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A study published in Cell Stem Cell looks at generating sperm cells from human and non human primate pluripotent stem cells.
Dr Harry Leitch, Associate Professor in Clinical Genetics & Genomic Medicine, UCL Great Ormond Street Institute of Child Health, said:
“In recent years, there have been major advances in our understanding of germline development – the process by which healthy gametes (sperm and eggs) are made. A major research focus has been the use of stem cell models to make lab grown gametes – so called ‘in vitro gametogenesis’. In mice, it is now possible to make functional sperm and eggs, that can give rise to live animals, entirely in the lab. These techniques are less developed using human stem cells as currently we can only make the earliest stages.
“This study pushes the field forwards, as it reports a method to achieve further maturation of male germ cells in both men and male non-human primates. This builds on previous work from the Saitou lab using a similar method to mature female germ cells.
“This is a high quality study from one of the leading labs in the field. They directly compare ‘lab grown’ germ cells with real in vivo cells from both humans and non-human primates, which adds confidence that the cells made in the lab represent a close approximation of normal development. This study represents an important and significant advance, as improvements in these methods will help us better understand how human germ cells are formed and how this can go wrong leading to infertility.
“It is important to emphasise that this is a complex method, that involves mixing stem cell-derived germ cells from humans with testicular cells from mice, and still falls short of making functional human sperm. While this may be possible in the future, there would be major ethical and regulatory barriers to prevent the use of lab grown sperm for reproductive purposes – until this could be proven to be safe and to meet a legitimate medical need.”
Prof Allan Pacey, Professor of Andrology at the University of Manchester, said:
“This is an interesting paper which uses pluripotent stem cells from the macaque and the human to create the early stages of sperm production in the lab. What is really interesting is that these cells then self-assemble into structures that look like seminiferous tubules, the cellular structures in the testicle in which sperm are made. In my mind this opens up two possibilities:
It creates a system that could be used in the lab as a model to work out why things go wrong in some men and why they don’t produce sperm. This is incredibly difficult to study and we don’t have any good model systems that allow this.
This takes us one step further on a pathway to the day when we can create sperm for infertile men in the laboratory. This would be revolutionary for the treatment of male factor infertility, but there is still a lot of science to do before this is possible.
“It’s important to note that in this paper the authors have not made sperm, just the early stages of germ cells before they start to start to divide and grow tails. But it is a great step forward.
“It’s also important to know that if sperm were ever produced in the lab one day that it would be illegal in the UK to use them in infertility treatments without a change in the law. And there would be a lot more data and safety information required for this to be considered.
“But a good step forward by these authors and a great, if rather technical, paper.”
‘Generation of spermatogonia from human and nonhuman primate pluripotent stem cells’ by Eoin C. Whelan et al. was published in Cell Stem Cell at 16:00 UK time on Friday 10 July 2026.
DOI: 10.1016/j.stem.2026.06.001
Declared interests
Dr Harry Leitch: “No conflicts.”
Prof Allan Pacey: “AAP is a member of the Cryos International External Scientific Advisory Committee. In the last two years he has also undertaken consultancy for Carrot Fertility, and has delivered educational lectures for IBSA Institut Biochemique SA, and Mealis Group but all monies were paid to the University of Manchester. He is also the co-chair of the UKNEQAS Reproductive Sciences Advisory Committee, is a member of the Advisory Boards for the Progress Educational Trust (Charity Number 1139856) and the Science Media Centre (Charity Number 1140827) and Patron of the Fertility Alliance (Charity Number 1206323 (all unpaid). He is a member of the Guidelines Development Groups for the National Institute for Health and Care Excellence, and the World Health Organisation (again all unpaid).”