Biomedical Engineering Reference
In-Depth Information
suggested that implant surface microgrooves were unable
to influence the wound healing process at all (
den Braber
et al.
, 1997; Walboomers
et al.
, 1998b
). These differing
results may hint at multiple surface-texture-related
factors that are not yet identified and controlled.
Besides the effect on wound healing, microtextured
implants have also been used to inhibit epidermal
downgrowth along skin penetrating devices (
Chehroudi
et al.
, 1989
, 1990, 1992). This downgrowth is considered
as a major failure mode for this type of implant. Indeed,
the experiments suggested that epidermal downgrowth
can be prevented or delayed by percutaneous devices
provided with surface microgrooves.
that the ECM possesses mechanical properties. The
ECM is not a rigid structure, but a dynamic mass of
molecules. Many
in vitro
studies have already indicated
that cell-generated forces of tension and traction can
reorganize the ECM into structures that direct the be-
havior of single cells (
Erickson, 1994; Choquet
et al.
,
1997; Janmey and Chaponnier, 1995; Janmey, 1998
). As
cells cannot penetrate very shallow or small grooves, we
suppose that on those surfaces the forces as exerted by
the cells will result in an enhanced reorganization of the
deposited ECM proteins. Consequently, contact guid-
ance and other cell behaviors are induced. No doubt, cell
surface receptors and inside-outside cell signaling phe-
nomena play an important role in this process. As far as
in vivo
applications of surface microtexturing, more re-
search has to be done to learn and understand the full
impact of surface microtexturing for medical devices. A
first step is the development of techniques that enable
the production of standardized microstructures on non-
planar surfaces. Evidently, this development will benefit
not only biomaterial research, but also the production of
microelectronic, mechanical, and optical devices and
subsytems. As a second step, the relationship between
the surface topographical design of an implant and his-
tocompatibility has to be further documented. These
studies must focus not only on the soft tissue response;
they must also involve bone tissue behavior.
Directions for further developments
Considering the
in vitro
experiments, none of the earlier
mentioned hypotheses to explain contact guidance has
been fully supported. Therefore, based on various find-
ings we suggest a new theory that is a refinement of the
''mechanical'' theory discussed earlier. The breakdown
and formation of fibrous cellular components, especially
in the filopodium, is influenced by the microgrooves.
These microgrooves create a pattern of mechanical
stress, which affects cell spreading and causes the align-
ment of cells. On the other hand, we must also notice
Bibliography
Binnig, G., Quate, C. F., and Gerber,
C. (1986). Atomic force microscopy.
Phys. Rev. Lett.
56: 930-933.
Brauker, J. H., Carr-Brendel,
V. E., Martinson, L. A., Crudele, J.,
Johnston, W. D., and Johnson, R. C.
(1995). Neovascularization of synthetic
membranes directed by membrane
microarchitecture.
J. Biomed. Mater.
Res.
29: 1517-1524.
Brunette, D. M. (1996). Effects of surface
topography of implant materials on cell
behavior in vitro and in vivo. in
Nanofabrication and Biosystems,
H. C. Hoch, L. W. Jelinski, and H. G.
Craighead, eds. Cambridge University
Press, Cambridge, UK, pp. 335-355.
Brunette, D. M., Kenner, G. S., and Gould,
T. R. L. (1983). Grooved titanium
surfaces orient growth and migration
of cells from human gingival explants.
J. Dent. Res.
62: 1045-1048.
Campbell, C. E., and von Recum, A. F.
(1989). Microtopography and soft tissue
response.
J. Invest. Surg.
2: 51-74.
Chehroudi, B., Gould, T. R., and Brunette,
D. M. (1988). Effects of a grooved
epoxy substratum on epithelial cell
behavior in vitro and in vivo.
J. Biomed.
Mater. Res.
22: 459-473.
Chehroudi, B., Gould, T. R. L., and
Brunette, D. M. (1989). Effects of
a grooved titanium-coated implant
surface on epithelial cell behavior
in vitro
and
in vivo. J. Biomed.
Mater. Res.
23: 1067-1085.
Chehroudi, B., Gould, T. R., and Brunette,
D. M. (1991). A light and electron
microscope study of the effects of
surface topography on the behavior of
cells attached to titanium-coated
percutaneous implants.
J. Biomed.
Mater. Res.
25: 387-405.
Chehroudi, B., Gould, T. R. L., and
Brunette, D. M. (1990). Titanium
coated micromachined grooves of
different dimensions affect epithelial
and connective tissue cells differently
in vivo. J. Biomed. Mater. Res.
24:
1203-1219.
Chehroudi, B., Gould, T. R. L., and
Brunette, D. M. (1992). The role of
connective tissue in inhibiting epithelial
downgrowth on titanium-coated
percutaneous implants.
J. Biomed.
Mater. Res.
26: 493-515.
Chen, C. S., Mrksich, M., Huang,
S., Whitesides, G. M., and Ingber, D. E.
(1997). Geometric control of cell life
and death.
Science
276: 1425-1428.
Choquet, D., Felsenfeld D. P., and Sheetz,
M. P. (1997). Extracellular matrix
rigidity causes strengthening of integrin-
cytoskeleton linkages.
Cell
88: 39-48.
Chou, L. S., Firth, J. D., Uitto, V. J., and
Brunette, D. M. (1995). Substratum
surface topography alters cell shape and
regulates fibronectin mRNA level,
mRNA stability, secretion and assembly
in human fibroblasts.
J. Cell Sci.
108:
1563-1573.
Clark, P., Connoly, P., and Curtis, A. S. G.
(1987). Topographical control of cell
behavior I: simple step clues.
Development
99: 439-448.
Clark, P., Connoly, P., and Curtis, A. S. G.
(1990). Topographical control of cell
behavior II: multiple grooved substrata.
Development
108: 635-644.
Clark, P., Connoly, P., and Curtis, A. S. G.
(1991). Cell guidance by ultrafine
