O-209 Identifying toxicity trends: analysis of over 6700 Mouse Embryo Assays performed on 16 categories of IVF supplies
Authors: Martínez-Casado A , Mestres E , Casals A , Acacio M , Villamar A , Matia-Algué Q , Franco-Roig A , Mendoza M , Castelló C , Calderón G , Costa-Borges N 
Published: July 2024

Abstract

Study question
What type of disposables and solutions exhibit a higher frequency of Mouse Embryo Assay (MEA) failure and where should manufacturers put special attention during production?

Summary answer
Flexipet-pipette types, protein supplements, ovum-pick-up needles, catheters, steripettes, culture media, and mineral oils showed higher MEA-failure frequencies and/or lethality levels due to embryotoxicity among IVF-supplies.

What is known already
The MEA is considered the gold standard assay for quality control of IVF products. It is based on the analysis of in vitro mouse embryonic development under direct or indirect presence of a to-be-tested product, and it requires over 80% expanded blastocyst formation rates (EBFRs) for a product to be considered non-toxic and be released to the market.
Recent episodes reported toxicity issues found in embryo culture supplies and IVF industry devices that were recalled by manufacturers. This underscores the necessity for more specific characterization of products, guidelines, and rigorous quality control protocols to prevent potentially adverse clinical outcomes.

Study design, size, duration
MEAs were conducted over 5 years on 6759 batches encompassing 16 categories of IVF products from various manufacturers. Results were retrospectively analysed based on MEA test outcomes for each category. A total of 217 dishes, 610 catheters, 1182 culture media, 135 steripettes, 1907 mineral oils, 167 glass-pasteur pipettes, 66 protein supplements, 207 flexipet-pipettes, 191 pipette tips, 96 PVPs, 68 syringes, 126 tubes, 1294 vitrification kits, 182 micropipettes, 98 disinfectants, and 213 needles lots were analysed.

Participants/materials, setting, methods
All procedures adhered to protocols approved by an Ethical Committee. Samples underwent classification as toxic or non-toxic based on MEAs results, and the proportion of samples that tested positive for embryotoxicity was determined for each category. Statistical comparisons were made among categories to identify those most prone to be identified as toxic. Additionally, in failed assays, mean EBFRs were categorized into 0-30%, 30%-70%, and 70%-80% ranges to assess extreme, mild and low sample-toxicity levels, respectively.

Main results and the role of chance
Out of 16 studied categories, only 5 of them exceeded a 5% of toxic lots.
Flexipet-pipette types were reported as the highest toxic-samples rate category, with 72 out of the 207 tested batches (34.8%) failing the MEA. Protein supplements were found to be the second highest toxicity-ranked category, with 14/66 noxious lot samples (21.2%). They were followed by needles and catheters with 36/213 (16.9%) and 68/610 toxic lot samples (11.2%), respectively. Finally, a considerably lower toxicity rate was obtained with steripettes, with 10/135 samples reported as toxic (7.4%).
Among these five top toxic-samples rate categories, protein supplements were found to possess a mild lethal effect on embryos, with a 43.6% mean EBFR in failed assays. However, extreme embryotoxic effects were reported for the remaining highest toxic-samples rate categories, based on their mean EBFR in failed assays: 20.8% for flexipet-pipette types, 16.2% for needles, 10.8% for steripettes, and 10.3% for catheters.
Interestingly, although culture media and mineral oils were not among the top MEA-failure frequencies, as only 48/1182 (4.1%) and 23/1907 (1.2%) toxic lot samples were registered for each category, respectively, both categories showed a nearly-extreme lethality caused by their toxic-assessed samples, reflected in 31.7 and 35.1% mean EBFRs.

Limitations, reasons for caution
Increasing the number of sample-providing manufacturers per category might strengthen the wider market representativeness of the results. Moreover, it should be noted that the identification of specific sources of toxicity results highly difficult, hindering the implantation of corrector modifications within the manufacturing process.

Wider implications of the findings
These findings indicate that protein supplements, flexipet-pipette types, steripettes, catheters and needles exhibit a heightened toxicity tendency. Additionally, toxic mineral oils and culture media-linked high-embryotoxicity levels were observed. Therefore, special attention should be given to the production of these demonstrated potentially embryotoxic products to identify and mitigate clinical toxicity risks.

Trial registration number
Not applicable