Nanoparticle administration method in cell culture alters particle-cell interaction

Abstract

As a highly interdisciplinary field, working with nanoparticles in a biomedical context requires a robust understanding of soft matter physics, colloidal behaviors, nano-characterization methods, biology, and bio-nano interactions. When reporting results, it can be easy to overlook simple, seemingly trivial experimental details. In this context, we set out to understand how in vitro technique, specifically the way we administer particles in 2D culture, can influence experimental outcomes. Gold nanoparticles coated with poly(vinylpyrrolidone) were added to J774A.1 mouse monocyte/macrophage cultures as either a concentrated bolus, a bolus then mixed via aspiration, or pre-mixed in cell culture media. Particle-cell interaction was monitored via inductively coupled plasma-optical emission spectroscopy and we found that particles administered in a concentrated dose interacted more with cells compared to the pre-mixed administration method. Spectroscopy studies reveal that the initial formation of the protein corona upon introduction to cell culture media may be responsible for the differences in particle-cell interaction. Modeling of particle deposition using the in vitro sedimentation, diffusion and dosimetry model helped to clarify what particle phenomena may be occurring at the cellular interface. We found that particle administration method in vitro has an effect on particle-cell interactions (i.e. cellular adsorption and uptake). Initial introduction of particles in to complex biological media has a lasting effect on the formation of the protein corona, which in turn mediates particle-cell interaction. It is of note that a minor detail, the way in which we administer particles in cell culture, can have a significant effect on what we observe regarding particle interactions in vitro.

Quantitative Particle Uptake by Cells as Analyzed by Different Methods

“…ii) While it might seem intuitive to think that having the double particle concentration in half of the cell culture results to the same exposure conditions in terms of particles added per cell, this in fact in general is not true . Higher particle concentration in a smaller volume allows particles to reach the adherent cells on the bottom of the culture substrate faster than in the case of lower particle concentrations in a larger volume, though the number of particles added per cell is the same . iii) In general there is less particle uptake under serum supplemented than under serum depleted cell culture conditions .…”

“…To describe particle uptake by cells, most importantly all the details about the experimental set‐up need to be provided . Concerning the particles, this involves details about the metrics with which particle concentrations are quantified .…”

“…when the surface area of the culture substrate is known, the added volume of medium), iii) the used cell medium, and iv) optionally also some information about the used cell line, such as proliferation rate (i.e. the reciprocal time required until subsequent cell division has led to the double number of cells), cell surface area and cell volume . This is needed, as i) particle internalization depends on cell density, that is, cells in a confluent cell layer incorporate particles differently than isolated cells.…”

Analyse quantitativer Partikelaufnahme von Zellen über verschiedene Messmethoden

“…Um Partikelaufnahme von Zellen zu beschreiben, ist von höchster Wichtigkeit, dass alle Details des experimentellen Aufbaus zur Verfügung stehen . In Bezug auf die Partikel sind damit die Details der Einheitensysteme gemeint, mit denen Partikelkonzentrationen quantifiziert werden .…”

“…Zweitens sollten, in Bezug auf Zellkulturen, Informationen über i) die Zelldichte (d. h. die Anzahl kultivierter Zellen pro Oberfläche des Kultursubstrats), ii) die Höhe des Zellkulturmediums über den Zellen (d. h. wenn die Oberfläche des Kultursubstrats bekannt ist, das hinzugefügte Volumen an Medium), iii) die Art des genutzten Zellmediums und iv) optional auch weitere Informationen über die genutzte Zelllinie, bspw. über die Proliferationsrate (d. h. die reziproke benötigte Zeit bis sich durch Zellteilung die Anzahl der vorliegenden Zellen verdoppelt hat), die Zelloberfläche und das Zellvolumen . Dies ist notwendig, da i) Partikelaufnahme von der Zelldichte abhängig ist, d. h. Zellen in konfluenten Zellschichten weisen zu isolierten Zellen eine unterschiedliche Partikelaufnahme auf.…”