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Boris V. Stanzel, Zengping Liu, Ralf Brinken, Norbert Braun, Hans M. Helb, Frank G. Holz, Nicole Eter; Subretinal Implantation Of A Potential RPE Carrier Substrate With Gelatine Encapsulation Using A Shooter Design In Rabbits. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4021.
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© ARVO (1962-2015); The Authors (2016-present)
To develop instrumentation and a technique for atraumatic implantation of a RPE cell carrier into rabbit subretinal space.
Acellular, oval carrier substrates were made from rigid porous polyester membranes (PET/ Corning, Inc.). Some substrates were encased in sterile filtered 15% gelatine, to protect and facilitate handling of cellularized implants in future. Gelatine implant sterility was tested with and without antibiotics (n=20, each). Gelatine dissolution assays were perfomed at 37C in balanced salt solution (BSS). Calcium free BSS (CF BSS) has been shown to facilitate atraumatic RPE- photoreceptor separation. 12 rabbits (2-2.5kg) received a core vitrectomy by BS or NE, with vitreous cavity perfusion of least 10 minutes with either regular BSS (n=5), CF BSS at room temperature (n=5), or CF BSS at 37 C (n=2). Bleb retinal detachments were made, and implants with (n=9) or w/o gelatin (n=3) inserted subretinally with a custom-made metallic shooter instrument (Geuder). Postoperative follow up was at 3, 7, and 14 days with SD-OCT and with fundus photography (Spectralis®/ Heidelberg Engineering). Histology was done with 2% glutaraldehyde perfusion fixation at 14 days post OP and semithin sections.
All membranes tested sterile. Dissolution assays showed complete melting of gelatine from implants within 10 to 15 seconds. Infusion with CF BSS at 37C decreased visibility, which compromised subretinal implantation. Regular BSS or CF BSS at room temperature resulted in good visibility and implantation. Gelatine embedded implants were ejected smoothly, while naked implants frequently got trapped with the instrument. On follow up, CF BSS resulted in 4/7 cases in a persistent retinal detachment at day 3, while BSS cases had all reattached. Gelatin implants showed a persistent subimplant hyporeflective band on SD-OCT. All implants showed a hyperreflective band above the implant. Retinal and outer nuclear layer (ONL) thinning on SD-OCT plateau-ed by 7 days postOP. On histology, more large clear vacuoles were observed underneath gelatine than under naked implants. The area around the implant showed subretinal scarring and ONL atrophy, but continuous inner retinal layers in both implant types.
Subretinal implantation of rigid RPE carriers with a shooter instrument appears safe and reproducible. While gelatine further facilitates their delivery, the use of CF BSS however carries a high complication rate.
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