Application of Chitosan-Based Biomaterials in Tissue Engineering - Chitosan Based Hydrogels: Functions and Applications - page 419

TAble 9.2
Chitosan-Based Biological Factor or Cell Delivery Systems for Tissue Engineering

Growth Factors Actions Substrate Material Applications

BMP-2 Bone morphogenesis Chitosan Bone regeneration

Chitosan-poly(glutamic acid) Osseointegration

PDGF-BB Mitogenic Chitosan Bone regeneration

Bone formation and
remodeling

Chitosan-chondroitin sulfate Periodontics

Chitosan-poly(l-lactide) Orthopedics

Plastic surgery

TGF-β Multifunctional Chitosan Bone and cartilage

regeneration

Chitosan-collagen
Chitosan-tricalcium phosphate
Chitosan-collagen-chondroitin sulfate

FGF-2 Mitogenic Chitosan-lactose hydrogel Angiogenesis

Angiogenic Photocross-linkable azide-chitosan-

lactose hydrogel

Wound healing

Regulates cell
differentiation

EGF Angiogenic

EC proliferation

Chitosan Wound healing

VEGF Angiogenic

EC proliferation

Chitosan-dextran sulfate nanoparticles Angiogenesis

Source: From Jiang, T. et al. 2008. Curr Top Med Chem 8: 354-364. With permission.

difficult to control. That all these behaviors depended on the electrostatic interactions
between growth factors and scaffolds is the main factor. One can modulate the release
behaviors by adjusting the interactions between growth factors and chitosan-based scaf-
folds. The isoelectric points of bFGF, platelet-derived growth factor-BB (PDGF-BB), and
transforming growth factor-β (TGF-β) are 9.6, 9.8, and 8.59, respectively. Under physio-
logical conditions, ionic repulsion between chitosan and these growth factors exists,
which results in low absorption and burst release. The rapid release phenomena are more
obvious when some cationic polymer or protein (isoelectric point higher than 7.4) is
incorporated into the chitosan scaffold. For example, the release rate of TGF-β loaded in
chitosan-collagen scaffolds is higher than that in pure chitosan scaffolds [75]. It is favor-
able to reduce the release rate when some polyanion polymers are incorporated into
chitosan due to the electrostatic attraction interaction between polyanion polymers and
growth factors or chitosan. For example, a more steady release of PDGF-BB may be obtained
by using the chitosan-chondroitin-4-sulfate scaffold than by using chitosan alone. And
the release of PDGF-BB is efficiently sustained because the content of chondroitin-4-sulfate
in the chitosan scaffold increased [76]. In order to improve the binding efficiency and
decrease the burst release of bFGF, Mi and coworkers [77] conjugated heparin on the chi-
tosan-alginate scaffold surface. The heparinized scaffolds exhibited higher affinity than
the chitosan-alginate scaffold alone. The scaffolds are uniquein their ability to bind bFGF
depending on the amount of conjugated heparin. The more the content of heparin, the
higher the binding efficiency. Moreover, the rate of bFGF release from the scaffold decreased
in a controlled manner with decreasing burst effect. For all that, the physical adsorption