Can human life be grown from stem cells in the laboratory in the future?
Japanese scientists managed to breed healthy mice from stem cells. This brings them closer to the dream of mankind to create human life in the laboratory. After all, the researchers were able to obtain egg cells from stem cells, from which healthy, fertile mice in the womb then developed through artificial insemination. The Japanese study could show new ways for sterile couples.
Obtaining egg cells from stem cells trendsetting? In a mouse experiment, the researchers at Kyoto University succeeded in obtaining healthy, functional egg cells from stem cells. These were then fertilized artificially. In the womb, the "artificially" bred mouse babies, such as mouse embryos, developed in the normal way. The Japanese researchers were not only happy about healthy mice, but also that the animals themselves were able to reproduce. Similar experiments with sperm had already been carried out last year.
Amander Clark, stem cell biologist at the University of California, considers the study results of the Japanese to be a great success and believes in an "ongoing influence on the field of reproductive cell biology and genetics", as she explained to the specialist magazine "Science".
Egg cells obtained from embryonic and induced pluripotent stem cells
Study leader Mitinori Saitou and his team use embryonic stem cells for their experiments, which are obtained from embroyons and are able to differentiate into any type of cell. On the other hand, the Japanese researchers used so-called induced pluripotent stem cells (iPS cells), which come from previously developed body cells and are therefore less ethical. iPS cells can differentiate into numerous cells. Both types of cells were grown in cultures with a cocktail of proteins to produce primordial germ cell-like cells. Primordial germ cells can develop into egg cells and sperm. In order to obtain egg cells or precursors of egg cells, the researchers mixed the primordial germ cells with fetal ovarian cells, which were supposed to form ovaries and were planted on natural ovaries of living mice. After a period of four weeks and four days, the primordial germ cells in egg cells had differentiated, reports “Science”. The scientists removed the egg cells, fertilized them in vitro and used the resulting embryos as surrogate mothers. After about three weeks, normal and apparently healthy mouse babies were born, as the scientists report in the specialist magazine.
Healthy and fertile mice developed from both cell types and continued to reproduce. According to the Japanese researchers, the success rate is still relatively low, but the study results could be used as the basis for the development of human egg cells in the laboratory. "The study has provided critical evidence that egg cells can be obtained from induced pluripotent stem cells," Clark told Science. In terms of humans, the results could be used for the production of egg cells from iPS cells by infertile women, the expert added.
Sperm cells obtained from embryonic stem cells Last year, Japanese scientists succeeded in cultivating functional sperm cells in the laboratory. At that time, the researchers removed testicular tissue from mice and stimulated the early stages of the sperm contained in the tissue to mature. The mature sperm were then used to fertilize the egg cells, which gave birth to healthy mouse babies. "The work provides evidence that primordial germ cells derived from embryonic stem cells can develop into functional germ cells," Clark told "Science" at the time, who described the results as "critical progress in our basic understanding of the principles of germ cell development". (ag)
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