Scientists crackelusive technique formaturing eggs outside the ovaries.
Fertility 'breakthrough' as human eggs grown in lab for first time
Human eggs with the potential to becomefertilised embryos have been grown in a laboratory for the first time in a breakthroughthat could unlock future fertility treatments - writes independent.co.uk.
In a landmark development, scientists have been able to replicate the process where egg cells mature in the ovaries outside of the body.
Using strips of ovarian tissue removed in a biopsy, itrepresents an advance onIVF (in vitro fertilisation),where a mature egg is fused with a sperm in the lab and the fertilised embryo is implanted.
Under the new process, in vitro maturation (IVM), the maturation of eggs takes place in the lab, raising the prospect of new hope for women who losetheir fertility.
The study’s seniorauthor,Professor EvelynTelfer of the MRC Centre for Reproductive Health at theUniversity of Edinburgh, toldThe Independent: “If we can show these eggs are normal and can form embryos, then there are many applications forfuture treatments.”
Simply having a process to study egg development in the lab is a major benefit for researchers, and her team isnow focused on “optimising” their technique and seeing how healthy the embryos are.
If shown to be effective, it could help women who do not not ovulate naturally and therefore do not respond to IVF, and could preservefertility in cancer patients.
Younggirls, in particular,have very few options for preserving their fertility before chemotherapy or radiotherapy.
Currently the ovarian tissue is stored in the hope that this could be transplanted back when they’re in remissionto restore some fertility.
“That could be a risky business,” said ProfTelfer.”Many of these young girls have blood-borne cancers and if some of the abnormal cells are there you’d never take the risk of transplanting it back.
“So this kind of technology could then be applied.”
Theoretically it could even be applied in post-menopausal women, though it would be difficult to get a piece of ovary that contains enough egg cells.
“The honest answer is we really don’t know at this stage,” said ProfTelfer. “It’s proof of concept at the moment,we have a lot of work to do and safety always has to be the priority”.
While the eggs in the study are atthe final stage of maturation,it is not known whether they could form a healthy embryo.ProfTelfersaid they havea significant ethical and regulatory process ahead before they can attempt fertilisation.
Independentexperts agreed there would be several years before this treatment would appear in fertility clinics,butsaid itmay be looked back on as a “seminaladvance”.
The research effort is the culmination of 30 yearsof international collaboration, which has previously only demonstrated start-to-finish IVM in animals, where ovarian tissue samples are much more plentiful.
Several teams, including ProfTelfer’s, have previously been able to complete parts of the maturation process.
The latest advance, published in the journal Molecular Human Reproduction today, began withovarian tissue from 10 women, aged between 25 and 39, who were giving birth by caesarean section.
Women are born with millions of immature eggs, contained within folliclecells in the ovary, but only a few hundred are released over a lifetime.
These follicle cells, and the eggs within, are very sensitive to hormone levels and other environmental factors at each stage of development.
So, in conjunction with medical experts, the Edinburgh team had to replicate these conditions.
The biopsied ovarian tissuewas first examined to remove any follicles that had already begun the maturation process, before the growth phase began.
Whenthe follicle had matured sufficiently, the egg was squeezed out “under gentle pressure” for the final stage of development.
From numerous primary follicles they matured just54 eggs and were able to get nine that might be capable of forming a healthy embryo and growing a baby.
Step one: very small, immature human eggs within ovarian tissue are placed in culture in the lab, and begin to develop; Step two: after initial development, eggs have grown and are more than double their initial size. The ovarian follicles that contain the eggs are separated before further growth and monitoring; Step three: eggs and their surrounding cells are removed from liquid culture to undergo further development in a nutrient-rich membrane (Prof Evelyn Telfer and Dr Marie McLaughlin, the University of Edinburgh)
While this remains a lot less efficient than IVF, where women take regular follicle stimulatinghormone injections to mature multiple eggs and give them the best chance of pregnancy, it could be another route where IVF isn’t an option.
“This is an elegant piece of work, demonstrating for the first time that human eggs can be grown to maturity in a laboratory,” said Dr Channa Jayasena, a member of the Society for Endocrinologyand clinical senior lecturer at Imperial College London, who was not involved with the research.
“It would take several years to translate this into a therapy. However, this is an important breakthrough, which could offer hope to women with infertility in the future.”
Professor Daniel Brison, scientific director of the Department of Reproductive Medicine, University of Manchester, agreed, saying: “This could pave the way for fertility preservation in women and girls with a wider variety of cancers than is possible using existing methods.”
But Professor Robin Lovell-Badge, group leader of the Francis Crick Institute, said the results showed limitations in the technique at present.
There were signs the embryos might be abnormal and their chances of being fertilised are unknown, and the ovaries of girls pre-puberty “will be at an early stage and perhaps quite different from those in an adult”, he said.
He added: “While this work may contain an important step, many more will have to be taken to reach the destination. But you can’t make an omelette without breaking eggs.”
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