Blastocyst formation--good indicator of clinical results after ICSI with testicular spermatozoa

Molecular Drivers of Developmental Arrest in the Human Preimplantation Embryo: A Systematic Review and Critical Analysis Leading to Mapping Future Research

Developmental arrest of the preimplantation embryo is a multifactorial condition, characterized by lack of cellular division for at least 24 hours, hindering the in vitro fertilization cycle outcome. This systematic review aims to present the molecular drivers of developmental arrest, focusing on embryonic and parental factors. A systematic search in PubMed/Medline, Embase and Cochrane-Central-Database was performed in January 2021. A total of 76 studies were included. The identified embryonic factors associated with arrest included gene variations, mitochondrial DNA copy number, methylation patterns, chromosomal abnormalities, metabolic profile and morphological features. Parental factors included, gene variation, protein expression levels and infertility etiology. A valuable conclusion emerging through critical analysis indicated that genetic origins of developmental arrest analyzed from the perspective of parental infertility etiology and the embryo itself, share common ground. This is a unique and long-overdue contribution to literature that for the first time presents an all-inclusive methodological report on the molecular drivers leading to preimplantation embryos’ arrested development. The variety and heterogeneity of developmental arrest drivers, along with their inevitable intertwining relationships does not allow for prioritization on the factors playing a more definitive role in arrested development. This systematic review provides the basis for further research in the field.

Potential of testicular sperm to support embryonic development to the blastocyst stage is comparable to that of ejaculated sperm

PURPOSE

Recent studies have shown that improved clinical outcomes can be achieved by transferring blastocysts rather than cleavage-stage embryos. However, blastocyst transfer is not performed in all patients. The aim of this study was to compare clinical outcomes of intracytoplasmic sperm injection (ICSI) cycles using testicular sperm (TE) with those of ICSI cycles using ejaculated sperm (EJ).

METHODS

ICSI was performed using EJ in 141 cycles and TE in 37 cycles. Embryos were cultured for 5 days. The quality of embryos was assessed on days 3 and 5 before embryo transfer.

RESULTS

Fertilization rate was 77.3% in the EJ group and 69.6% in the TE group (p < 0.05). The good-quality embryos on day 3 and 5 were not different between the EJ and TE groups. Embryos did not develop to blastocyst stage in 7 cycles of the EJ group (5.0%) and 2 cycles of the TE group (5.4%). There were no significant differences in blastocyst formation and blastocyst quality (46.1% vs. 47.5% and 5.7% vs 5.8%, respectively) on day 5 between both groups. Embryos were transferred in all cycles. Implantation (22.8 vs. 24.7%), clinical pregnancy (44.7 vs. 43.2%), miscarriage (21.7 vs. 33.3%), and delivery (76.5 vs. 66.7%) did not differ between EJ group and TE group. Clinical outcomes of ICSI were not different between the EJ and TE groups.

CONCLUSIONS

In conclusion, the potential of testicular sperm supporting embryonic development to blastocysts is comparable to that of ejaculated sperm. Therefore, this study suggests that blastocyst transfer can be a very useful assisted reproductive technique in the ICSI cycles that require the use of testicular sperm, and the clinical outcomes of the cycles are comparable to those of ICSI cycles using ejaculated sperm.

The male factor of infertility should not be an issue for the selection of patients for extended embryo culture programmes

This study evaluated the influence of sperm origin and basic sperm parameters on blastocyst implantation competence. The study included 2912 embryos obtained from 370 patients undergoing intracytoplasmic sperm injection cycles, with embryo transfer on day 5 of development. The embryos were divided into experimental groups according to their origin: (i) embryos originated from ejaculated-derived spermatozoa (Ejaculated group, n = 2093), from epididymal-derived spermatozoa (Epididymal group, n = 463) and from testicular-derived spermatozoa (Testicular group, n = 356). The groups were compared in relation to their blastocyst implantation competence. In addition, the influence of sperm parameters on blastocyst implantation was investigated. The sperm origin was determinant to the success of implantation. When blastocysts originating from testicle-derived spermatozoa were transferred, 66.4% implanted, while only 35.8 and 48.6% of blastocysts originated from epididymis- and ejaculate-derived spermatozoa implanted respectively (p = 0.001). The sperm volume and concentration were increased in cycles in which the implantation rate was 100 compared to the 0% implantation rate cases; however, the sperm motility and morphology did not differ among the groups. These results suggest that, with the exception of sperm volume and concentration, the male factor of infertility should not be an issue for the selection of patients for extended embryo culture programmes, even when azoospermic patients are considered.

Single blastocyst transfer after ICSI from ejaculate spermatozoa, percutaneous epididymal sperm aspiration (PESA) or testicular sperm extraction (TESE)

PURPOSE

To investigate the outcome of IVF following intracytoplasmic sperm injection (ICSI) from ejaculate, percutaneous epididymal sperm aspiration (PESA) and testicular sperm extraction (TESE), with subsequent blastocyst culture and single blastocyst transfer.

METHODS

Single blastocyst transfer was performed after ejaculate ICSI (oligozoospermia) in 587 patients, TESE/PESA (azoospermia) in 31 patients, and standard IVF in 680 women.

RESULTS

There were only minor differences in IVF characteristics between the standard IVF and the PESA-TESE couples. Couples where ejaculate ICSI were performed seemed to represent a slightly poorer prognostic group. A viable fetus after the 12th gestational week, i.e. ongoing pregnancy, was present in 41.4% after ICSI/ET, 51.6% after PESA-TESE/ET and in 40.4% after standard IVF/ET (no significant differences).

CONCLUSION

Single blastocyst transfer after ejaculate ICSI or after PESA/TESE appears to give similar results as conventional IVF blastocyst culture.

Single or multiple embryo transfer following in vitro fertilisation for improved neonatal outcome: A systematic review of the literature

BACKGROUND

The aim of the current review was to determine if single versus two or more embryos, or double versus three or more embryos, transferred to the woman of a subfertile couple at in vitro fertilisation (IVF) maximises the likelihood of pregnancy, while minimising the likelihood of multiple pregnancy and adverse sequelae.

METHODS

Studies were identified that reported maternal, infant and cost outcomes following embryo transfer at IVF.

RESULTS

Three randomised trials and 17 cohort studies were included. From two randomised trials, single embryo transfer was found to result in decreased incidence of clinical pregnancy, multiple pregnancy and low birthweight. In the cohort studies for single embryo transfer compared with transfer of two or more embryos the incidence of live birth and singleton pregnancies was unchanged, and the incidence of multiple pregnancies and low birthweight was reduced. For double embryo transfer compared with the transfer of three or more embryos, the incidence of clinical pregnancy, live birth, preterm birth and low birthweight babies was reduced.

CONCLUSIONS

Information on neonatal and maternal outcomes following transfer of different numbers of embryos is limited. Transfer of one embryo does not alter the likelihood of a singleton pregnancy or birth when compared to transfer of two or more embryos. Transfer of one or two embryos decreases the risk of a multiple pregnancy, preterm birth and low birthweight. Further large, well-designed randomised trials are required to provide maternal and neonatal outcomes of relevance to a couple undergoing IVF.