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.
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.
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.
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.
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This work is supported by the California Institute for Regenerative Medicine DR1-01444, TG2-01161, TG2-01151, CL1-00521 and FA1-00616 grants, NIH Core Grant EY03040, Research to Prevent Blindness, The Arnold and Mabel Beckman Foundation, The Beatrice Apple Revocable Living Trust, The Garland Initiative for Vision, The Foundation Fighting Blindness Wynn-Gund Translational Research Acceleration Program, and the UCSB Institute for Collaborative Biotechnologies through grant W911NF-09-0001 from the U.S. Army Research Office. The content of the information does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred. Michael Koss received a research fellowship grant from the German Research Foundation (DFG), Bonn, Germany (DFG Ko4294/1-1). The authors thank Ernesto Baron and his team for excellent technical assistance with the histology. We also thank J. Cito Habicht, PhD, and Teisha R. Rowland, PhD, who provided writing and editing assistance.
The California Institute for Regenerative Medicine provided financial support in the form of grant funding (DR1-01444, TG2-01161, TG2-01151, CL1-00521, and FA1-00616). The U.S. National Institutes of Health provided financial support in the form of grant funding (NIH Core Grant EY03040). Research to Prevent Blindness, The Arnold and Mabel Beckman Foundation, The Beatrice Apple Revocable Living Trust, The Garland Initiative for Vision, The Foundation Fighting Blindness Wynn-Gund Translational Research Acceleration Program, and the UCSB Institute for Collaborative Biotechnologies provided financial support through grant W911NF-09-0001 from the U.S. Army Research Office. The content of the information does not necessarily reflect the position or the policy of the U.S. Government, and no official endorsement should be inferred. The German Research Foundation (DFG), Bonn, Germany provided financial support in the form of a research fellowship grant to Michael J. Koss (DFG Ko4294/1-1).
The sponsors had no role in the design or conduct of this research.
Conflict of interest
MSH, DRH, and DOC are co-founders of Regenerative Patch Technologies (RPT), LLC. All other authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
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Koss, M.J., Falabella, P., Stefanini, F.R. et al. Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs. Graefes Arch Clin Exp Ophthalmol 254, 1553–1565 (2016). https://doi.org/10.1007/s00417-016-3386-y
- Human embryonic stem cells
- Retinal pigment epithelium
- Macular degeneration
- Preclinical trial
- Animal model