Do calcifying nanoparticles promote nephrolithiasis? A review of the evidence

Although much has been learned regarding the pathogenesis of kidney stones, the reason(s) why some individuals form stones while others do not remains incompletely understood. Nanoparticles, which have been observed in geologic samples, have also been isolated from biologic specimens, including kidney stones. These nanoparticles have certain properties that are consistent with a novel life form, including in vitro self-replication, and contain lipids, DNA and proteins. Therefore, it has been hypothesized that nanoparticles may represent a type of infective agent that initiates stone formation in some individuals. Despite a large body of intriguing and suggestive evidence, the true biologic nature of these entities has been elusive, and controversy remains as to whether these nano-sized particles are analogous to other recently described unusual and novel microorganisms, or a transmissible, yet inert nanoparticle. Although unique DNA or RNA has yet to be identified, a proteomic biosignature is beginning to emerge that may allow more definitive clinical investigation. This review evaluates the current evidence regarding nanoparticles as causal to disease and emphasizes the need for additional research to further elucidate their role in human stone formation.