Biomedical Engineering Reference
In-Depth Information
Finally with respect to EC response, it is interesting to note that even a
simple chemical treatment can lead to nano-rough topographies. For example,
Serrano et al.
67
showed improved EC adhesion and proliferation on nano-
rough poly(caprolactone) films (compared with untreated samples) synthesized
using sodium hydroxide (NaOH) etching. In contrast, Miller et al.
68
revealed
decreased EC adhesion and proliferation on poly(lactic/glycolic) acid (PLGA)
films with surface nano-topographies (compared with micron-sized) created
using NaOH etching.
d
n
4
t
3
n
g
|
0
2.5.5.2 Morphology and Response of Smooth Muscle Cells
Micro- and nano-grated topographies have been shown to influence the
response of smooth muscle cells (SMCs) on surfaces, particularly those
composed of polymers such as PDMS and poly(methyl methacrylate)
(PMMA). The general trend in findings is that micro-grated polymers yield
increased alignment, elongation and orientation but with reduced prolife-
ration.
69
For example, Yim et al.
70
showed significant elongation, alignment
and reduced proliferation of SMCs on PMMA and PDMS nanopatterned
gratings produced by nano-imprint lithography. The same authors also
demonstrated that a nanostructured surface favored the polarization of
microtubule organizing centers in the direction of the cell alignment axis,
whereas in the case of non-structured surfaces, microtubule organizing centers
were polarized towards the wound edge.
With regard to nano-pits, it has been shown that there is no substantial
influence of Ti
6
Al
4
V surfaces (produced by treatment with H
2
SO
4
/H
2
O
2
) on the
growth of SMCs.
71
Similarly, in another study, Nguyen et al.
72
showed an
unchanged response in SMC adhesion, an alteration in cell morphology and
enhanced cell proliferation for cells grown on 200 nm pit surfaces compared
with 20 nm pit surfaces. Interestingly, this study also reported that exposure of
SMCs to 200 nm pits induced the expression of various genes involved in cell
cycle processes such as DNA replication, cell proliferation and signaling
transduction pathways.
Finally, numerous studies have examined the response of SMC on random
nano-topographies. Gao et al.
73
studied the effect of SMCs in the presence of
serum on nano-rough poly(glycolic acid) (PGA) fibers prepared by surface
hydrolysis with NaOH. This work demonstrated a significant increase in the
density of SMC on surface-hydrolyzed PGA fibers. Increased bladder cell and
vascular SMC adhesion and proliferation have also been reported on nano-
structured casts of PLGA, polyurethane (PU) and poly(caprolactone) (PCL)
films that were chemically treated with NaOH
67
or HNO
3
.
74
In contrast, Peng
et al.
66
demonstrated decreased proliferation of SMCs and increased expression
of smooth a-actin on nanotubular TiO
2
surfaces.
n
3
.
2.5.5.3 Morphology and Response of Fibroblast Cells
Fibroblast cells (FCs) have been widely studied as a model to investigate the
influence of micro- and nano-grating island, pit and post geometries on cellular
