Chorioamnionitis accelerates granule cell and oligodendrocyte maturation in the cerebellum of preterm nonhuman primates.

BACKGROUND: Preterm birth is often associated with chorioamnionitis and leads to increased risk of neurodevelopmental disorders, such as autism. Preterm birth can lead to cerebellar underdevelopment, but the mechanisms of disrupted cerebellar development in preterm infants are not well understood. The cerebellum is consistently affected in people with autism spectrum disorders, showing reduction of Purkinje cells, decreased cerebellar grey matter, and altered connectivity. METHODS: Preterm rhesus macaque fetuses were exposed to intra-amniotic LPS (1 mg, E. coli O55:B5) at 127 days (80%) gestation and delivered by c-section 5 days after injections. Maternal and fetal plasma were sampled for cytokine measurements. Chorio-decidua was analyzed for immune cell populations by flow cytometry. Fetal cerebellum was sampled for histology and molecular analysis by single-nuclei RNA-sequencing (snRNA-seq) on a 10× chromium platform. snRNA-seq data were analyzed for differences in cell populations, cell-type specific gene expression, and inferred cellular communications. RESULTS: We leveraged snRNA-seq of the cerebellum in a clinically relevant rhesus macaque model of chorioamnionitis and preterm birth, to show that chorioamnionitis leads to Purkinje cell loss and disrupted maturation of granule cells and oligodendrocytes in the fetal cerebellum at late gestation. Purkinje cell loss is accompanied by decreased sonic hedgehog signaling from Purkinje cells to granule cells, which show an accelerated maturation, and to oligodendrocytes, which show accelerated maturation from pre-oligodendrocytes into myelinating oligodendrocytes. CONCLUSION: These findings suggest a role of chorioamnionitis on disrupted cerebellar maturation associated with preterm birth and on the pathogenesis of neurodevelopmental disorders among preterm infants.

Barriers in translating stem cell therapies for neonatal diseases.

Over the last 20 years, stem cells of varying origin and their associated secretome have been investigated as a therapeutic option for a myriad of neonatal models of disease, with very promising results. Despite the devastating nature of some of these disorders, translation of the preclinical evidence to the bedside has been slow. In this review, we explore the existing clinical evidence for stem cell therapies in neonates, highlight the barriers faced by researchers and suggest potential solutions to move the field forward.

Neonatal intermittent hypoxia persistently impairs lung vascular development and induces long-term lung mitochondrial DNA damage.

Adults born preterm have an increased risk of pulmonary vascular disease. Extreme preterm infants often require supplemental oxygen but they also exhibit frequent intermittent hypoxemic episodes (IH). Here, we test the hypothesis that neonatal IH induces lung endothelial cell mitochondrial DNA (mitDNA) damage and contributes to long-term pulmonary vascular disease and pulmonary hypertension (PH). Newborn C57BL/6J mice were assigned to the following groups: 1) normoxia, 2) hyperoxia (O2 65%), 3) normoxia cycling with IH (O2 21% + O2 10%), and 4) hyperoxia cycling with IH (O2 65% + O2 10%) for 3 wk. IH episodes were initiated on postnatal day 7. Lung angiogenesis, PH, and mitDNA lesions were assessed at 3 wk and 3 mo. In vitro, the effect of IH on tubule formation and mitDNA lesions was evaluated in human pulmonary microvascular endothelial cells (HPMECs). Data were analyzed by ANOVA. In vitro, IH exposure reduced tubule formation and increased mitDNA lesions in HPMECs. This was most marked in HPMECs exposed to hyperoxia cycling with IH. In vivo, neonatal IH increased lung mitDNA lesions, impaired angiogenesis, and induced PH in 3-wk-old mice. These findings were pronounced in mice exposed to hyperoxia cycling with IH. At 3 mo follow-up, mice exposed to neonatal IH had persistently increased lung mitDNA lesions and impaired lung angiogenesis, even without concomitant hyperoxia exposure. Neonatal IH induces lung endothelial cell mitDNA damage and causes persistent impairment in lung angiogenesis. These findings provide important mechanistic insight into the pathogenesis of pulmonary vascular disease in preterm survivors.NEW & NOTEWORTHY Our current study demonstrates that neonatal intermittent hypoxia (IH) alters lung endothelial cell function, induces mitochondrial DNA lesions, and impairs lung vascular growth into adulthood. Moreover, when superimposed on hyperoxia, neonatal IH induces a severe lung vascular phenotype that is seen in preterm infants with PH. These findings suggest that neonatal IH contributes to PH in adults born preterm and importantly, that mitochondrial protection strategies may mitigate these deleterious effects.

Mesenchymal Stem Cell-derived Extracellular Vesicles Prevent Experimental Bronchopulmonary Dysplasia Complicated By Pulmonary Hypertension.

Mesenchymal stem cell (MSC) extracellular vesicles (EVs) have beneficial effects in preclinical bronchopulmonary dysplasia and pulmonary hypertension (BPD-PH) models. The optimal source, dosing, route, and duration of effects are however unknown. The objectives of this study were to (a) compare the efficacy of GMP-grade EVs obtained from Wharton's Jelly MSCs (WJ-MSCs) and bone marrow (BM-MSCs), (b) determine the optimal dosing and route of administration, (c) evaluate its long-term effects, and (d) determine how MSC EVs alter the lung transcriptome. Newborn rats exposed to normoxia or hyperoxia (85% O2) from postnatal day (P)1-P14 were given (a) intra-tracheal (IT) BM or WJ-MSC EVs or placebo, (b) varying doses of IT WJ-MSC EVs, or (c) IT or intravenous (IV) WJ-MSC EVs on P3. Rats were evaluated at P14 or 3 months. Early administration of IT BM-MSC or WJ-MSC EVs had similar beneficial effects on lung structure and PH in hyperoxia-exposed rats. WJ-MSC EVs however had superior effects on cardiac remodeling. Low, medium, and high dose WJ-MSC EVs had similar cardiopulmonary regenerative effects. IT and IV WJ-MSC EVs similarly improved vascular density and reduced PH in hyperoxic rats. Gene-set enrichment analysis of transcripts differentially expressed in WJ-MSC EV-treated rats showed that induced transcripts were associated with angiogenesis. Long-term studies demonstrated that a single early MSC EV dose has pulmonary vascular protective effects 3 months after administration. Together, our findings have significant translational implications as it provides critical insight into the optimal source, dosing, route, mechanisms of action, and duration of effects of MSC-EVs for BPD-PH.

Comparative Effects of Bone Marrow-derived Versus Umbilical Cord Tissue Mesenchymal Stem Cells in an Experimental Model of Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is a life-threatening condition in preterm infants with few effective therapies. Mesenchymal stem or stromal cells (MSCs) are a promising therapeutic strategy for BPD. The ideal MSC source for BPD prevention is however unknown. The objective of this study was to compare the regenerative effects of MSC obtained from bone marrow (BM) and umbilical cord tissue (UCT) in an experimental BPD model. In vitro, UCT-MSC demonstrated greater proliferation and expression of anti-inflammatory cytokines as compared to BM-MSC. Lung epithelial cells incubated with UCT-MSC conditioned media (CM) had better-wound healing following scratch injury. UCT-MSC CM and BM-MSC CM had similar pro-angiogenic effects on hyperoxia-exposed pulmonary microvascular endothelial cells. In vivo, newborn rats exposed to normoxia or hyperoxia (85% O2) from postnatal day (P) 1 to 21 were given intra-tracheal (IT) BM or UCT-MSC (1 × 106 cells/50 µL), or placebo (PL) on P3. Hyperoxia PL-treated rats had marked alveolar simplification, reduced lung vascular density, pulmonary vascular remodeling, and lung inflammation. In contrast, administration of both BM-MSC and UCT-MSC significantly improved alveolar structure, lung angiogenesis, pulmonary vascular remodeling, and lung inflammation. UCT-MSC hyperoxia-exposed rats however had greater improvement in some morphometric measures of alveolarization and less lung macrophage infiltration as compared to the BM-MSC-treated group. Together, these findings suggest that BM-MSC and UCT-MSC have significant lung regenerative effects in experimental BPD but UCT-MSC suppresses lung macrophage infiltration and promotes lung epithelial cell healing to a greater degree.

Placental tissue stem cells and their role in neonatal diseases.

Neonatal diseases such as hypoxic ischemic encephalopathy, diseases of prematurity and congenital disorders carry increased morbidity and mortality. Despite technological advancements, their incidence remains largely unabated. Stem cell (SC) interventions are novel therapies in the neonatal world. In pre-clinical models of neonatal diseases, SC applications have shown encouraging results. SC sources vary, with the bone marrow being the most utilized. However, the ability to harvest bone marrow SCs from neonates is limited. Placental-tissue derived SCs (PTSCs), provide an alternative and highly attractive source. Human placentas, the cornerstone of fetal survival, are abundant with such cells. Comparing to adult pools, PTSCs exhibit increased potency, decreased immunogenicity and stronger anti-inflammatory effects. Several types of PTSCs have been identified, with mesenchymal stem cells being the most utilized population. This review will focus on PTSCs and their pre-clinical and clinical applications in neonatology.

Soluble Klotho, a biomarker and therapeutic strategy to reduce bronchopulmonary dysplasia and pulmonary hypertension in preterm infants.

Preterm infants with bronchopulmonary dysplasia (BPD) and pulmonary hypertension (PH) have accelerated lung aging and poor long-term outcomes. Klotho is an antiaging protein that modulates oxidative stress, angiogenesis and fibrosis. Here we test the hypothesis that decreased cord Klotho levels in preterm infants predict increased BPD-PH risk and early Klotho supplementation prevents BPD-like phenotype and PH in rodents exposed to neonatal hyperoxia. In experiment 1, Klotho levels were measured in cord blood of preterm infants who were enrolled in a longitudinal cohort study. In experiment 2, using an experimental BPD-PH model, rat pups exposed to room air or hyperoxia (85% O2) were randomly assigned to receive every other day injections of recombinant Klotho or placebo. The effect of Klotho on lung structure, PH and cardiac function was assessed. As compared to controls, preterm infants with BPD or BPD-PH had decreased cord Klotho levels. Early Klotho supplementation in neonatal hyperoxia-exposed rodents preserved lung alveolar and vascular structure, attenuated PH, reduced pulmonary vascular remodeling and improved cardiac function. Together, these findings have important implications as they suggest that perinatal Klotho deficiency contributes to BPD-PH risk and strategies that preserve Klotho levels, may improve long-term cardiopulmonary outcomes in preterm infants.

Central Venous Catheter Retention and Mortality in Children With Candidemia: A Retrospective Cohort Analysis.

BACKGROUND: Candidemia causes significant morbidity and mortality among children. Removal of a central venous catheter (CVC) is often recommended for adults with candidemia to reduce persistent and metastatic infection. Pediatric-specific data on the impact of CVC retention are limited. METHODS: A retrospective cohort study of inpatients <19 years with candidemia at the Children's Hospital of Philadelphia between 2000 and 2012 was performed. The final cohort included patients that had a CVC in place at time of blood culture and retained their CVC at least 1 day beyond the blood culture being positive. A structured data collection instrument was used to retrieve patient data. A discrete time failure model, adjusting for age and the complexity of clinical care before onset of candidemia, was used to assess the association of CVC retention and 30-day all-cause mortality. RESULTS: Two hundred eighty-five patients with candidemia and a CVC in place at the time of blood culture were identified. Among these 285 patients, 30 (10%) died within 30 days. Central venous catheter retention was associated with a significant increased risk of death on a given day (odds ratio, 2.50; 95% confidence interval, 1.06-5.91). CONCLUSIONS: Retention of a CVC was associated with an increased risk of death after adjusting for age and complexity of care at candidemia onset. Although there is likely persistence of unmeasured confounding, given the strong association between catheter retention and death, our data suggest that early CVC removal should be strongly considered.

Comparative effectiveness of fungicidal vs. fungistatic therapies for the treatment of paediatric candidaemia.

Adult data suggest that echinocandins for treatment of candidaemia are associated with decreased mortality, attributed to their fungicidal activity. There are limited data comparing antifungals in children. We compared 30-day all-cause mortality among paediatric candidaemia patients treated with fungicidal vs. fungistatic agents. All inpatients (>6 months and <19 years of age) with candidaemia between 2000 and 2012 at The Children's Hospital of Philadelphia were retrospectively identified. Definitive therapy with fungicidal (amphotericin B and caspofungin) agents was compared with fungistatic (fluconazole) agents. A propensity score model generated the inverse probability of receiving a fungicidal agent, which was included in a weighted logistic regression model. Among 203 children meeting inclusion criteria, 151 (74.4%) and 52 (25.6%) received a fungicidal and fungistatic agent, respectively. Overall, 18 (8.9%) patients died within 30 days. There was no statistically significant difference in mortality between patients started on a fungicidal or fungistatic agent (OR: 2.19, 95% CI: 0.42-11.48). In a propensity score-weighted model, definitive therapy with a fungicidal agent did not result in a significant decrease in mortality. These data suggest that both agents can be considered definitive therapy for paediatric candidaemia. The results should be interpreted with caution given the small sample size. Larger cohort studies are needed.

Serial plasma concentrations of adiponectin, leptin, and resistin during therapy in children with acute lymphoblastic leukemia.

PURPOSE: To investigate adipocytokine secretion, at diagnosis and during chemotherapy in children with the acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Serial measurements (6/patient) of the anti-inflammatory cytokine adiponectin and the proinflammatory adipocytokines leptin and resistin were performed at diagnosis and in nearly the entire period of therapy (up to 21 months), in 9 patients with ALL aged 2 to 7 years (median 4.3 y). Body mass index and leukemic burden were estimated at the same time points and correlated with adipocytokine levels. Nine healthy children matched for age, sex, and body mass index were used as controls. RESULTS: At diagnosis, mean adiponectin levels were low (P<0.001) and mean leptin and resistin levels were high, compared with controls (P<0.001). During maintenance phase, adiponectin increased significantly (P=0.024), whereas leptin and resistin decreased (P=0.018 and P=0.020, respectively), compared with baseline values. However, adiponectin, despite its progressive increase, remained at lower levels toward the end of the maintenance phase, compared with controls, (P<0.001). Delta (final-baseline) mean adiponectin was negatively correlated with leukemic burden (P=0.019), whereas delta mean leptin and resistin were positively correlated with it (P=0.011 and P=0.031, respectively). CONCLUSIONS: Low-plasma adiponectin and high leptin and resistin level are present at the ALL diagnosis. Adipocytokines alterations are progressively restored during therapy.