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expert reaction to study looking at CRISPR and surrogate sires in livestock and mice

A study, published in PNAS, reports on a new method of utilising CRISPR techniques to produce surrogate sires in livestock and mice, for the potential use in breeding trait selection. 

This Roundup accompanied an SMC Briefing.


Prof Dusko Ilic, Profesor of Stem Cell Science, King’s College London, said:

“In this proof-of-concept study, a team of international scientists demonstrated the potential of surrogate sire technology, which allows the creation of sperm in male animals that lack their own germline cells, but have transplanted spermatogonial stem cells from donor male animals.

“The technology might be beneficial for preservation of endangered species or animal breeding programs.  Given considerable risks and a need for large investment over multiple years associated with this technology, we might not witness its practical implementation any time soon.”


Dr Harry Leitch, Germline and Pluripotency Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, said:

“It is through germs cells that we pass on our genes to the next generation.  Understanding germ cells and developing technology that allows us to manipulate and transplant them is important for a wide number of possible future applications: technologies involving germ cells could one day enable us to conserve endangered species, to improve livestock species or to treat infertility.

“As such, this paper, authored by highly-regarded leaders in the field, represents an important technical advance.  They build on previous work to demonstrate that removing a single gene can lead to male animals without sperm, and expand this analysis to four different species.  Next, they show that germ cells can be transplanted into these ‘empty’ testes, restoring sperm production (and fertility) in mice, and leading to the generation of sperm in both pigs and goats.

“The next step in pigs and goats will be to demonstrate that this sperm is functional – meaning that it can fertilise an egg and make healthy offspring.  If possible, this will offer a route to rapid genetic modification of livestock species.  This currently is tightly regulated and would not be legal, but it is only by increasing knowledge in this area that we will know if and when the correct time is to move forwards safely.

“More broadly this study is also an advance in germline regenerative medicine approaches – such improvements in technology may even one day impact treatment of severe infertility in humans, albeit this work is currently very much in the research setting in animal models.”


‘Donor-derived spermatogenesis following stem cell transplantation in sterile NANOS2 knockout males’ by Michela Ciccarelli et al. was published in PNAS at 20:00 UK time on Monday 14 September 2020.

DOI: 10.1073/pnas.2010102117


Declared interests

Prof Dusko Ilic: “I declare no conflict of interest.”

Dr Harry Leitch: “I have no conflicts of interest to declare.”

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