Biomedical Engineering Reference
In-Depth Information
we investigated cell behavior at the boundary by using the intersecting grooves
(
w
= 1 ʼm;
s
= 3, 5, 7, 10, and 15 ʼm). The results of each form of cell behavior
(being repelled or attracted at the boundary) are plotted in Fig.
10.7b
with the verti-
cal axis as the angle of approach
θ
and the horizontal axis as the groove spacing
s
.
Narrow grooves with various spacings ranging from 0.5 to 15 ʼm repel migrating
cells with a high frequency, irrespective of the angle of approach. The result con-
firms the finding discussed in Chap.
9
that narrower grooves (
w
= 1 ʼm) repel cells
with great efficiency.
10.5.4
Effect of Groove Arrangement on Cell Migration
To assess the importance of groove arrangement, we next demonstrate the condi-
tions for cell repulsion and attraction using a single line groove (
w
= 4 ʼm). As seen
in Fig.
10.7c
, the single groove has a tendency to repel cells with lower angle of
approach and attract cells with higher angle of approach. The threshold angle esti-
mated according to the Youden Index in Eq. (
10.1
) is 41.0, which is almost the same
as that of the intersecting grooves with the same width (
w
= 4 ʼm,
s
= 5 ʼm).
However, in this case, the upper limit of the angle of approach for repelled cells
encountering the single line groove (
w
= 4 ʼm) is larger than that for intersecting
grooves of the same width (
w
= 4 ʼm,
s
= 5 ʼm), and the lower limit of the angle of
approach of cells for cell attraction is even smaller. The AUC of 0.86 for the single
line groove (
w
= 4 ʼm) indicates that the intersecting grooves with the same width
(
w
= 4 ʼm; AUC 1.00) give a better discrimination performance of a given angle of
approach than a single line groove (
w
= 4 ʼm). Altogether, the groove arrangement
and the groove width are important design variables for discrimination of cells
based on the angle of approach at the boundary with the grooved surface.
10.6
Mechanism of Modulation of Cell Migration
by Extracellular Matrix Microtopography
In this section, we explain how ECM micro-topography modulates cell migration
based on the findings mentioned in Sects.
10.4
and
10.5
.
10.6.1
Key Design Variables
The effects of grooves on cell behavior have been extensively studied and well char-
acterized by using parallel grooves and various types of cells such as fibroblasts
(Kim et al.
2009a
; Fraser et al.
2008
; Crouch et al.
2009
; Kaiser et al.
2006
), epithe-
lial (Fraser et al.
2008
; Clark et al.
1990
), endothelial (Uttayarat et al.
2005
), neu-
trophils (Tan and Saltzman
2002
), and neurons (Clark et al.
1990
). In these studies,
