Application of Chitosan-Based Biomaterials in Tissue Engineering - Chitosan Based Hydrogels: Functions and Applications - page 451

TAble 9.4
Application of Chitosan-Based Biomaterials in Tissue Engineering

Blood Vessel Skin Cartilage Bone Nerve Liver

Chitosan/collagen + +++ +++ + ++ ++

Chitosan/gelatin + +++ +++ + ++ +++

Chitosan/heparin +++

Chitosan/GAG ++ ++ +++ + ++ ++

Chitosan/alginate + +++ ++ ++ ++

Chitosan/pectin +

Chitosan/PVA ++ +

Chitosan/PLA ++ ++

Chitosan/PEO +

++

Chitosan/PLGA

++ ++

Chitosan/PLAGA
Galactosylated chitosan

+++

Fructose chitosan +++

Chitosan/HAp +++ +

Chitosan/TCP +++ +

Note: +++, optimal; ++, excellent; +, appropriate; blank, no data.

9.6.1 Design of Complicated Scaffolds

Tissues in nature exhibit gradients across a spatial volume, in which each identifiable layer
has specific functions to perform so that the whole tissue-organ can behave normally.
Such a gradient is termed a functional gradient. In the process of tissue regeneration, more
than one cell type is necessary. These different cell types have obviously different environ-
ments in vivo . The chitosan-based scaffold should have gradient chemical constitution and
matrix stiffness to construct a special ECM matrix for different cells. The tissues consist of
layers having different microstructures, which can vary in terms of porosity, density, and
pore size. They have different scaffold requirements, such as different pore sizes, porosi-
ties, and mechanical properties [208]. Table 9.5 summarizes the optimal properties for dif-
ferent cells types. A chitosan-based scaffold should be designed to fit these characteristics.
At present, some bilayer or multiple layer chitosan-based porous scaffolds have been
developed via freeze-drying [8] or the LBL assembly technique combined with choosing
salt as the porogen [209]. These multilayer structures have distinctive interfaces between

TAble 9.5
Optimal Microstructures of Chitosan-Based Scaffolds for Different
Tissues

Tissue Pore Size ( μ m) Matrix Stiffness

Blood vessel 60-150

Nerve Soft

Skin 20-125

Liver 45-150

Cartilage 70-120

Bone 100-400 Rigid