EPITHELIAL REGENERATION AFTER LIMBUS-TO-LIMBUS DEBRIDEMENT - EXPRESSION OF ALPHA-ENOLASE IN STEM AND TRANSIENT AMPLIFYING CELLS

Purpose. To examine the expression of the glycolytic enzyme alpha-enol ase after limbus-to-limbus epithelial debridement in the rabbit. Metho ds. Corneas were debrided, leaving limbal epithelium intact, and were allowed to heal from 2 days to 8 weeks. Immunofluorescence microscopy was used to observe the expression of alpha-enolase. To quantitate cha nges in alpha-enolase levels 2 days to 4 weeks after wounding, epithel ium was harvested, homogenized, and assayed using anti-alpha-enolase i n immunoslot blots. Results. Expression of alpha-enolase appeared to i ncrease in the limbus and the central cornea during epithelial migrati on (2-day time point) with intense labeling of all basal cells. These levels were maintained until wound closure (1 week). By 2 weeks, expre ssion in the limbal basal cells decreased to levels present in unwound ed corneas. Expression in the corneal epithelium decreased after 2 wee ks, progressing from central cornea to the periphery. At 4 weeks, anti body binding decreased concomitantly with a change in the shape of the basal cells from flattened or ovoid to columnar. At 8 weeks, expressi on of alpha-enolase was similar to that in control corneas. Immunoslot blot data indicated that alpha-enolase made up 0.28% of the total sol uble protein in unwounded corneal epithelium and 0.73%, 1.22%, 0.96%, and 0.49% at 2 days, 1 week, 2 weeks, and 4 weeks after debridement, r espectively. Conclusions. These data indicate that expression of alpha -enolase is elevated during corneal epithelial migration initiating fr om the stem (limbal basal) cell population and that expression is link ed to active migration. Furthermore, it appears that limbal basal cell s are metabolically active during the period of epithelial sheet movem ent, whereas peripheral corneal basal cells remain activated as long a s 4 weeks after wounding.