14.12.2011

Nanoparticles "boost eye drug delivery"

Nanoparticles "boost eye drug delivery"

By Adrian Galbreth

Diseases such as age-related macular degeneration and retinitis pigmentosa can severely impact people's lives and eventually lead to blindness, with the main problem for some being the fact that no highly effective drugs or means of delivering them are widespread yet.

However, this may soon change as a study by investigators at Mayo Clinic, Wayne State University and Johns Hopkins Medicine shows that using nanoparticles called dendrimers to deliver drugs to the retina offers a new way to treat these eye conditions.

Experts working on the study, which will appear in the journal Biomaterials, suggest that steroids attached to the dendrimers target the damage-causing cells associated with neuroinflammation, leaving the rest of the eye unaffected and preserving vision.

Mayo Clinic ophthalmologist Dr Raymond Iezzi, a lead author of the study, said there is no cure for these diseases, so an effective treatment could offer hope to hundreds of millions of patients worldwide.

Dr Iezzi and fellow principal author Rangaramanujam Kannan, an ophthalmology professor at The Wilmer Eye Institute of Johns Hopkins, have developed an intracellular, sustained-release drug delivery system.

The research was conducted in part at Wayne State University's Kresge Eye Institute with collaboration from Wayne State's College of Engineering and Ligon Research Center of Vision, and involved testing the dendrimer delivery system in rats that develop neuroinflammation.

Their target was microglial cells, which are inflammatory cells in charge of "cleaning up" dead and dying material in the eye; when activated, these cells cause damage through neuroinflammation, as the microglial cells eat the dendrimers, and the drug then shuts down the cells' activity.

Dr Kannan explained: "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."

Although the steroid offers only temporary protection, the treatment as a whole provides sustained relief from neuroinflammation, the specialists concluded.

by Alexa Kaczka


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