Cytotoxicity tests are performed at Gibraltar Laboratories for many different applications. The classic cytotoxicity tests
found in the USP is “<87>, Biological Reactivity, in vitro”. It is designed to determine the biological reactivity of mammalian fibroblast cells [L-929 (ATCC cell line CCL 1, NCTC clone 929) following contact with the elastomeric plastics and other polymeric materials with direct or indirect patient contact or of specific extracts prepared from the materials under test. Three cytotoxicity tests are described (i.e., the Agar Diffusion Test, the Direct Contact Test, and the Elution Test). The decision as to which type of test or the number of tests to be performed to assess the potential biological response of a specific sample or extract depends upon the material, the final product, and its intended use. Other factors that may also affect the suitability of sample for a specific use are the polymeric composition; processing and cleaning procedures; contacting media; inks; adhesives; absorption, adsorption, and permeability of preservatives; and conditions of storage. Evaluation of such factors should be made by appropriate additional specific tests before determining that a product made from a specific material is suitable for its intended use. Any leachable cytotoxic materials are extracted from the plastic using Sodium Chloride Injection containing 0.9% of NaCl or serum-free mammalian cell culture media or serum-supplemented mammalian cell culture media.
In the USP test grading of cytotoxicity is semi-quantitative. Changes in the cell morphology or the presence of cell damage are scored on a scale of 0-4 with 0 meaning no cell lysis and 4 meaning Severe%, damage or destruction.
In comparison, “ISO 10993-5 Biological Evaluation of Medical Devices-Part 5: Tests for in vitro cytotoxicity” provides further guidance and options including more targeted quantitative measurements using analytical instruments to quantitatively measure cellular activity. Thus, ISO groups measurements of cytotoxicity determination into four groups.
1) assessments of cell damage by morphological means [like USP];
2) measurements of cell damage;
3) measurements of cell growth;
4) measurements of specific aspects of cellular metabolism.
Using these sophisticated tests2-4 above Gibraltar Laboratories helps researchers to investigate potential anti-cancer and anti-viral drugs.