[Induction of genes into the rabbit eye by iontophoresis]

After inducing 6-carboxyfluorescein (6-FAM)-labeled phosphorothioate oligonucleotides (S-ODNs) noninvasively into albino rabbit eyes by iontophoresis, we assessed the transfer of S-ODNs into the ocular tissues, their stability, and the possible presence of injury to the ocular tissues.

The iontophoresis group consisted of 12 eyes of 6 rabbits and the control group consisted of 4 eyes of 2 rabbits given eye drops containing S-ODNs. Aqueous humor and vitreous humor were collected after iontophoresis, subjected to electrophoresis with a fluorescent DNA sequencer and analyzed by the Gene Scan program. Frozen sections at 10 microns were prepared for observations under a fluorescent microscope. A plasmid 4.7 kbp in size that expresses green fluorescent protein (GFP) was induced into 18 eyes of 9 rabbits by the same procedure.

In the iontophoresis group, S-ODNs were detected in the anterior chamber 5 minutes after electrophoresis and in the vitreous 10 minutes after. These S-ODNs maintained the same length as at the initial synthesis. S-ODNs could also be detected in the posterior retina 20 minutes after electrophoresis. No evidence of degeneration or inflammation due to the above procedure was found in the ocular tissues. Fluorescence showing GFP gene expressions were found in the cornea, the anterior chamber angle, and the ciliary subepithelial tissues.

These findings show that iontophoresis is an effective method to induce gene into rabbit eyes.