Zhimin Xin

Clinical outcome of emergency egg vitrification for women when sperm extraction from the testicular tissues of the male partner is not successful

The development of an effective oocyte cryopreservation system will have a significant impact on the clinical practice of reproductive medicine. However, the important option of emergency oocyte cryopreservation has yet to be well documented. In this report, we review the cases of 15 women with male partners who were diagnosed with nonobstructive azoospermia and for whom testicular sperm extraction on the day of oocyte retrieval failed. Emergency oocyte vitrification was performed and after two months, the vitrified oocytes were warmed and the surviving oocytes inseminated with frozen-thawed donor sperm by intracytoplasmic sperm injection (ICSI). A total of 117 mature oocytes from the 15 women were vitrified and warmed. The post-warming survival rate was 84.6% (99/117), and the fertilization rate following ICSI was 83.8% (83/99). We selected 30 embryos for transfer to 15 patients, 8 of whom became pregnant. The clinical pregnancy rate was 53.3% (8/15) and the implantation rate was 30.0% (9/30). Nine healthy live births resulted from 8 pregnancies. These results indicate that emergency oocyte vitrification is an effective rescue technique that can be applied clinically with acceptable pregnancy and live birth rates when testicular sperm extraction from the male partner failed on the day of oocyte retrieval. These results also highlight another important option for oocyte cryopreservation through the use of vitrification technology.

Increased IVF pregnancy rates after microarray preimplantation genetic diagnosis due to parental translocations

Abstract We successfully performed preimplantation genetic diagnosis (PGD) and simultaneous preimplantation genetic screening (PGS) using single nucleotide polymorphism (SNP) microarrays for couples with balanced chromosome rearrangements in China. A total of 428 molecular karyotypes were diagnosed from 62 couples undergoing 68 in vitro fertilization (IVF) cycles. Of these, 48.1% of the embryos were chromosomally normal without translocation errors or aneuploidy. Of the 428 total embryos, 18.0% embryos were euploid, but were imbalanced due to the transmission of single translocation chromosome derivatives. A total of 6.5% of the embryos had chromosome abnormalities involving the parental chromosome aberration and other chromosomes aneuploidies. Significantly, 27.4% of the embryos were normal/balanced for the rearranged chromosomes, but were abnormal due to aneuploidy affecting other chromosomes. When evaluated on a per IVF cycle basis, 84% of the cycles had at least one chromosomally normal embryo available for uterine transfer. The clinical pregnancy rate per IVF cycle was 54%. Diagnosing genomically balanced embryos through 24 chromosome SNP microarray PGD/PGS, rather than minimally targeted fluorescence in situ hybridization (FISH), is a promising strategy to maximize the pregnancy potential of patients with known parental chromosomal translocations. Moreover, this is the first study to report the clinical application of SNP arrays to screen all 24 chromosome pairs of blastomeres and trophectoderm cells from patients carrying reciprocal translocations in China.

Effect of coincubation time of sperm-oocytes on fertilization, embryonic development, and subsequent pregnancy outcome

Several studies have reported improved IVF by shortening the time of sperm-oocyte coincubation from 16–18 hours to 1–4 hours. The objective of this study was to examine the advantages and disadvantages of a shortened sperm-oocyte coincubation time in order to assess the effects of this insemination method for clinical IVF practice. Two insemination methods, the shortened method (4 hours) and the standard method (16–18 hours) of coincubation of sperm-oocytes for two groups of patients based on the quality of sperm were compared. Group I, was composed of couples without male factor; Group II, involved couples with mild male factor. Fertilization, good quality embryos, clinical pregnancy, and implantation rates were compared by two different insemination methods. In Group I, fertilization, clinical pregnancy, and implantation rates were not different between the two insemination methods. However, the polyspermy rate was significantly higher (P < 0.05) in the shortened (7.3%) than in the standard (4.1%) insemination method. In Group II, the fertilization rate was significantly lower (P < 0.05) using the shortened insemination method (62.6%) compared to the standard insemination method (68.7%). When fertilization failed with the shortened insemination method, the clinical pregnancy and implantation rates were 34.7% and 24.1%, respectively, from the rescue intracytoplasmic sperm injection (ICSI). The live birth rate from the rescue ICSI was 32.0% with normal infants. The duration of sperm-oocyte coincubation does not affect fertilization, embryo quality, clinical pregnancy, and implantation rates. However, fertilization rates will decrease with the shortened insemination method when the sperm parameters are poor. From the results of the present study we suggest that the combination of the shortened sperm-oocyte coincubation and rescue ICSI method may be an efficient method for IVF treatment in order to prevent fertilization failure when sperm parameters were poor as mild male factor.

Developmental potential of clinically discarded human embryos and associated chromosomal analysis.

Clinically discarded human embryos, which are generated from both normal and abnormal fertilizations, have the potential of developing into blastocysts. A total of 1,649 discarded human embryos, including zygotes containing normal (2PN) and abnormal (0PN, 1PN, 3PN and ≥4PN) pronuclei and prematurely cleaved embryos (2Cell), were collected for in vitro culture to investigate their developmental potential and chromosomal constitution using an SNP array-based chromosomal analysis. We found that blastocyst formation rates were 63.8% (for 2Cell embryos), 22.6% (2PN), 16.7% (0PN), 11.2% (3PN) and 3.6% (1PN). SNP array-based chromosomal analysis of the resultant blastocysts revealed that the percentages of normal chromosomes were 55.2% (2Cell), 60.7% (2PN), 44.4% (0PN) and 47.4% (0PN). Compared with clinical preimplantation genetic diagnosis (PGD) data generated with clinically acceptable embryos, results of the SNP array-based chromosome analysis on blastocysts from clinically discarded embryos showed similar values for the frequency of abnormal chromosome occurrence, aberrant signal classification and chromosomal distribution. The present study is perhaps the first systematic analysis of the developmental potential of clinically discarded embryos and provides a basis for future studies.

Effects of frozen timing on the spindle density, the angle between the polar body and spindle, and embryo development of intracytoplasmic sperm injection in mouse mature oocytes

Better pregnancy outcomes can be obtained by human mature oocyte vitrification, but many problems remain to be resolved in human mature oocyte vitrification. Since mature oocyte development possesses its own maturity cycle, there should be the optimal timing for mature oocyte vitrification. The purpose of this study was to observe the effects of frozen timing on the spindle density, the angle between the polar body and spindle, and embryo development of intracytoplasmic sperm injection (ICSI) in vitrified mouse mature oocytes and explore its possible mechanism. Mouse oocytes were randomly divided into three groups according to different frozen timing including Groups A, B, and C in which oocytes were vitrified within 2 h after ovum pick‐up, and 3–4 and 5–6 h after ovum pick‐up, respectively. Spindle‐related parameters were measured, ICSI was performed. The spindle occurrence rate of vitrified‐thawed oocytes was 98.4% in Group A, 82.3% in Group B, and 75.8% in Group C, without statistical differences between pre‐vitrification and post‐thawing and among the three groups (P > 0.05). The angles between the polar body and spindle were larger after thawing than before vitrification (P < 0.01). The spindle retardance values were lower after thawing than before vitrification in Groups B and C (P < 0.05), but higher in Group A (P < 0.05). The spindle retardance values before vitrification were higher in Group B than in Groups A and C (P < 0.05), but the spindle retardance value, oocyte survival and two‐cell rate after thawing were higher in Group A than in Groups B and C (P < 0.05). There were no statistical differences in ICSI fertility rate between the three groups (P > 0.05). The damage on the spindle is the slightest and embryo quality is the highest in the mouse oocytes vitrified within 2 h after ovum pick‐up. The spindle retardance value is more valuable than the spindle occurrence rate in the evaluation of vitrified‐thawed oocyte quality, and is positively correlated with embryo quality.

Effects of cumulus cells on vitreous cryopreservation of human mature oocytes and clinical pregnancy outcomes.

The purpose of this study was to explore the effects of cumulus cells on vitreous cryopreservation of human mature oocytes and clinical pregnancy outcomes. The study was divided into group A (cumulus cells were removed from the oocytes before freezing) containing 24 participants and 193 oocytes and group B (cumulus cells were retained with the oocytes before freezing) containing 26 participants and 240 oocytes. Based on no significant differences in age, duration of infertility, infertile causes, and number of retrieved oocytes between both groups when oocytes were retrieved from infertile women, we found that the survival rate of post thaw oocytes (88% vs 58%), cleavage rate (80% vs 56%), and high-quality embryo rate (75% vs 59%) were significantly higher in group B than in group A. Under the conditions that there were no significant differences between the 2 groups in the general status of the participants undergoing embryo transfer, the embryo implantation rate (37% vs 15%) and the clinical pregnancy rate (50% vs 17%) were significantly higher in group B than in group A, all with Ps < .05. We conclude that the retention of cumulus cells can improve the developmental competence of vitrified–thawed human mature oocytes and clinical pregnancy outcomes.

Pregnancy outcomes of day 5 embryo transfer in patients at high risk of developing ovarian hyperstimulation syndrome and analysis of factors affecting blastocyst formation

Objectives To investigate the effects of day 5 embryo transfer (D5ET) compared with day 3 embryo transfer (D3ET) in patients at high risk of developing ovarian hyperstimulation syndrome (OHSS); to analyse factors affecting blastocyst formation. Methods Patients at high risk of developing OHSS underwent either D3ET or D5ET. Results A total of 253 patients received D3ET; 263 received D5ET. The number of embryos transferred was lower in the D5ET group than in the D3ET group. There were no between-group differences in pregnancy or live birth rates. Implantation rate was higher, and multifetation rate lower, in the D5ET group compared with the D3ET group. In addition, the incidence of moderate or severe OHSS was lower in the D5ET group than in the D3ET group. The woman’s age, gonadotrophin dosage and insemination method were associated with the quality of blastocyst formation. Conclusions In patients with a high risk of developing OHSS, compared with D3ET, D5ET decreased the multifetation rate and the incidence of moderate or severe OHSS, but did not affect the pregnancy or live birth rate. Women of a younger age, who have had an appropriate gonadotrophin dose and insemination by in vitro fertilization, are suitable candidates for blastocyst transfer.