Biomedical Engineering Reference
In-Depth Information
a
Starting points
End points
Flat surface
w
= 2
µ
m,
s
= 5
µ
m
Grooved surface
b
Starting points
End points
Flat surface
Grooved surface
w
= 3
µ
m,
s
= 5
µ
m
c
Starting points
End points
Flat surface
Grooved surface
w
= 4
µ
m,
s
= 5
µ
m
Fig. 10.6
Cell trajectories around the boundary with the intersecting grooved surfaces of (
a
)
w
= 2 ʼm,
s
= 5 ʼm, (
b
)
w
= 3 ʼm,
s
= 5 ʼm, and (
c
)
w
= 4 ʼm,
s
= 5 ʼm (Miyoshi et al.
2010
). The
results of time-lapse observation every 30 s for a few minutes to tens of minutes are superimposed.
The position of each cell nearest to the grooved surface is set at the origin. Some of the observed
trajectories are flipped horizontally for representation of the starting points in the
left upper quad-
rant
. The end points of the repelled cells are displayed in the
right upper quadrant
. The end points
of the attracted cells are fixed at the origin. Cell numbers observed: (
a
) n = 16 (14 cells repelled, 2
cells attracted); (
b
) n = 16 (11 cells repelled, 5 cells attracted); (
c
) n = 16 (8 cells repelled, 8 cells
attracted). The scale bars correspond to 20 ʼm (Adapted with permission from Elsevier Ltd.:
[Biomaterials], copyright (2012))
10.5.1
Angle of Approach to the Boundary
To quantitatively characterize the migratory behavior of a cell at the boundary, we
will define the angle of approach,
θ
, as the angle between the direction of cell migra-
tion and the boundary between the flat surface and the grooved surface, as indicated
in Fig.
10.4
. The direction of cell migration is defined as the least-squares line cal-
culated from three consecutive centroids of a cell taken at an interval of 30 s just
before encountering the boundary. The centroids are determined from binarized cell
images of the reflective micrographs.
