Biomedical Engineering Reference
In-Depth Information
Etch gold islands
Agarose/etchant
Form EG SAM
Coat fibronectin
and plate cells
Tubulin
Actin
PY
a
b
c
d
Au
Glass support
Glass support
Glass support
Image
50
40
10 µm
YFP-CLIP170
Projection
CLIP tracks
e
f
30
20
10
0
g
100
80
60
40
20
0
100
80
60
40
20
0
0.0
2.5
4.9
8.6%
7.4
9.8
12.3
36.7%
Projection
FIGURE 6.9
Effect.of.cell.shape.on.microtubule.edge.impact.turning..Scale.bar.is.10.μm..(From.
Kristiana.Kandere-Grzybowska,.Christopher.Campbell,.Yulia.Komarova,.Bartosz.A..Grzybowski,.and.
Gary.G..Borisy,.“Molecular.dynamics.imaging.in.micropatterned.living.cells,”.
Nat. Methods
.2,.739-
741,.2005..Adapted.with.permission.from.the.Nature.Publishing.Group.)
asymmetric “teardrop” or similar shapes using PEG-thiol surface chemistry (see Section 2.6.1.1
and
Figure 2.27
). he shape constraint was then released by electrochemical desorption of the
thiol SAMs. he cells (whether 3T3 ibroblasts, endothelial cells, or COS-7 cells) always moved
toward their blunt ends. his experiment demonstrates that morphological polarity itself can
determine the direction of motility in the absence of chemoattractant gradients.
A team led by Gary Borisy at Northwestern University in Chicago has used molecular dynam-
ics imaging and total internal relection to visualize the motion of microtubules within live
micropatterned cells in real time. his team used a patterning technique developed by Bartosz
Grzybowski's group based on selectively etching gold with an etchant-soaked agarose stamp
(
Figure 6.9a
through
d
; see also
Figure 1.35
in Section 1.7). Microtubule dynamics, in particu-
lar the “edge impact turning” (a measure of the change in microtubules growth direction when
they hit the edge of the cell), was observed to depend on cell shape, because microtubules that
reach the straight edges of triangular cells turn more frequently than those encountering con-
vex edges of circular cells (
Figure 6.9e
and
g
). Restriction of cells to the islands did not inhibit
microtubule growth velocity (
Figure 6.9f
).
6.2.2 Microtopographical Signaling
In the late 1980s, Donald Brunette at the University of British Columbia in Vancouver (Canada)
pioneered the study of cell behavior on substrates containing micromachined grooves. He knew
