Effects of netrin-1 and netrin-1 knockdown on human umbilical vein endothelial cells and angiogenesis of rat placenta

Angiogenesis is an important process essential for the development of placenta. Netrin-1 was first discovered in nervous system and was later found to play roles in angiogenesis. In order to better understand the functional relevance of netrin-1 in placental angiogenesis, we investigated the effect of netrin-1 on human umbilical vein endothelial cells (HUVECs) and rat placenta by employing up-regulation and down-regulation strategies. HUVECs and rat placenta were treated with recombinant netrin-1, and netrin-1 expression in the cells and placenta was reduced by short hairpin RNA (shRNA) in vitro and in vivo. The inhibition efficiency was determined by real-time quantitative polymerase chain reaction (RT-PCR) and Western blotting. The expression of netrin-1 was immunohistochemically located. The results demonstrated that netrin-1 promoted viability, proliferation, migration and tube formation of HUVECs. A strong reduction in cell capability was observed in vitro after netrin-1 expression was inhibited with shRNA. Netrin-1 accelerated neovascularization of placenta in pregnant rats. Suppression of netrin-1 expression in placenta resulted in reduced vascular sprouting in vivo. These findings suggest that netrin-1 is essential for the proper functioning of HUVECs and angiogenesis of rat placenta, and it is involved in the development of placenta and fetus. The proangiogenic effect of netrin-1 might offer an alternative therapeutic approach for the treatment of vascular disease of placenta.