Pro-angiogenic activity of astragaloside IV in HUVECs in vitro and zebrafish in vivo.

Astragaloside IV (AS-IV) is a natural product isolated from the Chinese medical herb, Radix Astragali, which has been reported to be a potential candidate for treating diseases associated with abnormal angiogenesis; however, the effect of AS-IV on angiogenesis and its underlying mechanisms are yet to be fully elucidated. In the present study, we investigated the angiogenic effect of AS-IV in vitro using human umbilical vein endothelial cells (HUVECs), and in vivo using zebrafish. AS-IV was found to stimulate the proliferation and migration of HUVECs in an XTT assay and a wound healing migration assay, respectively. Moreover, AS-IV stimulated the invasive ability of HUVECs and significantly increased the mean tube length of HUVECs in Matrigel. AS-IV induced an angiogenic response in HUVECs and enhanced mRNA expression of vascular endothelial growth factor (VEGF) and a VEGF receptor known as kinase‑domain region/fetal liver kinase-1/VEGF receptor 2 (KDR/Flk-1/VEGFR2), as well as activation of Akt as demonstrated by quantitative real-time PCR and Western blot analysis, respectively. The AS-IV-induced proliferation of HUVECs was capable of being suppressed by a KDR inhibitor (SU5416) and an Akt inhibitor (SH-6). AS-IV also rescued blood vessel loss in Tg (fli-1:EGFP) zebrafish. Altogether, our results suggest that AS-IV exerts potential pro-angiogenic effects in vitro and in vivo, and that its pro-angiogenic activity probably involves both VEGF- and Akt-dependent signaling pathways.