There have been no advances in male contraception for over a century, with current options limited to condoms, the withdrawal method or a vasectomy. Despite promising research into male hormonal contraception, trials have had to be halted early due to side effects, and further work is required to reach an acceptable balance between efficacy and safety.
Currently the most promising new research is Vasalgel – a long-acting, non-hormonal contraceptive that works in a similar way as a no-scalpel vasectomy but is thought to be more easily reversible.
How does Vasalgel work?
Sperm is produced in the testes and is transported through tubes called the vas deferens. It is these vas deferens which are clamped, cut or otherwise sealed during a vasectomy, preventing the flow of sperm so that they are reabsorbed by the body. With this new method, Vasalgel is injected into the vas deferens and fills the interior of the tube (lumen) with a soft, semi-permeable gel barrier. Fluid remains able to pass through the tubes, reducing the back-pressure in the epididymis (sperm storage area), however the sperm themselves cannot and are instead reabsorbed by the body.
Image sourced from Parsemus Foundation on the 16th March 2017 (https://www.parsemusfoundation.org/projects/vasalgel/)
Does Vasalgel work?
Vasalgel was inspired by another polymer contraceptive known as 'reversible inhibition of sperm under guidance' (RISUG) that is currently undergoing advanced clinical trials in India. Some men have been using RISUG for over 15 years but only local men near the study sites are currently eligible for the trial. In addition, any formal reversibility studies have only been performed in animal models thus far, however this process is relatively simple and requires the gel to be 'flushed out' with another polymer.
Vasalgel was developed by the Parsemus Foundation for the rest of the world outside of India. Initial studies in rabbits over 12 months showed no sperm from the second semen sample onwards and a rapid return of sperm flow after the Vasalgel polymer had been flushed out.
In addition, a new study published earlier this year has shown that Vasalgel was 100% effective in trials using rhesus monkeys. 16 adult rhesus macaques received Vasalgel injections, had one week of recovery time and then returned to outdoor housing with between 3-9 breeding females with a successful reproductive history. All of the monkeys in the trial were housed with the females for at least one breeding season, and 7 out of the 16 were housed with breeding females for 2 years.
Following the 1-2 year period, the Vasalgel trial was 100% effective with no reported pregnancies amongst the breeding females. Overall, Vasalgel was very well-tolerated, and placement resulted in minimal complications, which were comparable to monkeys in the control group which had received vasectomies.
Elaine Lissner, executive director of the Parsemus Foundation said "What was important here was that this worked and was safe in animals similar to humans".
What's next?
The promising results of this study warrant further research, including studying the possibility of reversal, which thus far has been successful in rabbits but has not yet been shown in non-human primates.
Lissner and her team have further animal studies planned for this year and hope to start clinical trials in humans next year. There is still a way to go, but if the promising results observed in animal studies are transferable to humans it is possible that Vasalgel will be on the market in the not too distant future.
Additional notes
The Parsemus Foundation is developing Vasalgel as a 'social venture' company, meaning that it makes enough money to stay afloat but not to make large profits, with its mandate being affordable pricing and a wide availability. They rely on public support and donations to drive the development and bring Vasalgel to market with further information available here.
The California National Primate Research Centre (CNPRC) ensures a free-living environment with social groups for the well-being of it's primates.
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