New therapy that delivers proteins directly to testes may treat male infertility

SEOUL, South Korea — When it comes to having children, infertility is a problem both men and women may face. About 15 percent of all couples struggle with infertility, according to the Mayo Clinic. In over a third of these cases, men are unable to father children. Now, researchers in South Korea have developed a procedure they say can restore the normal reproductive function. Instead of working with gene therapy, their study relies on delivering vital proteins back into the testes.

A team from Seoul National University say one of the main causes of male infertility is a problem with sperm production. This lack of sperm in the semen can damage the blood-testis barrier (BTB). The barrier utilizes a protein called PIN1 to block toxins and drugs from harming reproductive cells.

The team’s study on mice who had PIN1 genetically deleted from their bodies found the animals were sterile, had small testes, depleted sperm stem cells, and had low overall sperm counts.

Switching from genes to proteins for male infertility

The Korean researchers say gene therapy procedures can be risky for men and their children. Such treatments could cause unwanted genetic changes to the patient’s reproductive cells and these may be passed on to their offspring if they successfully father children.

Researcher Hyun-Mo Ryoo and his team created a technique which which delivers PIN1 directly to a mouse’s testes. First, the team had to get the protein through the complex series of tubes inside the testicles.

Researchers developed a unique delivery system called Fibroplex. These structures are spherical nanoparticles made of silk fibroin with a lipid coating. Once scientists load PIN1 into the nanoparticles, they are delivered into the mouse’s cells. Researchers add this material appears to be safe for injection, with no toxic side-effects to the infertile mice.

The results show sterile mice given PIN1-loaded Fibroplex see their PIN1 and sperm stem cell levels restored to normal. The injection also repaired the BTB and gave mice about 50 percent of the sperm count of wild, unaltered mice.

The treatment lasted for about five months before the proteins degraded. During that time, Fibroplex-treated mice fathered a similar number of mice pups that normal fertile mice did. Mice who did not receive the PIN1 injection remained sterile throughout the experiment.

Study authors say this is the first successful test to directly deliver proteins to an infertile male’s body. It may eventually lead to a new avenue of treatment for human infertility cases.

The study appears in the journal ACS Nano.

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