Intervention Study Of RhVEGF₁₆₅ Therapy On A Hyperoxia-induced Neonatal Rat BPD Model Using Bovine Pulmonary Surfactant As The Carrier

Objective: An impaired VEGF signaling pathway could lead to alveolar damage and decreased pulmonary vascular density,which results in BPD-like changes.At present,virus-mediated VEGF gene therapy or simple intramuscular injection of VEGF protein are the main methods of intervention in the BPD animal model.However,VEGF is capable of increasing vascular permeability,with systemic application of VEGF exerting certain effects on other tissues and organs.This study proposes a local administration of an appropriate amount of VEGF in the airway,and reports an improvement of pulmonary organic structure of BPD.Methods:Method 1:24 one day old neonatal SD rats were divided into 2 groups,a group of air control group,a group of 75% oxygen environment in the establishment of a high oxygen induced neonatal rat BPD model.After 14 days,the neonatal rats were taken out of the oxygen environment,The two groups were made by self-made endotracheal intubation,through the way of the trachea intubation,2ul/g physiological saline was given in the airway.The body weight,the intubation time,the survival rate of newborn rats after intervention,Neonatal rat vigor in the two groups were observed,After the birth of 21 day,these rats were killed,the lung tissue was taken for HE staining,and the morphological changes were observed.Method 2:Postnatal day 1(P1)SD rats were placed in an oxygen or open air for 13 days.Rats in the hyperoxia group were separated from the oxygen environment and placed in the air at P14.Among them,rats in air group were randomly divided into a control group(R group)and a saline group(RN group);the rats in the oxygen exposure group were randomly divided into a normal saline control group(HN group),a VEGF group(HV group),a Calsurf group(HC group)and a Calsurf-VEGF mixed group(HCV group).Since P14,rats in different intervention groups were administrated 2ul/g﹒ d of different drugs into the airway for three days.Among them,the dosage of Calsurf was 50mg/Kg ﹒ d,and the dosage of rh VEGF165 was 20ug/Kg ﹒ d.Rats in different intervention groups were sacrificed at P21.Lung specimens were collected to observe the morphological changes of lung tissue by measuring the radial lung count(RAC)and pulmonary vascular density.The expression level of VEGF protein in lung tissue was detected by Western-blot,and the expression of e NOS and HGF proteins were detected by immunohistochemistry.Results: Saline administration into the airway had no obvious effect on the structure of normal lung tissue;hyperoxia exposure can decrease RAC,reduced pulmonary vascular density and expression levels of VEGF,e NOS and HGF proteins.Compared with the hyperoxia saline group,administration of Calsurf and VEGF mixture into the airway increased RAC and pulmonary vascular density,and augmented the expression level of VEGF,e NOS and rh HGF proteins.Compared with the air control group,there was no significant difference.The VEGF group and Calsurf group improved the morphological structure of lung tissue and the expression level of protein to a certain extent;compared with the hyperoxia saline group,VEGF administration in the airway increased the expression level of VEGF and e NOS to a certain degree.Calsurf administration into the airway increased the expression level of HGF,which was lower than those of the control group.Conclusion: Hyperoxia exposure can lead to BPD-like structural changes in lung tissue of the neonatal rat.Administration of appropriate amounts of rh VEGF165 into the airway by using calsurf pulmonary surfactant as the vehicle was capable of improving hyperoxia-induced lung impairments by regulating levels of e NOS and HGF protein.