VEGF promoted the generation of ES-sacs and subsequent platelets. (A) The effects of cytokine/growth factor(s) on production of ES-sacs via protocol 2. VEGF increased the numbers of ES-sacs generated, while BMP-4 inhibited the effect of VEGF on the ES-sac production. (B) Bevacizumab, an anti-VEGF neutralizing antibody, reversed the VEGF-induced increase in ES-sac formation on day 15 (i) or platelets on day 24 (ii), confirming that the phenomenon is VEGF dependent. (C) PlGF, but not bFGF, acted additively with VEGF to increase ES-sac formation. The number of ES-sacs obtained with no additional cytokine/factor(s) was assigned a value of 1.0 (control), and all results are means (± SD) of 3 independent experiments.