OBJECTIVETo investigate the effect of adenoviral-mediated exogenous HGF (Ad-HGF) gene transfer on lung angiogenesis in the rabbit lung in rabbits with hyperkinetic pulmonary artery hypertension.

METHODSA thoracotomy was performed through a midsternal incision in 1-month-old immature rabbit and an anastomosis between the left innominate artery and the pulmonary trunk was made to establish a chronic patent left to right shunt. Three months later, animals were randomly assigned to receive either Ad-HGF (2 x 10(9) Pfu in 0.2 ml PBS, H1 group), repeated administration of Ad-HGF after one week (H 2 group), Ad-GFP (2 x 10(9) Pfu in 0.2 ml PBS, G group), or PBS (0.2 ml, C group) by the intratracheal method of gene transfection. After two weeks, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemical examination was performed to identify HGF mRNA and HGF protein expression. The capillary density and small pulmonary artery density were determined by immunostained with antibodies against factor VIII and alpha-SMA. After 1 month, the collateral vessels were evaluated by angiogram under digital subtraction angiography (DSA).

RESULTSTwo weeks after Ad-HGF transfection, 484 bp bands could be found by RT-PCR in H1 and H2 groups, but not in other groups. The expression of HGF protein could be detected on alveolar epithelium and pulmonary vessel endothelium by immunohistochemistry examination. The number of factor VIII-positive pulmonary capillaries was also significantly increased in the H1 and H2 groups compared with the C and G groups (P < 0.05). The capillary density reached (17.0 +/- 3.3) mm(2) and (19.7 +/- 2.8) mm(2) in the H1 and H2 group, respectively, whereas it remained (13.2 +/- 3.2) mm(2) in the C group and (13.5 +/- 2.4) mm(2) in the G group (P < 0.05). One month after Ad-HGF transfection, the number of small pulmonary arteries was significantly increased in H1 and H2 group compared with control groups (P < 0.05). The collateral vessels were more abundant in HGF transfection groups than that in the two control groups reviewed by angiogram under digital subtraction angiography (DSA).

CONCLUSIONIn vivo gene transfection with HGF by means of the intra-tracheal injection could induce pulmonary angiogenesis in the early stage and small pulmonary arterial angiogenesis in later stage.