF activity in CDH rat model improves angiogenesis and lung development. This selective intervention may be a future therapeutic strategy to reduce the morbidity and mortality of this devastating condition.

Pulmonary vascular development in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a rare congenital anomaly characterised by a diaphragmatic defect, persistent pulmonary hypertension (PH) and lung hypoplasia. The relative contribution of these three elements can vary considerably in individual patients. Most affected children suffer primarily from the associated PH, for which the therapeutic modalities are limited and frequently not evidence based. The vascular defects associated with PH, which is characterised by increased muscularisation of arterioles and capillaries, start to develop early in gestation. Pulmonary vascular development is integrated with the development of the airway epithelium. Although our knowledge is still incomplete, the processes involved in the growth and expansion of the vasculature are beginning to be unravelled. It is clear that early disturbances of this process lead to major pulmonary growth abnormalities, resulting in serious clinical challenges and in many cases death in the newborn. Here we provide an overview of the current molecular pathways involved in pulmonary vascular development. Moreover, we describe the abnormalities associated with CDH and the potential therapeutic approaches for this severe abnormality.

Characterization of extracellular vesicles derived from cardiac cells in an in vitro model of preconditioning

Preconditioning is a promising technique to protect the heart from ischaemia-reperfusion injury. In this context, the crosstalk between different cardiac cell types and especially the exchange of cardioprotective mediators has come into the focus of current research. Recently, extracellular vesicles (EVs), nano-sized structures, emerged as possible communication mediators. They are taken up by recipient cells and can alter gene expression or activate intracellular signal cascades. It has been shown that all cardiac cell types are able to secrete EVs, but so far the influence of an in vitro preconditioning stimulus on EV concentration and composition has not been investigated. Therefore, we stimulated primary cardiac myocytes and fibroblasts from neonatal rats, as well as H9c2 cells, with two known in vitro preconditioning stimuli: hypoxia or isoflurane. EVs were isolated from cell culture supernatants 48 h after stimulation by differential centrifugation and size exclusion chromatography. They were characterized by transmission electron microscopy, tunable resistive pulse sensing, miRNA array and Western blot analysis. The detected EVs had the typical cup-shaped morphology and a size of about 150 nm. No significant differences in EV concentration were observed between the different groups. The protein and miRNA load was affected by in vitro preconditioning with isoflurane or hypoxia. EV markers like Alix, CD63, flotillin-1 and especially heat shock protein 70 were significantly up-regulated by the treatments. Several miRNAs like miR-92b-3p, miR-761 and miR-101a-5p were also significantly affected. A migration assay confirmed the physiological benefit of these EVs. Taken together, our findings show that a model of in vitro preconditioning of cardiac cells does not influence EV concentration but strongly regulates the EV cargo and affects migration. This might indicate a role for EV-mediated communication in isoflurane- and hypoxia-induced in vitro preconditioning.

Polygenic Causes of Congenital Diaphragmatic Hernia Produce Common Lung Pathologies

Congenital diaphragmatic hernia (CDH) is one of the most common and lethal congenital anomalies, and significant evidence is available in support of a genetic contribution to its etiology, including single-gene knockout mice associated with diaphragmatic defects, rare monogenetic disorders in humans, familial aggregation, and association of CDH with chromosomal abnormalities. Structural lung defects in the form of lung hypoplasia are almost invariably seen in patients with CDH and frequently in animal models of this condition. Better understanding of the mechanisms of pulmonary defects in CDH has the potential for creating targeted therapies, particularly in postnatal stages, when therapeutics can have maximum clinical impact on the surviving cohorts. Successful treatment of CDH is dependent on the integration of human genomic and genetic data with developmental expression profiling, mouse knockouts, and gene network and pathway modeling, which have generated a large number of candidate genes and pathways for follow-up studies. In particular, defective alveolarization appears to be a common and potentially actionable phenotype in both patients and animal models.