Coculture of human embryos with autologous human endometrial epithelial cells in patients with implantation failure

Organoids to model the endometrium: implantation and beyond

Despite advances in assisted reproductive techniques in the 4 decades since the first human birth after in vitro fertilisation, 1–2% of couples experience recurrent implantation failure, and some will never achieve a successful pregnancy even in the absence of a confirmed dysfunction. Furthermore, 1–2% of couples who do conceive, either naturally or with assistance, will experience recurrent early loss of karyotypically normal pregnancies. In both cases, embryo-endometrial interaction is a clear candidate for exploration. The impossibility of studying implantation processes within the human body has necessitated the use of animal models and cell culture approaches. Recent advances in 3-dimensional modelling techniques, namely the advent of organoids, present an exciting opportunity to elucidate the unanswerable within human reproduction. In this review, we will explore the ontogeny of implantation modelling and propose a roadmap to application and discovery.

Building a stem cell-based primate uterus

The uterus is the organ for embryo implantation and fetal development. Most current models of the uterus are centred around capturing its function during later stages of pregnancy to increase the survival in pre-term births. However, in vitro models focusing on the uterine tissue itself would allow modelling of pathologies including endometriosis and uterine cancers, and open new avenues to investigate embryo implantation and human development. Motivated by these key questions, we discuss how stem cell-based uteri may be engineered from constituent cell parts, either as advanced self-organising cultures, or by controlled assembly through microfluidic and print-based technologies.

Preimplantation Genetic Testing: Where We Are Today

Background: Preimplantation genetic testing (PGT) is widely used today in in-vitro fertilization (IVF) centers over the world for selecting euploid embryos for transfer and to improve clinical outcomes in terms of embryo implantation, clinical pregnancy, and live birth rates. Methods: We report the current knowledge concerning these procedures and the results from different clinical indications in which PGT is commonly applied. Results: This paper illustrates different molecular techniques used for this purpose and the clinical significance of the different oocyte and embryo stage (polar bodies, cleavage embryo, and blastocyst) at which it is possible to perform sampling biopsies for PGT. Finally, genetic origin and clinical significance of embryo mosaicism are illustrated. Conclusions: The preimplantation genetic testing is a valid technique to evaluated embryo euploidy and mosaicism before transfer.

The role of uterine microbiome and epithelial-mesenchymal transition in endometrial function

Reproductive period in woman is characterized by cyclic changes of endometrium and its regeneration. The factors important for proper function of the endometrium are anatomical structure, hormonal control and signalling pathways on molecular-genetic level. New knowledge on uterine microbiome, mutual epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) of endometrial cells refine our conception of changes on cellular level, endometrial receptivity and possible causes of endometrial dysfunction. Substantial information on bacterial colonisation of endometrium were discovered by new diagnostic methods using analysis of ribosomal RNA in 16S subunit which are able to detect and exactly identify bacteria that are not detectable by classic cultivation methods. Endometrial microbiome prevents development of pathogenous microorganisms and modulates function of endometrial cells. It has been proven that stromal cells contribute to regeneration of not only the endometrial stroma, but also of the epithelium. Activity of ovarian steroids and other factors leads to EMT/MET, which ensures different functions of endometrium throughout the menstrual cycle and pregnancy. The endometrial microbiome and mutual transition of stromal and epithelial endometrial cells are necessary for physiological functions of uterine mucosa including implantation and development of an embryo.

Running title: Microbiome and cells transition in endometrial function

Comparison of the transfer of equal numbers of blastocysts versus cleavage-stage embryos after repeated failure of in vitro fertilization cycles

PURPOSE

To evaluate the efficacy of blastocyst transfer in women with at least two previously unsuccessful in vitro fertilization-embryo transfer (IVF-ET) attempts.

METHODS

Retrospective analysis of 238 couples (with previous implantation failures) had equal number (two) of cleavage-stage embryos (n = 143) or blastocysts (n = 95) transferred in the same IVF center.

RESULTS

The clinical pregnancy rates and live-birth rates were similar in the cleavage-stage embryo transfer group and the blastocyst group (35.6% vs. 40% and 32.1% vs. 35.7%; p > 0.05, respectively). Miscarriage rates (9.8% vs. 10.5%) and multiple pregnancy rates (15.6% vs. 23.6%) did not differ. Although implantation rate was higher with blastocyst transfer than that with day 3 transfer, it did not reach to a statistical significance (24.7% and 19%, respectively, p > 0.05).

CONCLUSION

Blastocyst transfer in ICSI cycles does not yield a better outcome than that obtained with cleavage-stage embryos in women who had unsuccessful IVF attempts previously.

Human endometrial CD98 is essential for blastocyst adhesion

Background

Understanding the molecular basis of embryonic implantation is of great clinical and biological relevance. Little is currently known about the adhesion receptors that determine endometrial receptivity for embryonic implantation in humans.

Methods and Principal Findings

Using two human endometrial cell lines characterized by low and high receptivity, we identified the membrane receptor CD98 as a novel molecule selectively and significantly associated with the receptive phenotype. In human endometrial samples, CD98 was the only molecule studied whose expression was restricted to the implantation window in human endometrial tissue. CD98 expression was restricted to the apical surface and included in tetraspanin-enriched microdomains of primary endometrial epithelial cells, as demonstrated by the biochemical association between CD98 and tetraspanin CD9. CD98 expression was induced in vitro by treatment of primary endometrial epithelial cells with human chorionic gonadotropin, 17-β-estradiol, LIF or EGF. Endometrial overexpression of CD98 or tetraspanin CD9 greatly enhanced mouse blastocyst adhesion, while their siRNA-mediated depletion reduced the blastocyst adhesion rate.

Conclusions

These results indicate that CD98, a component of tetraspanin-enriched microdomains, appears to be an important determinant of human endometrial receptivity during the implantation window.

Influence of cumulus cell coculture and cumulusaided embryo transfer on embryonic development and pregnancy rates

OBJECTIVE

In this study, we aimed to evaluate the influence of autologous cumulus oocyte complex (COC) coculture on embryonic development and quality, and investigate the implantation and pregnancy rates after cumulus-aided embryo transfer in the ICSI-ET cycles.

MATERIAL AND METHODS

Ninety five consecutive infertile women undergoing their first cycle of IVF teratment were included in the study. The cases were divided into two groups. Group 1 consisted of 48 women undergoing ICSI, along with autologous cumulus embryo coculture and cumulus-aided emryo transfer. Group 2 comprised 47 consecutive patients who consented to undergo ICSI and in whom autologous cumulus embryo coculture and cumulus-aided embryo transfer were not performed. Implantation and pregnancy rates were compared between the two groups.

RESULTS

The demographic data and controlled ovarian hyperstimulation parameters were similar in the two groups. The fertilization and cleavage rates were found to be higher in group 1 when compared with group 2 (p=0.03 and 0.001, respectively). There were no statistical significant differences for the implantation and clinical pregnancy rates between the two groups.

CONCLUSION

Usage of autologous COCs as coculture may improve fertilization and cleavage rates. However, cumulus-aided embryo transfer does not produce an increase in implantation and pregnancy rates.

An in vivo culture system for human embryos using an encapsulation technology: a pilot study

BACKGROUND

Animal studies have demonstrated better embryo development in vivo than in vitro. This pilot study tested the feasibility of using a novel in utero culture system (IUCS) to obtain normal human fertilization and embryo development.

METHODS

The IUCS device comprised a perforated silicone hollow tube. The study included 13 patients (<36 years) undergoing a first intracytoplasmic sperm injection (ICSI) treatment and 167 metaphase II oocytes in three groups. In Group 1, 1-2 h after ICSI, sibling oocytes were assigned to IUCS or conventional in vitro culture. The device was retrieved on Day 1, and all zygotes were cultured in vitro till Day 5. In Group 2, fertilized oocytes were assigned on Day 1, embryos retrieved on Day 3 and all embryos cultured till Day 5. In Group 3, after Day 0 assignment, embryos were retrieved on Day 3 for blastomere biopsy and fluorescence in situ hybridization (FISH) and cultured until Day 5. The highest quality blastocysts were transferred on Day 5.

RESULTS

Fertilization and embryo development were comparable in the in vitro and IUCS arms, with a tendency towards better embryo quality in the IUCS. FISH analysis in Group 3 revealed more normal embryos using the IUCS (P = 0.049). Three clinical pregnancies and live births were obtained: two from the IUCS arm and one from the in vitro arm.

CONCLUSIONS

Our pilot study shows that this new IUCS appears to be feasible and safe, supporting normal fertilization, embryo development and normal chromosomal segregation. Furthermore, live births are possible after the transient presence of a silicone device in the uterus. Clinicaltrials.gov: NCT00480103.

An analysis of spontaneous hatching in a human endometrial epithelial coculture system: is assisted hatching justified?

PURPOSE

To evaluate spontaneous embryo hatching in an endometrial epithelial coculture system, and compare it with cases where coculture was performed because of maternal age, previous repeated implantation failures, or both. To clarify in which cases assisted hatching would be appropriate.

METHODS

Individual human embryos were cocultured on an endometrial epithelial cell monolayer until Day 6.

RESULTS

Blastocyst hatching rate at Day 6, depending on maternal age, was 9.1% (age <37 years) and 3.4% (age > or = 37 years). However, blastocyst hatching rates depending on number of previous IVF failures were similar.

CONCLUSIONS

Maternal age and previous implantation failures are factors affecting the ability of human embryos to reach the blastocyst stage in coculture. However, assisted hatching is not justified in these populations because of the absence of hatching rate differences between blastocysts obtained from these two groups and the control group.