Abstract
Purpose: :
Limbal stem cell deficiency (LSD) is characterized by in-growing conjunctiva into the cornea (pannus), chronic inflammation, impaired vision and in most of the cases dry eye. Transplantation of limbal stem cells (SC) cultivated on amniotic membrane (AM) has recently been developed to treat this condition. Membrane-associated mucins are an important component of the tear film. The objective of this study was to characterize the expression patterns of the membrane-associated mucins MUC1, MUC4 and MUC16 in cultivated limbal epithelium, cicatricial pannus tissue gained from in-growth after LSD and also healthy cornea and conjunctiva.
Methods: :
Total RNA was isolated from human limbal SC cultures on amniotic membrane (HLEC-AM) (n=6) and pannus samples (n=6) excised during SC transplantation. Healthy corneal and conjunctival tissue (n=6, each) from multi organ donors not suitable for transplantation, was used as control tissue. The expression of MUC1, MUC4 and MUC16 was analyzed by Real-Time PCR using TaqMan gene expression assays. Statistical analysis was performed by two sample t-test.
Results: :
Conjunctiva showed a significantly higher expression of MUC1 and MUC4 (p<0.001) than cornea, the expression of MUC16 was similar in both tissues. The expression of MUC1 was increased in cultured SCs (p<0.01), MUC16 decreased (p<0.0001) and MUC4 showed no significant difference when compared to cornea. The expression of all studied genes was in conjunctiva significantly higher than in cultured SCs (p<0.05), but was similar to pannus showing no significant differences. Pannus, like conjunctiva, revealed a significantly higher expression of studied genes when compared to cornea or cultured SCs (p<0.001).
Conclusions: :
Conjunctiva and pannus revealed both a higher expression of studied membrane-associated mucins than cornea or cultured SCs. The expression of studied mucins showed in cultured limbal epithelium more similarities to cornea and not to pannus or conjunctiva. The restoration of an expression pattern of membrane associated mucins similar to that of a healthy corneal epithelium may be an additional beneficial effect of limbal SCs transplantation.
Keywords: cornea: basic science • cornea: surface mucins • cornea: epithelium