Retinal disease
The retina is a thin layer of tissue on the inside back wall of human eye and contains millions of light-sensitive cells and other nerve cells. These cells receive and organize visual information and the retina sends this information to the brain through the optic nerves enabling one to see. Retinal diseases can affect the area of the retina that serves the central vision namely the macula and the fovea at the center of the macula. Many retinal diseases show common symptoms but with unique characteristics. The goal of retinal disease treatments is to stop or slow disease progression and preserve, improve or restore vision. Retinal pigment epithelium is the cell layer that contains the photoreceptors and its degeneration is a disease, especially is a function of age. Drugs have been developed for the prevention and treatment of age-related macular degeneration and the degenerative retinal diseases such as retinitis pigmentosa but with limitations. An effective treatment could offer hope to hundreds of millions of patients worldwide.
Macular degeneration and retinitis pigmentosa are caused by neuroinflammation, which progressively damages the retina and can lead to blindness. Macular degeneration is the primary cause of vision loss in elderly people particularly Americans and retinitis pigmentosa encompasses many genetic conditions affecting the retina.
Nanodevice
Researchers of Wayne State University have developed a clinically relevant, targeted, sustained-release drug delivery system using a simple nanodevice construct. Dendrimer nanoparticles offer a new way to treat age-related macular degeneration and retinitis pigmentosa. Their experimental work showed that one intravitreal administration of this nanodevice in microgram quantities could offer neuro protection at least for a month as per their report.
Dendrimers
Dendrimers are repetitively branched molecules which include arborols and cascade molecules. A dendrimer is typically symmetric around the core, and often adopts a spherical three-dimensional morphology. The first dendrimers were made by divergent synthesis approaches in 1978. A convergent synthetic approach introduced during1990 made dendrimer very popular.
Dendrimer delivery system
The researchers tested the dendrimer delivery system in rats that develop neuro inflammation leading to retinal degeneration. The target was activated microglial cells, the immune cells in charge of cleaning up dead and dying material in the eye. When activated, these cells cause damage via neuro inflammation which is a hallmark of each disease.
When drug carried dendrimers were administered the activated microglia in the degenerating retina eat the dendrimer selectively and retain them for at least a month. It was found that the drug is released from the dendrimer in a sustained fashion inside these cells, offering targeted neuro protection to the retina.
The treatment reduced neuro inflammation and protected vision by preventing injury to photoreceptors in the retina. Although the steroid offers only temporary protection, the treatment as a whole provides sustained relief from neuro inflammation, the study found. Thus the steroids attached to the dendrimers target and cure the damage-causing cells associated with neuro inflammation, leaving the rest of the eye unaffected and preserving vision.