Perturbations in the fibrinolytic pathway abolish cyst formation but not
capillary-like organization of cultured murine endothelial cells
N Dubois-Stringfellow, A Jonczyk and VL Bautch
Department of Biology, University of North Carolina at Chapel Hill 27599.
Fibrinolytic activity and its relation to morphogenesis was investigated in
several transformed murine endothelial cell lines and primary cultures of
endothelial cells. Two in vitro systems, fibrin gels and Matrigel
(Collaborative Research, Bedford, MA), were used. Fibrin gels model a
fibrin-rich extracellular matrix that frequently supports
neovascularization in vivo, and Matrigel models the basement membrane
surrounding quiescent endothelial cells in vivo. The transformed
endothelial cell lines have higher levels of plasminogen activator (PA)
mRNA than primary cultures of endothelial cells, and an increased
PA-mediated proteolytic activity was correlated with formation of cysts in
fibrin gels. Addition of neutralizing anti- urokinase antibodies,
plasminogen depletion, or addition of a plasmin inhibitor prevented cyst
formation. Addition of plasminogen restored the ability to form cysts in
the plasminogen-depleted system. Normal endothelial cells organized into
capillary-like structures in fibrin gels regardless of manipulations
affecting the fibrinolytic pathway. In Matrigel, both transformed and
primary cultures of endothelial cells rapidly formed a capillary-like
network that was not affected by plasminogen depletion or addition of
plasmin inhibitors. Thus, elements of the fibrinolytic pathway necessary
for cyst formation are not critical in capillary-like structure formation
on a reconstituted basement membrane. These results suggest that plasmin is
essential for hemangioma formation but is not critical to the
organizational behavior of normal endothelial cells.
Volume 83,
Issue 11,
pp. 3206-3217,
06/01/1994
Copyright © 1994 by The American Society of Hematology
