The cytotoxicity test is one of the biological evaluation and screening tests that use tissue cells
Biocompatibility is concerned with medical devices in a specific environment and location of the host, their ability to react with each other when directly or indirectly in contact with the host, the biological properties of medical devices when static, the dynamic process of change
Medical devices have been widely used in various clinical disciplines (
The cytotoxicity test, one of the biological evaluation and screening tests, uses tissue cells
Three types of cytotoxicity test are stated in ISO 10993-5: Extract, direct contact and indirect contact tests (including agar overlay assay and filter diffusion). In general, the extract test is suitable for detecting the toxicity of soluble substances of medical devices and is usually consistent with the results of animal toxicity tests. The direct contact assay is the most sensitive for testing the cytotoxicity of the medical devices; the medical devices can be measured even with weak cytotoxicity (
The mitochondrial dehydrogenase performance measurement, also known as the 3-(4,5-dimethyl-2-thiazolyl)- 2,5-diphenyl-2H-tetrazolium bromide (methyl thiazolyl tetrazolium; MTT) assay, is a rapid assessment of cell proliferation and cytotoxicity colorimetric assay to measure cell metabolism or function used (
The MTT assay is currently the most commonly used method to test cell growth rate and toxicity of the culture. Although the MTT assay has a sensitive response to the proliferation of medical devices, it has numerous problems in application. For example, the test results were not the same when using different doses of extract from natural latex rubber condoms. A previous study reported on 15 brands from 6 batches of condoms (6 cm2/ml proportion extraction) assessed by the MTT assay. When the extract doses were 50, 20 and 10%, the cell toxicity grades were 4, 2 and 1, respectively. However, when these medical devices were detected by the indirect method, all had a cell toxicity of grade 2. Similar results occurred with assessment of disposable catheters and medical gloves: When the doses of the extract tested were 50–100%, all the cytotoxicity results were grade 4; however, when the dose was 25%, the test results were distributed in grades 4, 3 and 2 (
Molecular filtration detects cytotoxicity by evaluating the activity of the monolayer succinate dehydrogenase effect by the medical devices. Monolayer cells are cultured on a cellulose ester filter first and the original culture medium is subsequently replaced with medium containing agar, allowing fresh medium gel on cells. Finally, the single-cell membrane gel is separated and reversed to expose the membrane upwards. Following exposure to the sample, the filter is removed and the metabolic activity of cells affected by the sample is measured (
This method is used to evaluate the biological medical devices that can leach toxic substances, and it can be performed on medical devices or extracts. Prior to the addition of 1% live cells containing dye (such as neutral red) agar or agars (low melting point) to update the trial media, the monolayer should be cultured first. Agar placed between the cells and the medical devices on the agar forms a barrier. Nutrients, gases and soluble toxic substances can penetrate and diffuse the agar (
The direct contact method yields direct contact of the solid medical devices with cultured mammalian cells
Cell growth inhibition tests, the ultraviolet spectrophotometer assay, cell rehabilitation method, the degree of cell proliferation assays, cell morphology observation, dentin barrier and high-pressure liquid chromatography are used for the cytotoxicity analysis. In recent years, the evaluation methods have been developed from the whole animal and cellular level to the molecular level using molecular biology techniques, such as the activation of proto-oncogenes and tumor-suppressor gene inactivation studies. Investigators have reported the restoration of the precipitated metal ions on the oral mucosa cells and osteoblast-like cells, DNA damage and induction of apoptosis at the molecular level (
The cytotoxicity test is one of the most important indicators of the biological evaluation system
The present study was supported by the Youth Development Research Foundation of National Institutes for Food and Drug Control (grant no. 2013WC1).