Nanomedicine for the brain and the eye: disease management in poorly accessible compartments of the body

Biological barriers represent a stumbling block to the pharmacological treatment of lesions occurring in central nervous system or retina. The advent of nanodrugs was welcomed as a means to tide over and cross the barriers. Expectations, however, have not been completely fulfilled, as nanocarriers often accumulated at the endothelial frontier, rather than cross it over. The super‐paramagnetism of iron oxide nanoparticles improved the diagnostic power of the magnetic resonance imaging and opened new perspectives. These nanoparticles, which can be addressed to the target organ by an external magnetic field, provide local imaging of the lesion, on‐demand release of therapeutic agent, and subsequent imaging of the repair. Nanogels that present a sol–gel phase transition at body temperature are easy to inject and remain immobilized near the site of injection. There they promote prolonged and sustained release of drugs, or frame a shell for cell precursors to fully develop into mature neurons or glia.