Figure 4

Rescue of vessel formation at 5 days in endothelial cultures treated with high-energy protons and Fe ions. HBMEC were allowed to begin vessel development for 24 hours. Cultures were then treated with PMA 15 minutes before irradiation. After maturation 5 days later, cultures were fixed and stained for all proteins (green) and for nuclei (red). A. Un-irradiated controls show robust vessel formation. B. 1 Gy Protons reduce vessel formation. Cellular processes extended short distances into the gel matrix and terminated in a dead end (arrow). C. 1 Gy protons and 30nM PMA, vessel growth is restored. D. Fe ions and 30nM PMA vessel growth is not restored. Cellular processes make connections but remain thin without lumens (arrow) similar to Fe ions without PMA (Figure 1). Bar = 50 μm. E. Quantitation of vessels under all conditions (length of vessel with lumen per cell). PMA rescues vessel formation inhibited by protons but not Fe ions.