Application of Sendai virus-“Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice”

    The study demonstrates that Sendai virus (SeV), despite its immunogenicity, can be successfully used for infertility treatment in mice. By microinjecting SeV into ovaries, researchers restored fertility in congenitally infertile KitlSl-t/KitlSl-t mice, which lack Kitl gene expression. The virus also protected against chemotherapy-induced infertility. SeV’s RNA-based mechanism avoids genome integration risks, making it a promising tool for future infertility treatments. These findings suggest SeV's potential for treating female infertility, especially in cases related to genetic conditions and cancer therapy.

Results

Introduction of SeVs into wild-type ovaries

    

（PNAS Nexus, Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice）
     Despite the high immunogenicity of Sendai viruses (SeVs), injecting SeV-Egfp into wild-type mouse ovaries did not trigger significant inflammatory responses. Real-time PCR and histological analyses showed no increase in typical inflammatory markers or tissue damage. Furthermore, immunostaining revealed no notable infiltration of CD4 or CD8 lymphocytes in the ovaries. This suggests that the ovaries may provide a unique immune environment, preventing severe immune reactions even when infected by SeV, making SeV a potentially viable option for infertility treatment.

Defective blood-follicle barrier in KitlSl-t/KitlSl-t mice

Introduction of Kitl genes into wild-type ovaries

（PNAS Nexus, Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice）
    SeV-Kitl injection successfully restored fertility in mice without significant adverse effects. Despite concerns about Kitl overexpression potentially disrupting oogenesis or causing tumorigenesis, there were no significant differences in offspring production, ovary size, or apoptosis between the SeV-Kitl and control groups. Histological analyses confirmed normal oogenesis, and PCR results indicated no integration of viral genes into the genome of offspring. These findings suggest that SeV-Kitl allows safe and effective restoration of fertility without the risk of gene integration into germline cells.

Induction of oogenesis in Kitl^Sl-t/Kitl^Sl-t mice
（PNAS Nexus, Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice）

    SeV-Kitl microinjection into KitlSl-t/KitlSl-t mice successfully restored oogenesis and enabled fertility in a portion of the mice. The Kitl overexpression led to a 10.1-fold increase in expression, promoting follicle development and resulting in healthy offspring. Hormonal levels, despite showing no significant changes, did not prevent ovulation and pregnancy. Long-term oogenesis was sustained, although fewer follicles developed compared to wild-type mice, resulting in smaller litter sizes. Overall, SeV-Kitl proved effective in rescuing and maintaining fertility in this infertility model.

Restoration of infertility in busulfan-treated mice

（PNAS Nexus, Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice）
    SeV-Kitl is effective in protecting fertility in mice subjected to busulfan-induced infertility, a common side effect of cancer treatment. Mice treated with SeV-Kitl regained fertility in 70% of cases, whereas no control mice (SeV-Egfp) produced offspring. Histological analysis revealed that ovaries injected with SeV-Kitl were larger and contained more developing follicles and corpus luteum, indicating successful ovulation. These results demonstrate that SeV-Kitl can protect fertility and promote follicle development following cancer treatment.

Analysis of offspring

（PNAS Nexus, Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice）
    SeV-Kitl treatment in KitlSl-t/KitlSl-t mice does not lead to abnormal genomic imprinting in offspring, as demonstrated by the normal DNA methylation patterns in key imprinted genes. However, metabolic analysis revealed elevated glucose and HDL levels in offspring, indicating possible metabolic abnormalities. Despite these changes, the offspring remained fertile and produced F2 and F3 generations. The study suggests that SeV-Kitl therapy can restore fertility without major imprinting issues, though potential metabolic effects warrant further investigation.

Discussion
    The study concludes that Sendai virus (SeV)-mediated gene therapy offers a promising approach for treating both congenital and chemotherapy-induced infertility. By avoiding the risk of viral genome integration, SeVs present a safer option compared to other viral vectors like AAVs, AVs, or LVs. The therapy was effective in promoting oogenesis and restoring fertility in mouse models without triggering strong immune responses or significant inflammation. However, some metabolic abnormalities were observed in offspring, suggesting the need for further studies to assess long-term effects and potential clinical applications.

 
Link:Sendai virus-mediated RNA delivery restores fertility to congenital and chemotherapy-induced infertile female mice | PNAS Nexus | Oxford Academic (oup.com)

  We have developed an F-defective Sendai virus and are currently working on reducing its immunogenicity to replace lentiviral vectors. We welcome interested clients to contact us for collaboration on this technology.