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Scientists have made primitive forms of artificial sperm and eggs in a medical feat that could transform the understanding of age-related diseases and fertility problems. Researchers in Cambridge made the early-stage sex cells by culturing human embryonic stem cells under carefully-controlled conditions for a week.

Apparently this experiment follows an earlier experiment which demonstrated that a single procedure can convert skin tissues into foundations for sperm and egg cells. This, in turn, improves the success of making sex cells that are also genetically matching with the patient.

The experiments show that these cells should have the potential to grow into mature sperm and eggs, although this is something that has never before been accomplished in a laboratory. The next step, then, is for researchers to inject the newly formed precursor cells into mouse ovaries or testes to see if they can develop into fully grown animals over time.


Researchers have used skin cells to make primitive artificial sperm and eggs in a move that could transform fertility treatment.

Scientists in Cambridge made the sex cells by culturing human embryonic stem cells for five days under carefully-controlled conditions.

They then showed that the same process can convert adults' skin tissue into early-stage sperm and eggs.



British law prohibits fertility clinics in the UK from using artificial sperm and eggs to treat infertile couples. But if the law was revised, skin cells could potentially be taken from patients and turned into genetically identical sperm or eggs for use in IVF therapies.

"It's not impossible that we could take these cells on towards making gametes, but whether we could ever use them is another question for another time," Surani told the Guardian.

Researchers have made sperm and eggs from rodent stem cells before but have struggled do the same with human cells. In 2012, Japanese scientists created mouse eggs from stem cells and used them to make baby mice. Three years earlier, scientists at Newcastle University claimed to have made human sperm from stem cells, but their scientific paper was retracted amid allegations of plagiarism. In 2002, US researchers produced male and female mouse pups from male stem cells.

Surani's team tried a number of different approaches before hitting on a culture process that turned up to half of the human stem cells in the dish into precursors of sperm and eggs. Over the five day process, the scientists added natural chemicals called growth factors to nudge the cells in the right developmental direction.

"It's remarkably fast. We can now take any embryonic stem cell line and once we have them in the proper conditions, we can make these primordial cells in five to six days," Surani said. Details of the work, collaboration with the Weizmann Institute in Israel, are published in the journal, Cell.

Through studying the cells, scientists hope to unravel how sperm and eggs arise and mature into adult sex cells. The ability to make immature sperm and eggs from patients' skin means scientists will be able to compare how they develop differently when they are made from healthy versus infertile people. "This is really the foundation for future work," Surani said.

In the course of their work, Surani's team discovered that a specific gene, named SOX17, was crucial for turning human stem cells into early-stage sperm and eggs. The finding was a surprise, because in mice the equivalent gene does not play any role. The implications are wide-ranging. "Mice are the key model we use to study mammalian development and we extrapolate from mice to humans," said Surani.

"This work tells us that the extrapolation can be unreliable. I'm not saying that all work in mice doesn't apply in humans, but there are fundamental differences we need to be wary of," he said.