Biomedical Engineering Reference
In-Depth Information
network structure of collagen-based scaffold for tissue engineering. It has been shown
(Miron-Mendoza et al., 2010; Murphy et al., 2010) that collagen translocation ap-
peared to depend primarily on matrix stiffness, whereas cell spreading and migration
is less dependent on matrix stiffness and more dependent on collagen matrix porosity.
In creation of functional scaffolds for tissue engineering their dielectric properties
also play an important role. It is known that all the physiological processes are accom-
panied by the flow of electric current through such structural elements as intra- and
extra-cellular fluids and charge accumulation at the interface, for example of collagen
and water in the skin, tendon or bone. These conduction and polarization mechanisms
in the tissues are possible thanks to their dielectric properties. So, in the tissue en-
gineering the dielectric properties of scaffolds should be similar or even better than
those of the regenerating tissues and organs. The results of the studies performed by
the dielectric spectroscopy over a wide range temperatures provide new information
on molecular interactions in cross-linked collagen (Marzec and Pietrucha, 2008; Pietrucha
and Marzec, 2005, 2007). For collagen-HA or collagen-CS systems cross-linking is
an effective way not only to decrease the biodegradation rate but also to optimize the
dielectric properties of these systems. In fact, in the whole temperature range (22-
230°C) the dielectric parameters are much higher for collagen-HA and collagen-CS
scaffolds than for unmodified collagen because of the greater number of sites among
which protons can jump and mobility of these carriers in the former.
To summarize, the result of the thermal and dynamic viscoelastic measurements
supports strongly the conclusion that the collagen modified with HA/CS using EDC/
NHS makes the materials stiffer and gives rise to a marked increase in their structure
thermostability. The influence of cross-linking on the permittivity of collagen is signif-
icant over the entire temperature range. This may be ascribed to the possible simulta-
neous occurrence of two reactions: collagen-collagen cross-links and covalent grafting
of HA to the collagen backbone, resulting in the formation of semi- interpenetrating
polymer network (IPN). The results suggest that these collagen/HA and collagen-CS
matrices as an analog of the natural 3D ECM may be useful
in vitro
investigation to
support the attachment and proliferation of a variety of cells.
strateGy For NeW aPProaCh to tissue eNGiNeeriNG
In the recently proposed projects, foundations are established for an entirely new ap-
proach to tissue engineering by constructing artificial scaffolds based on combination
of cells, biodegradable multi-component matrix, and bioactive molecules (selected
growth factors and genes) to recapitulate natural processes of tissue regeneration and
development. Cooperative interplay of these components is imperative to achieve bio-
logically functional engineered tissue.
scaffolds with Bioactive molecules
The researchers believe that combined nano- and micro-fibrous scaffolds, with high
surface area to volume ratio, loaded with genes of growth factors will be a good sys-
tem for treatment of chronic wounds.
The chronic wounds are characterized with low
proliferation activity of cells and increased of metalloproteinases activity. Delivery of
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