X-medics tantalum beads are tested for cytotoxicity according to ISO 10093-5 (Biological evaluation of medical devices — Part 5: Tests for in vitro cytotoxicity) by an ISO 17025 accredited laboratory. The test is done to verify that no unwanted substances (e.g. process chemicals, cleaning agents, or others) remain in critical (cytotoxic) amounts after the tantalum balls have been processed, handled and cleaned/passivated.
During the cytotoxicity test a sample from the produced batch of tantalum beads (a few hundred to a few thousand, dependent on the ball size) are sterilized and the sample is extracted by a cell culture medium for a period of 72 hours. A positive (cytotoxic) control – polyvinyl chloride, PVC, and a negative (non-cytotoxic) control – polyethylene, PE, is also extracted by similar medium (for 24 h). The extracts and controls are diluted in 5 steps, cell suspension is added, and the extract/cell mixtures are incubated for 72 hours. After the incubation the number of cells are counted at the different concentrations and the cell proliferation inhibition of the solutions are calculated.
The product extract (and negative control of course) should not show a cell proliferation inhibition exceeding 30 % that indicates a cytotoxic effect., whereas the positive control should have cell proliferation inhibition well above 30 %.
This video is a general demonstration of how a cytotoxicity test may be performed: