THE MORE A reliable means of contraception for men – and one that cannot fail or be dispensed with in the heat of the moment – is a vasectomy. But the procedure is largely irreversible: it involves stopping the flow of sperm from the testes by cutting ducts known as vas deferens and sealing or tying them. A reconnection, after a reconsideration, is no easy task.
Researchers are now looking at a different approach: blocking the vas deferens using compounds that combine to form a barrier that can later be removed. Lab tests involved four separate injections to establish a sperm-proof barrier, which could later be dissolved using a burst of focused infrared light.
Aware that repeated injections into the penis can affect men’s willingness to undergo such a procedure, Wanhai Xu, a urologist at Harbin Medical University in China, and his colleagues propose a different idea: a barrier that can be placed with an injection and broken. with ultrasound.
The recipe from Dr. Xu includes three parts, primarily a polymer known as a hydrogel that thickens inside the body and is already approved for medical use. Crucially, that gel contained a lot of thioketals, compounds that break down when exposed to reactive oxygen-containing molecules, plus just a hint of titanium dioxide — an inert material that, when exposed to ultrasound, releases just those molecules.
To verify their work, Dr. Xu employed a few dozen male rats. Some received a traditional vasectomy, others an injection of the new material, and the rest injected with saline as a control. Each was then allowed to follow their essential nature with four females. Only those rats that received saline progenitor offspring.
The actual test, as the team reports in CHA nano, a nanotechnology journal, followed: half of the mice that received the new treatment were exposed to an ultrasound blast. This evidently dissolved the hydrogel in the creatures’ tubes: they were able to reproduce again, while those that were not detonated remained sterile.
What works in mice, unfortunately, doesn’t always work in humans, so more testing will be needed. But Dr. Xu hopes these findings represent a good idea for a reversible contraceptive – with fewer points of contention.
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This article appeared in the Science and Technology section of the print edition under the title “Tubular Gels”