Impaired fertility in adenomyosis: a murine model reveals endometrial receptivity and progesterone resistance imbalances.

In brief: The impact of adenomyosis on reproductive health needs to be fully understood. By using a murine model, this study provides novel insights into the nuanced mechanisms associated with fertility challenges and offers a foundation for targeted interventions. Abstract: This study investigates the intricate relationship between adenomyosis and reproductive health using a murine model, offering novel insights into this prevalent gynecological disorder. Adenomyosis, characterized by the invasive growth of endometrial tissue into the myometrium, is believed to negatively impact fertility. However, the challenge lies in disentangling this influence, as adenomyosis often coexists with other gynecological diseases. A tamoxifen-induced mice model presents a significant advantage by enabling the specific study of adenomyosis, devoid of confounding influences of concurrent gynecological diseases such as endometriosis. Focusing exclusively on adenomyosis, our study aims to elucidate pathogenic mechanisms underlying fertility issues, focusing on estrous cyclicity, ovarian follicle development, and overall fertility. Our findings uncover disruptions in estrous cyclicity, characterized by an increased duration of time spent in the estrus phase in adenomyosis-induced mice. These disturbances are potentially linked to observed compromised folliculogenesis and the remarkable reduction in litter number and size in mice affected by adenomyosis. Moreover, this study unveils potential drivers of subfertility such as progesterone resistance and altered endometrial receptivity. Within the uteri of mice with adenomyosis, reduced expression of the progesterone receptor and a decreased expression of two implantation-related markers (HoxA10 and integrin ß3) were observed. This comprehensive examination sheds light on the nuanced complexities of adenomyosis-associated reproductive challenges, providing a foundation for targeted interventions in addressing fertility issues related to this disease.

The mTOR Inhibitor Rapamycin Counteracts Follicle Activation Induced by Ovarian Cryopreservation in Murine Transplantation Models.

Background and Objectives: Ovarian tissue cryopreservation followed by autotransplantation (OTCTP) is currently the only fertility preservation option for prepubertal patients. Once in remission, the autotransplantation of frozen/thawed tissue is performed when patients want to conceive. A major issue of the procedure is follicular loss directly after grafting mainly due to follicle activation. To improve follicular survival during the OTCTP procedure, we inhibited the mTOR pathway involved in follicle activation using rapamycin, an mTOR inhibitor. Next, we compared two different in vivo models of transplantation: the recently described non-invasive heterotopic transplantation model between the skin layers of the ears, and the more conventional and invasive transplantation under the kidney capsule. Materials and Methods: To study the effects of adding rapamycin during cryopreservation, 4-week-old C57BL/6 mouse ovaries, either fresh, slow-frozen, or slow-frozen with rapamycin, were autotransplanted under the kidney capsule of mice and recovered three weeks later for immunohistochemical (IHC) analysis. To compare the ear with the kidney capsule transplantation model, fresh 4-week-old C57BL/6 mouse ovaries were autotransplanted to either site, followed by an injection of either LY294002, a PI3K inhibitor, vehicle control, or neither, and these were recovered three weeks later for IHC analysis. Results: Rapamycin counteracts cryopreservation-induced follicle proliferation, as well as AKT and mTOR pathway activation, in ovaries autotransplanted for three weeks under the kidney capsule of mice. Analyses of follicle proliferation, mTOR activation, and the effects of LY294002 treatment were similar in transplanted ovaries using either the ear or kidney capsule transplantation model. Conclusions: By adding rapamycin during the OTCTP procedure, we were able to transiently maintain primordial follicles in a quiescent state. This is a promising method for improving the longevity of the ovarian graft. Furthermore, both the ear and kidney capsule transplantation models were suitable for investigating follicle activation and proliferation and pharmacological strategies.

Evaluation of an alternative heterotopic transplantation model for ovarian tissue to test pharmaceuticals improvements for fertility restoration.

BACKGROUND: Ovarian tissue cryopreservation and transplantation (OTCTP) is currently the main option available to preserve fertility in prepubertal patients undergoing aggressive cancer therapy treatments. However, a major limitation of OTCTP is follicle loss after transplantation. The mouse is a model of choice for studying ovarian function and follicle development after ovarian tissue grafting in vivo. In these mouse models, ovarian tissue or ovaries can be transplanted to different sites. Our aim was to evaluate a new alternative to heterotopic transplantation models that could be useful to test pharmaceutical improvement for ovarian grafts after OTCTP. METHODS: Slow frozen murine whole ovaries were transplanted into the mouse ears (between the external ear skin layer and the cartilage). Ovarian transplants were recovered after 3, 14 or 21 days. Grafts were analyzed by immunohistochemistry and follicle density analyses were performed. RESULTS: An increase of ovarian vascularization (CD31 and Dextran-FITC positive staining), as well as cellular proliferation (Ki67 staining) were observed 3 weeks after transplantation in comparison to 3 days. Fibrosis density, evaluated after Van Gieson staining, decreased 3 weeks after transplantation. Furthermore, transplantation of cryopreserved ovaries into ovariectomized mice favored follicle activation compared to transplantation into non-ovariectomized mice. CONCLUSION: The present study indicates that surgical tissue insertion in the highly vascularized murine ear is an effective model for ovarian grafting. This model could be helpful in research to test pharmaceutical strategies to improve the function and survival of cryopreserved and transplanted ovarian tissue.