Revealing the enigmas of implantation: what is the true impact of ovarian hyperstimulation?

Higher clinical pregnancy rates from frozen-thawed blastocyst transfers compared to fresh blastocyst transfers: a retrospective matched-cohort study

PURPOSE

The purpose of this matched-cohort study was to assess endometrial receptivity to blastocyst implantation in fresh embryo transfer by comparing implantation outcomes of fresh embryo transfer with frozen embryo transfer, where two blastocysts of good quality were transferred in good prognosis patients.

METHOD(S)

Fresh embryo transfer from intracytoplasmic sperm injection cycles and artificial frozen embryo transfer cycles performed from January 2012 to December 2013 at a private clinic were retrospectively analyzed and the pregnancy, clinical pregnancy, and implantation rates statistically compared. Cycles were stratified and matched according to the blastocyst expansion grade (grade 2, 3, 4, or 5) of the two blastocysts transferred. Five hundred ninety-eight fresh embryo transfer cycles were matched with 545 frozen embryo transfer cycles across four blastocyst cohorts.

RESULT(S)

In this study of 1143 blastocyst transfer cycles, fresh embryo transfer resulted in reduced pregnancy, clinical pregnancy, and fetal heart implantation rates in all four blastocyst cohorts. The fetal heart implantation rates for fresh embryo transfer ranged from 16.7 % in the grade 2 to 47.3 % in the grade 5 cohort, compared to 23.1 % in the grade 2 to 57.4 % in the grade 5 cohort for frozen embryo transfer. The trends in increasing pregnancy outcomes relative to increasing blastocyst expansion were similar in fresh embryo transfer and frozen embryo transfer.

CONCLUSION(S)

Blastocysts of good quality transferred in frozen embryo transfer had a significantly greater chance of implantation and clinical pregnancy compared to blastocysts of matched quality transferred in fresh embryo transfer, suggesting reduced endometrial receptivity in fresh embryo transfer.

Impact of serum estradiol levels on the implantation rate of cleavage stage cryopreserved-thawed embryos transferred in programmed cycles with exogenous hormonal replacement

PURPOSE

To investigate the impact of late follicular phase serum estradiol (E2) levels on implantation and pregnancy outcomes of cleavage stage cryopreserved/thawed embryos transferred in programmed cycles with exogenous hormonal replacement.

METHODS

Retrospective cohort analysis of IVF patients with transfer of cryopreserved-thawed day-3 embryos in E2 and progesterone (P4) supplemented cycles (n = 208 cycles).

MAIN OUTCOME MEASURES

implantation and pregnancy rates according to late follicular phase serum E2 levels and early secretory phase E2/P4 ratios.

RESULTS

Logistic regression performed for embryo implantation and for pregnancy outcome in relation to E2 (day 15), P4 (day 15 and 16), before (crude analysis) and after adjustment (adjusted analysis) for baseline characteristics (including age, BMI, serum basal cycle day 3 FSH levels, embryo quality, endometrial lining thickness) showed no significant association. Similarly, ROC analysis showed no impact of cycle day 16 E2/P4 ratio.

CONCLUSIONS

Neither late follicular phase serum E2 nor the early E2/P4 ratio were able to predict implantation or pregnancy outcome of day-3 cryopreserved-thawed embryos transferred in artificially programmed cycles.

The extrapituitary effects of GnRH antagonists and their potential clinical implications: a narrated review

Potential roles of gonadotropin-releasing hormone (GnRH) antagonists on GnRH/GnRH receptor systems and their effects on the extrapituitary tissues are largely elusive. In this narrated review, we summarized the systemic effects of GnRH antagonists on ovary, endometrium, embryo implantation, placental development, fetal teratogenicity, reproductive tissue cancer cells, and heart while briefly reviewing the GnRH and GnRH receptor system. GnRH antagonists may have direct effects on ovarian granulosa cells. Data are conflicting regarding their effects on endometrial receptivity. The GnRH antagonists may potentially have detrimental effect on early placentation by decreasing the invasive ability of cytotrophoblasts if the exposure to them occurs during early pregnancy. The GnRH antagonists were not found to increase the rates of congenital malformations. Comparative clinical data are required to explore their systemic effects on various extrapituitary tissues such as on cardiac function in the long term as well as their potential use in other human cancers that express GnRH receptors.

Gene expression confirms a potentially receptive endometrium identified by histology in fertile women

BACKGROUND

To use contemporary biochemical markers to characterize mRNA/gene expression in the potentially fertile secretory endometrium to confirm its identification based on histological characteristics in order to develop a clinically applicable test.

METHODS

Nine, fertile, cycling Caucasian women were sampled from one IVF clinic. Endometrial samples were collected from them in two to four menstrual cycles at 2 and 7 days post first significant rise in blood LH. Separate endometrial glands and stroma populations were obtained by laser microdissection. Linear polymerase chain reaction amplified mRNAs which were hybridized to both Affymetrix U133 Plus2 and Agilent 4 × 44K microarrays followed by gene set analysis. Four histopathologists reviewed the sample set using the same histological criteria to date and characterize the non-receptive and potentially receptive samples.

RESULTS

mRNA expression of microdissected glands and stroma provided molecular signatures that characterized the two specific phases of the cycle with distinct clustering patterns. Cell proliferation and five other associated biological pathways were significantly down-regulated when the endometrium is considered potentially receptive accompanied by an increase in secreted glycoproteins mRNAs in the potentially receptive glands. Reported histological findings identified the presence of one histological feature characteristic of each phase: glandular mitoses indicated a non-receptive endometrium, whereas a potentially receptive endometrium was distinguished by supranuclear vacuolation.

CONCLUSIONS

This study defined a transcriptome characteristic of active cell proliferation in the non-receptive samples with a marked overall down-regulation of this pathway in potentially receptive samples-suggesting a transitional state associated with receptivity but not implantation. However, microarrays involve expensive, specialized testing and require significant post-data analysis. Sampling according to endocrinological and molecular prediction improved the consistency of histological assessment and allowed reliable histological markers of glandular mitosis in the non-receptive phase and supranuclear vacuolation of the potentially receptive endometrium to be identified. Thus, histology can provide an affordable, clinically applicable test in the context of reproduction.

Gene and protein expression signature of endometrial glandular and stromal compartments during the window of implantation

OBJECTIVE

To map the changes in messenger RNA (mRNA) and protein abundance during the window of implantation in specifically endometrial stromal and glandular epithelial cells obtained using laser microdissection microscopy (LDM).

DESIGN

Endometrial samples were collected from two menstrual cycles at 2 and 7 days after first significant rise in blood LH, and separate cell populations were obtained using LDM. A new generation linear polymerase chain reaction (PCR) amplified the mRNA, which were hybridized to both Affymetrix U133 Plus2 and Agilent 4x44K microarrays followed by gene set analysis. Immunohistochemistry assessed protein expression between the two collection times.

SETTING

In vitro fertilization clinic.

PATIENT(S)

Nine Caucasian, fertile, cycling women.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Cycle dating using blood markers; microarrays on laser microdissected glands and stroma; dual platform microarray confirmation; immunohistochemical analysis of cell cycle proteins.

RESULT(S)

The two microarray platforms showed concordance. During the window of implantation, a statistically significant network of 22 mRNA associated with the cell cycle was down-regulated. Immunohistochemistry identified altered localization in stroma.

CONCLUSION(S)

Microarrays demonstrated glands and stroma have distinct mRNA signatures, each dependent on the day of the cycle. We characterized two compartments of the receptive endometrium with a transcriptomic signature identifying regulation of only the cell cycle. Immunohistochemical analysis of cell cycle proteins identified a signature staining pattern of nuclear relocalization of a group of cyclins of stromal cells, which may be clinically applicable.

A novel model of human implantation: 3D endometrium-like culture system to study attachment of human trophoblast (Jar) cell spheroids

There is an urgent need to develop optimized experimental models to examine human implantation. These studies aimed to (i) establish a human endometrium-like three-dimensional (3D) culture system, and (ii) examine the attachment of trophoblast-like Jar spheroids to the culture. In the present work, 3D endometrial cultures were constructed with fibrin-agarose as matrix scaffold, and using epithelial and stromal cells from both human primary cultures and established cell lines. An attachment assay between trophoblast cells and the 3D culture was developed. Epithelial cells (cytokeratin(+)) concentrated on top of the matrix forming a monolayer, and stromal cells (vimentin(+)) resided within the matrix, resembling the normal endometrial structure. The capability of primary epithelial cells to form glands spontaneously was observed. Human trophoblast cells (Jar cells) were hCG(+) by immunostaining, allowed to form spheroids, and confirmed to secrete hCG into the medium. Time-dependent experiments demonstrated a high rate of attachment of Jar spheroids to the epithelium, and adhesion was strongly related to the various cell types present in the 3D culture. An architecturally and functionally competent 3D endometrial culture system was established, that coupled with Jar spheroids mimicking trophoblast cells, provides a unique in vitro model for the study of certain aspects of human implantation.

Embryo cryopreservation rescues cycles with premature luteinization

OBJECTIVE

To determine whether embryo cryopreservation in cycles with elevated preovulatory P followed by thaw, extended culture, and transfer results in greater ongoing pregnancy rates than fresh blastocyst transfer.

DESIGN

Retrospective matched cohort study.

SETTING

Private fertility center.

PATIENT(S)

The study group consisted of 118 consecutive thaws of bipronucleate (2PN) oocytes derived from autologous cycles with elevated preovulatory P, resulting in 95 blastocyst transfers. The control group was selected by matching on the number of 2PN oocytes and patient age and consisted of 118 fresh cycles with elevated preovulatory P, including 108 fresh autologous blastocyst transfers. All patients were <41 years old at the time of stimulation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Implantation and ongoing pregnancy rates.

RESULT(S)

The study group had significantly fewer blastocysts per 2PN oocyte than the control group (19.7% vs. 36.8%, respectively) and a significantly greater cancellation rate (19.5% vs. 8.5%, respectively). However, the ongoing pregnancy rate per cycle was significantly higher in the study group than in the control group (56.8% vs. 32.2%, respectively), resulting from greater rates of implantation (56.8% vs. 26.9%, respectively) and of ongoing pregnancy per transfer (70.5% vs. 35.2%, respectively).

CONCLUSION(S)

In cycles with elevated preovulatory P, the probabilities of implantation and ongoing pregnancy are increased if all 2PN oocytes are cryopreserved and subsequently thawed and cultured to the blastocyst stage before transfer.