Injecting certain proteins into the testicles with the aim of increasing sperm production and treating male infertility, as the promise of a (successful) study conducted in mice.
In France, around one in eight couples consult because of difficulties in conceiving a child. In three quarters of the cases, it is a question of infertility of male, female or associated origin. In men, abnormalities in spermatogenesis (the process of producing sperm) are by far the most common causes of infertility . Among them stands out oligospermia, which is characterized by a lack of sperm production (less than thirty million/ml).
On this observation, researchers at Seoul National University have developed a way to reactivate this sperm production . Initial tests carried out in mice have proved to be very conclusive. Previously infertile males rapidly produced offspring at a rate similar to that of unaffected mice. Details of this work are published in the journal ACS Nano.
Similar to the blood-brain barrier that protects the brain, the blood-testis barrier protects the cells that produce sperm by isolating them from toxic substances capable of evolving in blood cells. If this barrier is damaged, then sperm production can be affected .
Specialists know that a certain protein called PIN1 plays a key role in the development of this blood-testis barrier. As part of this work, the researchers looked for a way to increase the levels of this protein in the testicles with the aim of "rebuilding" it.
Researchers embedded these proteins into lipid-coated silk fibroin nanoparticles. These were then injected directly into the testicles of male mice specially bred to lack PIN1 proteins. In other words, these were mice whose testicles had shrunk and whose sperm production was not sufficient.
Result:Subjects' testicles eventually grew to normal size and weight . Their sperm count also improved, although it remained around 50% lower to that of "healthy" mice. However, it didn't seem to affect their fertility. Over the following months, the mice treated with nanoparticles were indeed able to generate almost the same number of pups than their peers.
On the other hand, infertile mice in a control group, which did not benefit from the treatment, obviously remained infertile.
It is of course too early to know if this type of approach could also work for humans. In-depth studies will still be necessary on animal models before considering the first clinical trials.
