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

Large-volume vitrification of human biopsied and non-biopsied blastocysts: a simple, robust technique for cryopreservation

PURPOSE

To evaluate the transition from a proven slow-cooling cryopreservation method to a commercial large-volume vitrification system for human blastocysts.

METHODS

Retrospective analysis of de-identified laboratory and clinical data from January 2012 to present date for all frozen embryo replacement (FET) cycles was undertaken. Cryopreservation of trophectoderm-biopsied or non-biopsied blastocysts utilized during this time period was logged as either slow-cooling, small-volume vitrification, or large-volume vitrification. Blastocyst survival post-warm or post-thaw, clinical pregnancy following FET, and implantation rates were identified for each respective cryopreservation method.

RESULTS

Embryo survival was highest for large-volume vitrification compared to micro-volume vitrification and slow-cooling; 187/193 (96.9 %), 27/32 (84.4 %), and 244/272 (89.7 %), respectively. Survival of biopsied and non-biopsied blastocysts vitrified using the large-volume system was 105/109 (96.3 %) and 82/84 (97.6 %), respectively. Survival for micro-volume biopsied and non-biopsied blastocysts was 16/30 (83.3 %) and 2/2 (100.0 %) respectively. Slow-cooling post-thaw embryo survival was 272/244 (89.7 %). Clinical pregnancy and implantation rates outcomes for non-biopsied embryos were similar between large-volume and slow-cooling cryopreservation methods, 18/39 (46.2 %) clinical pregnancy and 24/82 (29.3 %) implantation/embryo, and 52/116 (44.8 %) clinical pregnancy and 67/244 (27.5 %) implantation/embryo, respectively. Comparing outcomes for biopsied embryos, clinical pregnancy and implantation rates were 39/67 (58.2 %) clinical pregnancy and 50/105 (47.6 %) implantation/embryo and 4/16 (25 %) clinical pregnancy and 6/25 (24.0 %) implantation/embryo, respectively.

CONCLUSIONS

The LifeGlobal large-volume vitrification system proved to be very reliable, simple to learn and implement in the laboratory. Clinically large-volume vitrification was as, or more effective compared to slow-cooling cryopreservation in terms of recovery of viable embryos in this laboratory.

Risk of contamination of germplasm during cryopreservation and cryobanking in IVF units

Cryopreservation of sperm, embryos and, more recently, oocytes plays an important and increasing role in assisted reproduction, due to improvements of old, and introduction of new technologies. In parallel, concerns are increasing about the technical and biological safety of these procedures. However, published data regarding the confirmed or theoretical hazards of these procedures are sparse and sometimes contradictory. The purpose of this review will summarize data and opinions about one of the most disputed risks, the potential hazard of contamination and disease transmission through cryopreservation. Special attention is concentrated on the weak points of the technology including open vitrification systems, sterilization of liquid nitrogen and safety of commonly used storage tanks including straws and cryovials. Suggestions are also made for practical measures to avoid these dangers while preserving the benefits and perspectives of new cryopreservation technologies.

Blastocyst rate and live births from vitrification and slow-cooled two-cell mouse embryos

OBJECTIVE

The purpose of this study was to develop a closed vitrification system, compare vitrification to a slow-cooled cryopreservation method, and compare the pup rate between both methods using two-cell mouse embryos.

DESIGN

Randomized, prospective animal study.

SETTING

Hospital-based IVF practice.

ANIMAL(S)

B6C3F1 mouse embryos.

INTERVENTION(S)

Two-cell mouse embryos were cryopreserved using a slow-cooled or vitrification method and then thawed at a later date. The embryos were cultured and transferred to recipient females.

MAIN OUTCOME MEASURE(S)

Embryos were observed for blastocyst rate and pups were observed for phenotypic anomalies and weighed at 30, 60, and 90 days after birth.

RESULT(S)

Neither the blastocyst rate, pup rate, nor pup weights were significantly different when the two cryopreservation methods were compared.

CONCLUSION(S)

Because there were no differences in blastocyst rates, pup rates, or pup weights, we plan to further investigate the potential effects of vitrification on genotypic damage via the Comet Assay.

Utilization of high-security straws for embryo freezing in an in vitro fertilization program: a prospective, randomized study

OBJECTIVE

To compare the outcome of frozen-thawed ET cycles where embryos had been stored in conventional versus ionomeric resin-based, high-security straws (HSSs).

DESIGN

Prospective, randomized study.

SETTING

Private assisted-reproduction unit.

PATIENT(S)

Three hundred and six freeze cycles, and 197 thaw cycles.

INTERVENTION(S)

Day 3 embryos (n = 1,268) were frozen, and 517 were thawed using HSSs. Alternately, day 3 embryos (n = 1,228) were frozen, and 505 were thawed using conventional straws.

MAIN OUTCOME MEASURE(S)

Cryosurvival, cleavage and morulae formation rates, and clinical pregnancy, implantation, and multiple pregnancy rates.

RESULT(S)

Although cycle characteristics did not show any differences, the cryosurvival rate was higher in the HSS group (94.7%) than in the conventional straw group (86%), as was the morulae formation rate (58.7% versus 42.7%). Despite a similar number of embryos being transferred, the clinical pregnancy rate (PR) was higher in the HSS group, but the difference lacked statistical significance (42.5% versus 31.2). Implantation rates (19.4% versus 11.4%) and multiple PRs (41.8% versus 16.6%) were significantly higher in the HSS group than in the conventional straw group.

CONCLUSION(S)

High-security straws are high effective in human embryo cryopreservation, because they provide higher cryosurvival and implantation rates, as well as a lower risk of cross-contamination compared to conventional straws.

Laboratory safety during assisted reproduction in patients with blood-borne viruses

For couples where one or both partners are infected with human immunodeficiency virus or hepatitis C, the doors to receiving fertility care are opening as a result of better antiviral medication, better long-term prognosis and consequent changes in attitude. In line with this, fertility centres electing to treat couples with blood-borne viral (BBV) infection need to re-examine their policies and procedures to ensure the safety of their staff and both non-infected and infected patients during assisted reproduction treatments. At a time when the European Tissue Directive aims to introduce quality standards for assisted reproduction throughout Europe, we highlight the risks involved when treating patients with known BBV infections and argue that safety cannot be met with any certainty unless samples from such patients are handled within a separate high security laboratory or laboratory area, technically adapted to ensure minimal cross-contamination risk to uninfected gametes and embryos.

Conservation en paillettes des gamètes et embryons humains : sécurité vis-à-vis du virus de type 1 de l'immunodéficience humaine

OBJECTIVE

The possibility of offering assisted reproductive technologies (ART) to HIV-positive couples has revived questions concerning the safety of the gametes and embryos cryopreservation in liquid nitrogen tanks.

PATIENTS AND METHODS

We evaluated the safety of three types of straws - polyvinyl chloride (PVC), polyethylene terephthalate glycol (PETG) and so-called 'high-security' ionomeric resin (IR) - containing HIV-1 under standard conditions of cryopreservation. Potential HIV contamination was assessed by RT-PCR and then nested PCR.

RESULTS

Under cryopreservation conditions, the sealed open ends of PVC and PETG straws were not safe. The ultrasound sealing system seems to be the weak link in obtaining total imperviousness of the straws. In contrast, both ends of the IR straws were safe for HIV in the framework of their use for ART.

CONCLUSION

Sealing cryopreservation straws ultrasonically could incur the risk of not assuring their impermeability. Under standard cryopreservation conditions thermosealing of IR straws appears to be safe for HIV.

Current and future concepts and practices in human sperm cryobanking

This article focuses on a range of issues that are of current concern to those working in human sperm cryobanking and considers them within a general framework of risk analysis and management, taking into account the available evidence and perceptions of 'best practice' from both the medical and legal perspectives. In particular, issues arising from concerns over the risk of cross-contamination between samples during storage immersed in liquid nitrogen have been analysed in detail. Even though such an occurrence has never been reported for spermatozoa or embryos, and the risk is generally accepted to be vanishingly small, it does represent a finite risk and all reasonable measures should be taken to reduce the chance of its occurring. It is concluded that all methods used to collect, cryopreserve, store, thaw and use cryobanked human spermatozoa must address the risk of contamination from any source throughout the entire process. To assist workers in this area, a series of recommendations as to current best practice are made, based upon conclusions from risk analyses using currently available information.

Practical aspects of sperm banking for cancer patients

Semen storage is now routinely offered to men of reproductive age who are diagnosed with malignant disease and who require surgical or chemotherapeutic treatments that have a significant risk of leaving them sterile or subfertile. There is a perception by the public at large and professionals in the field that this is a routine and simple process. Yet, semen storage for such men requires a number of unique skills from a multidisciplinary team of oncologists, nurses, counsellors and scientists (andrologists or embryologists) in order to provide a quality service to the patient. All too often it is seen as 'just another branch' of assisted conception treatment but there are sufficient unique issues for it to be considered a specialty in its own right. In the absence of professional guidelines to outline 'best practice', the British Andrology Society invited interested parties to attend a one-day workshop. This was designed as an interactive workshop for all those involved in the process of semen storage, be they clinicians, nurses, counsellors and scientific staff from either the disciplines of reproductive medicine or oncology. It was intended to examine the process of semen storage for such patients from the point of initial diagnosis, through the process of banking semen samples, to the point at which they are either used in treatment or are discarded. The programme was designed to promote maximum interaction between the speakers and the audience and between those from different specialties and disciplines so that they may learn from each other, developing and improving the service that is provided to these men.

[Evaluation of the interest of semen culture before cryoconservation]

OBJECTIVES

French guidelines recommend screening all patients for virus infection prior to cryopreservation of their semen. In case of viral risk, the use of specific high secure CBS straws is recommended. The objective of this work was to evaluate the microbiological risk by testing all semen samples before cryopreservation.

PATIENTS AND METHODS

Fifty one patients underwent a semen culture before cryopreservation.

RESULTS

The fifty one patients were classed into 3 groups following semen culture results: group I: negative culture (39/51, 76.47%), group II: positive culture with microbiological contamination (7/51, 13.73%) and group III: positive culture with pathogen (5/51, 9.8%). For 3 patients of the latter group, we tested a three-layer density gradient to eliminate bacteria before Assisted Reproductive Techniques.

DISCUSSION AND CONCLUSIONS

This paper discusses the risks related to microbiological contamination and the options available in this case.

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.

Cryopreservation of human sperm

Freezing of human sperm is considered a routine procedure in assisted reproductive technology (ART) laboratories. This article considers various aspects of cryopreservation of human sperm. Human sperm show a specific cryophysical behaviour and different sperm freezing protocols have been developed to avoid damage to the sperm cells. The damage can range from impaired motility and reduced viability to damage to the cellular organelles and effects at the molecular level, resulting in an impaired fertilizing potential. As testicular sperm are immature and only a small number can be retrieved, special techniques are required for successful freezing and thawing of these samples. Banking of human sperm has to be performed in a safe and controlled way and different guidelines are necessary to ensure that this is achieved.