Researchers from The University of Osaka in collaboration with Baylor College of Medicine have developed a new therapy for a severe form of male infertility called non-obstructive azoospermia (NOA). Using lipid nanoparticles (LNPs) to deliver specific mRNA into the testes of infertile mice, they were able to restart sperm production. The sperm produced were then used in intracytoplasmic sperm injection (ICSI) to successfully generate healthy and fertile offspring. The findings provide a crucial proof-of-concept for treating male infertility caused by genetic defects.