Testing for cytotoxicity is a good first step toward ensuring the biocompatibility of a medical device or pharmaceutical product. Cytotoxicity testing is performed in vitro according to ISO 10993-5.
Cell culture methods are used to assess the toxicity potential of medical devices, raw material and chemicals (solids, gels and liquid etc) for pharmaceutical manufacturing. Three types of qualitative cytotoxicity tests are stated in ISO 10993-5: Extraction, direct contact and indirect contact methods.
PRINCIPLE OF TEST:
1. The Extraction Method / MEM Elution
Uses an extract to test the device according to actual use conditions. The extract is titrated to produce a semi-quantitative measurement of cytotoxicity. After preparation, the extract is directly inoculated onto a cell monolayer and incubated. The cells are then examined microscopically for degeneration and cell lysis.
This method is suitable for most medical devices which may be tested as composite or individual components.
2. The Direct Contact Method
This method is recommended for low density material such as contact lens or clear liquid. In this method , a piece of contact lens or device or a series of dilutions is prepared and is placed directly onto the cell monolayer and incubated. During incubation, leachable chemicals in the test material can diffuse into the culture medium and contact the cell layer. Reactivity of the test sample is indicated by cell degeneration and cell lysis around the test material.
3. Indirect Contact Method / Agar Overlay
This Method is suitable for high density materials such as semi-solid ointment or gel. In this method, a thin layer of nutrient- supplemented agar is placed over the cell monolayer, the test material is placed on top of the agar layer and incubated. A zone of degenerative or lysed cells under or around the test material is examined microscopically.
- ISO 10993-5:2009 and 10993-12 Biological Evaluation of Medical Devices – Part 5: Tests for in-vitro Cytotoxicity.
Complete device or minimum of 10g samples