Researchers from Osaka University have, for the first time, succeeded in restoring spermatogenesis in animals with genetic infertility by using an mRNA delivery technology that targets the testicular tissue directly. The results of this breakthrough experiment were published in the Proceedings of the National Academy of Sciences (PNAS).

During the study, scientists injected lipid nanoparticles containing the mRNA (messenger RNA) of the Pdha2 gene—crucial for normal sperm formation—into the testes of infertile laboratory mice. Just three weeks later, mature germ cells appeared in the tissue. Using these cells through the ICSI (intracytoplasmic sperm injection) method, the researchers were able to obtain viable offspring.

Messenger RNA (mRNA) is a molecule that carries “instructions” from DNA to the cellular machinery responsible for protein synthesis. In this case, the mRNA temporarily replaced the missing or malfunctioning genetic instruction, allowing the production of the proteins necessary for sperm formation to resume. The mRNA did not integrate into the genome or alter the DNA, which was confirmed through genetic analysis.

According to the authors, this technology could become the basis for a new therapy for genetically caused male infertility. In the future, the method may be adapted to restore fertility in humans suffering, for example, from non-obstructive azoospermia—one of the most severe forms of impaired spermatogenesis.