Are lab-grown human sperm the real thing?
来源：未知 作者：还暑 时间：2019-03-08 10:03:00
By Andy Coghlan CALLS for more proof have greeted claims that human sperm have been created in the lab for the first time. If further tests show that the lab-grown sperm are indeed identical to the natural kind, they might be helpful in understanding male infertility. Karim Nayernia of the University of Newcastle, UK, and his colleagues treated male embryonic stem cells (ESCs) with a range of substances, which converted them first into germline stem cells and then into spermatogonial stem cells. These divided to produce “haploid” spermatocytes with just 23 chromosomes, which went on to mature into sperm. Independent researchers are demanding more evidence. “Although they find that some of the sperm cells have tails and can swim, this is not evidence of normality,” says Robin Lovell-Badge, who studies sperm formation at the UK National Institute for Medical Research in London. Indeed, all seven mouse pups produced by Nayernia’s team in 2006 after fusing normal eggs with mouse sperm created in the lab died within five months. This was because chemical caps called methyl groups had blocked vital genes in the sperm. Nayernia is now carrying out tests to see if the same thing happened with the human sperm. Nayernia has solved the problem in mice by putting spermatogonial cells into mouse testes before they mature. “The sperm then have a normal shape and normal methylation patterns,” he says. For humans, he claims to have developed “artificial testes” to do the same job. A more distant possibility is the creation of sperm from a woman’s cells, allowing a lesbian couple to have a child. Nayernia produced spermatogonial stem cells from female ESCs but they lacked genes needed to mature. Journal reference: Stem Cells and Development, DOI: 10.1089/scd.2009.0063 More on these topics: