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"Leather" sperm and eggs

A group of Japanese and English researchers based at the Gurdon Institute  in Cambridge  created primitive forms of artificial sperm and eggs, for which they tried to grow human embryonic stem cells under carefully controlled conditions during the week.

They advanced progressively, step by step, proving that the same procedure can turn an adult’s tissue into precursors for sperm and eggs, which increases the likelihood of creating germ cells that are genetically comparable with patients.

At the same time, cells must have the potential for growth in mature sperm and eggs, although this has never been done before in laboratory conditions. The next stage of research will be the introduction of cells into the ovaries to find out whether they fully develop in living organisms.

British law prohibits fertility clinics in the UK from using artificial sperm and eggs for the treatment of infertile couples. But if the law is revised, which is very likely, skin cells can potentially be taken from patients and turned into genetically identical sperm and egg cells for use in in vitro fertilization therapy or surrogacy programs.

Skin cells in women can only be used for eggs, because they have no Y chromosome. Sperm cells and, theoretically, egg cells can be grown from male skin cells, although scientists believe that it is unlikely based on current knowledge.

“It is possible that we can use these cells to create gametes, but whether we can ever use them is still a matter of the future,” says Azim Surani, a scientist who leads the research.

Before that, scientists managed to create sperm and eggs from stem cells of rodents. In 2012, Japanese doctors created eggs from the stem cells of mice. Two years later, scientists at the University of Newcastle claimed to have made human sperm from stem cells, but their scientific work was questioned because of suspicions of plagiarism.

The Surani team tried several different approaches before making a unique breakthrough in research, which resulted in the conversion of up to half of human experimental stem cells into sperm and egg precursors. Over the course of a week, scientists added natural chemicals called growth factors to push cells to the right direction.

By studying cells, scientists hope to unravel how sperm and eggs appear and mature in the germ cells of adults. The opportunity to create, albeit imperfect, sperm and eggs from the skin cells of patients means that scientists can now compare how they develop differently when they are made from the biomaterial of healthy and infertile people.

Perhaps even more intriguing is the fact that cells can keep secrets for the treatment of certain age-related diseases. As people age, they accumulate not only genetic mutations, but also other changes in their DNA. These epigenetic changes can be caused by smoking, exposure to chemicals in the environment, unhealthy diets and lifestyles, and other adverse factors. But the cells from which sperm and eggs are created are first cleared of epigenetic changes. “This can tell us how to erase epigenetic mutations. Epigenetics is used to regulate gene expression, but in age-related diseases, these changes can be aberrant and incorrectly regulate genes,” - says Surani.

Allan Pacey, senior professor of andrology at the University of Sheffield, suggests that Surani cells may have other uses. Most often, people taking chemotherapy become infertile. Artificially grown human sperm can be used to screen for new anti-cancer drugs that are not so dangerous for sperm.

In the course of their work, the Surani team discovered that a certain gene, called SOX17, is crucial for the transformation of human stem cells into precursors of sperm and eggs.

 

Photo: MedicalRF.com/Corbis

Based on The Guardian

 

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