DESIGN OF BIOMIMETIC SCAFFOLDS FOR LIVER TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 406

Moreover, liver functions of the hepatocytes such as albumin secre-
tion and urea synthesis in the GAC were improved compared with
those in the AC. During preparation of AC, galactosylated chitosan 39
or XG 40 as ECMs were entrapped together. Encapsulation of hepato-
cytes in the AC with ECMs exhibited a higher metabolic function in
albuminsecretioncomparedwiththoseentrappedinACthemselves
duetotheenhancedmulticellularspheroidformationofhepatocytes
by the ECMs.
Hydrogels are 3D, hydrophilic, polymeric networks capable
of imbibing large amounts of water. 41 Therefore, the soft and
hydrophilic nature of hydrogels makes them suitable as scaffolds in
tissue engineering after freeze-drying. Alginate, a block copolymer
of β -D-mannuronic acid and α -L-guluronic acid, easily gels in the
presence of divalent cations. Chung et al . 42 prepared an alginate/GC
scaffold by mixing GC into an alginate sponge for hepatocyte attach-
ment. The introduction of GC into an alginate sponge enhanced
hepatocyte adhesion and mechanical properties of the sponge and
better retained the differentiated cell functions. Also, the pore sizes
of the sponge were greatly by the freezing temperature. Seo et al . 43
introduced heparin into an alginate/GC sponge to modulate the
binding and signaling of various growth factors secreted by fibrob-
lasts.Theresultsindicatedthatthelevelofalbuminsecretioninalgi-
nate/GC/heparin sponges was markedly elevated compared with
that in alginate/GC ones in the presence of hepatocyte growth fac-
tor. Hong etal . 44 coupledgalactosemoietieswithgelatinforhepato-
cyteattachment.Thegalactosylatedgelatinspongeexhibitedhigher
hepatic-specific metabolic functions, such as the secretion of serum
albumin and the synthesis of urea, than those cultured on a col-
lagen type 1-coated monolayer. Chen et al . 45 introduced galactose
moieties into a vegetable sponge for the culture of hepatocytes in a
packed-bed bioreactor. The immobilized cells in the galactosylated
sponge maintained high albumin and urea production rates during
long-termperfusion culture.
The nanofibers are continuous and potentially providing for
integrated manufacturing of 3D nanofibrous scaffolds with high
porosity and high interconnectivity. 46 Highly porous nanofiber scaf-
folds can be prepared by electrospinning. Chua et al . 47 reported
that a galactosylated poly(epsilon-caprolactone-co-ethyl ethylene