ABSTRACT
Nanoparticles (NPs) offer revolutionary new possibilities in various fields of nanomedicine. Biodegradable nanoparticles like Doxil, DaunoXome and Depocyt were already approved by the Food and Drug Administration (FDA) in the last century, and together with Abraxane, which was approved in 2005 for metastatic breast cancer, are standard medications in the treatment of cancer. Nonbiodegradable NPs are less widely used, but iron oxides in magnetic resonance imaging (MRI) and silver NPs for topical antimicrobiosis also have an established place in medical diagnosis and treatment. As they are not biodegradable and may accumulate in the body, their effects upon chronic exposure are of major importance. As most
particles accumulate in organs of the reticuloendothelial system, in lymph nodes, liver and spleen, immune effects are of particular importance. For the exposure to non-biodegradable medical NPs no systematic studies are available so far, but the data on biological effects of wear particles from orthopaedic implants and the action of environmental NPs on the respiratory system could serve as an indication for potential immune effects of medical NPs. This review compares the effects on the immune system of non-biodegradable NPs used in nanomedicine to those of wear particles and of environmental particles in order to identify common principles. Studies on wear particles mostly originate from long-term exposures of humans with rather low levels of particles compared to animal exposures, which often use high doses of particles for short exposure times.
