Cytotoxicity and its test methodology for a bioabsorbable nitrided iron stent

Area of Science:

• Biomaterials Science
• Materials Engineering
• Biocompatibility Testing

Background:

• Nitrogen-treated iron is a promising bioabsorbable metallic material for medical implants.
• Understanding its in vitro cytotoxicity is crucial for clinical applications.
• Previous assessments lacked comprehensive evaluation of influencing factors.

Purpose of the Study:

• To comprehensively assess the in vitro cytotoxicity of nitrogen-treated iron.
• To identify factors influencing material precipitation during extraction and incubation.
• To evaluate the suitability of current testing methodologies for bioabsorbable iron-based materials.

Main Methods:

• In vitro cytotoxicity tests including MTT assay, fluorescent staining, and direct contact method.
• Extraction and standing experiments to analyze precipitation factors.
• Analysis of corrosion products from nitrogen-treated iron stents and foils.

Main Results:

• Extraction medium and oxygen availability significantly influence precipitation.
• High concentrations of iron ions in stent extracts showed no cytotoxicity to L929 fibroblasts.
• In vitro cytotoxicity was attributed to the size effect of corrosion particles, not the bulk material.

Conclusions:

• Nitrogen-treated iron exhibits good in vitro biocompatibility.
• Corrosion particle characteristics, not inherent material toxicity, drive observed cytotoxicity.
• A combination of multiple testing methods is essential for a thorough evaluation of bioabsorbable iron-based material cytocompatibility.