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 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 expression 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. Key words: Hemangioma; Propranolol; Cell proliferation; Apoptosis; Gene expression profiling; Oligonucleotide array sequence analysis