Biomedical Engineering Reference
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outreaching rete ridges retreated to where they originally resided
and the histology appeared to be similar to that of normal skin
(Fig. 34.12,
right
). Furthermore, histological and transmission elec-
tronicmicroscopeexaminationrevealedthepresenceofabasement
membrane structure in the tissue-engineered skin. Likewise, only
granulation tissue was observed in the control group histologically.
Supported by the
in vivo
result, we are currently investigating the
possibility of
in vitro
skin engineering using the same strategy. The
preliminary results showed that a double-layer skin was formed
after
in vitro
culturefortwoweeks,whichcontainedbothepidermis
anddermis.Atfourweeks,theengineeredskinbecamemoremature
by formation of stratified epidermis, deposition of abundant matrix
inthedermis,andpartialformationofabasementmembrane.Thus,
we propose that a synthetic biopolymer might be qualified as a
scaffold for
in vitro
skin engineering.
8
34.5 PGA Fibers for Corneal Stroma Engineering
Sincethecornealstromarepresentsthemajorcomponentresponsi-
bleforcornealtransparency,theprimaryeffortwasmadetotestthe
possibility of stroma engineering. To prepare the cell-scaffold con-
struct, PGA fibers (Albany International Research, Mansfield, MA),
15
μ
m in diameter and weighing 5 mg, were made into plate con-
structs, with a diameter of 5 mm and a thickness of 1 mm. The con-
structs were soaked in 75% ethanol for one hour and washed with
PBS three times, followed by washing with an F-12 medium con-
taining 10% fetal bovine serum (FBS). The medium was removed
afterward, and the constructs were air-dried for 30 minutes under
ultraviolet light. Corneal stromal cells were collected and resus-
pended in aculture mediumatadensity of 5
×
10
7
cells/mL. Incul-
ture dishes, 1
×
10
7
cells were seeded evenly onto the PGA fibers,
and the cell-scaffold constructs were kept in an incubator for four
hours to allow complete adhesion of the cells to the PGA fibers.
Ham's F-12 was then added, and the cell-scaffold constructs were
incubated for seven days before
in vivo
transplantation. The culture
medium was replaced twice per week.
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