Use of modified human hemangioma tissue cultures and human umbilical vein endothelial cell cultures to gain mechanistic insights into imiquimod treatment for infantile hemangioma.

Infantile hemangiomas (IH) are a common entity encountered by dermatologists, otolaryngologists, and other surgeons. Oral propranolol is a mainstay of treatment for IH and is well-tolerated, though propranolol-refractory IH and other drug-related adverse events are documented and can limit its usage. There are few in vitro testing systems for putative treatment agents. To address this, we modified a tissue culture system for human hemangioma treatment testing to evaluate the treatment impact of the immune modifier, imiquimod. Human umbilical vein endothelial cells (HUVEC) and hemangioma cultures were treated with several concentrations of imiquimod followed by MTT assays, reporter gene assays, PCR, ELISA, and Western blotting for IL-8, VEGF, Cyclin D1, and IFNα and immunohistochemistry for Cyclin D1 and Ki-67. HUVEC showed acute decreases in IL-8, VEGF, and Cyclin D1 promoter activity and increases in IFNα mRNA after imiquimod treatment. Hemangioma samples showed no change in Ki-67 or Cyclin D1 staining after treatment with imiquimod after 27 d, with significantly increased IL-8 and VEGF. From this preliminary analysis, we discerned that hemangioma tissues can be grown in tissue culture and used for drug treatment studies. We also conclude acute and chronic modulation of cell cycle, angiogenesis factors, and immunostimulatory conditions may be associated with imiquimod mechanisms of action in hemangioma involution.