In vitro system completely restores oogenesis in congenitally infertile mice

Area of Science:

• Reproductive biology
• Gene therapy
• Ovarian function

Background:

• In vivo gene delivery for infertile mouse models faces challenges like low efficiency and safety concerns.
• Complete functional restoration of gene deficiencies via in vitro oogenesis has not been previously reported.

Purpose of the Study:

• To investigate the efficacy of in vitro systems combined with transient gene expression or factor supplementation to restore fertility in congenitally infertile mice.
• To establish a controllable in vitro platform for fertility restoration without permanent genomic modification.

Main Methods:

• Adeno-associated virus (AAV) vectors expressing Kitl or recombinant KITL protein were used to treat KitlSl-t/KitlSl-t mouse ovaries in vitro.
• Ovaries were cultured to promote follicle development, followed by in vitro maturation (IVM) and in vitro fertilization (IVF) of oocytes.
• Offspring were assessed for AAV integration and fertility.

Main Results:

• AAV8-Kitl and recombinant KITL supplementation effectively promoted primordial follicle activation and secondary follicle formation in infertile mouse ovaries.
• Over 10% of fertilized oocytes developed to term, and all offspring were fertile with no detectable AAV DNA integration.
• Specific AAV serotypes (AAV8, AAV9, AAVrh.10, AAVrh.32.33) showed higher expression efficiency in wild-type ovaries.

Conclusions:

• Transient gene expression or factor supplementation in vitro can completely restore fertility in a mouse model of congenital infertility.
• This study presents a novel platform for studying gene function in oogenesis, modeling reproductive disorders, and developing fertility restoration strategies.
• The applicability of this in vitro oogenesis approach to other species, including humans, requires further investigation.