title: RPE cell transplants to non-immune-privileged sites of the eye transform into fibroblast-like cells.
abstract: OBJECTIVE
  In vitreoretinopathy membranes and in vitro, RPE cells lose pigment and transform into fibroblast-like cells. The purpose of this study was to investigate whether the immune privileged status of different eye compartments influence morphological changes of adult RPE cell transplants.
  
  
  METHODS
  RPE cells from adult C57BL/6 mice were transplanted either intravitreally (n = 31), subretinally (n = 28), intrachoroidally (n = 21) or subconjunctivally (n = 33) into one eye of BALB/c mice and intravitreally (n = 5) into rd-mice with loss of ACAID (14-16 months). Eyes were enucleated after 1, 2, 4 and 6 weeks, and transplants investigated by light (n = 128) and electron microscopy (n = 40).
  
  
  RESULTS
  Allogeneic adult RPE cells lost pigment and transformed into spindle shaped cells when injected into the recipient subconjunctiva. In vitreous or subretinal space they remained rounded and pigmented. In the choroid, they were spindle shaped but contained more pigment and were larger than those in the conjunctiva. No inflammatory reaction in the uvea or development of epiretinal membranes was seen. In contrast, in all rd-mice an inflammation of the uvea and development of epiretinal membranes was observed.
  
  
  CONCLUSIONS
  Our findings suggest that changes in the environment of RPE in single cell suspension dictate the phenotype the cells adopt. It is possible that changes in microenvironmental factors contribute to the pathogenesis of proliferative vitreoretinal (PVR) membranes.
authors.affiliation: Department of Anatomy II, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany. anat2.gl@anatomie2.med.uni-erlangen.de
authors.forename: Tina
authors.initials: T
authors.lastname: Knoernschild
authors.forename: Thomas
authors.initials: T
authors.lastname: Grasbon
authors.forename: Caren
authors.initials: C
authors.lastname: Wilsch
authors.forename: Anselm
authors.initials: A
authors.lastname: Kampik
authors.forename: Elke
authors.initials: E
authors.lastname: Lütjen-Drecoll
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D017690:Cell Transplantation / Q000379:methods; D002829:Choroid / Q000473:pathology / Q000601:surgery; D003228:Conjunctiva / Q000473:pathology / Q000601:surgery; D005347:Fibroblasts / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008854:Microscopy, Electron; D010857:Pigment Epithelium of Eye / Q000166:cytology* / Q000276:immunology / Q000637:transplantation*; D012160:Retina / Q000473:pathology / Q000601:surgery; D012162:Retinal Degeneration / Q000235:genetics / Q000473:pathology / Q000601:surgery; D023001:Transplantation Tolerance; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous; D014185:Transplantation, Isogeneic; D014822:Vitreous Body