title: Evolution of hemangioma endothelium.
abstract: Infantile hemangioma is a benign vascular tumor, characterized by a unique life cycle consisting of rapid growth and spontaneous regression. Three distinct phases (proliferating, involuting, and involuted) take place over the course of approximately 5-8 years, with specific cell types defining each separate phase. The origin of the cells comprising hemangiomas has been deliberated over since the late 1800s. We have recently provided experimental evidence that hemangiomas arise from multipotent stem cells. These hemangioma stem cells that give rise to the endothelial cells are also the essential source of adipocytes during hemangioma involution. The molecular mechanisms that regulate the differentiation of the hemangioma stem cells remain unclear. Although recent studies have elucidated a number of signaling pathways underlying hemangioma pathogenesis, many unanswered questions remain. Herein, we review the unique cellular composition of infantile hemangioma, as well as some of the signaling pathways active within hemangioma-genesis. Understanding the mechanisms behind changes in cellular fate throughout the hemangioma growth pattern will not only provide insight into the stem cell population that resides within the tumor, but will help to establish more effective eradicating therapies.
authors.affiliation: Department of Pathology, University of Western Ontario, London ON, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Kleiman
authors.forename: Emily C
authors.initials: EC
authors.lastname: Keats
authors.forename: Nancy G
authors.initials: NG
authors.lastname: Chan
authors.forename: Zia A
authors.initials: ZA
authors.lastname: Khan
mesh_terms: D014408:Biomarkers, Tumor / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism / Q000473:pathology*; D018324:Hemangioma, Capillary / Q000473:pathology* / Q000628:therapy; D006801:Humans; D039902:Multipotent Stem Cells / Q000378:metabolism / Q000473:pathology*; D009386:Neoplastic Syndromes, Hereditary / Q000473:pathology* / Q000628:therapy; D009389:Neovascularization, Pathologic / Q000378:metabolism / Q000473:pathology*; D015398:Signal Transduction
chemical_list: D014408:Biomarkers, Tumor