Biomedical Engineering Reference
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Figure 44.6. Corneal epithelial cell sheet transplantation. Limbal stem
cells are collected and seeded on temperature-responsive culture surfaces.
After 2 weeks in culture with an MMC-treated 3T3 feeder layer, all the
multilayered cells are harvested as a cell sheet using a doughnutshaped
PVDF membrane after release by temperature reduction. The cell sheet
is grafted onto the corneal stroma without sutures. Abbreviation :PVDF,
poly(vinylidene difluoride). Reprinted with permission from Ref. 50. Copy-
right 2004Lippincott Williams& Wilkins, Inc.
observed in a small portion of cells. These multilayered corneal
epithelialcellscouldbeharvestedasatransplantablecellsheetsim-
ply by reducing the culture temperature to 20 C, without the use
of proteases or ethylenediaminetetraacetic acid (EDTA). Harvested
sheets, flattened on their basal and apical surfaces, comprised three
to five cell layers with small basal cells, flattened middle cells, and
polygonal, flattened superficial cells. Such morphologic characteris-
tics are similar to human corneal epithelium in vivo to some extent;
however, they were less mature and differed in that the multilayer
characteristics seemed to vary depending upon location and that
the basal cells tended to be flattened, not cuboidal, especially in
regions with fewer layers. Interestingly, only the flattened superfi-
cial cells expressed keratin 3, whereas BrdU uptake was detected
in some basal cells. p63, which has recently been proposed as a
corneal epithelial stem cell marker, was expressed continuously in
 
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