gms | German Medical Science

In 1986 it was demonstrated that the corneal epithelial stem cells are located in the basal epithelium of the limbus, a transition zone between the corneal and the neighbouring conjunctival epithelium. A very particular local environment is necessary to maintain the equilibrium allowing stem cells to divide, preserve stem cell potential and sustain the corneal epithelium turnover, or moreover regenerate the tissue in simple corneal damages.

In severe ocular damage instead, such as chemical burns, Stevens-Johnson syndrome derived complications or pemfigus, a sever alteration of this balanced microenvironment is produced and consequently a serious corneal stem cell deficiency is determined: these conditions do not allow to perform normal surgical treatment or simple corneal transplant, due to the lack of regenerative potential of the host eye.

For this reason, some years ago transplantation of limbal stem cells was advocated for ocular surface reconstruction in these severe cases: this procedure can assure the enrichment of depleted tissue with new stem cells capable to restore a regenerative capacity in the ocular surface so allowing successful regeneration or successful cornea transplant also in such severe pathologies.

Differences in surgical protocols are to be underlined, since we can transplant the entire limbus zone from a cadaver donor (KLAL - keratolimbal allograft) and we can only excise a little portion with conjunctical tissue from a related living donor (lr-CLAL - living related - Conjunctival limbal allograft)or from the other healthy eye with conjunctival tissue (CLAU - Conjunctival limbal autograft).