Birth Control for Men: Gene Editing Lets Scientists Turn Off Sperm Production

Men wearing condom-style hats watch marine traffic at the Cannes Film Festival in 2007. Jean-Paul Pelissier/Reuters

At a time when access to reproductive health care for women is newly imperiled, the scientific press is revisiting a topic that emerges and fades into the woodwork every few years: male birth control. A new study from Michigan State University published in Nature Communications breaks new ground in approaching a male contraceptive pill.

The study has been called a "genetic foundation for male birth control." Although the results are far from anything that could be used in humans, they lay solid groundwork, according to Peter Schlegel, chair of urology at Weill Cornell Medicine and New York Presbyterian in New York City.

The scientists found that by shutting off a pathway using CRISPR gene editing, they could stop sperm production in mice. The gene they spliced out codes for an enzyme that makes sure sperm cells are made correctly, and its removal rendered the mice sterile.

While translating results from mice to men can be tricky in most research, according to Schlegel, rodents are great for sperm. When it comes to sperm production, he says, rats and mice are far more efficient than humans. So if an intervention can stop sperm production in a mouse, it's almost a guarantee that it can do the same in humans.

Still, this study provides, if anything, a very preliminary road map. The gene that the researchers spliced out of the mice is part of a pathway that drug developers could target. Of course, as Schlegel notes, most people taking a birth control pill would probably want to be able to produce sperm again at some point.

"You've got to stop production of 100 million sperm in a day without knocking out potential for production in the future," he says.

In addition to not sterilizing a person, an effective male birth-control drug would have to leap over some other biological hurdles. To do its job, a pill taken by mouth would have to overcome the "blood-testes" barrier, which safeguards the testicles from much of the matter dissolved in a person's blood. It would also have to be proved safe, and with a minimum of side effects.

Schlegel says that compounding the years to identify a drug with the years to test it, "you're looking at a minimum of five to 10 years." And that's before all of the steps that go into getting a drug approved, regulated and marketed. Of course, whether such a contraceptive is necessary and desirable is a separate question.

"Unfortunately, the authors sometimes overstate the potential of these studies," Schlegel says. While the pathway is promising, "it's really far away from anything that could be usable."