In Vitro Cytotoxicity Testing of Medical Devices

In vitro cytotoxicity testing employs cell culture techniques to determine cellular responses such as cell death (e.g., cytolysis), growth inhibition, colony formation, and other effects on cells caused by medical devices, materials, or their extracts.

Within the biological evaluation system for medical devices, in vitro cytotoxicity testing stands as one of the most crucial indicators. Through cytotoxicity assessment, the potential in vitro cytotoxicity of medical devices and biomaterials can be evaluated. Serving as a simulated experiment prior to the use of tissues and cells in biological organisms, in vitro cytotoxicity testing plays a predictive role in assessing reaction outcomes. In vitro cytotoxicity testing methods are cost-effective, straightforward, and amenable to batch testing, providing essential screening materials for whether samples should proceed to animal laboratory experiments.

Evaluation Categories

Among the numerous methods utilized in in vitro cytotoxicity assays, evaluation categories can be divided based on measurement endpoints into the following:

1. Assessment of cell damage through morphological methods;

2. Measurement of cell damage;

3. Measurement of cell growth;

4. Measurement of specific aspects of cellular metabolism.

Solutions

SGS Laboratories possess extensive experience in cytotoxicity testing, offering comprehensive testing systems for medical devices and biomaterials cytotoxicity assessments. Testing methods for medical devices and biomaterials cytotoxicity typically fall into two main categories: quantitative cytotoxicity testing and qualitative cytotoxicity testing.

Quantitative Cytotoxicity Testing: MTT Assay

Principle

This test is based on observing cell metabolic activity. MTT is a yellow water-soluble reagent that is metabolized by viable cells into a purple formazan, which is then dissolved in isopropanol and measured using a spectrophotometer. The number of viable cells is directly proportional to the optical density.

Reference Standards

▪ ISO 10993-5:2009 Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity.

▪ ISO 10993-12:2021 Biological evaluation of medical devices – Part 12: Sample preparation and reference materials.

▪ GB/T 16886.5-2017 Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity.

Notes

Laboratory testing sampling methods typically involve using extraction fluid for experiments. Suitable extraction ratios are selected based on the characteristics and thickness of the samples according to standards, followed by further sample preparation.

Qualitative Cytotoxicity Testing: ISO Qualitative Method

Principle

Medical device leachables are cultured with cells, and biological responses of the cells are observed under a microscope. Evaluation of whether cells change is based on cell morphology, vacuole formation, cell detachment, cell lysis, and cell membrane integrity, among other factors, and is then graded accordingly.

Reference Standards

▪ ISO 10993-5:2009 Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity.

▪ GB/T 16886.5-2017 Biological evaluation of medical devices – Part 5: Tests for in vitro cytotoxicity.

Qualitative Cytotoxicity Testing: USP Qualitative Method

Principle

This testing method assesses the impact of leachables from elastic or polymeric materials that come into direct or indirect contact with patients on cell morphology, determining the biological response of the extract.

Reference Standard

USP-NF <87>: BIOLOGICAL REACTIVITY TESTS, IN VITRO: Elution Test.