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. 2011 May;6(5):301-305.
doi: 10.1049/mnl.2011.0184. Epub 2011 May 30.

Leukocyte rolling on engineered nanodot surfaces

X Lin-Schmidt  1 , A S W Ham  1 , M L Reed  2 , M B Lawrence  1 , B P Helmke  1
Affiliations

Leukocyte rolling on engineered nanodot surfaces

X Lin-Schmidt et al. Micro Nano Lett. 2011 May.

Abstract

Leukocyte rolling on the blood vessel wall represents the first step in the process of inflammation. In this study, nanofabricated substrates were designed with two different sets of feature size and spacing to mimic the expected distribution of discrete molecular adhesion patches on the surfaces of endothelial cells lining the blood vessel wall. P-selectin was attached to these nanopatterned dots, and the rolling behaviour of HL60 cells was analysed as a function of wall shear stress. When wall shear stress was less than 1 dyne/cm2, rolling velocity was independent of substrate patterning. However, when wall shear stress was higher than 2 dyne/cm2, rolling velocity was increased on the patterned substrates compared with the unpatterned sample, and rolling velocity increased with nanodot spacing distance. The influence of pattern spacing on the waiting time, the duration of zero-velocity pauses during rolling, also increased for wall shear stresses greater than 2 dyne/cm2. Additionally, the variance of instantaneous rolling velocities increased among substrates when the shear stress was greater than 6 dyne/cm2, indicating that the spatial arrangement of the nanodot pattern influenced not only the average velocity with which the cells rolled but also the saltatory nature of rolling. These results suggest that nanodot substrates represent a tool to investigate the biophysical and biochemical mechanisms regulating dynamic adhesion of leukocytes to the blood vessel wall.

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Figures

Figure 1
Figure 1. Characterisation of Au nanopatterned surfaces
SEM images of nanodots fabricated by anodisation in a Oxalic acid at 40 V (‘S40’) b Sulfuric acid at 25 V (‘S25’). Scale bar, 200 nm c Mean centre-to-centre inter-nanodot distance and nanodot diameter; error bars, standard deviation; *p < 0.05, unpaired t-test d Mean contact angle on untreated or cystamine-treated substrates
Figure 2
Figure 2. Cumulative frequency of instantaneous rolling velocity at wall shear stress magnitude
a 0.5 dyne/cm2 b 1 dyne/cm2 c 2 dyne/cm2 d 6 dyne/cm2 e 10 dyne/cm2 Rolling velocities were measured in 40–50 0.1 s intervals per cell for 23–26 cells at each level of wall shear stress magnitude
Figure 3
Figure 3. 23–26 cells per substrate at each level of wall shear stress magnitude
a Mean rolling velocity (measured in 10 s intervals) b Step velocity (40–50 intervals per cell) c Pause time (40–50 zero-velocity intervals per cell) Error bars, standard deviation
Figure 4
Figure 4. Variance of instantaneous rolling velocity
Error bars, standard deviation
Figure 5
Figure 5. Schematic diagram of close-packed array of circular nanodots used to estimate specific surface area, the ratio of total nanodot area to total surface area
d, average nanodot diameter; c, average centre-to-centre distance between nanodots
See this image and copyright information in PMC

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