Biomedical Engineering Reference
In-Depth Information
Cell
Integrin
α
β
Ca
2+
RGD = Arginine-Glycine-Aspartic acid
Proteins:
Fibronectin, vitronectin, etc.
Substrate
Figure 7.12.
Surface properties affecting protein conformation and bioactivity. Adapted
from [128].
adsorbed on biomaterial [128] . Interactions between cell - membrane integrins
and extracellular proteins are often facilitated by the RGD sequence. These inter-
actions are important for the adhesion of many cells types. Integrin-mediated cell
attachment infl uences and regulates cell migration, growth, differentiation, and
apoptosis [128]. Various proteins—such as all types of collagen, fi bronectin, and
vitronectin—are known to be particularly important in mediating osteoblast ad-
hesion; importantly, RGD is contained in all of these proteins and is recognized
by cell membrane integrin receptors. Capitalizing on the use of such sequences
may enhance cell targeting and adhesion to specifi c receptors, and also cell behav-
ior via activation of specifi c signaling cascades, as shown in Figure 7.12.
The central hypothesis of biomimetic surface engineering is that peptides
that mimic part of the extra-cellular matrix affect cell attachment to the material,
and that surfaces or 3D matrices modifi ed with these peptides can induce tissue
formation according to the cell type seeded on the material. Therefore, extensive
research over the last decade has been performed on the incorporation of adhe-
sion promoting oligopeptides onto the biomaterial surfaces. Further, the major
advantage of using small peptides (such as RGD) with respect to larger peptides
or proteins is their resistance to proteolysis and their ability to bind with high
affi nities to integrin receptors. Combining this approach (covalently linking
peptides) with the use of nanomaterials has maximized cell responses.
In conclusion, as shown in Figure 7.13, nanomaterials have favorable surface
chemistry, nano structure and bioactive surfaces as well as improved various
Search WWH ::
Custom Search