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‐α 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‐α 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.