Biomedical Engineering Reference
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(Green Cross P. D. Co., Yongin, Korea) and (2) culture medium. PLGA
scaffolds were pretreated with calcium chloride solution for the
PLGA/fibrin group prior to cell seeding. The chondrocytes-fibrin
admixture was seeded into PLGA scaffolds and was allowed to
polymerize within five minutes. The chondrocyte suspension in the
culture medium was seeded directly into PLGA scaffolds and incu-
bated for five minutes before adding the culture medium. All con-
structs were cultured for three weeks
in vitro
and then implanted
at the dorsum of athymic nude mice. Resulted
in vitro
and
in vivo
constructs were harvested at one, two, and four weeks postimplan-
tation.
The morphology of cells and the distribution of cartilaginous
ECM in the fibrin/PLGA and PLGA were examined via histologi-
cal staining (Fig. 16.2). Before implantation, hematoxylin and eosin
(H&E)stainingshowedthatcellsandECMfilledthespaceofthefib-
rin/PLGA. A significant number of round morphological chondro-
cytes clusters and cartilaginous ECM formation were observed in
the fibrin/PLGA hybrid construct than in the PLGA construct. The
invitro
fibrin/PLGAconstructsexhibitedsuperiorhistoarchitectural
characteristics of cartilage-like tissue compared with the control.
Thecloselypackedcartilage-isolatedcellswerehomogeneouslydis-
tributed in the ECM and exhibited rounded morphology with lacu-
nae embedded in the basophilic ground substance. The pericellular
and interterritorial matrix was strongly stained by the characteris-
tic red of Safranin O, to indicate the presence of a proteoglycan-rich
matrix in the construct. Cartilaginous ECM deposition was further
demonstrated by positive Alcian blue staining to confirm the pres-
ence of accumulated glycosaminoglycans(GAGs).
The formation of cartilaginous tissue in fibrin/PLGA constructs
was remarkably evident at each time point of one, two, and four
weeks after
in vivo
implantation. In the fibrin/PLGA construct, an
increase in the implantation period resulted in a lower cells-to-
matrix ratio, similar to that of native hyaline cartilage. Cartilage-
isolated cells with lacunae were sparsely distributed within the
homogenous ECM in concert with the presence of a specific his-
tochemical property of the accumulated proteoglycan-rich matrix
and GAG. Whereas, in PLGA, the presence of chondrocytes in
their natural round morphology increased with an increase in the
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