Figure 2

High-energy protons but not high-energy Fe ions reduce the frequency of specialized motile tips of endothelial cells extending into the matrix. A and B low magnification 3-D images (projected onto a single plane) of HBMEC 24 hours after plating and 2 hours after, sham exposure A and exposure to 1Gy of protons B. Cultures are stained for microtubules (green) and actin (red). Cells appear similar although microtubules are more concentrated in un-irradiated cultures. Bar = 25 μm. C and D Higher magnification in controls C reveals motile tips - streamlined cellular processes with motile actin structures such as filopodia (arrowhead) and bundled microtubules (arrow). In cultures exposed to 1 Gy of protons D cellular processes are less streamlined with unbundled microtubules (arrowhead). In cultures exposed to Fe ions E cellular processes contain bundled microtubules (arrow) as in the controls. Bar = 10 μm. F. Line scans measuring pixel brightness (grey value) along the horizontal lines shown in C-E demonstrate the determination of bundled microtubules (Materials and Methods), a single peak denotes bundled microtubules whereas multiple peaks seen after proton exposure reveals unbundled microtubules. G. Quantitation of processes with bundled microtubules shows that motile tips are inhibited 4-fold by protons but not by 1Gy of Fe ions.