A number of models have been used to examine human and animal
corneal wound healing.
16 17 18 19 20 21 22 23 24 25 26 27 28 The organ culture model was
chosen in the present study because it (a) preserves corneal
architecture, (b) permits the interaction of different cell types
(e.g., epithelial cells, keratocytes), (c) retains limbal cells, a
source of epithelial cells, (d) maintains characteristics such as
centripetal migration, (e) enables the utilization of human tissue, and
(f) provides a means to examine the importance of endogenous and
exogenous growth factors.
16 Subsequent to McCarey and
Kaufman’s
29 report of media (MK media) in which human
corneas could be stored for up to 14 days before transplantation, two
major methods of culturing human corneal tissues have been published.
These include culturing of explants/corneas in media by
immersion
17 18 19 20 21 22 23 24 25 26 or by an air–liquid interface
technique.
16 27 28 The advantages and disadvantages of
both methods of tissue culture have been widely
discussed.
16 17 18 19 20 21 22 23 24 25 26 27 28 In the present study we used a
modification of the immersion technique that included placing corneas
in culture with the epithelial side facing up to avoid disturbance of
the epithelium,
17 22 exclusion of dextran in the media to
avoid detrimental alterations,
19 and media changes daily
to ensure a frequent replenishment of nutritive substances and to
eliminate waste. Moreover, exclusion criteria for the selection of
corneas based on such factors as patient history, infectious diseases,
and biomicroscopic examination were chosen to optimize and standardize
the investigations, and to enhance the viability and well-being of the
corneas. The use of the immersion technique appeared to provide the
appropriate environment for experimentation. Thus, immersion of the
cornea was not observed to be adverse to corneal architecture,
especially the structure of the epithelium, for the 7 days of organ
culture, concurring with the observations of previous
reports.
28 Cell generative processes were maintained, and
DNA synthesis was detected in the central and peripheral cornea as well
as the limbus. Human corneas in culture reepithelialized, indicating
that such properties as cellular migration and proliferation were not
compromised. Additionally, the rates of healing were comparable to
those in organ cultures using an air–liquid
environment,
16 27 as well as in
patients,
30 31 suggesting that wound repair processes were
intact and similar to that occurring in vivo.