ENDOMETRIAL RECEPTIVITY ARRAY

Dr. Gayathiri Ganesan RamMS(O.G), Fellow in Reproductive Medicine and Andrology.

Consultant Reproductive Medicine SpecialistARC Fertility Hospitals

INTRODUCTION

• Implantation is the most crucial stage in establishment of pregnancy.

• In humans, it has been estimated that between 30 – 70% of concepts are lost before or at the time of implantation without women being aware of having been pregnant.

• Successful embryo implantation depends on interactions between the embryo and the uterus.

• The human endometrium is a highly dynamic tissue that has the capacity to undergo physiological changes in response to steroid hormones, with the ultimate purpose of creating a receptive status that is synchronized with the arrival of an implanting blastocyst.

DEFINITION

• Implantation is defined as the process by which an embryo attaches to uterine wall and first penetrates the epithelium and then circulatory system forms the placenta.

• Human implantation is a highly complex and multifactorial process.

• Successful implantation at the very least, requires the presence of a healthy embryo, a receptive endometrium, a synchronized and successful molecular dialogue between the two and immune protection from the host.

• Due to lack of objective and accurate methods of assessment, endometrial receptivity (ER) is rarely investigated in an infertile patient or even prior to in-vitro fertilization (IVF).

• Advent of “Omics” that is, the analysis of biological sampling �������has revived interest in the study of ER particularly in the context of implantation failure (IF) in IVF.

• The human endometrium is a dynamic tissue; it undergoes changes at multiple levels during the menstrual cycle in response to ovarian hormones and paracrine secretions.

• The endocrine and paracrine secretions control gene expression of the differentendometrial cell types. The proliferative phase, controlled by estrogen allows for the proliferation of stromal cells and glands and elongation of the spiral arteries. The postovulatory progesterone (P) rise brings about secretory changes and the endometrium implantation of the blastocyst. ��������

• During the phase of receptivity, the endometrium undergoes morphological, cytoskeletal, biochemical, and genetic changes to become functionally competent.

• The ability to enhance the outcome of fertility ������treatments such as IVF.

WOI

• This period of receptivity is known as the “window of implantation” (WOI). The WOI opens on day 19 or 20 of the cycle and remains open for just 4–5 days at the time when P reaches peak serum concentrations.

MARKERS OF ENDOMETRIAL RECEPTIVITY

• Diagnosis of ER has posed a challenge because of the lack of an accurate, noninvasive, and clinically applicable test.

• Histological, biochemical, and ultrasound markers of ER have been proposed for use to improve implantation rates (IRs) in IVF.

• Unfortunately, most of these methods are invasive and none have any predictive value.

• Though limited in value, ultrasound markers of ER are used in the value, ultrasound markers of ER are used in �������the clinical settings.�������

HISTOLOGICAL MARKERS

• Endometrial pinopodes identified on electron microscopy also generated interest as a marker of ER.

• Pinopods are cytoplasmic projections of the luminal epithelial cells, abundant during the WOI, thought to promote blastocyst adhesion.

• The presence of pinopods was demonstrated in post receptive endometrium, and this precluded their use as a useful marker of ER.

BIOCHEMICAL MARKERS

• A number of molecules present during the mid-secretory phase have been studied as markers of ER.

• The ones which have shown significant changes include integrins, leukemia inhibitory ���factor, homeobox A10, mucin 1, calcitonin, and cyclo-oxygenase 2.

• Many more are being investigated; however, none have found their place in clinical setup.�����

MOLECULAR MARKERS

• The various molecular approaches for the study of biological samples are collectively called the “Omics” and include - genomics (study of genes), epigenomics (study of gene expression), proteomics (quantification of proteins), metabolomics and lipidomics (composition transcriptomics is considered ��the most established technology available for evaluation of the endometrial factor.

ERA

• Search for an adequate marker of ER, led to the development of a molecular diagnostic test – the endometrial receptivity array (ERA). ERA consists of a customized microarray based on the human endometrium is receptive to �����������blastocyst adhesion.

• It has been designed to identify ER by comparing the hormone (LH) + 7 controls in a ������natural cycle, or on day 5 of P administration (P + 5) after E2 priming in a HRT .

ERA

NATURAL CYCLE

• Biopsy on 7th day after LH surge.• LH surge is determined in urine/serum once

the follicle has reached 15mm.• Considering LH surge ad day 0,seven days

must be counted from that day.

BIOPSY

• Prepare and label one of the supplied cryotubes.

• Immediately after the biopsy, introduce the sample in the cyrotube and shake the sample vigourouslyfor 10 sec.

STORAGE

• Keep in fridge (4 – 8c) for 4 hrs.• This preserved sample, in cryotube can be

immediately shipped at room temp.• Sample at room temp should reach the main

lab within 4 to5 days.• Results will be ready in 20 days after receiving

samples.

The accuracy and reproducibility ofthe endometrial receptivity array is

superior to histology as a diagnostic

method for endometrial receptivity

• Patricia Díaz-Gimeno et al, Fertil Steril 2013

• Objective: To compare the accuracy and reproducibility of the endometrial receptivity array (ERA) versus standard histologic methods.

• Design: A comparative prospective study (May 2008–May 2012).

• Setting: University-affiliated infertility clinic.• Patient(s): Eighty-six healthy oocyte donors,

regularly cycling, aged 20–34 years with a body mass index (BMI) of 19–25 kg/m2.

• Intervention(s): Endometrial biopsies were collected throughout the menstrual cycle. For the accuracy study, 79 samples were grouped into two cohorts: the training set (n ¼ 79) for ERA machine-learning training and dating, and a dating subset (n ¼ 49) for comparison between histologic and ERA dating. For the reproducibility study, seven women underwent ERA testing and it was repeated in the same patients on the same day of their cycle 29–40 months later.

• Main Outcome Measure(s): Concordance of histologic and ERA dating related to LH as a reference, and interobserver variability between pathologists were statistically analyzed by the quadratic weighted Kappa index.

• The ERA reproducibility was tested and its gene expression visualized by principal component analysis.

• Result(s): For each pathologist, concordance against LH peak yielded values of 0.618 (0.446–0.791) and 0.685 (0.545–0.824). Interobserver

• variability between pathologists yielded a Kappa index of 0.622 (0.435–0.839). Concordance for ERA dating against LH peak

• showed a value of 0.922 (0.815–1.000). Reproducibility of the ERA test was 100% consistent.

• Conclusion(s): The ERA is more accurate than histologic dating and is a completely reproducible

• method for the diagnosis of endometrial dating and receptivity status. (Fertil Steril2013;99:508–17. 2013 by American Society for Reproductive Medicine.)