The effect of P-selectin pattern width on HL-60 cell rolling behavior

Abstract

The effect of varying the width of P-selectin band patterns on the rolling behavior of HL- 60 myeloid cells along edges of the band patterns was studied. The P-selectin and polyethylene glycol (PEG) pattern was produced via microcontact printing using a polydimethylsiloxane (PDMS) stamp. HL-60 cells were flowed across the pattern using a syringe pump at low and high volume flow rates, and the lengths of the cells' tracks along the edge and velocities along the edge were obtained using a designed Matlab code. It was found that on the 5[mu]m P-selectin band with patterns, the cells were moving horizontally instead of along the edge because the patterns were too thin, while they were rolling along the edge for the wider patterns. The 10[mu]m, 15[mu]m, and 20[mu]m patterns reflected the expected trend of resulting in increased track length along the edge with increasing P-selectin widths. The 15[mu]m band width corresponded to the highest rolling velocities along the edge. The 5[mu]m width gave the next to highest velocity which resulted likely because the 5[mu]m had the smallest P-selectin area to which the cells could interact, except that the cells were not rolling along the edge at this width. In addition, the 10[mu]m band width resulted in the lowest rolling edge velocity, which was unexpected. As expected, the rolling velocities along the edge for the 10[mu]m and 15[mu]m decreased when the flow rate was increased because only the cells with the strongest adhesion interactions remained on the patterns under higher shear stress. But the 5[mu]m and 20[mu]m patterns showed the opposite trend of decreasing with increasing flow rate. The unexpected results suggest that there are still important considerations to be studied when researching cell rolling behavior.