Application of Chitosan-Based Biomaterials in Tissue Engineering - Chitosan Based Hydrogels: Functions and Applications - page 415

Figure 9.12
EM micrograph of chondrocytes seeded on uncross-linked and cross-linked films. Representative SEM images
of chondrocyte cells (passage 2) on cross-linked chitosan films with (a) 3.8 kPa, (b) 7.4 kPa, (c) 15.3 kPa, and (d)
19.9 kPa. (From Subramanian, A. and Lin, H. Y. J Biomed Mater Res 75A: 742-753. With permission.)
For example, rigid chitosan-gelatin-pectin film can promote osteogenic differentiation of
MSCs compared with the relatively soft chitosan-gelatin film [61].
9.3.4 effect of the Spatial Architecture of Chitosan-based biomaterials
At present, two types of chitosan-based biomaterial scaffolds have been used in tissue
engineering. One is the implanting scaffold, and the other is the injectable scaffold. The
implanting chitosan-based scaffold has a special spatial architecture and can be prepared
by various methods, such as thermally induced phase separation, freeze-drying, electro-
static spinning, and so on. The porosity and pore size of these scaffolds are easily controlled
and have excellent mechanical properties to maintain macroscopic shape during the appli-
cation. Compared with 2D film, cells seeded in these 3D scaffolds exhibit different cell
behaviors. Cells seeded in chitosan-based 3D cultures showed higher cell survival relative
to 2D chitosan-based substrata. On 2D substrata, cells are restricted to spreading on a flat
plane and an important factor affecting cellular activity is whether the substrate contains
a cell adhesion binding domain or not. On the contrary, 3D scaffolds provide spatial advan-
tages for cell-cell and cell-matrix adhesion as well as support for cell traction ( cf. Figure 9.13)
[62,63]. In addition, the pore size of the scaffold should be greater than the size of the cell,
and many cell types are unable to completely colonize scaffolds with pore sizes >300 μm