Ex vivo permeation of erythropoietin through porcine conjunctiva, cornea, and sclera

The aim of this study is to test the permeation of human recombinant erythropoietin (rHuEPO) across conjunctiva, cornea, and sclera in an ex vivo model. Thirty fresh pig eyes were collected from a slaughterhouse. Conjunctivas (n = 10), corneas (n = 10), and scleras (n = 10) were surgically dissected from surrounding tissues. Ocular membranes were placed into Franz diffusion cells and rHuEPO was administered into the donor phase of each cell, except for control samples. Samples were collected from the receptor phase at seven time points, from 30 min to 6 h of incubation. Erythropoietin (EPO) was quantified by enzyme-linked immunosorbent assay (ELISA) technique. Ocular membranes immunohistochemistry was also performed at the end of the study. EPO was detected in all test samples. After 6 h of incubation, conjunctiva was the most permeable membrane to rHuEPO (509.3 +/- 89.8 mIU/cm(2), corresponding to 0.52% of the total rHuEPO administered on the donor phase), followed by sclera (359.1 +/- 123.7 mIU/cm(2), corresponding to 0.35%) and finally cornea (71.0 +/- 31.8 mIU/cm(2), corresponding to 0.07%). Differences between ocular membranes' permeation were statistically significant (p < 0.001). EPO immunostaining signal was positive for the three ocular membranes. We have demonstrated in an ex vivo model that porcine conjunctiva, cornea, and sclera are permeable to rHuEPO protein. These are promising results concerning ocular EPO administration.