News & Analysis

The collaboration of scientists used hydroxylterminated polyamidoamine (PAMAM) dendrimers for targeted drug therapy of neuroinflammation in the retina. The team found that the dendrimers themselves selectively localized within the activated outer retinal microglia in two different rat models of retinal degeneration, but not in the retina of healthy rats. This selective biodistribution was then exploited for the targeted drug delivery of fluocinolone acetonide, a steroid that was covalently conjugated to the dendrimer particles. Their research, reported in Biomaterials, showed that the drug was released from the PAMAM dendrimers in a sustained manner, over 90 days. An intravitreal injection of 1 μg of the steroid attached to 7 μg of the PAMAM dendrimer nanoparticles was able to arrest retinal degeneration, preserve the number of photo receptor outer nuclear cells and attenuate the activated microglia for over a month. Macular degeneration is caused by neuroinflammation, which leads to damage of the retina and results in a loss of vision in the centre of the visual field and possible blindness. According to the National Institutes of Health, it affects more than 7 million Americans. One of the lead authors of the study, Raymond Iezzi (Mayo Clinic, Rochester, MN, USA) acknowledged the impact this research could have, explaining that as there is no cure for macular de generation and that an effective treatment could help millions of people worldwide.