FIGURE 2.

Melanoma cells interact with platelets under flow conditions and in vivo. A and B, firm adhesion of CMFDA-labeled B16 cells (2 × 10⁵/ml) was assessed after 3 and 5 min of flow at a shear rate of 500 s⁻¹ on a monolayer of b.END.3 cells preincubated with freshly isolated murine platelets (PLT, 1 × 10⁸/ml) or Tyrode's buffer (ctrl.). A, adherent cells appear in yellow after merge of frames 50 and 55 in the off-line analysis at the respective time points after the perfusion was started. B, quantification of B16 cell adhesion experiments to a monolayer of b.END.3 cells. Data are representative of four individual experiments with similar results. *, p < 0.05, means ± S.D. is depicted. C and D, intravital video microscopy demonstrating the in vivo kinetics of firm adhesion of i.v. injected DCF-labeled B16 cells (2 × 10⁵ cells in 250 μl of PBS/mouse i.v.) to the endothelium of mesenteric vessels of C57BL/6J mice. Intravital video microscopy was performed before ligation of a jejunal branch of the superior mesenteric artery and at the indicated time points after reperfusion. Mice were depleted of platelets 30 min before tumor inoculation. Data are pooled from two experiments with 6–8 mice per group (means ± S.D.). *, p < 0.05 compared with control group. D, representative pictures of intravital video microscopy analysis before perfusion and at 60 min after reperfusion. Scale bar, 100 μm.