Testicular mRNA-LNP Delivery: A Novel Therapy for Genetic Spermatogenic Disorders

Uniform testicular maturation arrest is a severe form of male infertility characterized by the presence of germ cells that do not complete spermatogenic development. It is usually caused by meiotic arrest with genetic variants and difficult to treat via drugs or surgery. mRNA-lipid nanoparticle (LNP) delivery is a promising therapeutic option for maturation arrest with monogenic variants via protein replacement therapy. Herein, a spermatocytes-tropic LNP (Pool1-LNP3) was identified via a library of 30 ionizable lipids screening. Andin vivodelivery of this novel LNP composition using rete testis microinjection was showed to be high spermatocytes targeting with high transfection efficiency. Thereafter, it was revealed thatin vivodelivery of Pool1-LNP3 encapsulatingMsh5mRNA could promote crossover formation and restore spermatogenesis inMsh5^D486Y/D486Ymouse models with DSB recombination defects. Notably, the offspring without genomic integration was born using intracytoplasmic sperm injection (ICSI) derived from rescue ofMsh5^D486Y/D486Ymouse and embryo transfer. Furthermore, no obvious inflammation and histologic damage in any tissue were detected afterin vivodelivery of mRNA-LNP. In addition, it was demonstrated thatMapsmRNA-LNP3 recovered spermatogenesis inMapsKO mouse with meiotic arrest. Altogether, these findings suggested that this spermatocytes-tropic mRNA-LNP delivery could become a viable and broad applicable strategy for treatment of spermatogenic disorders with genetic defects, providing a foundation for future clinical application.