Nano-enhanced Optical Gene Delivery to Retinal Degenerated Mice

Background: The efficient and targeted delivery of genes and other impermeable therapeutic molecules into retinal cells is of immense importance for the therapy of various visual disorders. Traditional methods for gene delivery require viral transfection, or chemical methods that suffer from one or many drawbacks, such as low efficiency, lack of spatially targeted delivery, and can generally have deleterious effects, such as unexpected inflammatory responses and immunological reactions. Methods: We aim to develop a continuous wave near-infrared laser-based Nano-enhanced Optical Delivery (NOD) method for spatially controlled delivery of ambient-light-activatable Muti-Characteristic opsin-encoding genes into retina in vivo and ex vivo. In this method, the optical field enhancement by gold nanorods is utilized to transiently permeabilize cell membrane, enabling delivery of exogenous impermeable molecules to nanorod-binding cells in laser-irradiated regions. Results and Discussion: With viral or other non-viral (e.g. electroporation, lipofection) methods, gene is delivered everywhere, causing uncontrolled expression over the whole retina. This will cause complications in the functioning of non-degenerated areas of the retina. In the NOD method, the contrast in temperature rise in laser-irradiated nanorod-attached cells at nano-hotspots is significant enough to allow site-specific delivery of large genes. The in vitro and in vivo results using NOD, clearly demonstrate in vivo gene delivery and functional cellular expression in targeted retinal regions without compromising the structural integrity of the eye or causing immune response. Conclusion: The successful delivery and expression of MCO in the targeted retina after in vivo NOD in the mice models of retinal degeneration opens a new vista for re-photosensitizing retina with geographic atrophies, such as in dry age-related macular degeneration.