沒男性也能生育後代 日本培育出人工精子

Scientists have used artificial sperm to restore fertility in a breakthrough that could allow thousands of men to fulfill their dream of fatherhood.

In ‘hugely exciting’ experiments, they have made sperm from scratch, and, for the first time, succeeded in using it to produce healthy young.

Remarkably, the baby mice in the experiments went on to have offspring themselves. The landmark research paves the way for new drugs for infertility, the heartbreaking but little-understood condition that affects one in six couples.

But it also opens a Pandora’s box of ethical dilemmas. Possibilities raised range from men being made ‘redundant’ from the process of creating life, to babies being created through entirely artificial means.

Critics also question whether it is right to meddle with the building blocks of life just to allow couples to satisfy their desire to have children.

Scientists have been trying for years to coax embryonic stem cells – ‘master cells’ widely seen as a repair kit for the body – into turning into sperm. They have had some success but any mice that became pregnant by such means gave birth to unhealthy offspring that quickly died.

Now, Japanese scientists have come up with a series of steps that appear to solve the problem.

They started with stem cells taken from mouse embryos in the first days of life and, using a cocktail of chemicals and vitamins, turned them into sperm in the earliest stages of development. These were then transplanted into the testicles of infertile mice, where they grew into fully-functional sperm.

The ‘artificial sperm’ were then used to fertilise eggs, leading to the birth of 60 ‘grossly healthy’ baby mice, who went on to have families of their own, the journal Cell reports.

The Kyoto University researchers hope to be able to repeat their success using slivers of skin as starting material, allowing men to father children that are genetically their own.

Josephine Quintavalle, of campaign group Comment on Reproductive Ethics, said the work was ‘total narcissism’ and raised the possibility of ‘male eggs’ from men’s skin and ‘female sperm’ from women’s skin.

She added: ‘Who needs men? Who needs women? All that is required now are artificial wombs and we will have completely rewritten human reproduction.’科學家近日突破性地培育出“人工精子”，可以使不育男性重獲生育能力，幫助數千男性實現“父親夢”。

在激動人心的實驗中，科學家從零開始製造精子，而且首次成功地用這些精子培育出了健康的鼠寶寶。

值得注意的是，這些老鼠寶寶還能自己繁殖後代。這項具有里程碑意義的研究爲研發新的治療不育的藥物鋪平了道路。每六對夫婦中，就有一對遭遇到令人傷心，但原因不明的不育難題。

但該研究也開啓了潘多拉魔盒，帶來了倫理困境。這可能使男性在生寶寶的過程中成爲“多餘的人”，也可能使嬰兒完全成爲“人造寶寶”。

批評者們質疑，爲了滿足人們爲人父母的願望，就打亂正常的生育過程是否妥當。

多年以來，科學家們一直試圖將胚胎幹細胞培育成精子。這種主細胞被普遍看做人體的維修工具箱。科學家們取得過一些成果，但通過這種方式受孕的老鼠生出的後代無一健康，不久便夭折。

現在，日本科學家們已經提出一系列措施，這一難題有望解決。

首先，他們取下老鼠胚胎幹細胞，使用化學品和維他命混合物，將幹細胞培育成早期精子。然後將其植入不育老鼠的睾丸裏，它們便會發育爲功能健全的精子。

據《細胞》雜誌報道，這些“人工精子”隨後用於使卵細胞受精，並培育出60個非常健康的老鼠寶寶，它們自己就能傳宗接代。

日本京都大學的研究者們希望可以複製他們的成功經驗，以皮膚組織爲原始材料，讓男性擁有自己的親生孩子。

英國公益組織“生殖倫理學評論”的約瑟芬•昆塔瓦萊卻說這項工作“太自戀了”，最後很可能從男性皮膚中提取出“男性卵子”，從女性皮膚中提取出“女性精子”。

她說：“還需要男人和女人嗎？現在唯一需要的就是人工子宮，我們將徹底改寫人類的生殖史。”