Biomedical Engineering Reference
In-Depth Information
Figure 21.1.
Chemical structure of PVLA (from Ref. 23).
biomaterials. Especially, bulk modification of biomaterials is bene-
ficialtotissueengineeringapplicationswhereinjectablebiomimetic
materials are necessary to match the complex shape of native tissue
at defect sites.
18
Weigel
et al
.
19
firstly immobilized galactose groups to the
poly(acryl amide) among the synthetic polymers. Rat hepatocytes
were bound to a specific sugar in a Ca
2
+
-dependent manner,
20
and
thecellbindingtothesesurfaceswasspecificallyinhibitedbyasialo-
orosomucoid.
21
Weisz
et al
.
22
also coupled galactose groups to the
poly(acryl amide). Akaike
et al.
reported that galactose-carrying
polystyrene (PS), as shown in Fig. 21.1, is an excellent artificial ECM
to guide hepatocyte adhesion through the unique ASGPR-galactose
interaction,
23
andtheroundmorphologyofhepatocytesadheredon
the polymer was found to trigger the formation of spheroids of the
hepatocytes in the presence of epidermal growth factor (EGF), lead-
ing to enhanced cell functions.
24
Lopina
et al
.
25
immobilized galactose or glucose to the
poly(ethylene oxide) hydrogels. The results indicated that hepato-
cytes adhered to the gels bearing galactose but not glucose. The
amino galactose was conjugated with poly(styrene-co-maleic acid)
(SMA) through amide bond linkage by Donati
et al
.
26
The galactose-
coupled SMA showed about fivefold adhesion of HepG2 than SMA
itself.
Natural polymers have been used as an artificial ECM because
they have excellent physiological properties such as cell adhesion,
mechanical properties similar to natural tissues, and biocompatibil-
ity, although they have several disadvantages such as risk of viral
infection, antigenicity, instability, deterioration, and limited versa-
tility in designing an ECM with specific properties.
7
Park
et al
.
27
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