The creation of a male contraceptive has been in the pipeline for the last 50 years, and yet there has been shockingly little development. Now, a group of researchers have revealed that they may be a step closer to developing a reversible contraceptive for men, but say it will likely be years before any form of production.

The researchers were not specifically looking for a male contraceptive, but instead were studying peptides – short strings of amino acids – that are able to enter sperm cells and then change how they function. This, they hope, may help enable men who are infertile due to low sperm motility to conceive by getting their semen moving. Conversely, it may also allow the researchers to design a new treatment to do just the opposite.

“We are basically designing peptides that can alter the physiology of sperm,” explains Dr Sarah Jones of the University of Wolverhampton. “Ironically, sperm are notoriously difficult to penetrate, but with cell-penetrating peptides we are now able to cross an otherwise impermeable barrier to manipulate the intracellular biology of sperm so as to enhance or inhibit motility. We hope to develop something that will be clinically useful and can be taken forward in the future.”

Dr Jones, along with Professor John Howl, have been leading research looking into cell-penetrating peptides, and have found that it's possible to design them so that when they enter the sperm cell, they are able to target and alter the expression of certain proteins related to the cell's ability to swim. In tests conducted with bovine sperm, and replicated by partners in Portugal using human sperm, they found that the peptides are able to reduce the sperm’s motility within minutes.

“Dr Jones and I have proven, through extensive research studies, that it is feasible to design cell-penetrating peptides to be biologically active,” says Professor Howl. “Such molecules, synthesized in our laboratory, represent a new class of agent that we have named bioportides. This state-of-the-art technology enables the control of processes that happen inside cells and which often represent intractable targets for conventional drugs.”

They suggest that with some development this could potentially lead to a male contraceptive in the form of a pill, sub-skin implant, or even a nasal spray that could be taken a few hours before sex is expected to occur, and could possibly last for a few days. If found to be true, it could revolutionize contraception. Some women, for example, are unable to take the pill for long periods of time due to health complications, not to mention that birth control should not be the sole responsibility of the woman in the first place.