Biomedical Engineering Reference
In-Depth Information
tent of GlcN depends on DD. For neutrophil-like HL60 cells, the migration indices for
55.8% DD chitosan elicited a significantly greater migration index than 83.3% DD chitosan.
Hydrophobicity can prolong physical interactions between cells and chitosan since neutro-
phils demonstrate an affinity for high-DD chitosan with hydrophobic surfaces. Prolonged
physical interactions between cells and chitosan may be a possibility for increased IL-8
secretion with increased N - acetylation. IL-8 will not only cause further chemotaxis toward
chitosan, but migrating cells will further secrete more IL-8, resulting in a positive feedback
loop that may account for the continuous migration and infiltration of neutrophils into
chitosan [44]. Du and coworkers [45] reported that chitooligosaccharides can significantly
offset the promotion of human hepatoma carcinoma cells-culture-fluid on the migration
and tube formation of endothelial cells (ECs) in a concentration-dependent manner.
Chitosan (with high DD 97.4% and MW 540 kDa) could induce inflammatory cell migra-
tion and angiogenetic activity, favoring high vascularization of the neo-tissue [46].
9.3.1.4 Differentiation
The differentiation fate of cells, especially stem cells, is influenced by transcription factor,
growth factor, cell-cell interactions, mechanical stimulation, and so on. At present, there
are very few reports on differentiation behaviors related to the molecular structure of
chitosan. Amaral et al. [47] found that rat bone marrow stroma cells cultured on chitosan
carrying a DD of 96% are able to reach a higher level of osteogenic differentiation than
on other chitosans with low DD and the control. Suphasiriroj et al. [42] found that the
chitosan-collagen scaffolds that contained low-DD chitosan supported greater alkaline
phosphatase activity in MC3T3-E1 cells than did chitosan-collagen scaffolds that con-
tained high-DD chitosan, irrespective of the MW. The different phenomena may be attrib-
uted to either different cell types or different materials. However, the detailed reason is
unclear till now, and it is necessary to study this differentiation mechanism with the devel-
opment of stem cell technology in the future.
9.3.2 effect of Chemical Composition
Tissues of the human body contain significant extracellular space, into which ECM mole-
cules are secreted by the cells to form a complex network ( cf. Figure 9.8) [48]. The ECM
provides mechanical support for tissues, organizes cells into specific tissues, and controls
cell behavior. Chitosan exhibits cell compatibility and elicits minimal immunological
responses. However, chitosan is not the main component of ECM and, to some extent, it
restricts cell spreading and cytoskeleton actin distribution. The reduction in cell size is
thought to be the result of strong electrostatic interactions. In order to mimic the ECM and
modulate the electrostatic interactions between chitosan and cells, some polymer or inor-
ganic minerals are incorporated into the chitosan network, and they can endow chitosan-
based biomaterials with a special cell response. In general, the combination of collagen,
gelatin, alginate, and hyaluronic acid (HA) into the chitosan network is mainly to modu-
late the cell behaviors of fibroblasts, and to also influence the behaviors of osteoblasts and
chondrocytes. Adjusting the chondrocyte response to chitosan-based biomaterials is
mainly by adding glycosaminoglycans (GAGs) and alginate. Introducing alginate can influ-
ence the osteoblasts and never cell behavior, while it is a more effective method to promote
the proliferation of osteoblasts by introducing hydroxyapatite (HAp) into the chitosan-
based network. Combining heparin can influence the character of smooth muscle cells
(SMCs). In addition, the content of these materials in chitosan-based biomaterials is also
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