Application Prospects for Synthetic Nanoparticles in Optogenetic Retinal Prosthetics

Optogenetic prosthetics is an approach to restore visual function in retinal degenerative diseases. It implies the delivery of genes encoding light-sensitive proteins to retinal cells that survived degeneration, primarily bipolar and ganglion cells. As a result, these cells turn into “pseudophotoreceptors” which are able to take on the function of rods and cones lost in disease. The key element of the optogenetic prosthetic procedure is a vector that delivers exogenous DNA to the nucleus of a retinal cell. There are two main categories of vectors: viral and synthetic. The latter include nanoparticles derived from various polymers, lipids and inert metals. Previously, it was believed that viruses transfect living cells more efficiently than their synthetic counterparts due to the presence of specialized gene delivery mechanisms. However, to date, there have been developed nanoparticles that can effectively penetrate through tissue barriers, get into the cell, and successfully deliver nucleic acid molecules to the nucleus. This review addresses the current approaches to the development of nanocarriers and defines the major requirements for their physicochemical properties to ensure most efficient transfer of the genetic material across the intraocular barriers and its delivery to bipolar and ganglion cells. Based on the literature data, several types of nanoparticles have been selected that appear most promising in terms of optogenetic retinal prosthetics.