Sensitization potential of medical devices detected by in vitro and in vivo methods

Medical devices have to be tested before marketing in accordance with ISO EN 10993-10 in order to avoid skin sensitization. This standard predominantly refers to the in vivo test; however, it doesn't exclude the use of in vitro methods, which have been sufficiently technically and scientifically validated for the purpose of medical devices testing. It is foreseen that due to the complexity of the sensitization endpoint, combination of several methods will be needed to address all key events occurring in the sensitization process. The objective of this pilot study was to evaluate sensitization potential of selected medical devices using a combination of in vitro (LuSens, OECD TG 442D), in chemico (DPRA, OECD TG 442C) and in vivo (LLNA DA, OECD TG 442A) methods and to suggest a possible testing strategy for the safety assessment of medical devices extracts. Overall, one of the 42 tested samples exhibited positive results in all employed test methods, while 33 samples were predicted as samples with non-sensitizing potential in all three performed methods. This study demonstrated good agreement between in vitro and in vivo results regarding the absence of skin sensitization potential; however, discrepancies in positive classification have been recorded. The mismatch between in vitro and in vivo results might be caused by specific response of the immune system of the living organism. The in vitro methods require optimization of procedure, in particular the choice of appropriate extraction vehicle and applied volumes.