AAV-mediated gene therapy restores natural fertility and improves physical function in the Lhcgr-deficient mouse model of Leydig cell failure

Leydig cell failure (LCF) caused by gene mutations leads to testosterone deficiency, infertility and reduced physical function. Adeno-associated virus serotype 8 (AAV8)-mediated gene therapy shows potential in treating LCF in the Lhcgr-deficient (Lhcgr^−/−) mouse model. However, the gene-treated mice still cannot naturally sire offspring, indicating the modestly restored testosterone and spermatogenesis in AAV8-treated mice remain insufficient to support natural fertility. Recognizing this, we propose that enhancing gene delivery could yield superior results. Here, we screened a panel of AAV serotypes through in vivo transduction of mouse testes and identified AAVDJ as an impressively potent vector for testicular cells. Intratesticular injection of AAVDJ achieved markedly efficient transduction of Leydig cell progenitors, marking a considerable advance over conventional AAV8 vectors. AAVDJ-Lhcgr gene therapy was well tolerated and resulted in significant recovery of testosterone production, substantial improvement in sexual development, and remarkable restoration of spermatogenesis in Lhcgr^−/− mice. Notably, this therapy restored fertility in Lhcgr^−/− mice through natural mating, enabling the birth of second-generation. Additionally, this treatment led to remarkable improvements in adipose, muscle, and bone function in Lhcgr^−/− mice. Collectively, our findings underscore AAVDJ-mediated gene therapy as a promising strategy for LCF and suggest its broader potential in addressing various reproductive disorders.