中国科学家成功培育出正常功能的小白鼠精子

Scientists in China have finally succeeded in creating functioning sperm ¹ from mice in the laboratory. To accomplish this feat ², the researchers coaxed ³ mouse embryonic ⁴ stem cells to turn into functional ⁵ sperm-like cells, which were then injected into egg cells to produce fertile mouse offspring. The work, reported February 25 in Cell Stem Cell, provides a platform for generating sperm cells that could one day be used to treat male infertility ⁶ in humans. "Reproducing germ cell development in vitro has remained a central goal in both reproductive biology and reproductive medicine," says co-senior study author Jiahao Sha of Nanjing Medical University. "We established a robust ⁷, stepwise approach that recapitulates ⁸ the formation of functional sperm-like cells in a dish. Our method fully ⁹ complies with the gold standards recently proposed by a consensus ¹⁰ panel of reproductive biologists, so we think that it holds tremendous promise for treating male infertility.", ,Infertility affects up to 15% of couples, and about one-third of cases can be traced to the man. One major cause of male infertility is the failure of precursor ¹¹ germ cells in the testes to undergo a type of cell division called meiosis to form functional sperm cells. Several studies have reported the successful generation of germ cells from stem cells, but they did not fully evaluate the functionality of the germ cells or provide proof for all key hallmarks of meiosis., ,Recently, a panel of reproductive biologists proposed gold standard criteria ¹² to prove that the major events of meiosis have taken place in engineered germ cells. For example, researchers must show evidence of the correct nuclear DNA ¹³ content at specific meiotic stages, normal chromosome ¹⁴ number and organization, and the capacity of germ cells to produce viable ¹⁵ offspring. Until now, the recapitulation of all of the essential steps of meiosis has remained a major obstacle to the production of functional sperm and egg cells in a dish. , ,To overcome this hurdle ¹⁶, Sha teamed up with co-senior study authors Qi Zhou and Xiao-Yang Zhao of the Institute of Zoology ¹⁷ at the Chinese Academy of Sciences to develop a stem cell-based method that fully recapitulates meiosis and produces functional sperm-like cells. The first step was to expose mouse embryonic stem cells (ESCs) to a chemical cocktail ¹⁸, which coaxed the ESCs to turn into primordial ¹⁹ germ cells. Next, the researchers mimicked ²⁰ the natural tissue environment of these precursor germ cells by exposing them to testicular cells as well as sex hormones ²¹ such as testosterone.