Abstract
Purpose::
Therapeutic options in bilateral total limbal stem cell deficiency are limited. Adult bone-marrow stem cells are able to differentiate into specific cell lines as autologous reconstructive source. In this study conjunctival and corneal behavior was investigated in experimental limbal stem cell deficiency and in different methods of corneal surface reconstruction in rabbits including transplantation of enriched autologous bone-marrow stem cells. A first approach was the analysis of well-known parameters in humans: the distribution of goblet cells (GC) as well-known proof for conjunctivalization (1) and the distribution patterns of CK 3 and 12 as sign for corneoepithelial differentiation (2).
Methods::
Total limbal stem cell deficiency was produced by epithelial abrasion with n-heptanol and 360°-limbectomy in 21 eyes of 21 New Zealand rabbits. Clinically, a total conjunctivalization of the cornea was observed four weeks later. 6 eyes served as untreated control (G1). After removal of the pannus 5 eyes were covered with amniotic membrane (AM) alone (G2). In 4 eyes additionally autologous limbal stem cell transplantation from the healthy eye was performed (G3). In 6 eyes enriched autologous bone-marrow stem cells were injected under the AM (G4). After a follow-up time of up to 6 months corneoscleral discs were excised. Paraffin-embedded specimens were analyzed for the amount of GC and for CK 3/12 expressions. Clinically, the eyes were examined regarding neovascularisation and opacity of the cornea.
Results::
GC were mostly not present on the central cornea. CK 3/12 were expressed in all corneal regions and epithelial layers in all groups including the healthy eyes: intensity of expression was highest in G1, followed by G3, 4 and 2 (p<0.05). There was no correlation between immunohistochemical findings and clinical presentation of the corneas.
Conclusions::
(1) Distribution and amount of GC turned out to be non-predictive tools to characterize a conjunctivalized ocular surface in rabbits. (2) CK 3/12 expressions have limited predictive power, since some kind of transdifferentiation from conjunctival to corneal epithelium has been proven by small amounts of CK 3/12 expression. Higher expression in G3 and G4 in contrast to G2 might be evident for corneal epithelial differentiation. Further analyses are needed.
Keywords: cornea: epithelium • wound healing • immunohistochemistry