Effect of oxygen on the expression of hypoxia-inducible factors in human fetal lung explants.
BACKGROUND
Fetal lung development requires proper coordination between lung epithelial and vascular morphogenesis. A major determinant in lung vascular development is vascular endothelial growth factor (VEGF), which is regulated by hypoxia-inducible factors (HIFs). VEGF is expressed in the airway epithelium, while its receptors (VEGFRs) are expressed in the pulmonary mesenchyme. The hypoxic environment in utero is beneficial for fetal organogenesis, especially vascular development. However, little is known about the expression of HIFs and VEGFR-2 in the human fetal lung in vitro.


OBJECTIVE
The purpose of this study was to investigate the effects of hypoxia on fetal lung morphology and mRNA expression of VEGF, VEGFR-2, HIF-2alpha, and HIF-3alpha.


METHODS
An explant culture technique was used to study the effects of normoxic and hypoxic conditions on human fetal lung.


RESULTS
The morphology remained largely unchanged in explants cultured under hypoxic or normoxic conditions. Quantitative RT-PCR showed that the mRNA expression of VEGF-A, but not VEGFR-2 is upregulated in explants cultured at 1.5% compared with 21% oxygen. We observed a nonsignificant increase in HIF-2alpha and HIF-3alpha mRNA expression in explants cultured at 1.5% oxygen. These data suggest that the mRNA expression of VEGF, and possibly HIF-2alpha and HIF-3alpha, is regulated by hypoxia in the developing human lung.


CONCLUSIONS
This lung explant culture model appears to be a valuable model to unravel the molecular mechanisms of human lung development.
Rajatapiti
Prapapan
P
Department of Pediatric Surgery, Sophia Children's Hospital, The Netherlands.
de Rooij
Jessica D
JD
Beurskens
Leonardus W J E
LW
Keijzer
Richard
R
Tibboel
Dick
D
Rottier
Robbert J
RJ
de Krijger
Ronald R
RR
D051017:Apoptosis Regulatory Proteins; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005333:Fetus / Q000187:drug effects* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000196:embryology* / Q000378:metabolism; D009924:Organ Culture Techniques; D010100:Oxygen / Q000494:pharmacology*; D012097:Repressor Proteins; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
D051017:Apoptosis Regulatory Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010100:Oxygen; D012097:Repressor Proteins; D042461:Vascular Endothelial Growth Factor A; D040301:Vascular Endothelial Growth Factor Receptor-2; D000099162:Endothelial PAS Domain-Containing Protein 1; C116973:HIF3A protein, human; C467484:VEGFA protein, human