GoKawiilResearchers are trying to make human sperm (shown here in a colourized electron microscope image) from stem cells in the lab.Credit: Juergen Berger/Science Photo Library
It sounds like science fiction: collecting a person’s blood cells, engineering them so they eventually transform into immature sperm, and then incubating them in a tiny pouch grown on a mouse’s kidney.
The quest to make babies with lab-grown eggs and sperm
But it’s not. Today, a team of researchers reported in the journal Cell Stem Cell1 that it has successfully carried out the procedure, with the ultimate goal of making mature human sperm in the laboratory.
For now, that goal remains elusive. The lab-grown cells stopped developing at an immature stage. Many hurdles need to be overcome to create mature sperm in the lab, says Eoin Whelan, a reproductive biologist at the University of Pennsylvania in Philadelphia who is a member of the research team. But the latest feat is a step in the right direction.
In the meantime, the procedure could be used to study early stages of human sperm development and to hunt for reasons behind male infertility. Around 40% of male-infertility cases have no known cause. “We are approaching this from a basic science perspective,” Whelan says. “We are a long way from clinical application.”
An elusive goal
Some of the potential clinical applications are controversial, particularly the idea of using lab-grown sperm or eggs to make babies. Although some researchers hope that the approach could be used to treat specific cases of infertility, the practice also raises ethical concerns. One of these is that the technique could make it easier to genetically modify reproductive cells to produce ‘designer babies’.
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So far, a handful of researchers have been able to make mouse eggs and sperm from mouse skin cells. These cells are genetically reprogrammed so that they transform into induced pluripotent stem (iPS) cells — ‘youthful’ cells that act like those in embryos and can be chemically or genetically coaxed to turn into completely different cells, such as sperm. One team even used the approach to generate offspring from two male mice2.
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