Characterizing the Role of Biologically Relevant Fluid Dynamics on Silver Nanoparticle Dependent Oxidative Stress in Adherent and Suspension In Vitro Models

Abstract

Silver nanoparticles (AgNPs) are being employed in numerous consumer goods and applications; however, they are renowned for inducing negative cellular consequences including toxicity, oxidative stress, and an inflammatory response. Nanotoxicological outcomes are dependent on numerous factors, including physicochemical, biological, and environmental influences. Currently, NP safety evaluations are carried out in both cell-based in vitro and animal in vivo models, with poor correlation between these mechanisms. These discrepancies highlight the need for enhanced exposure environments, which retain the advantages of in vitro models but incorporate critical in vivo influences, such as fluid dynamics. This study characterized the effects of dynamic flow on AgNP behavior, cellular interactions, and oxidative stress within both adherent alveolar (A549) and suspension monocyte (U937) models. This study determined that the presence of physiologically relevant flow resulted in substantial modifications to AgNP cellular interactions and subsequent oxidative stress, as assessed via reactive oxygen species (ROS), glutathione levels, p53, NFκB, and secretion of pro-inflammatory cytokines. Within the adherent model, dynamic flow reduced AgNP deposition and oxidative stress markers by roughly 20%. However, due to increased frequency of contact, the suspension U937 cells were associated with higher NP interactions and intracellular stress under fluid flow exposure conditions. For example, the increased AgNP association resulted in a 50% increase in intracellular ROS and p53 levels. This work highlights the potential of modified in vitro systems to improve analysis of AgNP dosimetry and safety evaluations, including oxidative stress assessments.

Implementation of a Dynamic Co-Culture Model Abated Silver Nanoparticle Interactions and Nanotoxicological Outcomes In Vitro

“…In order to establish a dynamic exposure environment, a multi-channel peristaltic pump (Ismatec, model #ISM939D; Cole Parmer, Vernon Hills, IL, USA) was implemented, as previously described [ 24 , 25 ]. The tubing, 1/16 inch inner diameter, was tightly secured into pre-drilled holes in individual wells of a 24-well plate, generating unilateral flow across the cellular surface.…”

“…These studies have determined that fluid movement modified particle transport by adding a third lateral force, in addition to NP diffusion and sedimentation [ 23 ]. Altered dosimetry profiles within dynamic conditions converted into differential NP-dependent bioresponses, aligning with changes to the nano-cellular interface [ 24 , 25 ]. Lastly, to provide a level of protection from foreign material, such as NPs, initial studies have been carried out that incorporated representative immune elements [ 26 ].…”

A Study on Myogenesis by Regulation of Reactive Oxygen Species and Cytotoxic Activity by Selenium Nanoparticles

“…Importantly, biomaterials for tissue-engineered skeletal muscle provide a biophysical microenvironment to help myoblast differentiation and tissue formation [ 17 , 18 , 19 ]. In particular, nanoparticles with diameters of 1–100 nm can modulate cell fate by directly delivering themselves to intracellular sites, such as to the cytosol and nucleus [ 20 , 21 , 22 ]. Recently, metal (gold, silver, selenium, strontium, copper, and ceria)-incorporated nanoparticles showed outstanding biocompatible and antioxidant effects in various areas of tissue regeneration [ 20 , 23 , 24 , 25 , 26 , 27 ].…”

Oxidative Stress in Human Toxicology

“…Silver nanoparticle (AgNP) interaction with cultured human adherent (lung epithelial A549) and suspension (monocytic U937) cells under static and dynamic flow conditions was investigated by K.E. Burns et al [ 9 ]. The measured parameters included AgNP cell association, oxidative stress-related (intracellular ROS and GSH/GSSG ratio (GSSG is oxidized glutathione)) levels, activation of oxidative stress sensitive signaling pathways (phosphorylation of tumor suppressor protein p53 and nuclear factor kappa B (NFκB)), and production of inflammatory cytokines (interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)).…”

“…Oxidative stress levels were found to be a function of cell type and flow conditions. U937 monocytes secreted considerably more cytokines (also when untreated) than alveolar epithelial A549 cells [ 9 ].…”