The effects of fibroblast co-culture and activin A on in vitro growth of mouse preantral follicles

Restoring Ovarian Fertility and Hormone Function: Recent Advancements, Ongoing Efforts and Future Applications

The last 20 years have seen substantial improvements in fertility and hormone preservation and restoration technologies for a growing number of cancer survivors. However, further advancements are required to fill the gaps for those who cannot use current technologies or to improve the efficacy and longevity of current fertility and hormone restoration technologies. Ovarian tissue cryopreservation (OTC) followed by ovarian tissue transplantation (OTT) offers those unable to undergo ovarian stimulation for egg retrieval and cryopreservation an option that restores both fertility and hormone function. However, those with metastatic disease in their ovaries are unable to transplant this tissue. Therefore, new technologies to produce good-quality eggs and restore long-term cyclic ovarian function are being investigated and developed to expand options for a variety of patients. This mini-review describes current and near future technologies including in vitro maturation, in vitro follicle growth and maturation, bioprosthetic ovaries, and stem cell applications in fertility restoration research by their proximity to clinical application.

Improvement of Mouse Preantral Follicle Survival and Development following Co-Culture with Ovarian Parenchyma Cell Suspension

BACKGROUND

The parallel and continued improvements in both infertility treatment and the management of malignancy cases have brought to the forefront the potential for fertility preservation. Using ovarian follicular resources can effectively improve reproductive capacity and prevent infertility. The primary aim of this research was to try to generate an appropriate in vivo environment for the growth of the mouse follicles. Hence, the possible effects of the ovarian parenchyma cell suspension were explored on the growth and maturation of preantral follicles in vitro.

MATERIALS AND METHODS

In this experimental study, ovarian parenchymal cells were mechanically dissociated from preantral follicles of 12-14 days-old NMRI mice and then divided into 5 experimental groups (G1: Control, G2: Fresh follicle with fresh parenchyma cell suspension, G3: Vitrified-warmed follicle with fresh parenchyma cell suspension, G4: Fresh follicle with frozen-thawed parenchyma cell suspension, and G5: Vitrified-warmed follicle with frozenthawed parenchyma cell suspension). The diameter of the follicles and immature oocytes, viability, antrum formation, resumption of meiosis, in vitro fertilization (IVF), and Gdf9, Bmp6, and Bmp15 gene expression were examined on different periods.

RESULTS

The diameter of the follicles and the oocytes on days 4 and 8, as well as the survival rate of the follicles up to day 12, were significantly higher in G2 and G4 compared to the Ctrl group (G1: 73.66%, G2:87.99%, G3: 82.70%, G4: 94.37%, and G5: 78.59%). Expression of growth marker genes for G3, and G5 groups was significantly higher than other groups, which indicated the protective effects of parenchyma cell suspension on follicles damaged by vitrification solutions.

CONCLUSION

The growth, survival, and maturation of preantral follicles could be enhanced by co-culturing them with ovarian parenchyma cells. Further studies are needed to optimize the conditions for a successful parenchyma cell suspension-induced in vitro maturation (IVM) to occur in infertility clinics.

The role of FSH and TGF-β superfamily in follicle atresia

Most of the mammalian follicles undergo a degenerative process called “follicle atresia”. Apoptosis of granulosa cells is the main characteristic of follicle atresia. Follicle stimulating hormone (FSH) and the transforming growth factor β (TGF-β) superfamily have important regulatory functions in this process. FSH activates protein kinase A and cooperating with insulin receptor substrates, it promotes the PI3K/Akt pathway which weakens apoptosis. Both Smad or non-Smad signaling of the transforming growth factor β superfamily seem to be related to follicle atresia, and the effect of several important family members on follicle atresia is concluded in this article. FSH and TGF-β are likely to mutually influence each other and what we have already known about the possible underlying molecular mechanism is also discussed below.

Effect of Fetal Mouse Lung Tissue Co-Culture on In Vitro Maturation of Mouse Immature Oocytes

OBJECTIVES

The aim of this study was to evaluate the fetal mouse lung tissue co-culture on in vitro maturation (IVM) of mouse immature oocytes.

MATERIALS AND METHODS

In this experimental study, germinal vesicle (GV) oocytes from ovaries of a group of 25 female mice, 6-8 weeks of age, were dissected after being stimulated by 7.5 IU pregnant mare serum gonadotropin (PMSG) through an intraperitoneal (IP) injection. The fetal lung tissues were then prepared and cultured individually. A total number of 300 oocytes were cultured in the following three groups for 24 hours: control group (n=100) containing only base medium, group I (n=100) containing base medium co-cultured with 11.5- to 12.5-day old fetal mouse lung tissues, and group II (n=100) containing base medium co-cultured with 12.5- to 13.5-day old fetal mouse lung tissues. The proportion of GV and metaphase І (MI) oocytes matured into MІІ oocytes were compared among the three groups using analysis of variance (ANOVA). Correlation test were also used to evaluate the successful rate of IVM oocytes.

RESULTS

The proportions of GV oocytes reaching MІІ stage were 46, 65, and 56%, in control, I and II groups, respectively (P<0.05). The percentage of the oocytes remaining at the GV stage were higher in control group as compared with two treatment groups (P<0.05).

CONCLUSIONS

This study indicated that fetal mouse lung tissue co-culture method increased the percentage of GV oocytes reaching MII stage.