PEDF Peptide Eye Drops Reduced Vision Loss, Inflammation, and Nerve Damage in Diabetic Mice

Two PEDF-derived peptide eye drops (P60, antiangiogenic; P78, neuroprotective) penetrated through the cornea and reached the retina within 1-4 hours when applied topically to diabetic mice. Both peptides reduced vascular leakage by ~60% and restored tight junction proteins (ZO1 and occludin) to non-diabetic levels. The neuroprotective P78 peptide reduced inflammatory cytokines (9 of 20 measured, including TNF-α, IL-6, and IFN-γ), prevented microglia activation by ~60%, reduced retinal ganglion cell death by ~22%, and prevented inner retinal thinning by ~13%. These effects were achieved with just once-weekly eye drops for 15 weeks.

Ins2(Akita) mice (a genetic model of type 1 diabetes) received PEDF peptide eye drops once weekly for 15 weeks starting at the onset of high blood sugar. Peptides were fluorescently labeled to track their penetration through the eye. Researchers measured vascular leakage, tight junction protein expression, inflammatory cytokine levels (20 cytokines), microglia activation, retinal ganglion cell survival, and retinal layer thickness. Signaling pathways (ERK1/2, AKT) were analyzed in Müller glial cells.

Diabetic retinopathy is the leading cause of blindness in working-age adults, and current treatments (laser therapy, injections into the eye) are invasive and burdensome. This study shows that peptide eye drops — applied just once a week — can penetrate to the retina and simultaneously address three major aspects of diabetic eye disease: vascular leakage, inflammation, and nerve cell death. If this works in humans, it could replace painful eye injections with simple drops.

Current diabetic retinopathy treatments — anti-VEGF injections directly into the eye — are effective but dreaded by patients and require frequent clinic visits. The idea that a peptide eye drop could replace injections while addressing not just leaking vessels but also inflammation and nerve damage is transformative. PEDF peptides target the disease from multiple angles simultaneously, which is unusual for any single treatment approach.

This was an animal study in a genetic mouse model of diabetes, which may not perfectly replicate human diabetic retinopathy. The once-weekly dosing achieved moderate vitreous concentrations, and optimal dosing for humans is unknown. Only type 1 diabetic mice were studied. Long-term safety of repeated topical peptide application wasn't assessed beyond 15 weeks.