Restoring vision in AMD may be a possibility with stem cell transplantation.
Two such trials were published in 2018. The first UK trial (Nature Biotech 2018; doi: 10.1038/nbt.4114) included two patients with severe visual loss from subretinal hemorrhage from wet AMD. Both patients had substantial letter gains (29 and 21 letters) in vision at the 1-year follow-up. However, the letter gains may have resulted from the clearing of the subretinal hemorrhage and not the RPE grafting. A second surgery was needed to address the retinal detachment with PVR.
In the second trial (Sci Transl Med DOI: 10.1126/scitranslmed.aao4097) performed at the University of Southern California, five patients had dry AMD and geographic atrophy with severe visual loss. Four received the implant and one of the four gained 17 letters of vision; three of the four had improved fixation. The complications included mild-to-moderate hemorrhages in all cases; one developed a subretinal hemorrhage postoperatively.
“Both of these studies were quite exciting,” Dr. Rao said.
Other approaches and future directions
Other cell sources, according to Dr. Rao, are exploration of other suprachoroidal approaches for cell delivery; organoid-based photoreceptor transplantation, which he described as the holy grail; organoid-based full-thickness retinal “sandwich” transplantation; bone marrow, fetal retinal progenitor cells, and 3-dimensional printing. There is also a move to include patients with moderate rather than severe visual loss. He also pointed out that there is interest among some investigators in implanting cones over sandwich transplants that would contain more than just one cell type.
The orbital subretinal delivery system (Biotime), which used a suprachoroidal delivery approach, was used in the first patient during summer 2019.
Rajesh Rao, MD
Dr. Rao has no financial interest in any aspect of this report.