Contact guidance of human neutrophil leukocytes

Abstract

The influence of the alignment of the substratum on the direction of locomotion of human neutrophil leukocytes was studied using time-lapse cinematography ( a) of cells moving on the grooves of serum-coated Neubauer counting chambers; ( b) of cells moving within the matrix of aligned hydrated gels of collagen or fibrin. When cells moving across the plane surface of serum-coated glass chambers met a groove, they were highly likely to join and migrate along the groove. Analysis of the tracks of neutrophils migrating within the matrix of aligned collagen and fibrin gels showed a significant bias towards locomotion in the axis of fibre alignment, compared with other directions. There was no evidence of chemotaxis and the locomotion was bi-directional, suggesting contact guidance. A sensitive method for quantifying guidance responses in gels was found to be measurement of the angle to the axis of alignment of the gel made by each segment of the cell path. Indices, based on these measurements, that can be used to compare different experiments are described. Neutrophils on air-dried aligned fibrin surfaces failed to show guidance, suggesting that guidance of neutrophils in gels may be a response to the shape of non-planar substrata, as has been suggested previously in studies on fibroblasts. Interactions between two forms of directed locomotion, chemotaxis and contact guidance, obviously require to be considered in the assessment of leukocyte accumulation in inflamed sites.