Comment: Reversible vasectomy method raises hopes of male contraceptive
A "reversible vasectomy" form of male contraception has been successfully tested in monkeys, bringing it a step closer to human patients.
Valsalgel is injected into the vas deferens - the tube that carries sperm out of the testicles - where it forms an impenetrable gel barrier.
A study in rabbits last year showed that it had the potential to provide a reversible alternative to vasectomy, which involves cutting and sealing off the vas deferens.
The research showed that the gel could be removed by flushing the duct with baking soda solution.
In the new trial, Valsalgel prevented any conceptions occurring in a test group of 16 rhesus monkeys.
"Our research shows that Valsalgel placement into the vas deferens produces reliable contraception in mature male rhesus monkeys as shown by the lack of pregnancies in reproductively viable females with which the males were housed," lead scientist Dr Catherine VandeVoort, from California National Primate Research Centre, said.
"Importantly, we show that the method of Valsalgel placement is safe and produced fewer complications than usually occur with a vasectomy.
"Valsalgel shows real promise as an alternative to vasectomy because research in rabbits has previously shown the product to be reversible. Although it is possible to reverse a vasectomy, it is a technically challenging procedure and patients often have very low rates of fertility following reversal."
One of the treated monkeys showed signs of sperm granuloma, a hard build-up of sperm in the vas deferens.
The same non-serious complication affected around 60pc of men undergoing a vasectomy, said the researchers.
The findings, reported in the journal 'Basic and Clinical Andrology', pave the way for clinical trials expected to begin next year.
Valsalgel, which is not classified as a pharmaceutical product, is made by the non-profit Parsemus Foundation in Berkeley, California.
"If free of side-effects then this novel approach has the potential for great promise as a male contraceptive," Professor Adam Balen, chairman of the British Fertility Society, said.