Noora Svahn

The NRU assay is a quantitative test to determine the potential biological reactivity of a mammalian cell culture in response to a medical device extract. It is described in Annex A of ISO 10993-5 and is one of the most commonly used methods for medical device cytotoxicity testing. The test item is extracted in cell culture medium, which is suitable for both polar and non-polar extracts. The cells are exposed to the extract, and their viability is assessed after staining with neutral red (NR) solution. The number of viable cells correlates with the color intensity determined by photometric measurements, as non-viable cells do not absorb NR. The medical device is considered non-cytotoxic if the percentage of viable cells is ≥ 70 % of the untreated control.

Assessment of skin sensitization potential using the ARE-Nrf2 luciferase test method outlined in OECD Test Guideline 442D and listed in Annex C of ISO 10993-10 as an in-vitro alternative to traditional in vivo sensitization tests. The method has been validated for medical device extracts. The assay models the keratinocyte activation pathway — key event 2 in the skin sensitization adverse outcome pathway (AOP) as described by the OECD. Human keratinocytes are exposed to the test substance at a range of concentrations. If the substance has skin sensitization potential, it activates the Nrf2 transcription factor, which binds to the antioxidant response element (ARE) and induces luciferase expression. The measured luciferase activity thus correlates with the sensitization potential of the substance. According to Annex C of ISO 10993-10, a substance is classified as a skin sensitizer if luciferase activity increases by 50% relative to the solvent control at a concentration where cell viability is not significantly reduced. Two extracts (one polar and one non-polar) are prepared per tested device, and testing is performed in duplicate for each solvent.

Microbiological test package for pharmaceutical or cosmetic products and ingredients according to European Pharmacopoeia methods Ph. Eur. 2.6.12 and Ph. Eur. 2.6.13. The most recent edition of the pharmacopoeia is followed. The following parameters can be included in the analysis package: Total aerobic microbial count (TAMC) according to Ph. Eur. 2.6.12, Total combined yeasts and moulds count (TYMC) according to Ph. Eur. 2.6.12, Tests for specified microorganisms according to Ph. Eur. 2.6.13, including e.g., S. aureus, P. aeruginosa, E. coli, and C. albicans. These analyses are commonly conducted on the finished product and/or starting materials and intermediates as part of pharmaceutical batch release testing.

The bacterial reverse mutation (AMES) test is used to evaluate the genotoxic effect of a medical device or its extract when in contact with a bacterial suspension. The test is conducted according to OECD 471 and ISO 10993-3 by exposing a bacterial suspension of Salmonella spp and Escherichia coli to 5 concentrations of the medical device or its pure extracts. The AMES test is a preliminary "screening test" for genotoxicity. A full genotoxicity evaluation usually includes testing the device with two in vitro methods, of which AMES is typically performed first. An additional in vivo method can be used if needed. Measurlabs can support you with the full genotoxicity evaluation. Please contact our experts for a quote.