A modified embryo cryopreservation method increases post-thaw survival with a concomitant increase in implantation

A pragmatic RCT of conventional versus increased concentration sucrose in freezing and thawing solutions for human embryos

BACKGROUND

Intact frozen-thawed embryos have a greater potential than damaged embryos to establish successful pregnancies. This study aimed to determine whether elevated concentrations of sucrose during freezing would increase the proportion of patients with ≥ 50% of embryos intact after thawing (primary outcome), and improve clinical outcome.

METHODS

In a two arm, parallel group, pragmatic trial, IVF/ICSI couples were randomized prospectively to have their supernumerary embryos frozen in a medium containing 0.1 M sucrose (control; n = 99) or 0.3 M sucrose (intervention; n = 102).

RESULTS

More control (74/99) than intervention (63/102) couples had at least one embryo thawed (P = 0.07). Significantly more (P = 0.005) intervention (53/63) than control (45/74) couples had ≥ 50% of embryos intact. Freezing in a medium containing 0.3 M sucrose increased by 3.4-fold [95% confidence interval (CI) (1.45, 7.82)] the likelihood of a couple having ≥ 50% of their embryos intact. In the fresh cycle, live birth rate per transfer was similar in the control (35/95) and intervention (36/93) groups (P = 0.91). More control (19/63) than intervention (9/59) couples had a live birth after frozen embryo transfer (P = 0.08). When fresh and frozen cycles were combined, fewer intervention (n = 102) than control (n = 99) couples had at least one live birth (42 versus 53%). The difference in cumulative live birth rate was not significant [hazard ratio = 0.75, 95% CI (0.49, 1.13); P = 0.17].

CONCLUSIONS

Increasing the concentration of sucrose in the freezing medium improves embryo survival, but this is not reflected by increased cumulative birth rates.

CLINICAL TRIALS REGISTRATION NUMBER

ISRCTN93314892.

Rhesus monkey sperm cryopreservation with TEST-yolk extender in the absence of permeable cryoprotectant

Recently, there has been increased interest in ultra-rapid freezing with mammalian spermatozoa, especially for vitrification in the absence of cryoprotectants. Sperm cryopreservation in non-human primates has been successful, but the use of frozen-thawed sperm in standard artificial insemination (AI) remains difficult, and removal of permeable cryoprotectant may offer opportunities for increased AI success. The present study intended to explore the possibility of freezing rhesus monkey sperm in the absence of permeable cryoprotectants. Specifically, we evaluated various factors such as presence or absence of egg yolk, the percentage of egg yolk in the extenders, and the effect of cooling and thawing rate on the success of freezing without permeable cryoprotectants. Findings revealed that freezing with TEST in the absence of egg yolk offers little protection (<15% post-thaw motility). Egg yolk of 40% or more in TEST resulted in decreased motility, while egg yolk in the range of 20-30% yielded the most motile sperm. Cooling at a slow rate (29 degrees C/min) reduced post-thaw motility significantly for samples frozen with TEST-yolk alone, but had no effect for controls in the presence of glycerol. Similarly, slow thawing in room temperature air is detrimental for freezing without permeable cryoprotectant (<2% motility). In addition to motility, the ability of sperm to capacitate based on an increase in intracellular calcium levels upon activation with cAMP and caffeine suggested no difference between fresh and frozen-thawed motile sperm, regardless of treatment. In summary, the present study demonstrates that ejaculated and epididymal sperm from rhesus monkeys can be cryopreserved with TEST-yolk (20%) in the absence of permeable cryoprotectant when samples were loaded in a standard 0.25-mL straw, cooled rapidly in liquid nitrogen vapor at 220 degrees C/min, and thawed rapidly in a 37 degrees C water bath. This study also represents the first success of freezing without permeable cryoprotectant in non-human primates.

Sole use of sucrose in human sperm cryopreservation

Glycerol alone or in combination with other additives is one of the most widely used and successful cryoprotectants for human sperm. The glycerol method requires rigorous post thaw sample washing for use in ART and this may lead to low sperm yield from oligospermic samples. In this study the feasibility of the use of sucrose in sperm cryopreservation was explored. Sucrose as cryoprotectant was combined with direct plunging of sample into liquid nitrogen (vitrification) as a freezing method. Sucrose treated sperm from normozoospermic and severly oligozoospermic samples underwent rapid freeze and thaw. Motility and viability were evaluated before freezing (after sucrose equilibration) as well as post freezing (after thaw). The 100 mM concentration of sucrose showed better cryoprotectant features compared to that of higher concentrations (200-1000 mM). Sucrose (100 mM)treated sperm maintained low but acceptable motility (30%) and satisfactory viability (60%) after freezing and thawing. The cryoprotectant capacity of sucrose for normozoospermic and oligozoospermic samples were identical. The sucrose method utilizes rapid freezing of a micro volume of sample and thus quickly freezes, thaws, and maximizes recovery of the sperm from the sample.

Ovarian cryopreservation with transposition of a contralateral ovary: a combined approach for fertility preservation in women receiving pelvic radiation

OBJECTIVE

To describe a technique of fertility preservation by ovarian transposition combined with ovarian cryopreservation in the setting of oncologic pelvic radiation for a reproductive age woman.

DESIGN

Case report.

SETTING

IVF center at a tertiary care hospital.

PATIENT(S)

Thirty-year-old nulligravid women who previously underwent lumbar spinal cord tumor debulking requested fertility preservation before pelvic radiation.

INTERVENTION(S)

Laparoscopic ovarian transposition with cryopreservation of the contralateral ovary.

MAIN OUTCOME MEASURE(S)

New technique in fertility preservation.

RESULT(S)

Laparoscopic surgery was used to evaluate, select, and remove a single ovary that then underwent cryopreservation. Transposition of the remaining ovary was subsequently successfully performed, placing it of out of the pelvis.

CONCLUSION(S)

The combination of ovarian cryopreservation and ovarian transposition may maximize future fertility options for women facing pelvic irradiation. This combined approach should be included among the options offered to reproductive age women before pelvic radiation.

The CryoLoop facilitates re-vitrification of embryos at four successive stages of development without impairing embryo growth

BACKGROUND

Vitrification has been shown to be an effective method of cryopreservation, but little is known about re-vitrification of embryos. This study investigated the effect of re-vitrification on mouse embryo preimplantation development and viability post-transfer.

METHODS

Mouse embryos at the 1-cell stage were vitrified using the CryoLoop technique. Embryos were warmed and then re-vitrified successively at the 2-, 8-cell and blastocyst stages. The effects of multiple rounds of vitrification on development, differentiation and viability were assessed and compared with non-vitrified embryos.

RESULTS

Development to the 8-cell stage on day 3 and blastocyst on day 5 were not affected by re-vitrification. However, better hatching rates were observed in the non-vitrified control group. Total cell number and the number of cells allocated to the inner cell mass (ICM) were not different between treatments. The percentage of ICM development was also not different between treatments. Implantation rate and fetal weights were the same between treatments. However, overall there were fewer fetuses per embryo transferred in the re-vitrified group.

CONCLUSION

Re-vitrification of mouse embryos has minimal effect on preimplantation embryo development or implantation potential.