The effects of nanoparticles on the renal system.

Through a process of translocation across biological barriers, nanoparticles can reach and deposit in secondary target organs where they may induce adverse biological reactions. Therefore, a correct assessment of nanoparticle-induced adverse effects should take into account the different aspects of toxicokinetics and tissues that may be targeted by nanoparticles. For this reason, a comprehensive evaluation of renal nanotoxicity is urgently needed as kidneys are particularly susceptible to xenobiotics and renal excretion is an expected and possible elimination route of nanoparticles in living organisms. On one hand, summarizing the findings of in vitro and in vivo studies that have investigated the adverse effects of nanoparticles on the kidney, this review intends to provide a thorough insight into the nephrotoxicity of these substances. The evaluation of the in vitro studies revealed that different types of nanoparticles (carbon, metal and/or silica nanoparticles) are able to exert significant cytotoxic effects (i.e., decreased cell viability, induction of oxidative stress, mitochondrial or cytoskeleton dysfunction and cell membrane and DNA damage). On the other hand, in vivo studies demonstrated that nanoparticles exhibited an important nephrotoxic potential both at tubular (i.e., degeneration of tubular epithelial cell, cellular fragments and proteinaceous liquid in tubule lumen, renal interstitial fibrosis) and glomerular level (i.e., swollen glomeruli, changes in Bowman's space and proliferation of mesangial cells). Although the data currently available indicate that nanoparticles may adversely impact the renal system, further studies are needed in order to clarify all the potential molecular mechanisms of nephrotoxicity induced by these xenobiotics, in particular at glomerular level.