title: Transplantation of iris pigment epithelium into the choroid slows down the degeneration of photoreceptors in the RCS rat.
abstract: BACKGROUND
  Trophic factors [e.g. basic fibroblast growth factor (bFGF)] released by transplanted retinal pigment epithelial (RPE) cells are able to slow down the hereditary degeneration of the retina in the Royal College of Surgeons rat in sites distant from the site of transplantation where rod outer segment (ROS) phagocytic activity is not reconstituted by the transplants.
  
  
  METHODS
  To investigate whether iris pigmented epithelial (IPE) cells are also able to generate this rescue by trophic factors, we transplanted IPE cells from Long-Evans rats into the choroid and subretinal space of 17 young RCS rats. The eyes were enucleated after 6 months and prepared for light microscopy. Six age-matched RCS rats served as controls. Light microscope sections from the whole choroid, healthy choriocapillaris, transplanted cells and the maximum thickness of the choroid, and outer nuclear layer parameters were analyzed by computer-assisted morphometry.
  
  
  RESULTS
  In transplanted animals photoreceptor cells were rescued from degeneration although the majority of the transplanted IPE cells were located in the choroid. In the non-transplanted group photoreceptors were absent.
  
  
  CONCLUSIONS
  Transplantation of IPE cells slows down degeneration of the photoreceptors in the RCS rat. This photoreceptor-sparing effect by the IPE cells was observed even when the transplants were predominantly located within the choroid. The beneficial effect observed may be related to trophic factors possibly secreted by the transplanted IPE cells.
authors.affiliation: Department of Vitreoretinal Surgery, University of Cologne, Joseph Stelzmann Str. 9, 50931 Cologne, Germany. U.Schraermeyer@uni-koeln.de
authors.forename: U
authors.initials: U
authors.lastname: Schraermeyer
authors.forename: P
authors.initials: P
authors.lastname: Kayatz
authors.forename: G
authors.initials: G
authors.lastname: Thumann
authors.forename: T T
authors.initials: TT
authors.lastname: Luther
authors.forename: P
authors.initials: P
authors.lastname: Szurman
authors.forename: N
authors.initials: N
authors.lastname: Kociok
authors.forename: K U
authors.initials: KU
authors.lastname: Bartz-Schmidt
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000502:physiology; D017690:Cell Transplantation; D002829:Choroid / Q000601:surgery*; D007091:Image Processing, Computer-Assisted; D007498:Iris / Q000166:cytology*; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology / Q000502:physiology*; D010857:Pigment Epithelium of Eye / Q000637:transplantation* / Q000648:ultrastructure; D051381:Rats; D011922:Rats, Mutant Strains; D012162:Retinal Degeneration / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*