Biomedical Engineering Reference
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of degradation as was shown for the poly 2-hydroxyethyl methacrylate (pHEMA)
based MGs [Bolgen et al., 2007a]. The incorporation of the degradable co-
monomers (as 2 - hydroxyehthylmethacrylate - L - Lactide HEMA - LLA) or
macromers (as HEMA-LLA-dextran) into the polymeric backbone allows for
developing MGs with open porous structure and controlled rate of degradation
level [Bolgen et al., 2007b]. The dextran-MA based non-degradable MGs (pre-
pared through the free radical polymerization of dextran-MA macromer at
−
20 °C) were stable for degradation under
in vitro
conditions (37 ° C in PBS buffer,
pH 7.2) for at least four months (Figure 14.15a) while incorporating HEMA-
LLA and HEMA-LLA-dextran degradable grafts into the MGs network resulted
in pronounced degradation (evaluated as loss of weight) of the MGs (Figure
14.15 b).
Different MGs were tried as 3D-supports for cell culture applications. These
MGs can be divided into two categories, one prepared from synthetic precursors
and other MGs prepared from the natural biopolymers such as agarose, gelatin,
chitosan and dextran. The pAAm MG, coated with gelatin (which is considered
as one of the most common materials to facilitate the attachment of anchorage
dependable cells [Bloch et al., 2005; Kumar et al., 2006a,b], were tested as poten-
tial 3D-scaffolds for cell culturing. The human HT116 colon cancer cells were
effectively attached and colonized onto the gelatin-coated pAAm MGs [Kumar
et al., 2006a,b].
Another type of MG scaffolds was prepared on the basis of natural materials
as agarose [Bloch et al., 2005], dextran [Bolgen et al., 2007a,b; Plieva et al., 2006c],
gelatin [Dubruel et al., 2007] and chitosan (unpublished results). The agarose
MG scaffolds, prepared at subzero temperature in the shape of small discs with
thickness of two millimeters, had sponge-like morphology and interconnected
pores (channels) with size up to 200-400
m in diameter. The agarose
scaffolds were coated with gelatin to facilitate the attachment of insulinoma
cells (INS-1E). No toxic affect of the agarose cryogel sponge on cell viability
and proliferation was found. However, the cells displayed low affi nity to agarose
per se. Insulinoma cells seeded on gelatin-coated sponges attached to the
cryogel surface and proliferated. The cell monolayer covered 80% of the cryogel
surface. Both cells attached to gelatin-coated agarose cryogels and
cells attached to plastic dishes (used as control) demonstrated time-dependent
increased insulin secretion and approximately equal insulin content [Bloch et al.,
2005 ].
Mouse fi broblast 3T3-L1 cells were seeded into the dextran-MA based
scaffolds to examine the cell attachment and proliferation [Plieva et al., 2006c];
3T3 - L1 fi broblasts demonstrated attachment to the gel surface and showed the
spread and elongated shape characteristic for fi broblasts [Plieva et al., 2006c].
After eight days from the beginning of differentiation in the dex-MG scaffold, a
change in cell morphology from elongated fi broblasts to regular, round adipo-
cytes was observed. The biological function of the differentiated adipocytes in
dex-MG scaffolds was confi rmed by the lipolysis assay which showed more than
2.4 times increased glycerol release from the differentiated adipocytes in
μ
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