How Does Cell Deform Through Micro Slit Made by Photolithography Technique?

Several slits sort cell according to the deformability in vivo. A micro slit (0.87 mm of width, 0.010 mm height) was newly designed between a micro ridge on a transparent polydimethylsiloxane plate and micro ridges on a borosilicate glass plate. These ridges made by photolithography technique make contact each other in the perpendicular position to make the slit between the ridges. A one-way flow system was designed to observe each cell passing through the slit in vitro. Four kinds of cells were used in the test: C2C12 (mouse myoblast cell), HUVEC (human umbilical vein endothelial cell), Hepa1-6 (mouse hepatoma cell), and Neuro-2a (mouse neural crest-derived cell). The suspension of each kind of cells was injected to the slits. The deformation of each cell passing through the slit was observed with an inverted phase-contrast microscope. At the microscopic images, the outline of each cell was traced, and the area (S) was calculated. The deformation ratio was calculated as the ratio (S₂/S₁) of the projected area of each cell before the slit (S₁) and that in the slit (S₂). The velocity of the cell passing through the slit was calculated by the trace at the microscopic movie. The experimental results show that each cell deforms to the flat circular disk and passes through the micro slit. Hepa1-6 is flattened with the increase of the passing velocity, and HUVEC is elongated along the flow. The designed slit between micro ridges is effective to evaluate the deformability of cells.