Magnetic nanoparticles for tissue specific ocular drug delivery

The chronic ocular diseases lead to blindness and their treatment is a big challenge for National public health institutes due to the aging of the population. The eye is divided in two segments: anterior and posterior, deputed to light focusing and signal transduction, respectively. Unfortunately, the physical and functional ocular barriers make drug administration poor effective and current drug delivery strategies lack of any cell type specificity. In particular, disorders of the posterior segment (composed by retina, retinal pigment epithelium (RPE) and choroid) are responsible for the majority of blindness both in childhood and adulthood. Besides, strategies for selective drug delivery to the posterior segment, and the different cell layers within, still lack. Recently, we demonstrated in zebrafish embryos that intravitreal injected magnetic nanoparticles (MNP) are able to rapidly cross the retina and persistently localise within the RPE in an autonomous manner. Interestingly, their fate can be changed by functionalising MNP surface with biomolecules. For example, in order to guide MNP localization to the choroid, we took advantage of the vascular endothelial growth factor, naturally secreted by RPE towards the choroidal layer, demonstrating that such functionalisation successfully address the MNPs to the choroid. Moreover, we demonstrate that MNP carrying neurotrophins are able to efficiently protect the retina from oxidative damage. Our data indicate that MNP represent a powerful therapeutic carrier for cell-specific drug delivery in the posterior segment of the eye.