Biomedical Engineering Reference
In-Depth Information
Felice Frankel
c
a
b
c
~1 µm
Master
100
80
60
40
20
0
Hepatocytes
100
80
60
40
20
a
PDMS
b
PDMS
0
1600 3500 4800 10000 Unlimited
c
Adhesive island area (µm
2
)
d
25
60
PDMS
Endothelial
cells
Endothelial cells
50
20
d
CH
3
(CH
2
)
15
SH
40
PDMS
15
30
10
20
e
5
10
Cell
HEG-thiol SAM
SAM (2-3 nm)
Au (10-200 nm)
Ti (1-10 nm)
Si (0.5-2 nm)
0.2-100 µm
f
g
0
0 1000
Adhesive island area (µm
2
)
0
2000
FIGURE 2.26
Microengineering. cell. shape. and. function. using. microstamped. SAMs.. (From. Rahul.
Singhvi, Amit. Kumar,. Gabriel. P.. Lopez,. Gregory. N.. Stephanopoulos,. Daniel. I.. C.. Wang,. George. M..
Whitesides,.and.Donald.E..Ingber,.“Engineering.cell.shape.and.function,”.
Science
.264,.696,.1994; and.
Christopher.S..Chen,.Milan.Mrksich,.Sui.Huang,.George.M..Whitesides,.and.Donald.E..Ingber,.“Geometric.
control.of cell life.and.death,”.
Science
.276,.1425,.1997..Figure.contributed.by.George.Whitesides.)
island size (see
Figure 2.26c
). In addition, albumin secretion rates, which are known to decrease
with increasing culture time as part of a hepatocyte dediferentiation process, decreased at a slower
pace for smaller islands. his indicates that, at least to some degree, cell function can be tailored by
modifying its shape. In a follow-up, highly-cited article, the same laboratories presented in 1997 a
study on how endothelial cells proliferate and go into apoptosis when constrained into single-cell
islands; as it turns out, both behaviors correlate with island size (see
Figure 2.26d
).
2.6.1.2 PEG Interpenetrated Networks
here is a wealth of evidence that, regardless of the chemistry used, micropatterning of PEG is a
successful long-term strategy for conining cell spreading. Kevin Healy and coworkers have also
demonstrated precise control of the shape of individual cells by photopatterning thin layers of
PEG-IPN of poly(acrylamide) and PEG onto glass (see Section 2.2.2 and
Figure 2.4
). Vitronectin
preferentially physisorbed onto aminosilane-derivatized glass areas surrounded by a PEG copo-
lymer background and directed the selective attachment and spreading of osteoblasts, as shown
in
Figure 2.27
. Cells constrained to attach to small (<900 μm
2
) islands were not able to organize
Actin filament organization
No actin organization
100 µm
FIGURE 2.27
Cell. shape. and. cytoskeleton. organization. constrained. by. PEG-IPN. micropatterns..
The images.show.actin.ilament.immunostaining..(From.C..H..Thomas,.J.-B..Lhoest, D. G. Castner, C. D..
McFarland,.and.K..E..Healy,.“Surfaces.designed.to.control.the.projected.area.and.shape.of.individual.
cells,”.
J. Biomech. Eng.
121,.40,.1999..Figure.contributed.by.Kevin.Healy.)
