Differentiation of neutrophil-like HL-60 cells strongly impacts their rolling on surfaces with various adhesive properties under a pressing force

Abstract : BACKGROUND: HL-60 cells have been used in in vitro experiments of neutrophils rolling. They lose uniform spherical appearance and enhance deformability by differentiation to neutrophil-like cells, which would affect their rolling characteristics. OBJECTIVE: We investigate the influence of differentiation and coating of target substrate on the fundamental rolling characteristics of the cells under a constant pressing force which mimics the pressing force to the vessel wall by erythrocytes in vivo. METHODS: Motions of undifferentiated and differentiated HL-60 cells on plain or MPC-polymer-coated flat glass substrate were compared using a homemade inclined centrifuge microscope system. RESULTS: Most of the cells alternated between stop and go during the motion. The differentiation resulted in a high temporal ratio of the non-moving state and low mean velocity during the moving state, together with a high suppression performance of cell adhesion by the polymer. It was also suggested that the cells were mostly rolling but that the coating probably induced an infrequent slip on the substrate to stabilize the cells motion. CONCLUSIONS: Differentiation strongly affects adhesivity of HL-60 cells but less affects the mean velocity. Our findings also demonstrate the importance of the pressing force and advantage of the present system with respect to classical flow chambers.