A Communications Medicine study has posited H105A peptide eye drops as a minimally invasive therapy for slowing photoreceptor loss in retinitis pigmentosa (RP). Conducted by an international research team, the study demonstrated that these peptide-based drops successfully preserve photoreceptors, and improve retinal function in both murine models and human retinal organoids.
With most RP treatments currently focusing on managing symptoms rather than halting disease progression, the study explored pigment epithelium-derived factor (PEDF)-based peptides, known for their neuroprotective properties, and tested two peptide candidates – H105A and 17-mer – as potential therapeutic agents.
They found that both peptides, delivered via eye drops, reached the retina and helped to slow down photoreceptor degeneration. In RP mouse models, the treated eyes showed increased photoreceptor survival and improved retinal function compared to untreated eyes. Similarly, in RhoP23H/+ mice – a common model for RP – daily H105A peptide eye drop treatments slowed retinal degeneration, preserving outer nuclear layer (ONL) thickness and maintaining photoreceptor morphology.
Electroretinography (ERG) tests also confirmed that the treated mice retained better retinal responses to light stimuli. Using lab-grown human retinal organoids, the researchers tested H105A’s effect under oxidative stress conditions and found that it prevented photoreceptor death, reinforcing its therapeutic potential for human patients. In addition to the peptide eye drops, the team engineered an adeno-associated virus (AAV-H105A) for intravitreal delivery, which was also found to extend photoreceptor survival in RP mice for up to six months.
The study marks an advancement in the search for non-invasive treatments for retinal degenerative diseases. The success of H105A eye drops suggests that topical peptide-based treatments could become a viable alternative to intravitreal injections in the future, potentially reducing the need for more invasive procedures.
