Report on investigation of ISO 10993-12 extraction conditions.

The international standard ISO 10993-12 describes extraction conditions for generating extracts of medical devices to be used in testing of biological safety. Questions about the adequacy of the extraction conditions (and their variations) for hazard identification drove the development and execution of a round robin study. Four relevant device materials were each evaluated by four laboratories following an established protocol that specified multiple options of extraction solvent, temperature, duration, and ratio of solvent volume to quantity of test article. The resulting samples were analysed by three instrumental methods to identify and quantify extracted organic and elemental substances; however, quantification was not achieved due to lab resource constraints, and only numbers of compounds were reported. Results showed an increased number of volatile organic compounds extracted with organic solvents; however, no clear effect of varying the other extraction parameters could be discerned. Quantification of a small subset of analytes showed sensitivity that may be adequate for hazard identification. An unplanned post hoc comparison of results across labs showed differing numbers of compounds detected; however, fundamental differences in sample preparation and specific analysis methods as well as lack of quantification render the results poorly suited to either exonerate or indict the adequacy of chemical characterization as practiced by the participating laboratories.

Using the monocyte activation test as a stand-alone release test for medical devices.

Monocyte activation tests (MAT) are widely available but rarely used in place of animal-based pyrogen tests for safety assessment of medical devices. To address this issue, the National Toxicology Program Interagency Center for the Evaluation of Alternative Toxicological Methods and the PETA International Science Consortium Ltd. convened a workshop at the National Institutes of Health on September 18-19, 2018. Participants included representatives from MAT testing laboratories, medical device manufacturers, the U.S. Food and Drug Administration's Center for Devices and Radiologic Health (CDRH), the U.S. Pharmacopeia, the International Organization for Standardization, and experts in the development of MAT protocols. Discussions covered industry experiences with the MAT, remaining challenges, and how CDRH's Medical Device Development Tools (MDDT) Program, which qualifies tools for use in evaluating medical devices to streamline device development and regulatory evaluation, could be a pathway to qualify the use of MAT in place of the rabbit pyrogen test and the limulus amebocyte lysate test for medical device testing. Workshop outcomes and follow-up activities are discussed.

Response of monocytes exposed to phagocytosable particles and discs of comparable surface roughness.

This in vitro study characterized the temporal cytokine expression profile from human monocytes exposed to phagocytosable Ti particles (0.78+/-0.12 microm) and to Ti discs of comparable surface roughness. Human THP-1 monocytes were cultured in six well tissue culture polystyrene (TCPS) plates. Each well was either bare, contained Ti particles (the particles were clearly engulfed by the monocytes), or contained a Ti disc. Half of the wells were treated with 1 microg/mL lipopolysaccharide (LPS), while the other half were left unstimulated. Unstimulated and LPS-stimulated cells in bare wells were the negative and positive controls, respectively. Supernatant was sampled from each well at 1, 6, 24, 48, and 72 h and assayed for the expression of nine different cytokines using a Luminex system. Three cytokines (IL-1beta, GM-CSF and IL-13) gave little to no response under all conditions, while six cytokines (TNF-alpha, IL-6, MIP-1alpha, MCP-1, VEGF, and IL-1ra) were clearly detectable. Expression levels generally increased with culture time, particle concentration, and LPS stimulation. Most significantly, it was found that cells treated by Ti discs produced in many instances a higher cytokine expression than did particles.