Safety of cryopreservation straws for human gametes or embryos: a study with human immunodeficiency virus-1 under cryopreservation conditions

Background The possibility of assisted reproductive technology (ART) for couples carrying viruses, especially HIV-1, necessitates consideration of the safety of cryopreserving human gametes or embryos in liquid nitrogen tanks. Following our evaluation of the safety of three kinds of straws containing HIV-1 at 37 degrees C, we have now examined the HIV-1 imperviousness of the same straws under cryopreservation conditions. Methods Polyvinyl chloride (PVC), polyethylene terephthalate glycol (PETG) and high-security ionomeric resin (IR) straws (24 each) were tested. Each straw was filled with 100 microl of HIV-1-containing supernatant [reverse transcriptase (RT) activity: 15 000 c.p.m./50 microl]. Then PVC and PETG straws were sealed ultrasonically only at their free-end, and IR straws were thermosoldered at both ends. Each straw was put in a 15 ml Falcon tube which was capped and submerged in a liquid-nitrogen tank for 7 days. After bleach decontamination or not, the outside of each end of the straw was rinsed with RPMI medium (1 ml) before cryopreservation and after thawing. Viral RNA was extracted from the medium and then amplified by RT-polymerase chain reaction (PCR) followed by nested-PCR using HIV-1 protease-specific primers. Results HIV-1 RNA was detected in some PVC and PETG rinse media, probably resulting from splashing during ultrasonic sealing, but not in the rinse media of thermosoldered IR straws. Conclusion Under cryopreservation conditions, IR straws would appear to be safe for HIV-1 storage in ART. For PVC and PETG straws, as highlighted in this study, the ultrasonic sealing could be the weak safety link.