Toxicology and clinical potential of nanoparticles

TLDR

Nanoparticles are increasingly used in technology, research, and medicine, and their small size and unique chemical and physical properties enable diverse biomedical applications. This review examines toxicity studies of clinically relevant nanoparticles, emphasizing cytotoxicity mechanisms and the difficulty of translating cell‑based findings to humans. The authors critique the proof‑of‑principle approach that employs unrealistically high nanoparticle concentrations, highlight discrepancies between in vitro and in vivo results, and argue for a unified protocol to generate realistic toxicity data. The reliance on exaggerated concentrations casts doubt on nanomedicine research and can provoke unnecessary public alarm.

Abstract

In recent years, nanoparticles (NPs) have increasingly found practical applications in technology, research and medicine. The small particle size coupled to their unique chemical and physical properties is thought to underlie their exploitable biomedical activities. Here, we review current toxicity studies of NPs with clinical potential. Mechanisms of cytotoxicity are discussed and the problem of extrapolating knowledge gained from cell-based studies into a human scenario is highlighted. The so-called 'proof-of-principle' approach, whereby ultra-high NP concentrations are used to ensure cytotoxicity, is evaluated on the basis of two considerations; firstly, from a scientific perspective, the concentrations used are in no way related to the actual doses required which, in many instances, discourages further vital investigations. Secondly, these inaccurate results cast doubt on the science of nanomedicine and thus, quite dangerously, encourage unnecessary alarm in the public. In this context, the discrepancies between in vitro and in vivo results are described along with the need for a unifying protocol for reliable and realistic toxicity reports.