Katsuhiko Hayashi of Kyoto University in Japan has published research in which skin cells from mice were used to create primordial germ cells or PGCs. These cells, the common precursor of both male and female sex cells, were then developed into both sperm and eggs. Using these live-births were created via in vitro fertilisation.
Although the techniques involved are still in their infancy, the possibilities for reproductive medicine are startling. Not only could the research of Hayashi and his senior professor Mitinori Saitou allow infertile women to have babies by creating eggs from their skin cells, but it might make it possible for sperm and eggs cells to be created from either males or females.
The process begins by extracting pluripotent stem cells from early-stage embryos and somatic cells, and then converting these into PGCs using ‘signalling molecules’. These germ cells were transplanted into the ovaries and testes of living mice to develop. Once these cells were mature they were extracted and used to fertilise one another in vitro.
The initial research took place in October 2012, with the live-births only a ‘side effect’ used to demonstrate that the creation of PGCs had been successful. Since then, scientists around the world have been realising the full potential of the research, and the team involved is now exploring how their work might transfer to humans.x
Writing in Scientific American, David Cyranoski explains that other researchers have replicated the production of PGCs but have been unable to produce any live births. The scientists involved also have many other hurdles to overcome including the production ‘fragile’ and ‘misshapen’ eggs.
“But,” writes Cyranoski, “the most formidable challenge will be repeating the mouse PGC work in humans.” This is because the ‘signalling molecules’ used to create the PGCs are vastly more complicated in humans than in mice. Research is further hampered by restricted access to human embryos.
The Japanese team led by Saituou and Hayashi are currently using monkey embryos as a stepping stone between the species and when speaking to Scientific American, Hayashi predicts that they could succeed with primates within ‘5-10 years’, with the creation of human PGCs following ‘shortly after’.
However, even if the process is successfully transferred to monkeys there will still be many dangers that may take years to address. It’s already known that embryonic stem cells developed in laboratories frequently pick up various genetic mutations and epigenetic irregularities. Even if healthy offspring are created from this method, scientists have questioned how many generations would have to be observed before they are considered genetically ‘safe’.
Scientists agree that research is compelling but that it will be many years before anything like a viable treatment for infertility might be made available to the public.
This would allow gay couples to have children genetically their own, although many scientists are sceptical about whether it is possible to create sperm from female cells, which lack the male Y chromosome.
This breakthrough could unlock many of the secrets of egg and sperm production, leading to new drug treatments for infertility.
Defects in sperm and egg development are the biggest cause of infertility but, because many of the key stages occur in the womb, scientists have struggled to study the process in detail.
However, safety and ethical concerns mean that artificial sperm and eggs are much further away from use.
'Whether one builds the boundaries on religion or just on an internal sense or of right and wrong, these are important. In this field, it is not "anything goes".'
Scientists at Newcastle University in US claimed to have made sperm from embryonic stem cells earlier this year but the research paper has been retracted.
Dr Allan Pacey, a Sheffield University expert in male fertility said: 'Ultimately this may help us find a cure for male infertility. Not necessarily by making sperm in the laboratory, I personally think that is unlikely, but by identifying new targets for drugs or genes that may stimulate sperm production to occur naturally.
'This is a long way off, but it is a laudable dream.'
Dr Peter Saunders, of the Christian Medical Fellowship, said that IVF should be the preserve of married couples.
'The question is, why are we creating artificial gametes (eggs and sperm) and aborting 200,000 babies a year when there are many, many couples willing to adopt?'
Josephine Quintavalle, of the campaign group Comment on Reproductive Ethics, warned that any flaws in the artificial sperm or eggs could be passed on to future generations.
Anthony Ozimic, of the Society for the Protection of Unborn Children, said: 'The use of artificial gametes in reproduction would distort and damage relations between family members.
'There are no instances of any major medical advance achieved by abandoning basic ethical principles such as safeguarding the right to life.'
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