Alternative route for erythropoietin ocular administration

Area of Science:

• Ophthalmology
• Neuroscience
• Pharmacology

Background:

• Erythropoietin (EPO) possesses known neuroprotective and neuroregenerative properties.
• Ocular drug delivery faces challenges in achieving therapeutic concentrations within the retina.
• Subconjunctival injection is explored as a potential route for ocular EPO administration.

Purpose of the Study:

• To assess the ocular penetration of EPO following subconjunctival injection.
• To evaluate the distribution and persistence of EPO within retinal layers.
• To determine potential side-effects of subconjunctival EPO on hematocrit levels over 28 days.

Main Methods:

• Wistar Hannover rats (n=42) were used, divided into control and EPO-treated groups.
• EPO (1,000 UI) was administered via subconjunctival injection in one eye.
• Retinal EPO distribution was analyzed by immunohistochemistry at various time points (12-60 hours); hematocrit was monitored for 28 days.

Main Results:

• Subconjunctival EPO demonstrated strong immunostaining in retinal layers, particularly the retinal ganglion cell (RGC) layer starting at 24 hours and persisting until 60 hours.
• EPO reached multiple neuronal cells across all retinal layers.
• No significant alterations in hematocrit values were observed over the 28-day study period.

Conclusions:

• Subconjunctival administration effectively delivers EPO to the retina, reaching the RGC layer.
• EPO presence in the retina was confirmed from 24 to 60 hours post-injection.
• This route is a safe and promising alternative for ocular EPO delivery, without adverse hematopoietic effects.