Quantitative
(A) and qualitative (B-E) analysis of endothelial cell apoptosis (HUVEC)
after treatment with different cytokines. A defined number of spheroids
was stimulated with different cytokines for 24 h and the presence of
nucleosomal fragmentation products was quantitated by ELISA (A). Data
are expressed as percentage deviation of the level of apoptosis from the
untreated control spheroid population. In HUVE cells, VEGF, FGF-2 and
ANG-1 but not ANG-2 act as survival factors. They reduce HUVEC apoptosis
in spheroids by >30% (B, control HUVEC spheroid; C, VEGF + FGF-2
stimulated HUVEC spheroid; D, ANG-1 stimulated HUVEC spheroid; E, ANG-2
stimulated HUVEC spheroid). Note that only center EC die by apoptosis
that can be increased by treatment with a neutralizing monoclonal
antibody to FGF-2 but not to VEGF.
