Endometrial Receptivity Array (ERA)
6/24/2020 02:02:00 AM
Have you ever heard
the phrase of personalized precision IVF?
Nowadays, the
individualized medication is more prevalent.
Embryo implantation is a highly complex process
incorporating with a healthy embryo, a receptive endometrium, and a molecularly
communicative dialogue in between. Until 2016, Stork Fertility Center has
comprehensive applied individualized
COS, IMSI/ICSI, blastocyst culture, PGS/PGD, donor
gametes, and frozen
embryo transfer for
the cases with specific indications. Moreover, all patients would be requested
to take the hysteroscopy, hysterosalpingograrphy, and cervical
bacteria culture before
entering the transfer cycle. However, still, some patients failed after couples of transfers.
Why?
Except for the quality of embryos and the physically
normal observation of uterus and endometrium (EM) through ultrasound, a hidden
culprit must exist in between—the dialogue for permitting implantation.
Actually, the human endometrium is a dynamic tissue, which undergoes changes
during multiple levels in a menstrual cycle. The changes in histological markers,
biochemical markers, molecular markers, and transcriptomics (Omics) have been
reported in the previous articles. Generally, the period of EM receptivity is
known as the "window of implantation, WOI," which opens during the cycle day 19 or 20
and remains open for 4-5 days. During WOI, the EM becomes functionally
competent for the embryo implantation.
Using the assisted statistical tool, principal
component analysis (PCA), hundreds of transcriptome (gene expression) during
different phase of EM (proliferative [PE], early secretory [ESE], mid-secretory
[MSE], and late secretory [LSE]) could be analyzed and clustered into four
groups: proliferative, pre-receptive, receptive, and post-receptive.
Through
examining these transcriptomes in EM biopsies from different people, several
studies found that the WOI is not fixed, as was believed before. It means that
a fixed transfer protocol to all the patients could not be applicable. Thus
several clinical approaches for detecting the receptivity of EM tissue were
developed recently, and the endometrium receptivity array (ERA) was one of
them. The ERA was used to analyzed the expression of 238 genes in an EM biopsy
obtained from either an HRT or natural cycle. After priming of progesterone in
an HRT or of LH in a natural cycle, the EM would be biopsied and analyzed. If
the result showed receptive, transferring embryo at the same time in another
cycle would be recommended. If the result showed non-receptive, transferring
time would be adjusted according to the expressions of pre- or
post-receptivity.
Based on the clinical trial of IGENOMIX, a leading team of reproductive genetics in Spain,
around 30% in the population had a WOI which is not located in the general
frame (P+5 or LH+7), and four-fifths of these non-receptive are pre-receptive
(80%). The introduction of ERA has been reported to solve the problem in part
of patients suffering from repeated implantation failure, and thus to increase
the success rate in IVF.
At Stork
Fertility Center, the indications for ERA is as below:
A. Repeated implantation failure after undergoing hysterosalpingogram, hysteroscopy
and autoimmune examinations.
B. Repeated failures after transferring four Day 5 blastocysts graded over BB
in accumulationThe pregnancy rate of transferring a good blastocyst with PGS+ERA can reach at 80%. On the other hand, 10~20% increase compared to those with PGS, only 60~70%. This is the Third generation IVF Plus: “precise selection + precise implantation”.
C. Repeated failures after transferring two euploid
blastocysts in accumulation
D. Elderly women over 43 years old.
The pregnancy rate of transferring a good blastocyst with
PGS+ERA can reach 80%. On the other hand, 10~20% increase compared to those
with PGS, only 60~70%. This is the Third generation IVF Plus: “precise
selection + precise implantation”.