New discovery pinpoints the `golden window' for IVF success

Date:
August 23, 2021
Source:
RMIT University
Summary:
Researchers find a way to better pinpoint the 'golden window'
when a womb is ready for pregnancy, in a discovery that could help
boost IVF success rates.



FULL STORY ========================================================================== Researchers have found a way to better pinpoint the "golden window" when
a womb is ready for pregnancy, in a discovery that could help boost IVF
success rates.


==========================================================================
It's long been known that correctly timing an embryo transfer is critical
to the chance of achieving pregnancy.

Identifying the right moment in a woman's cycle with absolute precision
remains a challenge however, contributing to low IVF success rates,
which remain on average under 50%.

But now RMIT University researchers may have found a way forward, by identifying a Teflon-like molecule that makes the surface of the womb
slippery and prevents embryos from implanting.

The team discovered that the levels of this molecule on the womb's
surface decrease at a certain point in the menstrual cycle.

This allows the womb to become stickier, opening the "golden window"
for pregnancy success.



========================================================================== Previously, scientists believed implantation hinged on molecules that
actively promoted the adhesion of an embryo to the wall of the uterus.

Lead researcher Professor Guiying Nie said the team's discovery changed
long- held scientific thinking about embryo implantation.

"We've been looking for something that helps embryos stick when the
vital part of the puzzle turned out to be a slippery molecule that has
the opposite effect -- it prevents them from sticking," she said.

The research found a significant difference in IVF success rates when
embryos were transferred while this molecule was present or absent on
the surface of the uterus.

"Every embryo is precious for families struggling with infertility,
so getting the timing right is critical," said Nie, who leads the
Implantation and Pregnancy Research Laboratory in the School of Health
and Biomedical Sciences at RMIT.



==========================================================================
"We hope with further development our discovery could help clinicians
identify precisely when each patient has the greatest chance of achieving pregnancy, delivering fully personalised IVF treatment." The findings, published in the journals Fertility and Sterility and Human Reproduction,
could have significant implications for IVF treatment and success rates.

Pregnancy success rates The retrospective clinical study, co-designed
by Nie and Professor Luk Rombauts from Monash IVF, examined levels
of the anti-implantation molecule, known as podocalyxin (PCX), in the endometrium of 81 women undergoing IVF treatment.

A biopsy of the uterus was taken at the mid-luteal phase (about seven
days after ovulation) of the women's menstrual cycle, one full cycle
before a frozen embryo was transferred.

While the women with low levels of PCX had a 53% pregnancy success rate,
those women where the molecule had not been reduced had a success rate
of just 18%.

Rombauts said measuring levels of PCX at the mid-luteal phase can be used
as a screening test but it could also indicate a reason for infertility,
making the molecule a potential target for treatment.

"These findings offer a promising path for us to both improve IVF success
rates and potentially treat an underlying cause of infertility," he said.

The research team has already begun work to better understand the role
of PCX and how it is regulated in the body, with the aim of developing infertility treatments.

Nie said the analysis of this molecule could be done in a standard
pathology laboratory, making it relatively cost-effective to implement
a future screening test.

"The only way we can currently test for PCX is through biopsies of tissue, which cannot be taken at the time when embryos are transferred," she said.

"We need further research to develop non-invasive and real-time approaches
for measuring PCX on the day of embryo transfer.

"Our hope is to deliver a simple test that can help patients and boost the precision and personalisation of IVF treatment." A patent application
has been filed for the technology, with collaborators from Monash IVF
now looking to further evaluate the potential clinical applications.

The work began at the Hudson Institute of Medical Research, before Nie's
team moved to RMIT in 2020.

The research was supported by the European Society of Human Reproduction
and Embryology, Monash IVF, and the National Health and Medical Research Council of Australia (NHMRC). Human embryo work in Brussels was supported
by Wetenschappelijk Fonds Willy Gepts.

========================================================================== Story Source: Materials provided by RMIT_University. Original written
by Gosia Kaszubska.

Note: Content may be edited for style and length.


========================================================================== Journal References:
1. Sophea Heng, Nirukshi Samarajeewa, Asma Aberkane, Wafaa Essahib,
Hilde
Van de Velde, Maxine Scelwyn, M. Louise Hull, Beverley Vollenhoven,
Luk J. Rombauts, Guiying Nie. Podocalyxin inhibits human embryo
implantation in vitro and luminal podocalyxin in putative
receptive endometrium is associated with implantation failure
in fertility treatment. Fertility and Sterility, 2021; DOI:
10.1016/j.fertnstert.2021.06.028
2. Sarah G Paule, Sophea Heng, Nirukshi Samarajeewa, Ying Li,
Mary Mansilla,
Andrew I Webb, Thomas Nebl, Steven L Young, Bruce A Lessey, M
Louise Hull, Maxine Scelwyn, Rebecca Lim, Beverley Vollenhoven,
Luk J Rombauts, Guiying Nie. Podocalyxin is a key negative
regulator of human endometrial epithelial receptivity for
embryo implantation. Human Reproduction, 2021; 36 (5): 1353 DOI:
10.1093/humrep/deab032 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210823110334.htm

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