Modelization of Early Endometrial-trophoblast Molecular Interaction

Despite significant advances in assisted reproductive technology, only 25% of in vitro fertilization (IVF) embryo transfers result in pregnancy, largely due to implantation failure.

Preeclampsia complicates 2 to 5% of pregnancies, causes 76,000 maternal deaths worldwide each year, and is one of the leading causes of extreme prematurity (20% of premature births occurring before 32 weeks of gestation). There is no curative treatment, and only delivery of the baby and placenta can cure the patient. During preeclampsia, early placental abnormalities occur in the first trimester of pregnancy, even though the initial stages of human embryo implantation (apposition, adhesion, invasion) and early placentation remain poorly understood.

The primary objective of the MEETMI project is to characterize, in the laboratory, the early endometrium-trophoblast molecular interactions that determine the initial stages of human implantation and placentation.

It is essential to collect human endometrial cells (epithelial and stromal cells) from endometrial biopsies performed as part of routine care in patients who have been previously informed and have given their consent to the research.

For the placental part, following models available in the Lecarpentier's laboratory at the Institut Cochin will be used: human trophoblast stem cells (hTSCs), placental organoids derived from first-trimester placenta .

• Diagnostic hysteroscopy with endometrial biopsy (Procedure): During the gynecological consultation prior to the diagnostic hysteroscopy, patients who meet the inclusion criteria will be offered participation in the MEETMI study. The patient's consent will be obtained during this consultation or no later than the day of the hysteroscopy. The hysteroscopy will preferably be performed on days 14-16 of the menstrual cycle, outside the menstrual period, in accordance with current practices. During this hysteroscopy: * Endometrial biopsies will be performed as part of the standard care * An expanded endometrial biopsy will be performed for research purposes. The extended biopsy is taken from the same location, with the same dimensions, and using the same technique as the biopsies performed as part of standard care. The extended biopsy does not significantly increase either the duration of the procedure or the risk associated with diagnostic hysteroscopy.

Primary outcomes

• Determine transcriptionnal and proteic signatures of endometrial-trophoblast [Day 20]: Determine transcriptionnal and proteic signatures of endometrial-trophoblast

Secondary outcomes

• Placental Penetration into the extracellular matrix [Day 20]: Quantity of placental penetrating cells will be measured using fluorescent confocal microscopy on live cells and fixed (formol 4%) slices (depth, cells proportion). Placental cells will be labelled using specific antibodies (syncytin, hCG).
• Viability of the co-culture [Day 20]: LDH assay for Viability of the blastoid/organoid/gastruloidco-culture viability. Viability will be assessed in the cells supernatant dosing Lactate Deshydrogenase (LDH). LDH is a commonly used method for determining cell viability and cell cytotoxicity following cell damage or death, such as by necrosis, apoptosis, and other forms of cell and tissue damage.
• Development of syncytiotrophoblast: To vizualise syncytiotrophoblast development: hCG concentration in co-culture supernatant [Day 20]: To vizualise syncytiotrophoblast development, investigators will quantify hCG secretion on the co-culture supernatant.
• Development of syncytiotrophoblast: sFLT1 concentration in co-culture supernatant [Day 20]: Investigators will also measure angiogenic factors in the supernantant (sFLT1)
• Development of syncytiotrophoblast: PlGF concentration in co-culture supernatant [Day 20]: PlGF concentration will be measured in the co-culture supernatant.
• Development of syncytiotrophoblast: Fusion index [Day 20]: Investigators will quantify fusion by calculating fusion index on fixed slices (formol 4%)

Sex: Female, ages: 18 Years to 50 Years

Inclusion Criteria:

* Medical indication for a diagnostic hysteroscopy between the ages of 18 and 50
* Comprehensive information provided prior to the hysteroscopy
* Informed consent signed by the patient

Exclusion Criteria:

* Current pregnancy
* Age < 18 or > 50
* Patient refusal
* Woman under court-ordered protection
* Not enrolled in the general social security system
* Patient who is HIV- or HCV-positive, regardless of viral load
* Patient whose medical history requires medication that may interfere with trophoblast biology (immunomodulators in cases of autoimmune diseases, anti-rejection drugs in transplant patients)
* Known genetic disorder in the patient
* Unable to understand and sign the consent form