Macro- and microvascular endothelial cells in vitro: Maintenance of biochemical heterogeneity despite loss of ultrastructural characteristics |
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Authors: | Donna Beer Stolz Bruce S Jacobson |
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Institution: | (1) Program in Molecular and Cellular Biology, University of Massachusetts, 01003 Amherst, Massachusetts |
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Abstract: | Summary Microvascular endothelial cells from bovine adrenal medulla and brain and macrovessel endothelial cells from bovine aorta
were isolated and cultured under similar conditions in order to determine morphologic and biochemical heterogeneity in vitro.
All three cell types exhibited nearly identical ultrastructural morphology and two-dimensional gel protein patterns of35S-methionine-labeled whole cells. Two-dimensional gel analysis of35S-methionine-labeled plasma membrane proteins however, revealed two-dimensional gel protein patterns unique to the tissue
type from which the endothelial cells were isolated. This suggests that the functional significance of these specific endothelial
cell types is manifested primarily in surface-associated proteins and that many of the differences are sustained in culture.
To determine the potential of aorta, brain, and adrenal medulla endothelial cell (EC) cultures to respond to developmentally
significant signals, morphology, growth pattern, and cell surface proteins were monitored in the presence and absence of growth
factors. A 17 to 26% increase in cell density as well as an increase in the number of elongated and overlapping cells resulted
when all three EC types were exposed to a mitogenic medium. Additionally, expression of specific glycoprotein profiles, as
determined by Concanavalin A Western blotting of two-dimensional gels, was dependent on the presence or absence of growth
factors in the medium. The ability to induce this morphologic and biochemical variation in the three endothelial cell types
was maintained into later passage. Taken together, these data imply that endothelial cells isolated from different tissues
exhibit and maintain biochemical heterogeneity and do not completely dedifferentiate into a common endothelial cell type in
culture. Furthermore, expression of specific subsets of cell surface proteins is dependent on environmental conditions, and
in some cases is both cell-type and media-type dependent. Thus, even though endothelial cells are considered terminally differentiated
cells, there exists additional or “latent” heterogeneity in the ability of these different cells to respond to “developmental
signals” (i.e. mitogenic medium) in vitro.
This work was supported in part by a grant from the American Heart Association (860929), NIH (GM29127), and a Biomedical Research
Grant from the University of Massachusetts. |
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Keywords: | endothelial cells aorta brain adrenal medulla heterogeneity growth factors |
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