Development of a new tissue injector for subretinal transplantation of human embryonic stem cell derived retinal pigmented epithelium

Abstract

Background Subretinal cell transplantation is a challenging surgical maneuver. This paper describes the preliminary findings of a new tissue injector for subretinal implantation of an ultrathin non-absorbable substrate seeded with human embryonic stem cell-derived retinal pigment epithelium (hESC-RPE).MethodsUltrathin Parylene-C substrates measuring 3.5 mm × 6.0 mm seeded with hESC-RPE (implant referred to as CPCB-RPE1) were implanted into the subretinal space of 12 Yucatan minipigs. Animals were euthanized immediately after the procedure and underwent spectral domain optical coherence tomography (SD-OCT) and histological analysis to assess the subretinal placement of the implant. Evaluation of the hESC-RPE cells seeded on the substrate was carried out before and after implantation using standard cell counting techniques.ResultsThe tissue injector delivered the CPCB-RPE1 implant through a 1.5 mm sclerotomy and a 1.0–1.5 mm retinectomy. SD-OCT scans and histological examination revealed that substrates were precisely placed in the subretinal space, and that the hESC-RPE cell monolayer continued to cover the surface of the substrate after the surgical procedure.ConclusionThis innovative tissue injector was able to efficiently deliver the implant in the subretinal space of Yucatan minipigs, preventing significant hESC-RPE cell loss, minimizing tissue trauma, surgical complications and postoperative inflammation.

A bioengineered retinal pigment epithelial monolayer for advanced, dry age-related macular degeneration

“…The IND application also included a custom-designed and manufactured surgical insertion forceps for delivery of the CPCB-RPE1 into the subretinal space ( fig. S1) (21). The substrate was engineered by one of us (M.S.H.)…”

“…The custom insertion forceps were manufactured specifically for handling and delivery of the CPCB-RPE1 and have been described previously (21,35). The insertion forceps consist of a handle, a thumbwheel, and a shaft that houses a retractable forceps for grasping, folding, and loading the CPCB-RPE1 ( fig.…”

“…This synthetic substrate was designed to mimic the structural and functional properties of Bruch's membrane by providing a substrate for RPE adhesion in a polarized monolayer and a diffusion barrier similar to Bruch's membrane (18). We have previously reported the safety, survival, and functionality of hESC-RPE monolayers cultured on this synthetic substrate in a rodent model of retinal degeneration (19) and the feasibility of subretinal implantation of hESC-RPE cultured on this synthetic substrate in minipigs (20,21). Here, we report the results of five subjects that were enrolled in a first-in-human phase 1/2a trial to assess the safety and efficacy of this composite subretinal implant for treating advanced NNAMD and severe vision loss.…”

Cell Therapy for Retinal Dystrophies: From Cell Suspension Formulation to Complex Retinal Tissue Bioengineering

“…The scheduling of the surgery should be anticipated to generate the grafting material on time. Such tissue therapy requires the development of specific injection systems in order to correctly graft the polarized epithelial tissue [79, 128, 138]. All these new constraints increase the costs.…”

Stem Cell Treatment for Age-Related Macular Degeneration: the Challenges

“…32 Submacular transplantation entails risk: with current techniques, this procedure involves a complete vitrectomy and relatively large retinotomy, which are certainly not risk free maneuvers. 33,34 An additional risk to consider is the retrograde escape of transplanted cells, though the retinotomy, that could divide or transform on the epiretinal surface. So far, pigmented preretinal growths have proved innocuous in the context of one clinical trial 2 but may pose a risk of epiretinal membrane formation if more cells escape out of the subretinal space.…”