CONSIDERATIONS ON THE STRUCTURE OF BIOMATERIALS FOR SOFT- AND HARD-TISSUE ENGINEERING - Intelligent Scaffolds for Tissue Engineering and Regenerative Medicine - page 518

Figure 26.5. Appearance, loupe image, and biocompatibility of a three-
layered electrospun scaffold. Histological findings revealed that three-
layered scaffolds have good biocompatibility compared with PCL and PLA
with elastin scaffolds. See also Color Insert.
26.2.5 Biocompatibility and Mechanical Properties of
Electrospun Synthetic Scaffolds
To evaluate in vitro biocompatibility of electrospun nanofiber scaf-
folds,“cell-seedingtests”wereperformed.Cellsweresimplyseeded
onto the inside and the outside of the grafts and were evaluated
histologically. When PLA was used as a material for electrospun
nanofiber scaffolds, cells could populate the inside of the scaffold
wall and form good adhesions to the scaffold (Fig. 26.3g). On the
other hand, when a mixture of PCL, PLA, and elastin was used, cells
attached only to the surface of the scaffold wall and did not pop-
ulate the inside of the wall (Fig. 26.3h,i). The results from scan-
ning electron microscopy (SEM) showed ultrastructural differences
between the scaffolds made by these two materials (Fig. 26.3d-
f). Although addition of PCL improved the mechanical strength of
the scaffold (details of scaffold mechanical strength are described
below), the fibers with PCL tended to attach to each other, which
reduced the space between the fibers (Fig. 26.3e). Since the size of
electrospunnanofibersisrelativelysmall,thismorphologicalchange
significantly affected the mobilityof the cells.
Next,wehypothesizedthatacombinationofPLA,whichhasgood
biocompatibility, and PCL, which has excellent mechanical strength,
could form a satisfactory scaffold. Arteries have a three-layered
structure, so we decided to create three-layered scaffolds to satisfy
both mechanical strength and biocompatibility. In the case of three-
layered scaffolds, the layers on both the inside and outside of the
wall were made of PLA so that infiltration of the cells was satisfac-
tory (Fig. 26.5). When generating electrospun nanofiber scaffolds,