Objective    To study the molecular mechanism of injection with hepatocyte growth factor (HGF) at different doses on angiogenesis in myocardium of dogs with acute myocardial infarction (MI).     Methods    Sixteen 1.5-year-old male hybrid dogs

weighing 11-13 kg

were divided into 500 μg HGF treatment group

1 000 μg HGF treatment group

sham operation group

and no MI interference group

4 dogs in ea

ch group. Expressions of VEGF

HGF

CD31

and platelet factor Ⅷ in myocardium of dogs with MI were detected

the number of micro blood vessels was calculated

and correlation between angiogenesis and expression of HGF and VEGF was analyzed in 28 d after the model was established.     Results    HGF gene therapy could up-regulate the expression of CD31 and VEGF. The expression of CD31 and VEGF mRNA was 0.82 and 0.39 respectively in 1 000 μg HGF group

and 0.47 and 0.21 respectively in 500 μg HGF group. The expression of VEGF mRNA was 0.09 and no expression of CD31 mRNA was found in MI group. HGF could increase the angiogenesis in infracted myocardium. The microvascular density was 126.4±10.6

79.8±6.0

and 21.7±2.5/mm

2

respectively

in 1 000 μg HGF group

500 μg HGF group

and MI group (P0.01).The angiogenesis was positively correlated with the expression of VEGF and HGF (P0.01).The angiogenesis and expression of VEGF increased with the increasing HGF dose.     Conclusion    HGF increases angiogenesis in dogs after myocardial ischemia by promoting formation of blood vessels and secretion of endogenous VEGF.