Abstract: Luo Yongqi, Zeng Yinghong, Hu Mengye, Tang Jianping Department of Dermatology, Hunan Children′s Hospital, Changsha 410007, China （Luo YQ, Zeng YH, Tang JP）; Department of Electrocardiography, Hunan Provincial People′s Hospital, Changsha 410002, China （Hu MY） Corresponding author: Tang Jianping, Email: jpingtang@126.com 【Abstract】 Objective To evaluate effects of propranolol on the proliferation and apoptosis of in vitro cultured hemangioma endothelial cells （HemEC）, and to explore their molecular mechanisms. Methods Hemangioma tissues were resected from 7 children with proliferative hemangioma, and used for in vitro culture of HemEC. Meanwhile, cultured human umbilical vein endothelial cells （HUVEC） served as controls. The 2 kinds of cells were treated with propranolol at different concentrations of 0, 25, 50, 75, 100, 125 and 150 μmol/L for 24, 48 and 72 hours separately. Methyl thiazolyl tetrazolium （MTT） assay was performed to evaluate cellular proliferative activity, and flow cytometry to determine the apoptosis rate. Some cultured HemEC were divided into 2 groups to be treated with 100 μmol/L propranolol-containing culture medium （propranolol group） and culture medium alone （blank control group）, respectively, for 18 hours. Total RNA in the 2 groups was extracted separately. Differentially expressed genes in HemEC between the above 2 groups were identified by DNA microarray technology, and verified by real-time quantitative PCR. Results The treatment with 25 μmol/L propranolol for 24 and 48 hours caused a slight proliferation of HemEC（P < 0.05）. The survival rate of HemEC was decreased after the treatment with propranolol at the concentration of ≥ 100 μmol/L for more than 24 hours, while the proliferation of HUVEC was inhibited by the treatment with propranolol at the concentration of ≥ 100 μmol/L for more than 48 hours. During 24 - 72 hours of treatment with 100 - 150 μmol/L propranolol, the survival rates of HemEC were significantly lower than those of HUVEC （P < 0.05）. After the treatment with 100 - 150 μmol/L propranolol, the apoptosis rate of HemEC gradually increased with the increase in treatment duration and concentrations of propranolol （all P < 0.05）. Compared with the blank control group, 186 differentially expressed genes （> 1.5-fold changes） were screened out by DNA microarray technology, including 128 up-regulated genes and 58 down-regulated genes. Real-time quantitative PCR showed that the mRNA of proprotein convertase subtilisin/kexin type 9 （PCSK9） and fatty acid binding protein 3 （FABP3） in the propranolol group were （9.88 ± 2.19） and （21.90 ± 8.18） times that in the blank control group respectively（t = 7.028, 4.427 respectively, P < 0.05）. Conclusions Propranolol at high concentrations can inhibit the proliferation of HemEC and HUVEC, and its inhibitory effect on HemEC is stronger than that on HUVEC. The inhibitory effect of propranolol on HemEC may be related to the inhibition of HemEC proliferation and promotion of HemEC apoptosis.