Heterotopic autotransplantation of vitrified mouse ovary

Two-Decade Experience of Royan Institute in Obtaining Mature Oocyte from Cryopreserved Ovarian Tissue: In Vitro and In Vivo Approaches

Ovarian tissue cryopreservation (OTC) holds promise for preservation of fertility among women who have lost their fertility due to diseases such as cancer. OTC has significantly assisted such cases by helping them maintain normal hormonal levels and menstrual cycles. Appropriate strategies to develop and extract mature oocytes from OTC could overcome a range of complications that are associated with ovarian dysfunction, caused by aging, and primary or secondary ovarian insufficiency. Scientists from different departments at The Royan Institute (Tehran, Iran) have been conducting studies to find the best way to extract mature oocytes from animal and human cryopreserved ovarian tissues. The various studies conducted in this area in the past 20 years, by researchers of the Royan Institute, are collated and provided in this review, in order to provide an idea of where we are now in the area of fertility preservation.

An in vitro study on oocyte and follicles of transplanted ovaries treated with vascular endothelial growth factor

OBJECTIVE

Retrieval of high quality follicles and oocytes from transplanted ovaries is essential for higher fertility preservation efficiency. The effect of vascular endothelial growth factor (VEGF) was evaluated on the survival rate of preantral follicles following ovarian transplantation.

MATERIAL AND METHODS

Prepubertal female mice were divided to 6 groups including: control (C), transplanted with no VEGF treatment (T) and transplanted with different dosages of VEGF [0.5 µg/mL (TV1), 1 µg/mL (TV2), 2 µg/mL (TV3), and 4 µg/mL (TV4)]. Twenty-one days later, the left ovaries were removed and transplanted on gluteal muscle. Each dose was injected directly into transplanted ovary. Twenty-one days after transplantation, the ovaries were taken, and follicles and cumulus-oocyte-complexes (COCs) were released using 26-gauge needles with a stereo microscope. The number of healthy COCs, matured oocytes, and in vitro developed embryos after fertilization in vitro were evaluated to determine the best dose of VEGF. Follicle number and follicular growth was evaluated relative to the dose of VEGF provided. Transplantation and VEGF treatment with the best dose was performed as mentioned above and in vitro follicle growth in transplanted ovaries was compared with opposite ovaries (OPP).

RESULTS

COC retrieval was significantly lower in the transplanted groups compared with the control group (p<0.05). The percentage of metaphase II oocytes was significantly lower in the group treated with 4 µg/mL VEGF compared with the controls (p<0.01). In the TV2 (1 µg/mL) and TV3 (2 µg/mL) groups, the percentages of morula and blastocysts were significantly improved compared with the T group (p<0.01). In the OPP group, the number of follicles was significantly higher compared with the transplanted groups (p<0.01).

CONCLUSION

The improving effect of VEGF on in vitro maturation and in vitro development outcome indicates that VEGF administration may increase transplantation efficiency for fertility preservation.

Assessment of DNA damage in goat preantral follicles after vitrification of the ovarian cortex

Effective methods for gamete preservation should have low impact on DNA integrity. The present study investigated the effects of vitrification of goat ovarian tissues on the occurrence of DNA fragmentation and DNA double-stand breaks using the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labelling (TUNEL) assay and detection of phosphorylated histone H2AX (γH2AX), respectively. Goat ovaries were collected at a local abattoir and 12 tissue fragments were prepared from each ovarian pair. Tissue fragments were used as fresh control samples or were cultured in vitro, vitrified or vitrified and cultured. Vitrification was performed using the Ovarian Tissue Cryosystem. Fragments from all groups (control and treatments) were processed for histology, transmission electron microscopy, TUNEL assay and immunofluorescence. Compared with fresh control samples, a lower percentage of morphologically normal follicles was detected in the vitrification followed by culture treatment group (P<0.05). Normal follicular ultrastructure was observed in all groups. Immunofluorescence revealed the presence of γH2AX foci in few oocytes and ovarian stromal cells. TUNEL-positive follicles were found in samples without significant differences among groups (P>0.05). In conclusion, the vitrification protocol used in the present study did not increase DNA damage in preantral follicles enclosed in goat ovarian tissues.

Effects of erythropoietin on ischemia, follicular survival, and ovarian function in ovarian grafts

Ovarian tissue transplantation is performed to preserve fertility in patients undergoing chemotherapy and radiotherapy. However, ischemia/reperfusion (IR) injury and free radical production occurring during the revascularization of the transplanted tissue are the major limitations of this procedure. The aim of this study was to investigate the effect of erythropoietin (EPO) as an antioxidant on oxidative stress and ovary survival following transplantation. The Naval Medical Research Institute (NMRI) mice (4–5 weeks old) were divided into three groups (six mice per group): control; autograft+saline, and autograft+EPO (500 IU/kg i.p.). After 28 days, ovary compartments were estimated stereologically. DNA fragmentation and plasma malondialdehyde (MDA), progesterone, and estradiol (E2) concentrations were also evaluated. The results were analyzed using one-way ANOVA and Tukey's test, and the means were significantly different at P<0.05. The mean total volume of ovary, cortex, and medulla and the number of follicles increased significantly in the autograft+EPO group (P<0.01). Apoptosis rate in the autograft+EPO group was lower than that in the autograft+saline group. The concentration of MDA decreased significantly in the autografted EPO-treated group than in the autografted saline-treated group (P<0.01). The concentration of E2 increased significantly in the autograft+EPO group than in the autograft+saline group (P<0.01). EPO reduced IR injury, increasing follicle survival and function in grafted ovaries.

Free Persian abstract

A Persian (Farsi) translation of the abstract is freely available online at http://www.reproduction-online.org/content/147/5/733/suppl/DC1

In vitro maturation, fertilization and embryo culture of oocytes obtained from vitrified auto-transplanted mouse ovary

BACKGROUND

The purpose of this study was to investigate the in vitro survival and developmental potential of oocytes obtained from vitrified mouse ovaries transplanted to a heterotopic site.

MATERIALS AND METHODS

In this experimental study, two-week-old mice were unilaterally ovariectomized after anesthesia. The ovaries were vitrified by cryotop. After two weeks, the ovaries were thawed and autotransplanted to the gluteus muscle tissue. Three weeks later the mice were killed, after which we removed and dissected the transplanted and opposite right ovaries. Cumulus oocyte complexes (COCs) and denuded oocytes were evaluated for in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro development (IVD). The control group consisted of sevenweek- old age-matched mice ovaries.

RESULTS

All vitrified-transplanted (Vit-trans) ovaries contained some oocytes that survived. Following IVM, IVF and IVD, there were 41.7% out of 12 cultured zygotes that reached the 8-cell stage.

CONCLUSION

Our experiment supports the progressive role of long-term graft survival after wholeovarian cryopreservation by vitrification and subsequent heterotopic transplantation. It is possible to recover viable follicles and oocytes that have the ability to develop in vitro.