Integration of endothelial cells in multicellular spheroids prevents apoptosis and induces differentiation.
Single endothelial cells (EC) seeded in suspension culture rapidly undergo apoptosis. Addition of survival factors, such as VEGF and FGF-2, does not prevent apoptosis of suspended EC. However, when cells are allowed to establish cell-cell contacts, they become responsive to the activities of survival factors. These observations have led to the development of a three-dimensional spheroid model of EC differentiation. EC spheroids remodel over time to establish a differentiated surface layer of EC and a center of unorganized EC that subsequently undergo apoptosis. Surface EC become quiescent, establish firm cell-cell contacts, and can be induced to express differentiation antigens (e.g., induction of CD34 expression by VEGF). In contrast, the unorganized center spheroid cells undergo apoptosis if they are not rescued by survival factors. The responsiveness to the survival factor activities of VEGF and FGF-2 was not dependent on cell shape changes since it was retained after cytochalasin D treatment. Taken together, these findings characterize survival factor requirements of unorganized EC and indicate that polarized surface EC differentiate to become independent of exogenous survival factors. Furthermore, they demonstrate that spheroid cell culture systems are useful not just for the study of tumor cells and embryonic stem cells but also for the analysis of differentiated functions of nontransformed cells.
Korff
T
T
Cell Biology Laboratory, Department of Gynecology and Obstetrics, University of Göttingen Medical School, 37075 Göttingen, Germany.
Augustin
H G
HG
D018952:Antigens, CD34 / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002448:Cell Adhesion; D002454:Cell Differentiation / Q000187:drug effects; D016764:Cell Polarity; D048429:Cell Size; D002470:Cell Survival; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008222:Lymphokines / Q000494:pharmacology; D008954:Models, Biological; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D018874:Spheroids, Cellular / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D018952:Antigens, CD34; D016228:Endothelial Growth Factors; D008222:Lymphokines; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019010:Vascular Cell Adhesion Molecule-1; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D016222:Fibroblast Growth Factor 2; D018799:Intercellular Adhesion Molecule-1