Biomedical Engineering Reference
In-Depth Information
Recently, we developed a new technique to fabricate pore-size-
gradient, cylindrical scaffolds by a simple centrifugation. In this
technique, the pore size ranges of the scaffold can be easily con-
trolled by adjusting the centrifugal speed. The pore-size-gradient,
cylindrical scaffolds were fabricated with alginate, chitosan, and
poly
-
-caprolactone(PCL)byacentrifugationtechnique,andtheir
characterizationsintermsofscaffoldporesizeswerediscussedin
thischapter.
ε
30.1 Introduction
The control of a 3D pore structure is of great importance for the
development of scaffolds for tissue engineering. Highly porous scaf-
folds with an interconnected pore structure are desirable in many
cases to facilitate cell seeding and adhesion, secretion of extracellu-
lar matrices, and eventual tissue regeneration. Numerous investiga-
tions, including scaffold fabrication,
1
surface modification,
2
-
4
and a
bioreactor system
5
for the development of the scaffolds, which can
provide a desirable environment for cell growth, have been actively
conducted. It is well recognized that the pore size of scaffolds plays
an important role for cell binding, migration, and ingrowth
6
,
7
and
tissue ingrowth and regeneration.
8
,
9
A number of cell types exhibit
a preference for binding to scaffolds with pore sizes significantly
larger than the characteristic cell size, often utilizing a characteris-
tic bridging mechanism where adjacent cells act as support struc-
tures to assist bridging large pores. Generally, it was reported that a
large pore size or porosity of the scaffold can allow effective nutri-
ent supply, gas diffusion, and metabolic waste removal but lead to
low cell attachment and intracellular signaling, while a small pore
sizeorporositycanprovideoppositepropertiesofabove.
6
,
9
,
10
Many
researchers have reported optimum pore size ranges for the differ-
entkindsofcellsortissues,forexample,theporesizesof
∼
5
μ
mfor
neovascularization,
11
5
∼
15
μ
mforfibroblastingrowth,
12
∼
20
μ
m
for hepatocyte ingrowth,
9
20
∼
125
μ
m for skin regeneration,
13
70
∼
120
μ
m for chondrocyte ingrowth,
14
40
∼
150
μ
mforfibroblast
binding,
15
45
m for liver tissue regeneration,
16
60
∼
150
μ
∼
150
m for vascular smooth muscle cell binding,
10
100
μ
∼
300
μ
mfor
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