ABSTRACT
BACKGROUND: All-trans retinoic acid (ATRA) is an ideal therapy for acute promyelocytic leukemia, which can induce promyelocytes to differentiate to mature granulocytes. However, differentiation syndrome is still a high risk for the patients undergoing ATRA therapy. Occurrence of this complication is closely related with cellular morphology change and expression and function of cellular adhesion molecules, especially selectin and integrin families. OBJECTIVE: To reveal rolling adhesion behavior and mechanical mechanism of ATRA treated HL-60 cells on the substrate coated with E-selectin under different fluid shear forces. METHODS: Using the equipment of parallel plate flow chamber, untreated and ATRA treated HL-60 cells were driven to roll on E-selectin-coated substrate. The mean rolling velocity and mean stop time were calculated. Here, the HL-60 cells were incubated in the medium containing 1×10-6mol/L ATRA for 0, 48, 72, 96 hours. The substrates were captured with 40 μg/L E-selectin overnight and the shear stresses were set to 0.02, 0.04, 0.06 Pa. RESULTS AND CONCLUSION: The velocity of untreated/treated HL-60 cells decreased firstly and then increased with monotonously increasing shear stress. On the contrary, the mean stop time and factional stop time increased firstly and then decreased. Therefore, we deduced that the flow enhanced rolling adhesion was regulated by the catch bond for the HL-60 cells rolling on E-selectin under flow. On the other side, rolling velocities decreased under the same shear stress even if treated with or without ATRA, and the mean stop time and factional stop time increased inversely, which further illustrate the rolling velocity is mainly regulated by stop time.