Challenges facing nanotoxicology and nanomedicine due to cellular diversity.

This review examines the interaction of nanomaterials (NMs) with cells from the perspective of major cellular differentiations. The structure and composition of cells reflect their role and function in a particular organ or environment. The normal differentiated-state and diseased cells may respond to NMs very differently. This review progresses with due care on nanotoxicology while emphasizing the potential of NMs in treating stress-associated disorders, including cancer and degeneration. The striking potential of NMs in inducing ROS, scavenging ROS, depleting cellular antioxidants, replenishing antioxidants, mimicking antioxidant enzyme activity, and modulating the immune system all show their considerable potential in treating cancer and other aging-associated disorders. It is now clear that NMs become more active and versatile when they come into contact with biological machinery, surprisingly in some cases, in a manner dependent on cell type. The mechanisms leading to the contrasting bioresponse of NMs ranging from toxicity to anticancer and from cell survival to carcinogenicity followed by their immuno-modulating potential show NMs to be a highly promising agent in biomedical therapy. This first-of-its-kind article seeks the challenges to be addressed that could provide a solid rationale in translating the promises of nanomedicine. A thorough understanding of normal and cancer biology could help to minimize the gap between basic and translational research in nanotechnology-based therapy.