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Jordi Mones, Rick Beckman, Kieran O'donovan, Ryan Woodward, Marc Biarnés, Eduardo Rodriguez, Miriam Garcia, Lucia Ferraro, Eli Aguilera, Elisabet Izquierdo, Blanca Reyes, Sara Patel; Bleb resolution time following subretinal injections of a cell therapy in porcine eyes appears sensitive to formulation osmolarity. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6398. doi: https://doi.org/.
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The injection of fluid into the subretinal space results in a bleb – a temporary and focal separation of photoreceptors from their supportive RPE. Delay of bleb resolution time could potentially contribute to photoreceptor dysfunction. We sought to understand the role of formulation osmolarity of a cell therapy (human retinal progenitor cells, hRPC) on bleb resolution time. To test our hypothesis, that higher formulation osmolarity in the subretinal space in the presence of a patent retinotomy leads to fluid flow from the vitreous into the subretinal space, manifesting as prolonged bleb presence, we studied bleb resolution time in mini-pigs using hRPC formulations with different levels of osmolarity (Fresh, Cryo and Diluted Cryo, 285, 355 and 311 mOsm/L, respectively).
This study was conducted in accordance with an approved study plan and the OECD Principles of Good Laboratory Practice (1997, Paris; 1999 EU directive; 2000 Real Decreto Spain). In a 3 port pars plana vitrectomy procedure, 12 eyes of 12 mini-pigs (n=4 per group) received a single subretinal injection of one of the 3 formulations. Blebs were evaluated using Optical Coherence Tomography (OCT) imaging at baseline, intraoperatively, and at days 1, 2, 3, 4, 5 and 6 post-treatment. The height and diameter of the blebs were measured in the OCT images. The thickness of the retinal outer nuclear layer (ONL) layer was measured at baseline (region into which a bleb was subsequently placed), and day 6 post-treatment. Two-way ANOVA was used to compare bleb resolution times of the tested formulations. At the end of the study period, eyes were enucleated and fixed in Davidson’s fixative prior to histopathology assessments.
There was a statistically significant difference in the bleb resolution times of the 3 tested formulations (Fresh<Diluted Cyro<<<Cryo). ONL thickness values at baseline were similar to those measured at Day 6 post-treatment of all 3 formulations. Histological findings were unremarkable suggesting all preparations were well-tolerated.
Conclusions: These results support our hypothesis that osmolarity of formulations can impact bleb resolution times following subretinal delivery. The effect of cells on bleb resolution was not tested.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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