Ultrasound–mediated gene transfer to the subconjunctival tissue

Abstract

Abstract: : Purpose: Recently, ultrasound–mediated gene transfer has been improved as one of the nonviral vectors, which are simple and safe approach. The medication to subconjunctival tissue/space has several advantages, that is; 1) it is close to the anterior ocular segment, including cornea and anterior chamber, and the peripheral retinal tissue, 2) it dose not contribute directly to visual acuity, 3) it is approached easily. In order to establish new ocular gene transfer approach, we here assessed the gene transfer efficiency to the subconjunctival tissue using ultrasound. Methods: We examined the gene transfer efficiency of naked plasmid DNA using ultrasound irradiation with echo contrast microbubble (Optison) in the subconjunctival tissue. We injected several concentrations of luciferase or GFP plasmid mixed with or without 50% Optison into the subconjunctival space and stimulated by ultrasound (1 MHz, 3.0 W/cm2, 2 minutes). The luciferase activities were measured using luminometer 2 days after gene transfer and GFP signals were observed using fluorescent steromicroscopy several days after gene transfer. Results: Optison treatment significantly up–regulated the gene transfer efficiency to the subconjuctival tissue. Most efficient gene transfer was performed with 100 É g/ml plasmid and 50% Optison. GFP positive cells were observed until at least 7 days after gene transfer. Conclusions: This is the first report of ultrasound–mediated gene transfer to ocular tissue. It is possible that this gene transfer method becomes a new therapeutic approach against the disorder of the anterior ocular segment.

Keywords: gene transfer/gene therapy • conjunctiva • anterior segment