Article
The effects of nanocolloidal wear medium in a cell culture model of human mononuclear cells
Search Medline for
Authors
-
L.E. Podleska
- Department of Trauma Surgery, University of Essen, Essen, Germany
-
B. Schmidt
- Department of Trauma Surgery, University of Essen, Essen, Germany
-
E. Dose
- Department of Trauma Surgery, University of Essen, Essen, Germany
-
R. Büscher
- Institute for product engineering (IPE II), University of Duisburg-Essen, Duisburg, Germany
-
D. Nast-Kolb
- Department of Trauma Surgery, University of Essen, Essen, Germany
-
G. Täger
- Department of Trauma Surgery, University of Essen, Essen, Germany
| Published: | September 28, 2006 |
|---|
Outline
Text
Wear of metallic implant materials leads to a contamination of the surrounding tissue not only with metallic particles but also with soluble wear products such as ions and nanocolloidal particles smaller 200nm. Most in vitro studies on biocompatibility however have performed in vitro research by contaminating cells with commercially available metal particles employing equal amounts of wear from different biomaterials though the wear rates from different biomaterials differ strongly.
It was the aim of this study to simulate the in vivo situation more closely and to compare inflammatory and toxic reactions from particles and nanocolloids by using realistic amounts of wear medium in a cell culture model.
Therefore isolated mononuclear cells from healthy human donors were contaminated with metallic wear medium that was exclusively generated for in vitro testing: Employed materials: 316L stainless steel and TiAl6V4 titanium alloy; sterile pin-on-disc setting in cell culture medium; following separation into a particle fraction (greater 200nm) and a nanocolloidal fraction (smaller 200nm); wear medium was frozen at -20°C.
Supernatants were taken after 20 hours of incubation and were analyzed for their content of proinflammatory cytokine TNF-α. Cells were further incubated with MTT to quantify cell vitality.
In a second step wear medium was aged over a period of two weeks under physiologic conditions (37°C, 5% CO2 atmosphere) to simulated prolonged exposure to the implant surrounding tissue. Medium and cells were analyzed as mentioned above.
We were able to determine that higher concentrations of nanocolloidal wear medium lead to a distinct decrease of cell vitality (see table [Tab. 1]: line 1, vital cells [%]). Presumably due to the reduced vitality the secretion of TNF-α fades with ascending doses of nanocolloidal wear medium while high doses of particle wear medium lead to a strong increase in TNF-α synthesis especially in titanium wear medium (see table [Tab. 1]: line 2, TNF-α production [pg/ml]).
On the other hand aged wear medium behaves differently: Neither nanocolloidal- nor particle-wear-medium leads to changes in cell vitality after incubation (see table [Tab. 1]: line 3, vital cells [%] incubated with aged wear medium). The inflammatory reaction on the other hand remains unchanged compared to un-aged wear medium: Higher doses of particles lead to higher concentrations of TNF-α (see table [Tab. 1]: line 4, TNF-α incubated with aged wear medium). This study shows that wear particles from titanium are not inert as widely believed. In fact they are able to induce a stronger inflammatory reaction than wear particles from 316L stainless steel. One can reason that both particles and nanocolloids lead to specific interactions with mononuclear cells regarding toxic and inflammatory reactions. Furthermore it appears reasonable to consider fabrication processes and aging phenomena of wear products when planning future research projects addressing the issue of biocompatibility.
