Skin cells could be turned into eggs ‘curing infertility’ in older women and cancer patients, scientists discover
SCIENTISTS have turned skin cells into egg cells that can form an embryo, a study shows.
The discovery could help women who have used up their eggs in older ages as well as those who lost them during cancer treatment get pregnant, US researchers said.
It could also allow gay male couples to have children sharing both fathers’ DNA, they suggested.
Dr Shoukhrat Mitalipov, of Oregon Health & Science University, said: “The goal is to produce eggs for patients who don’t have their own eggs.”
Around one in seven British couples — 3.5million people — are affected by infertility.
Girls are born with a fixed number of eggs that mature in the ovaries and are released over time.
When they are born, they have around 2million and this reduces to around 25,000 by the age of 37, according to the British Fertility Society.
This means that conceiving a child becomes less easy as time goes on.
Some chemotherapy treatments for cancer can also increase the risk of infertility because they affect the reproductive organs.
The study, published in Science Advances, looked at how new eggs can be formed using existing skin cells.
Researchers experimented on mice to see if they could create eggs that include half the genetic information of a mum-to-be.
To do this, they used donor egg cells from one mouse, which had been stripped of their nuclei, which contains their DNA.
They replaced the nucleus with one from the intended mum-to-be’s skin cells, transferring her DNA to it.
The nucleus then shed half its chromosomes to become a haploid egg, with only one set of chromosomes.
The advantage of our technique is that it avoids the long culture time it takes to reprogram the cell
Dr Paula Amato
This means it would be able to fuse with a sperm cell to produce an embryo and, in theory, a child.
Dr Mitalipov said: “This publication basically shows how we achieved haploidy.
“In the next phase of this research, we will determine how we enhance that pairing so each chromosome-pair separates correctly.”
Previous attempts to create egg cells had relied on turning skin cells into stem cells, before reprogramming them to become egg cells.
Co-author Dr Paula Amato, also of OHSU, said: “We’re skipping that whole step of cell reprogramming.
“The advantage of our technique is that it avoids the long culture time it takes to reprogram the cell.
“Over several months, a lot of deleterious genetic and epigenetic changes can happen.”
While the study showed it is possible to form egg cells, she said it will be several years before the technique can be used clinically in humans.
Dr Amato said: “This gives us a lot of insight.
“But there is still a lot of work that needs to be done to understand how these chromosomes pair and how they faithfully divide to actually reproduce what happens in nature.”
WHAT HAPPENS TO A WOMAN'S EGGS AS SHE AGES?
Girls are born with a fixed number of immature eggs in their ovaries.
The number of eggs decreases as women get older.
At birth, most girls have about 2 million eggs, at adolescence that number has gone down to about 400, 000, at age 37 there remain about 25,000.
By age 51 when women have their menopause they have about 1000 immature eggs but these are not fertile.
At every menstrual cycle one of the immature eggs will mature and be released during ovulation.
The eggs that are not released die and get re-absorbed into the body. The quality of the eggs also gets poorer as women get older.
All other things being equal the number and quality of the woman’s eggs determines her fertility.
Source: British Fertility Society