Transplanting photoreceptors (the eye’s light sensing cells) to restore sight is sometimes described as the “holy grail” of potential therapies. This is because it has the potential to help so many people living with a variety of different blinding eye diseases. In the laboratory, research has shown that it is possible to replace lost photoreceptors by injecting stem-cell derived photoreceptors into the eye (read more about Stem Cell Transplantation). Despite the incredible progress made towards this goal in recent years, researchers still face many challenges, but FFB-funded scientist Dr. Valerie Wallace and her collaborators have made a breakthrough that may speed the progress of this revolutionary therapy out of the laboratory and into the clinic.
Researchers studying photoreceptor transplantation constantly grapple with a seemingly simple issue: How can we distinguish between the injected photoreceptors and those that were already there? While methods have been developed and used to identify newly injected rod photoreceptors, there hasn’t been one for use with cone photoreceptors, hindering research into restorative therapies for cone degenerating disorders.
AMD and other retinal degenerative diseases such as Retinitis Pigmentosa (RP) are characterized by the progressive death of photoreceptors — cells responsible for converting light into the electrical signals processed by the retina and brain as vision. While RP is primarily associated with rod photoreceptor degeneration and a loss of peripheral/night vision, cone photoreceptors are lost later, as RP progresses. AMD causes a loss of cone photoreceptors and therefore central/detailed vision.
Dr. Wallace’s research team has solved an important problem for transplanting cone photoreceptors. Her team has discovered a powerful research tool to help future efforts. This tool allows researchers to carefully trace transplanted cones as they make new connections in the retina. Dr. Phil Nickerson, a collaborator on the project, explained the significance of this discovery. “There is considerable work being done on exploring rod cell transplantation in the eye, which has formed the basis for much of the field to this point. Although this work is of significant value to understanding photoreceptor transplantation, replacing a cell type that is responsible for low-light (night) vision in one’s periphery is not an end-point goal of this field.” This research in cone transplantation helps open up a new era for restoring high-acuity, daylight vision.
Thank you to all of the FFB donors who are helping to support this foundational work!
Story guest authored by Derek Waldner with contributions by Dr. Mary Sunderland. Derek is a neuroscience graduate student at the University of Calgary and a knowledge translation intern at the FFB.
About the Discovery:
The article: Establishment of a cone photoreceptor transplantation platform based on a novel cone-GFP reporter mouse line was published in the journal Scientific Reports on March 11, 2016 as a collaboration between 11 institutions and 21 contributing individuals, including:
Sheila Smiley, Philip E. Nickerson, Lacrimioara Comanita, Narsis Daftarian, Ahmed El-Sehemy, En Leh Samuel Tsai, Stuart Matan-Lithwick, Keqin Yan, Sherry Thurig, Yacine Touahri, Rajiv Dixit, Tooka Aavani, Yves De Repentingy, Adam Baker, Catherine Tsilfidis, Jeff Biernaskie, Yves Sauvé, Carol Schuurmans, Rashmi Kothary, Alan J. Mears & Valerie A.Wallace.