Abstract
Purpose: :
Limbal allograft transplantation has been shown to be a viable procedure for severe stem-cell deficiency. However, there is the lingering question of whether we are transplanting limbal stem cells(LSCs), or actually the stem cell niche. In this study, we investigated changes in Vogt Palisades and epithelial cells of the limbal allograft after transplantation by in vivo confocal microscopy(CM), to identify the roles of LSCs and stem cell niche in the reconstruction of ocular surface and the interactions between them.
Methods: :
31 eyes of 30 patients after limbal allograft transplantation were enrolled in this study. On the visit of 2w, 1m, 3m, 6m, 12m, 18m, 24m and 30m after transplantation, the clinical features were observed, and CM examination was performed on the inferior, superior, nasal and temporal limbus and the central cornea.
Results: :
The follow-up period of each patient was from 1m to 30m, with an average of 10.8m. On the last visit, 23 eyes presented a clear graft with a clinically health ocular surface; 8 eyes showed signs of rejection. On CM, typical Vogt Palisades were observed in all allografts on the first visit and sustained to the last visit in the 23 eyes with successful corneal reconstruction, In the 8 eyes with allograft rejection, Vogt Palisades were gradually destroyed. In the early period Vogt Palisades showed evident derangements with a large imflammatory cell infiltration, as well as a deletion of central corneal epithelium. Several months later, Vogt Palisades totally disappeared with fibrosis of limbal stroma, sustained inflammation and central corneal conjunctivalization. However, the limbal epithelium remained normal morphologic appearance without conjunctivalization(see Fig).
Conclusions: :
The successful reconstruction of ocular surface is highly dependant on the presence of Vogt Palisades, which would be eliminated by allograft rejection. Limbal epithelial cells could survive after rejection, yet could no longer accomplish corneal reepithelialization, indicating a functional suppression without the niche enviroenment of Vogt Palisades. This study demonstrats that stem cell niche plays an essential role in the corneal reconstruction after limbal allograft transplantation.
Keywords: transplantation • cornea: epithelium • microscopy: confocal/tunneling