In vitro characteristics of neonatal hemangioma endothelial cells: similarities and differences between normal neonatal and fetal endothelial cells

Background: Increased angiogenesis and eventual involution are major charac teristics of neonatal hemangiomas. The mechanism to explain this transition is not completely understood. Methods: To determine the nature of these changes, endothelial cells were i solated from eight hemangiomas and the growth characteristics and morpholog y of these cells were compared to cells isolated from normal fetal and neon atal skin. Three cells lines were further characterized by analyzing protei n expression with immunohistochemistry and FAGS analysis. Results: Hemangioma endothelial cells converted to a spindle-shaped morphol ogy similar to that of fetal endothelial cells whereas neonatal endothelial cells maintained their characteristic epithelioid morphology. While neonat al, hemangioma and fetal endothelial cells continued to express platelet-en dothelial cell adhesion molecule-1 (PE-CAM-1) and von Willebrand factor (vW f), hemangioma and fetal cells expressed both proteins at a lower level and in a distribution distinct from normal neonatal endothelial cells. Neonata l endothelial cells continued to express epithelial specific Type IV collag en, while hemangioma and fetal endothelial cells produced interstitial Type I collagen. Conclusions: Both cell morphology and protein expression of neonatal hemang ioma endothelial cells were more characteristic of embryonic microvascular endothelial cells than that of postembryonic cells demonstrating a similari ty in these two cell types and suggesting a dysfunction in the normal growt h and maturation of endothelial cells in this tumor.