title: Subretinal implantation of retinal pigment epithelial cells derived from human embryonic stem cells: improved survival when implanted as a monolayer.
abstract: OBJECTIVE
  To evaluate cell survival and tumorigenicity of human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE) transplantation in immunocompromised nude rats. Cells were transplanted as a cell suspension (CS) or as a polarized monolayer plated on a parylene membrane (PM).
  
  
  METHODS
  Sixty-nine rats (38 male, 31 female) were surgically implanted with CS (n = 33) or PM (n = 36). Cohort subsets were killed at 1, 6, and 12 months after surgery. Both ocular tissues and systemic organs (brain, liver, kidneys, spleen, heart, and lungs) were fixed in 4% paraformaldehyde, embedded in paraffin, and sectioned. Every fifth section was stained with hematoxylin and eosin and analyzed histologically. Adjacent sections were processed for immunohistochemical analysis (as needed) using the following antibodies: anti-RPE65 (RPE-specific marker), anti-TRA-1-85 (human cell marker), anti-Ki67 (proliferation marker), anti-CD68 (macrophage), and anti-cytokeratin (epithelial marker).
  
  
  RESULTS
  The implanted cells were immunopositive for the RPE65 and TRA-1-85. Cell survival (P = 0.006) and the presence of a monolayer (P < 0.001) of hESC-RPE were significantly higher in eyes that received the PM. Gross morphological and histological analysis of the eye and the systemic organs after the surgery revealed no evidence of tumor or ectopic tissue formation in either group.
  
  
  CONCLUSIONS
  hESC-RPE can survive for at least 12 months in an immunocompromised animal model. Polarized monolayers of hESC-RPE show improved survival compared to cell suspensions. The lack of teratoma or any ectopic tissue formation in the implanted rats bodes well for similar results with respect to safety in human subjects.
authors.affiliation: Doheny Eye Institute, Los Angeles, California, USA. dinizb@me.com
authors.forename: Bruno
authors.initials: B
authors.lastname: Diniz
authors.forename: Padmaja
authors.initials: P
authors.lastname: Thomas
authors.forename: Biju
authors.initials: B
authors.lastname: Thomas
authors.forename: Ramiro
authors.initials: R
authors.lastname: Ribeiro
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Hu
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Brant
authors.forename: Ashish
authors.initials: A
authors.lastname: Ahuja
authors.forename: Danhong
authors.initials: D
authors.lastname: Zhu
authors.forename: Laura
authors.initials: L
authors.lastname: Liu
authors.forename: Michael
authors.initials: M
authors.lastname: Koss
authors.forename: Mauricio
authors.initials: M
authors.lastname: Maia
authors.forename: Gerald
authors.initials: G
authors.lastname: Chader
authors.forename: David R
authors.initials: DR
authors.lastname: Hinton
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002470:Cell Survival; D002478:Cells, Cultured; D004195:Disease Models, Animal; D053595:Embryonic Stem Cells / Q000637:transplantation*; D004847:Epithelial Cells / Q000637:transplantation*; D005136:Eye Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D008297:Male; D051381:Rats; D011923:Rats, Nude; D012160:Retina / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000637:transplantation*
chemical_list: D005136:Eye Proteins
keywords: age-related macular degeneration; human embryonic stem cells; retinal pigment epithelium