Transplantable cultivated mucosal epithelial sheet for ocular surface reconstruction.

Ocular surface reconstruction by tissue engineering using somatic stem cells is a second-generation therapeutic modality. In view of future treatment of bilaterally affected, severe ocular surface disorders, two types of transplantable cultivated mucosal epithelial sheets can be used for reconstruction. One is an allogeneic corneal epithelial stem cell sheet, and the other is an autologous oral mucosal epithelial cell sheet. We first investigated the feasibility of amniotic membrane as an epithelial carrier, and found that denuded amniotic membrane was the most appropriate substrate for this purpose. Thus, cultivated corneal epithelial stem cell sheets were created by co-culturing with 3T3 fibroblast and air-lifting on amniotic membrane. These epithelial sheets demonstrated positive keratin 3 and 12 specific to in vivo corneal epithelium, light junction related proteins and proliferative activity. The transplanted allogeneic human corneal epithelial sheets existed successfully on the corneal surface, and were quite effective in achieving ocular surface stability in severe ocular surface disorders. A few cases, however, developed immunological reactions or opportunistic infections, etc. Secondly, we established transplantable autologous cultivated oral mucosal epithelial sheets in rabbits. The in vitro oral mucosal epithelial sheets showed histological characteristics similar to those of in vivo corneal epithelial sheets; for example, positive keratin 3 expression. Based on the fact that, the transplanted autologous oral mucosal epithelial sheets resembled corneal epithelium and that we achieved the recovery of corneal transparency in rabbits, we propose that cultivated oral mucosal epithelium may become the substitute for corneal epithelium in ocular surface reconstruction.