Expression of Collagen I, Smooth Muscle a-Actin, and Vimentin ...

3326 Investigative Ophthalmology & Visual Science, November 1993, Vol. 34, No. 12
Viiiuillin
e
9
0.1 mm
FIGURE 7. Immunostaining of alkali-burned and lacerated corneas with antibodies against
smooth muscle a-actin and vimentin. Alkali-burned and lacerated corneas healed for 2 weeks
were subjected to immunostaining as described in Figures 5 and 6. Panels a, b, c, and d,
alkali-burned cornea; panels e, f, g, and h, lacerated cornea; panels a, c, e, and g, anti-smooth
muscle a-actin; panel b, d, f, and h, anti-vimentin. RCM, retrocorneal membrane; arrows
indicate Descemet's membrane; *, granulation tissues in lacerated cornea. Magnification, bar
= 0.1 mm.
normal corneas are not stained by anti-vimentin antibody
(Fig. 6a), but the basal epithelial cells in alkaliburned
and lacerated corneas are stained by the antibody
{Figs. 7b, 7f). The anti-desmin antibody does not
react with any cell type in normal and injured corneas,
but it does react with ocular muscle cells (data not
shown).
DISCUSSION
In the present study, we measured the amounts of
al(I) mRNA in alkali-injured rabbit corneas. Our results
indicate that the amount of al(I) mRNA steadily
increases as the alkali-burned corneas heal, and it
reaches a plateau after 14 days of injury (Fig. 1). We
previously reported that the increase of the amount of
al(I) mRNA in lacerated rabbit corneas followed a
biphasic kinetics. 15 The difference in the levels of a 1(1)
mRNA can be explained by the fact that alkali burn
causes severe cell death, whereas laceration does not.
The increase of al(l) mRNA reflects the proliferation
of fibroblastic cells and increased cellular activities
when the alkali-burned corneas are allowed to heal
(Fig. 2).
The cell types that express a 1(1) mRNA are not
exactly identical in alkali-burned and lacerated corneas,
as judged by in situ hybridization (Figs. 2, 3). The
alkali-burned corneas often form a retrocorneal membrane
within a week after injury, and the fibroblastic
cells in this membrane express high levels of a 1(1)