In vivo gene transfer into the retina mediated by a novel liposome system

Purpose. To determine whether a reporter gene can be introduced into rat and mouse retinas in vivo using the authors' novel liposome system. Methods. Cytomegalovirus-promoted LacZ genes and nonhistone nuclear protein, high mobility group 1 (HMG1), were coencapsulated in liposomes by agitation and sonication. The liposomes were then coated with the envelope of inactivated hemagglutinating virus of Japan (HVJ; Sendai virus) by fusion (HVJ liposome). The HVJ liposome solution was injected into the vitreous cavity of adult Sprague-Dawley rats (n=30) or the subretinal space of adult CD-1 mice (n=42). LacZ expression was assessed by beta-galactosidase assay. Results. LacZ expression was demonstrated in the photoreceptors as long as 30 days after intravitreal and subretinal injections. beta-Gal activity was observed also in neurons and glial cells in the ganglion cell layer of the intravitreally injected rats and, although at lower intensity, in the retinal pigment epithelium of both animals. No inflammation or toxic effects secondary to the HVJ liposomes were detected on histologic examination. Conclusions. In vivo transfer and expression of a reporter gene into adult mammalian retina can be achieved using HVJ liposomes. This method offers a promise as a nonviral system for in vivo gene transfer into adult mammalian neural retina.