Text Box: PROMOTING EFFECTS OF ESTROGEN AND bFGF ON THE PROLIFERATION OF HEMANGIOMA VASCULAR ENDOTHELIAL CELLS IN VITRO Liu J-B, Xiao X-M, Sheng M-L,Lei Y-H Department of Surgery, Children’s Hospital, Medical Center of Fudan University, Shanghai, China Purpose: To observe the influences of estradiol (E2), basic fibroblast growth factor (bFGF), and 4OH-tamoxifen (4OH-TAM) on the proliferation of hemangioma vascular endothelial cells (HVECs). Methods: Two strawberry hemangiomas with positive estrogen receptor staining from 2 infants (case 1 and 2) were used for HVECs culture. The HVECs of passage 3 were culture in estrogen-free improved minimum essential medium for various treatments: group 1 (control), group 2 (+E2), group 3 (+bFGF), group 4 (+E2 +bFGF) and group 5 (+E2 +bFGF +4OH-TAM). Cell count (CC) and DNA proliferation index (PI) was determined on culture days 3,6, and 9. Results: At the end of the 9-day study in case 1: CC and PI remained unchanged in control group. When E2 was added, CC and PI slightly increased. When bFGF was added, CC and PI significantly increased, being 2.5 times that of the control group. When E2 and bFGF were added, CC and PI increased dramatically, being 1.5 time that of bFGF added only. When treated with E2, bFGF, and 4OH-TAM, CC and PI were similar to that of the control group. The results of case 2 were similar to those of case 1. Conclusions: In vitro, the promoting effect of bFGF on HVECs proliferation is much stronger than that of estrogen. The coexistence of estrogen and bFGF can enhance the proliferation still stronger, suggesting that a kind of comitogen-mitogen cooperative mechanism might be involved in the growth of hemangiomas. Tamoxifen can inhibit the proliferation induced by estrogen and bFGF. 1720