title: Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs.
abstract: OBJECTIVE
  A subretinal implant termed CPCB-RPE1 is currently being developed to surgically replace dystrophic RPE in patients with dry age-related macular degeneration (AMD) and severe vision loss. CPCB-RPE1 is composed of a terminally differentiated, polarized human embryonic stem cell-derived RPE (hESC-RPE) monolayer pre-grown on a biocompatible, mesh-supported submicron parylene C membrane. The objective of the present delivery study was to assess the feasibility and 1-month safety of CPCB-RPE1 implantation in Yucatán minipigs, whose eyes are similar to human eyes in size and gross retinal anatomy.
  
  
  METHODS
  This was a prospective, partially blinded, randomized study in 14 normal-sighted female Yucatán minipigs (aged 2 months, weighing 24-35 kg). Surgeons were blinded to the randomization codes and postoperative and post-mortem assessments were performed in a blinded manner. Eleven minipigs received CPCB-RPE1 while three control minipigs underwent sham surgery that generated subretinal blebs. All animals except two sham controls received combined local (Ozurdex™ dexamethasone intravitreal implant) and systemic (tacrolimus) immunosuppression or local immunosuppression alone. Correct placement of the CPCB-RPE1 implant was assessed by in vivo optical coherence tomography and post-mortem histology. hESC-RPE cells were identified using immunohistochemistry staining for TRA-1-85 (a human marker) and RPE65 (an RPE marker). As the study results of primary interest were nonnumerical no statistical analysis or tests were conducted.
  
  
  RESULTS
  CPCB-RPE1 implants were reliably placed, without implant breakage, in the subretinal space of the minipig eye using surgical techniques similar to those that would be used in humans. Histologically, hESC-RPE cells were found to survive as an intact monolayer for 1 month based on immunohistochemistry staining for TRA-1-85 and RPE65.
  
  
  CONCLUSIONS
  Although inconclusive regarding the necessity or benefit of systemic or local immunosuppression, our study demonstrates the feasibility and safety of CPCB-RPE1 subretinal implantation in a comparable animal model and provides an encouraging starting point for human studies.
authors.affiliation: Department of Ophthalmology, University of Heidelberg, Im Neuenheimer Feld 400, 69120, Heidelberg, Germany. michael.koss@me.com.|USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA. michael.koss@me.com.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Koss
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Paulo
authors.initials: P
authors.lastname: Falabella
authors.affiliation: Department of Ophthalmology, Federal University of São Paulo UNIFESP, Rua Botucatu 821, 04023-062, São Paulo, Brazil.
authors.forename: Francisco R
authors.initials: FR
authors.lastname: Stefanini
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Marcel
authors.initials: M
authors.lastname: Pfister
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Biju B
authors.initials: BB
authors.lastname: Thomas
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Amir H
authors.initials: AH
authors.lastname: Kashani
authors.affiliation: Department of Ophthalmology, Federal University of São Paulo UNIFESP, Rua Botucatu 821, 04023-062, São Paulo, Brazil.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Brant
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.|Department of Pathology, Keck School of Medicine, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Danhong
authors.initials: D
authors.lastname: Zhu
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, 93106-9625, USA.
authors.forename: Dennis O
authors.initials: DO
authors.lastname: Clegg
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.|Department of Pathology, Keck School of Medicine, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Hinton
authors.affiliation: USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.|Institute of Biomedical Therapeutics, University of Southern California, 1450 San Pablo Street, Los Angeles, CA, 90033-4682, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Humayun
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005240:Feasibility Studies; D005260:Female; D000066449:Human Embryonic Stem Cells / Q000637:transplantation*; D006801:Humans; D008268:Macular Degeneration / Q000175:diagnosis / Q000601:surgery*; D011446:Prospective Studies; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000637:transplantation*; D033581:Stem Cell Transplantation / Q000379:methods*; D013552:Swine; D013556:Swine, Miniature; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome
keywords: Animal model; Human embryonic stem cells; Macular degeneration; Preclinical trial; Retinal pigment epithelium