Characterization of a Polymer‐Based, Fully Organic Prosthesis for Implantation into the Subretinal Space of the Rat

Abstract

Replacement strategies arise as promising approaches in case of inherited retinal dystrophies leading to blindness. A fully organic retinal prosthesis made of conjugated polymers layered onto a silk fibroin substrate is engineered. First, the biophysical and surface properties are characterized; then, the long-term biocompatibility is assessed after implantation of the organic device in the subretinal space of 3-months-old rats for a period of five months. The results indicate a good stability of the subretinal implants over time, with preservation of the physical properties of the polymeric layer and a tight contact with the outer retina. Immunoinflammatory markers detect only a modest tissue reaction to the surgical insult and the foreign body that peaks shortly after surgery and progressively decreases with time to normal levels at five months after implantation. Importantly, the integrity of the polymeric layer in direct contact with the retinal tissue is preserved after five months of implantation. The recovery of the foreign-body tissue reaction is also associated with a normal b-wave in the electroretinographic response. The results demonstrate that the device implanted in nondystrophic eyes is well tolerated, highly biocompatible, and suitable as retinal prosthesis in case of photoreceptor degeneration.

Photoelectric Dye Used for Okayama University-Type Retinal Prosthesis Reduces the Apoptosis of Photoreceptor Cells

“…5,33,34 We initially considered that photoelectric dye-coupled polyethylene films in subretinal space of RCS rats' eyes would exert a similar protective effect on the retina, as described for other materials. This study revealed that the photoelectric dye could slow down the process of retinal degeneration in RCS rats.…”

Bioinspired Artificial Eyes: Optic Components, Digital Cameras, and Visual Prostheses

“…d,e) (d) GFAP and (e) FGF expression of a sham‐operated retina and a retina with an implanted device. Reproduced with permission . Copyright 2016, WILEY‐VCH.…”

“…Photovoltaic retinal prostheses that use soft organic materials have been developed as a solution (Figure c) . Such photovoltaic prostheses consist of a fibroin silk substrate, a poly(3‐hexylthiophene) (P3HT) photoabsorbing layer, and a PEDOT:polystyrene charge transfer layer.…”

Conjugated Polymers in Bioelectronics: Addressing the Interface Challenge

“…Ex vivo studies of the direct optical stimulation of explanted blind retina by the conjugated polymer poly(3‐hexyl thiophene) (P3HT) based devices have shown neuronal responses similar to those of healthy retina . A photovoltaic implant composed of P3HT, PEDOT:PSS and silk fibroin was implanted subretinally in rats for 5 months and showed excellent biocompatibility, relative retention of the optoelectronic layer, and good contact with the internal retina . The same device was then implanted for 6 to 10 months in Royal College of Surgeons (RCS) rats commonly used as a model for retinitis pigmentosa.…”