11 January 2018

Test tube spermatozoa

Scientists have gone halfway to obtaining artificial spermatozoa

Sergey Vasiliev, Naked Science

About 15 percent of married couples face the problem of infertility. From 20 to 30 percent of such cases are associated with the inability of a man's body to produce viable sperm. The technology of growing artificial spermatozoa from the donor's own cells could solve the problem. We already know how to turn ordinary skin fibroblasts into stem cells – it remains to learn how to direct their development in the right direction and maintain it until the end, until mature sperm are obtained.

A little less than two years ago, Chinese scientists demonstrated this possibility in mice by growing full-fledged sperm cells from embryonic stem cells, which fertilized eggs and gave healthy offspring. However, it is not yet possible to implement this process for human cells: the development of spermatozoa takes longer and is more difficult for us. However, recently doctors have made another important step towards such technology. This was told by a well-known geneticist from the University of Cambridge, the head of the Gardon Institute, Azim Surani, who recently spoke at the annual conference of the Progress Educational Foundation.

It is worth remembering that eggs and stem cells-precursors of spermatozoa are formed in the body before birth. For the first few weeks they develop along a common path, and only about the eighth week after fertilization they diverge – for comparison, in mice this happens on the 13th day. According to Azim Surani, the eight-week period is the key goal of all this work. It can be achieved by "artificial testicles", which have been tested by scientists under the leadership of Surani.

Miniature organoids consist of just a small clot of artificially grown germ cells suspended in a semi-liquid gel. The right combination of cells of different types, which secrete the appropriate substances, provides sperm precursors with the right maturation conditions and a favorable pace.

So far, scientists have managed to reach about the fourth week of development, but they are determined to get to the eighth week. Moreover, the authors have demonstrated that epigenetic markers – chemical modifications that "tune" the work of the genome taking into account the living conditions of parents - are successfully destroyed in cells. Azim Surani and his colleagues promised to tell more about this in an article already accepted for publication by one of the journals.

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