Abstract
Purpose: :
Corneal epithelial defects can heal only in the presence of stem cells (SC) that are located in the corneal marginal (limbal) zone. Severe damage to the ocular surface may lead to limbal stem cell deficiency (LSD) which is characterized by in growing conjunctival epithelium (pannus), chronic inflammation, and impaired vision. Transplantation of in vitro cultivated limbal SCs has been recently developed to treat LSD.The objective of this study was to characterize the changes taking place in the cornea during LSD and the effect of SC transplantation.
Methods: :
Eighteen patients with LSD were treated by transplantation of limbal SCs expanded on amniotic membrane (AM). Expression of epithelial lineage markers (keratin 3 (K3), K12, K19 and MUC5AC) and inflammatory markers (IL-1α, IL-1β, ICAM-1, VCAM-1 and VEGF) was analyzed using Real-Time PCR, Western blotting and immunofluorescence of the excised pannus. Healthy cornea (n=6) and conjunctiva (n=6) served as control tissue. At least six months after SC transplantation an additional penetrating corneal transplantation was performed in 4 patients. Excised corneal buttons were analyzed to assess the effect of SC transplantation.
Results: :
The expression of all studied markers differed significantly in healthy cornea and conjunctiva. Expression of lineage markers was in pannus similar to conjunctiva, not to cornea. Inflammatory markers such as IL-1-β, ICAM-1, VCAM-1 and VEGF were significantly increased in pannus compared to healthy control tissue. SC transplantation improved vision and reduced inflammation, vascularisation and discomfort. Lineage markers showed after SC transplantation a corneal phenotype and the expression of inflammatory markers was significantly reduced.
Conclusions: :
LSD is characterized by ingrowths of an abnormal inflamed tissue with conjunctival phenotype. Transplantation of in vitro cultivated limbal SCs on AM improved vision, facilitated restoration of a non-inflamed ocular surface and restored a corneal phenotype.
Keywords: cornea: epithelium • regeneration