Abstract
Purpose::
The transplantation of iris or retinal pigment epithelial cells as a therapeutic modality for retinal degeneration requires that the transplanted pigment epithelial cells form a monolayer in the subretinal space that will cover and establish communication with the exposed photoreceptors. Since previous studies have shown that transplanted pigment epithelial cells in suspension do not form a monolayer, it will be essential to transplant pre-formed pigment epithelial cell monolayers at the location of the exposed photoreceptors.
Methods::
To establish pre-formed cell monolayers, pigment epithelial cells were cultured on equine and porcine collagen Type I membranes. The cultured cells were examined for morphology ultrastructurally, for differentiation characteristics, for adhesion and proliferation. Membrane degradation and long-term biocompatibility were assessed following subconjunctival and subretinal implantation in rabbits.
Results::
The studies have shown that pigment epithelial cells adhere, proliferate, form monolayers, and acquire differentiated properties on collagen type I membranes. Surface morphology of the foils visualized by SEM appeared to have similar features of Bruch’s membrane. Transplantation subconjunctivally and subretinally showed that collagen membranes have excellent biocompatibility since there was no evidence of inflammation by fundus photography and by histological examination of the transplants for up to 12 weeks.
Conclusions::
Pigment epithelial cells cultured on collagen membranes acquire differentiated characteristics of in vivo retinal pigment epithelial cells and form complete monolayers that are amenable to be transplanted to the subretinal space. The collagen Type I membranes are biocompatible and do not elicit any rejection or inflammatory response when implanted subretinally or subconjunctivally in rabbits.
Keywords: transplantation • Bruch's membrane • retinal pigment epithelium