Nanoparticles help researchers deliver steroids to the retina
Offers potential treatment for macular degeneration and retinitis pigmentosa
US researchers have found a new way to treat age-related macular degeneration and retinitis pigmentosa using nanoparticles called dendrimers that deliver steroids onto the retina.
A collaborative study by researchers at Wayne State University, the Mayo Clinic and Johns Hopkins Medicine in the US has shown that steroids attached to the dendrimers targeted the damage-causing cells associated with neuroinflammation, leaving the rest of the eye unaffected and preserving vision.
The principal authors of the study, Raymond Iezzi (Mayo Clinic ophthalmologist) and Rangaramanujam Kannan (faculty of ophthalmology at The Wilmer Eye Institute of Johns Hopkins), have developed a targeted, sustained-release drug delivery system using a simple nanodevice. The experimental work in rat models was initiated and conducted mainly at Wayne State University, and showed that one intravitreal administration of the nanodevice in microgram quantities could offer neuroprotection at least for a month. The study appears in the journal, Biomaterials (33(3), 979-988).
Both dry age-related macular degeneration and retinitis pigmentosa are caused by neuroinflammation, which progressively damages the retina and can lead to blindness.
‘There is no cure for these diseases,’ said Iezzi. ‘An effective treatment could offer hope to hundreds of millions of patients worldwide. We tested the dendrimer delivery system in rats that develop neuroinflammation leading to retinal degeneration. The target was activated microglial cells, which are the immune cells in charge of cleaning up dead and dying material in the eye. When activated, these cells cause damage via neuroinflammation — a hallmark of each disease.’
Kannan added: ‘Dendrimers are tree-like, non-cytotoxic polymeric drug delivery vehicles (~ 4nm). Surprisingly, the activated microglia in the degenerating retina appeared to eat the dendrimer selectively and retain them for at least a month. The drug is released from the dendrimer in a sustained fashion inside these cells, offering targeted neuroprotection to the retina.’
The treatment reduced neuroinflammation in the rat model 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 neuroinflammation, the study found.