The use of flexible biocompatible synthetic materials could change our vision of artificial retinas thanks to research by chemist Vanessa Restrepo-Schild and colleagues at the Oxford University Department. The materials she is developing might ultimately be used to help treat degenerative eye conditions such as retinitis pigmentosa.
The retina, is the light sensitive layer at the back of the eye that converts impinging photons from the world around us into electrical signals interpreted in the visual cortex within our brain. Disease and damage to the retina often leads inevitably to visual impairment. Restrepo-Schild's team hope to address this problem through their development of a new synthetic, double-layered artificial retina that mimics that found in the human eye. Their synthetic retina comprises hydrogels and biological cell membrane proteins in an array of synthetic cells. Each "cell" within the array is a pixel that generates an electrical signal when light shines on it. [Restrepo-Schild et al, Sci Rep (2017); DOI: 10.1038/srep46585]
Having been created using synthetic cells this more natural, biodegradable system contains no rejectable materials and so could be seen as less invasive than an electronic or mechanical implant. Metal components in retinal implants can trigger inflammation or scarring and ultimately be rejected. A biological synthetic implant is soft and water based, so it could be much more readily accepted by the eye itself, Restrepo-Schild suggests. While the system is biocompatible it does not use any living cells and so avoids the problems that might arise from implanted donor tissue or a xenograft from an animal source. "This is a very important point," Restrepo-Schild told Materials Today. "Even if the cells are iPSCs (cells from the own patient) we have the advantage of not having any uncontrolled proliferation."
"I hope my research is the first step in a journey towards building technology that is soft and biodegradable," Restrepo-Schild says. So far, the synthetic retina has only been tested under laboratory conditions but Restrepo-Schild and her colleagues are keen to build on this initial work and explore the potential with living tissues. That would be a crucial next step before such synthetic soft systems could be used in what one might refer to as a bionic implant.
Restrepo-Schild has filed a patent application for this technology. The next step will be to extend the system from a monochrome (black and white) system to one that can detect different colors. The team will work with a larger synthetic retina for that research before investigating the potential for animal testing and ultimately clinical trials in people.
David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".