The Effect Of Glucocorticoid On The Expression Of Ang-1, Ang-2 And Tie2 In Human Hemangioma Graft Model

Purpose: Infantile hemangioma is one of the most common benigntumors of infancy, with an incidence between 1％and 10％. The pathogenesisof hemangioma is still unclear. Eithty percent of hemangioma cases canregress spontaneously without any intervention. However, intervention shouldbe introduced in time when lesions threaten vital functions or threaten the lifeof the patient. Glucocorticoids, whether administered systemically or locally, isthe first-line modality of treatment. The safest and most effective dose ofglucocorticoids for hemangiomas is still with contraversy. As the mechanismof glucocorticoids is unknown, we undertook an investigation to assess theexpression of angiopietin-1(Ang-1),angiopoietin-2(Ang-2) and Tie-2 whentriamcinolone acetonide(TA) was intralesionally administrated on the grafthemangioma in nude mouse, and to explore the mechanism of glucocorticoidintervention.Methods: The specimens of proliferating hemangioma were obtainedfrom a male infant of 2-month-old and a female of 3-month-old by surgery. The tissue was cut into small pieces 5 mm×4 mm×3 mm in size andgrafted onto nude mice subcutaneously (4 pieces each) and animal model wasestablished.The mice were devided into two groups at 45 th day after graft: In miceof group 1 (experimental group, n=4), 0.05ml(4mg/ml) triamcinoloneacetonide (TA) was administered intralesionally. Simultaneously, the samevolume of normal saline (NS) was given to the mice of group 2 (control group,n=4). The grafts were observed on volume with a vernier caliper before and1,2weeks after TA administration.Grafted specimens were harvested before and 2 weeks after TAadministration. Formalin-fixed and paraffin-embedded specimens were cutinto 6μm sections and stained with hematoxylin and eosin (HE) as well asimmunohistochemistry. We also take reverse transcription-polymerase chainreaction(RT-PCR) to observe the expression of Ang-1mRNA, Ang-2 mRNAand Tie-2 mRNA affected by TA. The data were analyzed with astatistical software package (SPSS 13.0 for Windows) and P＜0.05 wasconsidered statistically significant.Results: There was no significant difference between the two groups atthe 45th day after graft(P＞0.05), and significant decrease of graft volume wasobserved in the experimental group compared to that in control group(P＜0.01) at 1 and 2 weeks after TA administration. The grafts inexperimental group (TA) turned harden and whitish in 2 weeks. While controlgrafts involved large amount of proliferative capillaries and signs ofdestruction were not evident.Under microscopy, grafts of experimental group were mainly composed of lipofibrous tissue. Collapse and blockage of vascular lumens were frequent.However, grafts in control group were still proliferating. With administrationof TA, significant differences of the intergrated optical density (IOD) ofAng-2,Tie-2 and VEGF staining were obtained between experimental groupand control group, and between experimental group and the group beforeinjection(P＜0.01). The IOD of Ang-2, Tie-2 and VEGF turned weakersignificantly after TA injection. While there were no significant differences ofAng-1 staining when compared to the control group and the group beforeinjection.With administration of TA, significant differences of the expression ofAng-2mRNA and Tie-2mRNA were obtained when compared to the controlgroup and the group before injection (P＜0.01). The expression ofAng-2mRNA and Tie-2mRNA turned weaker significantly after TA injection.While there was no significant difference of Ang-1mRNA among all theabove groups(P＞0.05).Conclusion: It has been shown that triamcinolone acetonide, whichresulted in accelerated regression of a proliferating hemangioma, could affectthe expression of the family of angiopoietins and their acceptors.