Abstract
We hypothesized that cancer cells in vivo might actively migrate towards micro vessels in tumor tissue along oxygen concentration gradients. To test this hypothesis, we have devised the gap cover glass (GCG) that produces gradients of oxygen concentration in cultured MDA-MB-231 cells. Then, we tracked the position of individual cells under the GCG up to 12 hrs. At 12 hrs, number of the cell was decreased in regions >700 μm away from the oxygen entrance in the GCG (lower oxygen concentration) while number of the cells near the GCG edge (higher oxygen concentration) was increased. Next, we quantitatively evaluated the direction of cell movement using the forward migration index (FMI). We performed four experiments. For the cells under the GCG, the FMIx was either positive or negative indicating that no directional cell movement along the x-axis. On the other hand, in cells at 100, 300, 700, and 1500 μm, the FMIy was positive in 4/4 experiments indicating a directional migration towards the higher oxygen regions. Thus, we conclude that MDA-MB-231 cells cultured in collagen I coated culture dish migrates towards higher oxygen regions.
