In vitro-derived Gametes

What are in vitro-derived gametes?

Human sperm swimming towards an egg.

In vitro-derived gametes, also known as artificial gametes and in vitro gametogenesis, are egg and sperm cells created in a laboratory by reprogramming other cells, such as embryonic stem cells or skin cells, to become functional egg and sperm cells. The laboratory created eggs and sperm can then be used to create embryos.

What is happening in current scientific research?

Over the last decade, there have been significant scientific developments in the creation of artificial egg and sperm cells as researchers seek to identify the causes of infertility and to find possible solutions. These developments have mainly been led by researchers in Japan who, in 2016, derived the first functional female egg cells from reprogrammed mouse skin cells. By using IVF techniques, the team was able to produce healthy mouse offspring from the artificially created eggs.

Earlier in 2016, a team of researchers from China published a paper in the journal Cell Stem Cell, claiming that they had created artificial male sperm-like cells from mouse embryonic stem cells. However, these claims were contested and it was not until 2021 that a team from Japan announced the creation of the first functional artificial mice sperm cells, which were successfully used to produce live offspring.

At the Third International Summit on Human Genome Editing in March 2023, one of the lead Japanese researchers, Professor Katsuhiko Hayashi, announced the creation of mice with two biological fathers. This is the first time that viable artificial eggs have been generated from male cells.

Most recently, an alternative IVG approach to creating eggs has been developed at the Centre for Embryonic Cell and Gene Therapy in Oregon. The researchers there used Somatic Cell Nuclear Transfer (a form of cloning) to create an egg by replacing the nucleus from a donor mouse egg with a nucleus taken from a mouse skin cell. 

The scientific advances in the creation of artificial egg and sperm cells in mice are not proving as easy to replicate with human cells. This is largely because the precise mechanisms by which human cells differentiate into egg and sperm cells and how they develop naturally in the embryo is still not fully understood.

Scientists have, however, made some progress toward the development of human in vitro-derived gametes. For example, in 2015, a research team at the University of Pennsylvania successfully created an early-stage human sperm cell using male blood cells and has, more recently, produced the precursor to sperm, spermatogonia. Researchers from Japan have cultured human cells to the stage before they become eggs. The creation of functional, mature in vitro-derived human gametes is not currently scientifically possible and there are still a number of regulatory and technical challenges that need to be overcome.

Human sperm swimming toward an egg. However, if research on human in vitro-derived gametes does achieve the same results as the research on mice, it will open up new reproductive possibilities. In vitro-derived gametes will, for example, make it possible for individuals and couples, who are unable to produce viable gametes due to congenital anomalies or after certain medical treatments (e.g. for cancer), to create genetically related gametes for reproduction from their own skin or stem cells. This will allow those who have previously only been able to reproduce using donor gametes to conceive and birth children who are genetically related to them.

If human gametes can be artificially created, this may also disrupt various social and biological reproductive norms by enabling, for example, same sex couples to both be genetically related to their offspring; transgender women to contribute eggs and transgender men to contribute sperm; solo-parenting where a child would be genetically related to only one person; and multiplex-parenting where a child would be genetically related to more than two individuals. These possibilities raise complex issues and questions which need to be addressed before the creation of in vitro-derived human gametes becomes a reality.

What issues/questions do in vitro-derived gametes raise?

  • Do ‘solo’ genetic parenting, ‘multiplex’ parenting, or same-sex genetic reproduction raise any special ethical and legal problems?
  • Should children created through in vitro-derived gametes have a right to know how they were created?
  • Given the existence of alternative routes to parenthood, such as adoption and surrogacy, are the costs and risks associated with these new technologies worth incurring?
  • Should in vitro-derived gametes be publicly funded in countries with public healthcare systems?
  • Does the development of in vitro-derived gametes perpetuate damaging pro-natalist and genetic essentialist stereotypes regarding the ideal of parenthood and the social acceptability of infertility?

For a more in-depth discussion about in-vitro derived gametes, read about our IVG Policy Briefing Workshop, in collaboration with the Nuffield Council on Bioethics, here

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