Pulmonary Vascular Endothelial Growth Factor Expression and Disaturated Phospholipid Content in a Chicken Model of Hypoxia-Induced Fetal Growth Restriction

Abstract

Background: Prenatal hypoxia is an important cause of intrauterine growth retardation that affects fetal lung maturation, although previous studies have rendered conflicting results. The fetal chicken model allows the study of the isolated effects of hypoxia during development. Objectives: We hypothesized that prenatal hypoxia would differentially affect surfactant synthesis, depending on timing and duration of hypoxia. Pulmonary vascular endothelial growth factor (VEGF) expression was analyzed as a possible link between oxygen sensing and surfactant production. Methods: Fertilized White Leghorn eggs were incubated in normoxia, hyperoxia (60% O₂) from day 15 or hypoxia (15% O₂) from either day 6 or day 15 of incubation. Whole lung disaturated phospholipids (DSPL) and mRNA expression of VEGF isoforms were quantified at day 16 and 19. Results: Lung DSPL content increased approximately threefold between day 16 and 19 in control animals. Both hypoxia and hyperoxia from day 15 significantly increased DSPL content at day 19 versus control (103 ± 22 and 116 ± 18 vs. 81 ± 15 µg/mg protein, p < 0.01 and p < 0.001, respectively), while long-term hypoxia tended to decrease DSPL content (65 ± 17 µg/mg protein, p = 0.056). No differences in DSPL content were observed at day 16. Short-term hypoxia transiently up-regulated VEGF146 1.5-fold at day 16 (p < 0.05). A similar trend was observed for VEGF122 (p = 0.058) and VEGF190 (p = 0.08), while no differences were present at day 19. Conclusions: Both prenatal hypoxia and hyperoxia induced during critical windows of lung development differentially modulate surfactant synthesis. Our data support the concept that fetal oxygen tension is a key signal in the regulation of the surfactant system.

Early Alterations of Growth Factor Patterns in Bronchoalveolar Lavage Fluid From Preterm Infants Developing Bronchopulmonary Dysplasia

“…The latter observation corresponds to animal experimental evidence indicating a stimulatory effect of VEGF on pulmonary surfactant synthesis (24,25). The association between lower alveolar VEGF and total PL concentrations and subsequent BPD development supports the concept that a developmental arrest of the lung is a critical mechanism in the development of new BPD (2).…”

Cracking the Egg: Potential of the Developing Chicken as a Model System for Nonclinical Safety Studies of Pharmaceuticals

“…Neuronal growth and plasticity (Johnson and Jope, 1992) NeuN Marker for neuronal maturation (Sarnat et al, 1998) S-100 Marker enabling monitoring of brain injury in blood and CSF (Sun et al, 2012 Surfactants increase compliance, lower surface tension, and prevent atelectasis of the lungs; lack of surfactants causes respiratory distress of the newborn Hylka and Doneen, 1983;Makanya et al, 2007Makanya et al, , 2013Been et al, 2010;Bjornstad et al, 2014 Aquaporin 5 Expressed in human type I pneumocytes, vital for gas exchange (Kreda et al, 2001) Caveolin 1…”

“…In a study from 2010, fertilized eggs were incubated at various levels of oxygenation to support the concept that fetal oxygen tension is a key signal in the regulation of the surfactant system. Disaturated phospholipids and vascular endothelial growth factor were used as parameters of lung function at different stages of chicken embryo development, and a critical window of vulnerability to oxygen tension was established (Been et al, 2010). Another relevant example is surfactant protein B, which is expressed in chicken lungs from Evaluation of anticonvulsant drugs (Loscher, 1984;Johnson et al, 1985) and how seizures alter the development of the brain (Gong et al, 2003) Obese strain of chicken Studies of autoimmune thyroiditis as described in Wick, Sundick et al, 1974 andDietrich et al, 1999 Neuroendocrine alterations caused by thyroiditis (Schauenstein et al, 1987) Gain Kos et al, 2003 Transcription factor FoxD3 in the development of the neural crest (Kos et al, 2001) MRI, magnetic resonance imaging; PET, positron emission tomography; RNAi, RNA interference.…”

Nebulization of Poractant alfa via a vibrating membrane nebulizer in spontaneously breathing preterm lambs with binasal continuous positive pressure ventilation

“…The dry BALF was dissolved in a mixture of carbon tetrachloride and osmium tetroxide and disaturated phospholipids were isolated by means of alumina column chromatography according to Mason et al (41). DSPL were dissolved in chloroform and quantified by photometry according to Stewart with some minor modifications as described by Been et al (42,43). DSPL concentration was correlated to BALF volumes and DSPL pool size of the whole lung was calculated and adjusted for body weight.…”