The in vivo angiogenesis effect was studied by analyzing the number of ectopic sprouts formed upon sub-intestinal vessel of transgenic TG(fli1:EGFP)y1/+(AB) zebrafish embryos by fluorescence microscopy. Quantitative real-time PCR gene expression of the zebrafish embryos was further performed using a panel of 30 angiogenesis-associated genes designed for zebrafish sprout angiogenesis. Classical in vitro angiogenesis assays using human microvascular endothelial cells (HMEC-1) was accompanied.
We demonstrated that among all RR sub-fractions tested, C1-1 treated-zebrafish embryos possessed the most potent angiogenesis activities (from 190 to 780 ng/ml, p<0.001) in sprout formation in the zebrafish model. Quantitative gene expression of the treated embryos demonstrated significant up-regulation in MMP-9 (p<0.05), ANGPT1 (p<0.05), EGFR (p<0.05), EPHB4 (p<0.01), and significant down-regulation in Ephrin B2 (p<0.05), Flt-1 (p<0.05) and Ets-1 (p<0.05). C1-1 treatment could also significantly (p<0.001-0.05) stimulate HMEC-1 cell migration in scratch assay. Significant increase (p<0.05) in mean tubule length was observed in the C1-1-treated HMEC-1 cells in the tubule formation assay.
Our zebrafish sprout angiogenesis model-guided fractionation revealed that C1-1 possessed the most potent angiogenesis effect in RR. The design of the panel with 30 tailor-made angiogenesis-associated genes exhibited in zebrafish gene expression analysis showed that C1-1 could trigger differential expression of various angiogenesis-associated genes, such as VEGFR3 and MMP9, which played key role in angiogenesis. The pro-angiogenic activity of C1-1 was further confirmed in the translated study in motogenic and tubule-inducing effect using HMEC-1.