Subretinal Implantation of Retinal Pigment Epithelial Cells Derived From Human Embryonic Stem Cells: Improved Survival When Implanted as a Monolayer

Diniz, Bruno; Thomas, Padmaja B.; Thomas, Biju; Ribeiro, Ramiro; Hu, Yuntao; Brant, Rodrigo; Ahuja, Ashish; Zhu, Danhong; Liu, Laura; Koss, Michael; Maia, Maurício; Chader, Gerald J.; Hinton, David R.; Humayun, Mark S.

doi:10.1167/iovs.12-11239

Cited by 222 publications

(252 citation statements)

References 34 publications

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“…There was also no evidence of a local inflammatory response or peri-implant fibrosis in any of the eyes. In line with an earlier study we conducted in rats [12], no formation of teratoma or ectopic tissue was observed in the minipig eye. Immunohistochemistry for TRA-1-85 and RPE65 was positive in all of the CPCB-RPE1 implants, indicating that the hESC-RPE cells survived in those samples after 1 month of implantation.…”

Section: Discussionsupporting

confidence: 91%

“…The advantages of the surgically foldable MSPS carrier include customized macular shape in diameter and thickness [8], ultrathin parts with diffusion [7], and excellent RPE adherence [10,11] and survival [12], whereas its nondegradability and unknown long-term effects can be seen as disadvantages. The study criteria for successful implantation were appropriate placement of the implant in the subretinal space, as assessed by OCT and post-mortem histology.…”

Section: Discussionmentioning

confidence: 99%

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Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs

Koss

Falabella

Stefanini

et al. 2016

Graefes Arch Clin Exp Ophthalmol

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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 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 postmortem 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.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionmentioning

confidence: 99%

Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs

Koss

Falabella

Stefanini

et al. 2016

Graefes Arch Clin Exp Ophthalmol

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“…This is done either by unrolling a sheet of RPE cells underneath the retina through a slit, or by growing the cells on an artificial porous substrate and inserting both the cells and prosthetic into the subretinal space. The advantages of these techniques are obvious as the RPE cells do not need to "repolarize" upon implantation, and the potential formation of pigmented spheres of RPE cells that escape into the retina can be largely avoided 16,44 . However, these surgical techniques are inherently even more complicated.…”

Section: Sub-retinal Injection (~5 Min Per Injection)mentioning

confidence: 99%

Performing Subretinal Injections in Rodents to Deliver Retinal Pigment Epithelium Cells in Suspension

Westenskow

Kurihara

Bravo

et al. 2015

JoVE

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The conversion of light into electrical impulses occurs in the outer retina and is accomplished largely by rod and cone photoreceptors and retinal pigment epithelium (RPE) cells. RPE provide critical support for photoreceptors and death or dysfunction of RPE cells is characteristic of agerelated macular degeneration (AMD), the leading cause of permanent vision loss in people age 55 and older. While no cure for AMD has been identified, implantation of healthy RPE in diseased eyes may prove to be an effective treatment, and large numbers of RPE cells can be readily generated from pluripotent stem cells. Several interesting questions regarding the safety and efficacy of RPE cell delivery can still be examined in animal models, and well-accepted protocols used to inject RPE have been developed. The technique described here has been used by multiple groups in various studies and involves first creating a hole in the eye with a sharp needle. Then a syringe with a blunt needle loaded with cells is inserted through the hole and passed through the vitreous until it gently touches the RPE. Using this injection method, which is relatively simple and requires minimal equipment, we achieve consistent and efficient integration of stem cell-derived RPE cells in between the host RPE that prevents significant amount of photoreceptor degeneration in animal models. While not part of the actual protocol, we also describe how to determine the extent of the trauma induced by the injection, and how to verify that the cells were injected into the subretinal space using in vivo imaging modalities. Finally, the use of this protocol is not limited to RPE cells; it may be used to inject any compound or cell into the subretinal space.

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“…This will avoid prolonging experiments in animals where engrafted cells are incorrectly placed, under immune attack, or have died early in the experimental protocol. Although conventional in vivo imaging (rodent ophthalmoscopy) allows for some initial confirmation of subretinal bleb formation, 9,24,25 implying transplantation to the correct retinal layer, it is ineffective at determining subretinal graft presence past the day of transplantation. This is because ophthalmoscopy views the retina en face, making blebs of smaller profile harder to identify; moreover, aside from host erythrocytes (in cases where subretinal hemorrhaging occurs), graft and host cells cannot be differentiated through the neural retinal.…”

Section: Real-time Detection Of Graft Placement and Survivalmentioning

confidence: 99%

“…25,[28][29][30][31] However, the performance of these materials cannot be assessed in vivo using standard imaging techniques. A recent (2014) study, implanting a monolayer of RPE attached to a ridged polyester scaffold, utilized a similar approach to our bimodal imaging to help address this very limitation.…”

Section: Monitoring Biomaterials Efficacy In Generating Optimal Graft mentioning

confidence: 99%

Bimodal in vivo imaging provides early assessment of stem-cell-based photoreceptor engraftment

Laver

Metcalfe

Szczygiel

et al. 2015

Eye

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Purpose Subretinal transplantation of stem-cell-derived photoreceptor precursor cells (PPCs) is a promising and innovative approach to treating a range of blinding diseases. However, common barriers to efficient preclinical transplantation comes in the form of suboptimal graft architecture, limited graft survival, and immune-rejection, each of which cannot be assessed using conventional in vivo imaging (ie, rodent ophthalmoscopy). With the majority of PPCs reported to die within the first few weeks after transplantation, understanding the mechanisms of graft failure, and ultimately devising preventative methods, currently relies on lengthy end point histology.To address these limitations, we hypothesized that combining two imaging modalities, optical coherence tomography (OCT) and fluorescence confocal scanning laser ophthalmoscopy (fcSLO), could provide a more rapid and comprehensive view of PPC engraftment. Methods Human ESC-derived PPCs were transplanted into 15 retinal dystrophic rats that underwent bimodal imaging at 0, 8, and 15 days posttransplant. Results Bimodal imaging provided serial detection of graft: placement, architecture, and survival; each undetectable under ophthalmoscopy. Bimodal imaging determined graft placement to be either: subretinal (n = 7), choroidal (n = 4), or vitreal (n = 4) indicating neural retinal perforation. Graft architecture was highly variable at the time of transplantation, with notable redistribution over time, while complete, or near complete, graft loss was observed in the majority of recipients after day 8. Of particular importance was detection of vitreal aggregates overlying the graft-possibly an indicator of host-site inflammation and rejection. Conclusion Early real-time feedback of engraftment has the potential to greatly increase efficiency of preclinical trials in cell-based retinal therapeutics.

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Subretinal Implantation of Retinal Pigment Epithelial Cells Derived From Human Embryonic Stem Cells: Improved Survival When Implanted as a Monolayer

Cited by 222 publications

References 34 publications

Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs

Subretinal implantation of a monolayer of human embryonic stem cell-derived retinal pigment epithelium: a feasibility and safety study in Yucatán minipigs

Performing Subretinal Injections in Rodents to Deliver Retinal Pigment Epithelium Cells in Suspension

Bimodal in vivo imaging provides early assessment of stem-cell-based photoreceptor engraftment

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