Cytotoxicity

Cytotoxicity

Cytotoxicity

Cytotoxicity testing provides a rapid economical approach for evaluating the biocompatibility of  medical devices and raw materials . The cell culture used is sensitive and can be used in screening and QC programs.  Cytotoxicity testing is recommended for all device types listed in ISO 10993-1 for biocompatibility testing of devices and is an important part of cleaning and disinfection validations for reusable devices.  

LexaMed uses L-929 mouse fibroblast cells  in our laboratory because of its ease of use, dependability and sensitivity.  We perform ISO 10993-5 Biological evaluation of medical devices —Part 5: Tests for in vitro cytotoxicity Elution and Agar Overlay tests and USP Chapter <87> Biological Reactivity Tests, In Vitro Elution and Agar Overlay tests    

Agar Overlay Test

This method measures the cytotoxicity potential of devices or materials intended for contact with skin or mucosal tissue.  A representative portion of a device or component having patient contact is identified, replicate samples measuring ~ 1.0 cm2 are placed on an agar overlay over a cell monolayer.  The cell cultures are incubated and observed for toxicity, they are given a reactivity and assigned a grade which corresponds to the level of cytotoxicity.   Three (3) sample replicates are required for ISO testing and two (2) replicates for USP. 

Elution Test 

This method measures the cytotoxicity potential of an extract. This method is used to test devices intended for contact with body fluid and tissues.  A 120 cm2 or 4.0 gm portion of a medical device or component is extracted in a solution of MEM and the extract exposed to a cell monolayer.  Cell cultures are examined microscopically and given a reactivity and grade which corresponds to the level of cytotoxicity present in the device extract.   Three (3) sample replicates are required for ISO testing and two (2) replicates for USP. 

Test Sample Requirements:
  • Agar Overlay: > 7.5 cm2, > 0.3 g, or > 0.3 mL; divided into triplicate samples.
  • MEM Elution: > 120 cm2 (depending on thickness and material) or > 4.0 g. Testing with a known surface area preferred.

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