Comparative analysis of in vitro angiogenic activities of endothelial cells of heterogeneous origin

Endothelial cells are dynamic participants in many aspects of host defense, innate immunity, inflammation, angiogenesis, and vasculogenesis, but the interpretation of studies of their responses is often clouded by the source of the cells under observation. Thus, it is not clear which endothelial cell type should be utilized in in vitro studies to clarify the basis and physiological relevance of essential processes, including chemotactic migration and morphogenic differentiation. In this study, we compared responses of endothelial cells of a variety of origins, as well as an immortalized cell line, using both protein growth factors and biologically active lipid mediators as agonists. While cells of divergent origin displayed marked differences in the extent of their responsiveness, with a few notable exceptions, their pattern of responsiveness to receptor-dependent stimuli was remarkably similar. Moreover, even the immortalized endothelial cell line Py-4-l migrated in a pattern consistent to that seen with primary cells in culture although the immortalized cells failed to form capillarylike structures under any of the conditions tested. We conclude that although the immortalized endothelial cell line Py-4-l is not appropriate for investigations of endothelial cell morphogenic responses, cultured cells from other sources, including arteries, veins, and capillaries, often provide qualitatively similar results to divergent metabolic stimuli.