Methods:A total of 160 Wistar neonatal rats were assigned into normoxia group, HPH group, normoxia+PDGF-BB group, HPH+PDGF-BB group and HPH+PDGF-BB inhibitor (STI571) group using random number table method (32 rats in each group), each group was further assigned into 4 subgroups on d3, d7, d14 and d21 (8 rats in each subgroup). HPH model was established using nitrogen-oxygen mixture with an oxygen concentration of 10%±0.5%. PDGF-BB groups were injected with adenovirus encoding PDGF-BB in the tail vein. HPH+STI571 group was given STI571 intragastrically. On d3, d7, d14 and d21 after modeling, mean right ventricular systolic pressure (RVSP) was examined. Morphological changes of small pulmonary arteries were observed using HE staining and indicators of pulmonary vascular remodeling calculated. Immunohistochemistry was used to determine the protein levels of PDGF-BB, HIF-1α and proliferation-associated protein nuclear protein Ki67 in the pulmonary vasculature of each group. RT-qPCR was used to determine the mRNA levels of PDGF-BB, HIF-1α and Ki67 in lung tissue.Results:At all time points, RVSP was higher in the HPH group than the normoxia group ( P<0.05), higher in the HPH+PDGF-BB group than the HPH group ( P<0.05), and lower in the HPH+STI571 group than both the HPH+PDGF-BB group and the HPH group ( P<0.05). On d3 after modeling, pulmonary vascular remodeling occurred in the HPH+PDGF-BB group; on d7, pulmonary vascular remodeling occurred in the PDGF-BB group and the HPH group. Pulmonary vascular remodeling appeared later and to a lesser extent in the HPH+STI571 group than the other hypoxic groups. On d3, d7 and d21 after modeling, protein and mRNA levels of PDGF-BB, HIF-1α and Ki67 in the HPH+PDGF-BB group were higher than the other groups ( P<0.05). The protein and mRNA expression levels of PDGF-BB, HIF-1α and Ki67 in the HPH+STI571 group were lower than the HPH+PDGF-BB group and the HPH group at all timepoints ( P<0.05). Conclusions:PDGF-BB up-regulates HIF-1α expression, participates in PASMC proliferation, exacerbates pulmonary vascular remodeling and increases pulmonary artery pressure in neonatal rats with HPH.Obiective:To study the roles of platelet-derived growth factor-BB (PDGF-BB) in hypoxic pulmonary hypertension (HPH) and the mechanisms of regulating hypoxia-inducible factor-1α (HIF-1α) expression, promoting the proliferation of pulmonary arterial smooth muscle cells (PASMC) and participating in the remodeling of pulmonary vessels.

OBJECTIVES: To study the effect of platelet-derived growth factor-BB (PDGF-BB) on pulmonary vascular remodeling in neonatal rats with hypoxic pulmonary hypertension (HPH). METHODS: A total of 128 neonatal rats were randomly divided into four groups: PDGF-BB+HPH, HPH, PDGF-BB+normal oxygen, and normal oxygen (n=32 each). The rats in the PDGF-BB+HPH and PDGF-BB+normal oxygen groups were given an injection of 13 μL 6×10¹⁰ PFU/mL adenovirus with PDGF-BB genevia the caudal vein. After 24 hours of adenovirus transfection, the rats in the HPH and PDGF-BB+HPH groups were used to establish a neonatal rat model of HPH. Right ventricular systolic pressure (RVSP) was measured on days 3, 7, 14, and 21 of hypoxia. Hematoxylin-eosin staining was used to observe pulmonary vascular morphological changes under an optical microscope, and vascular remodeling parameters (MA% and MT%) were also measured. Immunohistochemistry was used to measure the expression levels of PDGF-BB and proliferating cell nuclear antigen (PCNA) in lung tissue. RESULTS: The rats in the PDGF-BB+HPH and HPH groups had a significantly higher RVSP than those of the same age in the normal oxygen group at each time point (P<0.05). The rats in the PDGF-BB+HPH group showed vascular remodeling on day 3 of hypoxia, while those in the HPH showed vascular remodeling on day 7 of hypoxia. On day 3 of hypoxia, the PDGF-BB+HPH group had significantly higher MA% and MT% than the HPH, PDGF-BB+normal oxygen, and normal oxygen groups (P<0.05). On days 7, 14, and 21 of hypoxia, the PDGF-BB+HPH and HPH groups had significantly higher MA% and MT% than the PDGF-BB+normal oxygen and normal oxygen groups (P<0.05). The PDGF-BB+HPH and HPH groups had significantly higher expression levels of PDGF-BB and PCNA than the normal oxygen group at all time points (P<0.05). On days 3, 7, and 14 of hypoxia, the PDGF-BB+HPH group had significantly higher expression levels of PDGF-BB and PCNA than the HPH group (P<0.05), while the PDGF-BB+normal oxygen group had significantly higher expression levels of PDGF-BB and PCNA than the normal oxygen group (P<0.05). CONCLUSIONS Exogenous administration of PDGF-BB in neonatal rats with HPH may upregulate the expression of PCNA, promote pulmonary vascular remodeling, and increase pulmonary artery pressure.
Rats ; Animals ; Hypertension, Pulmonary ; Becaplermin ; Animals, Newborn ; Proliferating Cell Nuclear Antigen ; Vascular Remodeling ; Pulmonary Artery/metabolism* ; Hypoxia ; Oxygen ; Cell Proliferation ; Myocytes, Smooth Muscle/metabolism*