Male Birth Control: Reversible New Technique Looks Like a Cocktail

When it comes to male birth control there aren’t a lot of choices: There’s the short-term choice of a condom and the long-term option of a vasectomy. Because condoms are often used incorrectly and vasectomies are not usually reversible, researchers have spearheaded a recent effort to find the ideal “medium-term” male contraception. On Wednesday, a team of scientists announced a new approach that mimics an unlikely source of genius: cocktails.

Researchers from China’s Nanchang University explain in the journal ACS Nano that they were inspired to create a new form of male birth control after considering layered cocktails — colorful, stratified drinks like the Galaxy that, once mixed, combine into a uniform liquid. They subsequently developed an approach in which layers of materials are injected into the vas deferens — the duct that conveys sperm from the testicle to the urethra. The intended result of all these layers, they report, is like a reversible vasectomy: Sperm can’t get through to impregnate a sexual partner.

Instead of layers of tonic and liquor, the layers used here are a little more complex: a hydrogel that works as the physical barrier to sperm, gold nanoparticles, a chemical that breaks down the hydrogel and kills sperm called ethylendediaminetetraacetic acid (EDTA), and a final layer of gold nanoparticles. Previous studies conducted on mice have found that heated gold nanoparticles can kill sperm cells.

We’re a long ways away from this technique being tried out on humans, but if this study’s rat trials are any indication, this layered injection could be the “medium-term” form of male contraception scientists have been hoping to invent. The injected rats proved unable to impregnate female rats for more than two months, and when the researchers shone a near-infrared lamp on the rats for a few minutes, the layers mixed and dissolved — in turn causing the birth control to become ineffective.

The idea is that, if this pilot study ever evolves into a human trial, men will have the option to reverse this form of birth control when they don’t want to use it anymore — with just a quick five minute “irradiation” session at home, fertility could be restored.

“For adult males with a fixed sexual life, it is more convenient, reasonable, and humanized to provide a medium to long-term contraception method with flexible reversibility,” the scientists write. “With the development of men’s ideas, consciousness, knowledge, and attitude, we believe that more and more men will feel obliged to shoulder the burden or pregnancy, both for fairness and risk aversion, which is also the best way to care and love their wives.”

It’s a sweet sentiment, if male birth control ever enters the market. As of now, other proposed methods aren’t actually available as options men can go out and try — save for the extremely problematic Jiftip. In November, the US National Institutes of Health announced it’s starting its own clinical trials, in which a potential form of male contraception will be tested on human subjects: A gel that, when applied daily to a man’s shoulders and back like a condom-lotion, is hypothesized to prevent pregnancy. With 40 percent of the world’s pregnancies unintentional, whether it’s a gel or a cocktail-inspired injection, the need for new male contraception appears crucial for reproductive health.

Abstract: Inspired by cocktails, we designed a medium term (2–20 weeks) male contraceptive strategy. Through a sequential injection process of four reagents (calcium alginate hydrogel, PEG-Au nanoparticles (PEG-AuNps), EDTA, and PEG-AuNps), physical clogging of the vas deferens and chemical inhibition of the sperm motility were realized simultaneously. The contraceptive period could be directly preset by adjusting the injection ratio of each reagent. More interesting, the embolism area could be readily dredged through a short-time noninvasive near-infrared irradiation. The present study offered an effective and reversible manner to fill the gap of current medium-term contraceptive strategy. In addition, the proposed in vivo pipeline plugging technology, with a flexible noninvasive self-cleared characteristic, might also provide a convenient and reliable strategy for some other biomedical engineering researches.