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Adewumi N. Adekunle, Alice Adkins, Wei Wang, Henry J. Kaplan, Juan Fernandez de Castro, Sang Joon Lee, Philip Huie, Daniel Palanker, Maureen McCall, Machelle T. Pardue; Integration of Perforated Subretinal Prostheses With Retinal Tissue. Trans. Vis. Sci. Tech. 2015;4(4):5. doi: 10.1167/tvst.4.4.5.
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To investigate the integration of subretinal implants containing full-depth perforations of various widths with rat and pig retina across weeks of implantation.
In transgenic P23H rhodopsin line 1 (TgP23H-1) rats and wild-type (WT) pigs, we examined four subretinal implant designs: solid inactive polymer arrays (IPA), IPAs with 5- or 10-μm wide perforations, and active bipolar photovoltaic arrays (bPVA) with 5-μm perforations. We surgically placed the implants into the subretinal space using an external approach in rats or a vitreoretinal approach in pigs. Implant placement in the subretinal space was verified with optical coherence tomography and retinal perfusion was characterized with fluorescein angiography. Rats were sacrificed 8 or 16 weeks post-implantation (wpi) and pigs 2, 4, or 8 wpi, and retinas evaluated at the light microscopic level.
Regardless of implant design, retinas of both species showed normal vasculature. In TgP23H-1 retinas implanted with 10-μm perforated IPAs, inner nuclear layer (INL) cells migrated through the perforations by 8 wpi, resulting in significant INL thinning by 16 wpi. Additionally, these retinas showed greater pseudo-rosette formation and fibrosis compared with retinas with solid or 5-μm perforated IPAs. TgP23H-1 retinas with bPVAs showed similar INL migration to retinas with 5-μm perforated IPAs, with less fibrosis and rosette formation. WT pig retina with perforated IPAs maintained photoreceptors, showed no migration, and less pseudo-rosette formation, but more fibrosis compared with implanted TgP23H-1 rat retinas.
In retinas with photoreceptor degeneration, solid implants, or those with 5-μm perforations lead to the best biocompatibility.
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