OBJECTIVETo investigate the inhibitory effects of saikosaponin-d (SSd) on angiogenesis in chicken embryos and its mechanism of action.

METHODSChorioallantoic membrane (CAM) model was established successfully in 86 chicken embryos. They were divided into 4 groups after fenestration: the three SSd treated groups (A, B and C) treated with high (20 microg/mL, n = 16), middle (10 microg/mL, n = 19) and low (5 microg/mL, n = 25) dose of SSd respectively, and the control group treated with 0.01 mol/L PBS (n = 26). The drug or reagent was administered by grafting 20 microL onto the surface of CAM. After incubation for 3 days, the vessel growth was recorded by digital photography; inflammatory cells were counted under light microscope with HE staining, and the positive rate of angiogenesis reaction was calculated by Leica image analyzer.

RESULTSOn the 6th day of the embryonic age, vessels in the chicken embryo CAM showed a radial growing in spok-wheel pattern around the gelatin sponges with lateral axis running through it. Whereas after 3 days of SSd treatment, the angiogenesis reduced significantly with vague microvessels around the sponge, and vascular truncation and absence revealed. Microscopic examinations showed that the number of microvessels and infiltrated inflammatory cells in the sponge and peripheral CAM mesenchyme in the SSd groups were less than those in the control group, especially on vessels of medium and small size (P < 0.05, P < 0.01, respectively), but was insignificant on great vessels (P > 0.05). Correlation analysis revealed no correlation between the number of the great vessels in CAM and the infiltrated inflammatory degrees (r = 0.117, P > 0.05), but the increase of small vessels in CAM was positively correlated with that of inflammatory cells (r = 0.971, P < 0.01).

CONCLUSIONSSSd could inhibit the physiological angiogenesis of chicken embryoe, especially for the medium and small vessels, while there was no significant effect on great vessels (P > 0.05). Its mechanism of action may be related to its inhibition on leukocyte migration and activation.