Biomedical Engineering Reference
In-Depth Information
applications of biodegradable scaffold-based tissue engineering are
extremelylimited.Inaddition,itispossiblethatbiodegradablescaf-
folds may not be ideal for the regeneration of cell-dense tissues,
including myocardium and hepatic structures.
4
−
7
Although the
degradation of biodegradable polymers, such as poly(lactic acid)
and poly(glycolic acid), theoretically allows for proliferating cells to
migrate into the spaces previously occupied by the degraded bio-
materials, large amounts of extracellular matrix (ECM) components
are often present within the scaffold structures. Additionally, signif-
icant inflammatory responses are commonly observed due to the
degradation of the polymer materials. Although this inflammatory
response can theoretically induce the recruitment of various leuko-
cytesandpossiblydirectnewbloodvesselformation,hostresponses
totheimplantedscaffoldscanalsopotentiallydamagethecellsboth
within the
8
implanted constructs and in the surrounding host tis-
sues. Based on these observations, tissue engineering techniques
that can re-create adequate blood supplies are likely to be required
to properly reconstruct tissues that possess the structure and func-
tion of the nativeorgans.
9
−
11
We have adopted an innovative approach to tissue engineer-
ing based on cell sheet technology.
12
Cell sheet technology consists
mainly of a temperature-responsive culture dish, which allows for
reversible cell adhesion to and detachment from the dish surface by
controllable hydrophobicity of the surface.
13
,
14
This enables a non-
invasive harvest of cultured cells as an intact monolayer cell sheet,
including deposited ECM. The monolayer cell sheet can be collected
simplybyreducingtheculturetemperaturetolessthan32
◦
Cforless
than one hour, without the need for any enzymes such as trypsin.
15
Byusingthistechnology,wecantransplantcellsheetstohosttissues
withoutusing biodegradable scaffolds(Fig. 44.1).
In thischapter, wefocuson the following:
(1) The basic mechanism of cell attachment to and detachment
from temperature-responsive cell culture surfaces
(2) Temperature-responsive cell culture surfaces that enable a
n-
itycontrol
(3) Applicationsfor regenerative medicine
(4) Future aspects forregenerative medicine
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