An Innovative Surgical Technique for Subretinal Transplantation of Human Embryonic Stem Cell-Derived Retinal Pigmented Epithelium in Yucatan Mini Pigs: Preliminary Results.

Graefes Arch Clin Exp Ophthalmol (2016) 254:1553–1565 DOI 10.1007/s00417-016-3386-y BASIC SCIENCE Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatan minipigs Michael J. Koss 1,2 & Paulo Falabella 2 & Francisco R. Stefanini 3 & Marcel Pfister 2 & Biju B. Thomas 2 & Amir H. Kashani 2 & Rodrigo Brant 3 & Danhong Zhu 2,4 & Dennis O. Clegg 5 & David R. Hinton 2,4 & Mark S. Humayun 2,6 Received: 16 December 2015 / Revised: 23 March 2016 / Accepted: 11 May 2016 / Published online: 22 June 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Purpose 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 differenti- ated, 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 Yucatan 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 Yucatan minipigs (aged 2 months, weighing 24–35 kg). Surgeons were blinded to the randomization codes and postoperative and post-mortem * Michael J. Koss michael.koss@me.com Department of Ophthalmology, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany USC Eye Institute, University of Southern California, 1450 San Pablo Street, Los Angeles, CA 90033-4682, USA Department of Ophthalmology, Federal University of Sao Paulo UNIFESP, Rua Botucatu 821, 04023-062 Sao Paulo, Brazil assessments were performed in a blinded manner. Eleven minipigs received CPCB-RPE1 while three control minipigs underwent sham surgery that generated subretinal blebs. All an- imals 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 immu- nohistochemistry 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 immu- nohistochemistry 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. Keywords Human embryonic stem cells . Retinal pigment epithelium . Macular degeneration . Preclinical trial . Animal model Department of Pathology, Keck School of Medicine, University of Southern California, 1450 San Pablo Street, Los Angeles, CA 90033-4682, USA Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA Introduction Institute of Biomedical Therapeutics, University of Southern California, 1450 San Pablo Street, Los Angeles, CA 90033-4682, USA Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly worldwide and is characterized