Identification of mesenchymal stromal cell survival responses to antimicrobial silver ion concentrations released from orthopaedic implants.

Antimicrobial silver (Ag) coatings on orthopaedic implants may reduce infection rates, but should not be to the detriment of regenerative cell populations, primarily mesenchymal stem/stromal cells (MSCs). We determined intramedullary silver release profiles in vivo, which were used to test relevant Ag concentrations on MSC function in vitro. We measured a rapid elution of Ag from intramedullary pins in a rat femoral implantation model, delivering a maximum potential concentration of 7.

The variable toxicity of silver ions in cell culture media.

The elevated interest in silver ions (Ag) as a broad spectrum antimicrobial for use on medical devices has increased the number and importance of in vitro biocompatibility testing, however little consideration is given to the culture environment in which the assessments are performed. The current investigation assessed the viability of mouse fibroblasts (L929) exposed to different concentrations of Ag in both Dulbecco's modified Eagle's medium (DMEM) and minimal essential medium Eagle, alpha modification (αMEM). We identified a significant increase in the EC of L929 cells exposed to Ag in αMEM compared to DMEM, which was matched by a corresponding decrease in Ag availability in αMEM at concentrations ≤400 μM, as detected by inductively coupled plasma mass spectrometry (ICP-MS).

Quantification of in vitro mineralisation using ion chromatography.

Analysis of in vitro mineralisation is an important tool in orthopedic research, allowing assessment of new therapeutic agents and devices; however, access to analytical equipment and accuracy of current methods can be a limiting factor. This current work investigated the use of calcium chelation with citric acid and subsequent analysis by ion chromatography as a method for accurately quantifying the extent of in vitro calcium deposition. Primary human osteoblasts were cultured on tissue culture plastic for 21 days under osteogenic conditions.