The impact of nanocolloidal wear‐particles on human mononuclear cells

Abstract

This article investigates the effects of metallic wear-medium prepared from 316L stainless steel and titanium alloy (TiAl6V4) in vitro. Wear was generated by a tribometer, under sterile conditions, disc-on-pin submersed in cell culture medium. Wear medium was separated into a particle fraction (>200 nm) and a nanocolloidal fraction (< 200 nm). A standardized cell culture model was employed using isolated mononuclear cells from peripheral human blood cells were incubated with increasing amounts of wear medium containing particles or nanocolloids. Vitality was assayed using MTT and inflammatory reactions were measured by TNF-a ELISA. In a second step wear-medium was aged over two weeks in an incubator to simulate passivation of the implant / particle surfaces.Dose dependant toxic reactions induced by nanocolloids from titanium alloy and even more from stainless steel were identified with the vitality decreasing to 50 % compared to untreated cells. Nanocolloids did not induce inflammatory effects. Particles had no apparent toxic effects on cells. On the other hand, particles from titanium alloy induced a higher secretion of TNF-a in the supernatants than 316L.Aged nanocolloids lost their toxic potential, but aged particles did still show a strong inflammatory reaction with titanium alloy being the stronger inflammatory agent.This study demonstrates that particles from titanium alloy can not be assumed as to be an inert biomaterial. In fact, titanium alloy particles induced a stronger inflammatory reaction rather than stainless steel. We conclude that both particles and nanocolloids show specific interactions with mononuclear cells in a sense of toxicity and inflammation. Furthermore, it seems to be of great importance to critically consider fabrication processes and age of particles used for cell culture settings in future research.Key words: wear-particles, nanocolloids, TNF-a, MTT-assay, biocompatibility Dieser Artikel vergleicht unterschiedliche metallische Verschleißprodukte aus 316L-Stahl und Titanlegierung (TiAl6V4) miteinander. Dabei dreht es sich um Partikel und um Nanokolloide, denen bisher wenig Beachtung in Biokompatibilitätsuntersuchun-gen geschenkt wurde. Hierzu wurde Verschleiß unter sterilen Bedingungen in Zellkulturmedium in einem Tribometer (Stift-Scheibe-Versuch) erzeugt. Das gewonnene Verschleißmedium wurde dann mittels Massenzentrifugation in eine Partikel-(> 200 nm) und eine Nanokolloidfraktion (< 200 nm) aufgeteilt. Um das toxische und das inflammatorische Potential der unterschiedlichen Fraktionen zu bestimmen, wurden humane mononukleäre Zellen des peripheren Blutes (PBMNC) mit unterschiedlichen Konzentrationen der verschiedenen Verschleißmedien inkubiert und aus den Ü berständen die TNF-a Konzentration mittels ELISA und die Vitalität mittels MTT-Test bestimmt. In einem zweiten Schritt wurde das Verschleißmedium gealtert, um Passivierungs-und Oxidationsvorgänge des Implantatmaterials und der Partikel zu simulieren.Es fand sich eine deutliche, dosisabhängige, toxische Reaktion der Zellen bei In...

The generation of nanocolloidal wear from stainless steel and titanium alloy and its toxic effects in a monocyte cell culture model

“…Correlating vitality and inflammatory response into a linear function we find that in 316L stainless steel the correlation is significant while titanium misses a significant correlation though the scatterplot still suggests coherence. Most interesting is the fact that J774 cells do not display a higher TNF production with increasing doses of titanium particles as it could be observed in a study conducted with freshly isolated human mononuclear cells employing the same wear medium fractions [20]. Further in vivo testing must shed light on the question whether titanium particles truly induce a higher inflammatory reaction in the implant surrounding tissue.…”

“…Maloney and Sun have described the interaction of wear particles and the surrounding proteins as opsonisation and were able to show that particles incubated with serum proteins were able to induce higher inflammatory reactions in the cell culture [22,23]. Mechanical wear of the implant material leads to the formation particles in sizes between 0.08 -250 lm [20,21]. Submicron sized particles (alternatively they are also referred to as nanoparticles) develop besides the well researched micron-sized particles in the implant surrounding tissue.…”