Blastocyst development after cryopreservation and subcutaneous transplantation of mouse ovarian tissue

VEGF and FGF2 Improve Revascularization, Survival, and Oocyte Quality of Cryopreserved, Subcutaneously-Transplanted Mouse Ovarian Tissues

This study was conducted to investigate the effect of the vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) on revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue. Autologous subcutaneous transplantation of vitrified-thawed mouse ovarian tissues treated with (experimental group) or without (control group) VEGF and FGF2 was performed. After transplantation to the inguinal region for two or three weeks, graft survival, angiogenesis, follicle development, and oocyte quality were examined after gonadotropin administration. VEGF coupled with FGF2 (VEGF/FGF2) promoted revascularization and significantly increased the survival rate of subcutaneously-transplanted cryopreserved ovarian tissues compared with untreated controls. The two growth factors did not show long-term effects on the ovarian grafts. In contrast to the untreated ovarian grafts, active folliculogenesis was revealed as the number of follicles at various stages and of mature oocytes in antral follicles after gonadotropin administration were remarkably higher in the VEGF/FGF2-treated groups. Although the fertilization rate was similar between the VEGF/FGF2 and control groups, the oocyte quality was much better in the VEGF/FGF2-treated grafts as demonstrated by the higher ratio of blastocyst development. Introducing angiogenic factors, such as VEGF and FGF2, may be a promising strategy to improve revascularization, survival, and oocyte quality of cryopreserved, subcutaneously-transplanted mouse ovarian tissue.

The Increased Expression of Connexin and VEGF in Mouse Ovarian Tissue Vitrification by Follicle Stimulating Hormone

Ovarian follicular damages were caused by cryoinjury during the process of ovarian vitrification and ischemia/reperfusion during the process of ovarian transplantation. And appropriate FSH plays an important role in antiapoptosis during ovarian follicle development. Therefore, in this study, 0.3 IU/mL FSH was administered into medium during mouse ovarian cryopreservation by vitrification to ascertain the function of FSH on ovarian vitrification and avascular transplantation. The results suggested that the expressions of Cx37, Cx43, apoptotic molecular caspase-3, and angiogenesis molecular VEGF were confirmed using immunohistochemistry, western blotting, and real-time PCR, and the results suggested that the treatment with FSH remarkably increased the number of morphologically normal follicles in vitrified/warmed ovaries by upregulating the expression of Cx37, Cx43, VEGF, and VEGF receptor 2, but downregulating the expression of caspase-3. In addition, the vitrified/warmed ovaries were transplanted, and the related fertility was analyzed, and the results suggested that the fertility, neoangiogenesis, and follicle reserve were remarkably increased in the FSH administrated group. Taken together, administration of 0.3 IU/mL FSH during ovarian cryopreservation by vitrification can maintain ovarian survival during ovarian vitrification and increases the blood supply with avascular transplantation via upregulation of Cx43, Cx37, and VEGF/VEGFR2, as well as through its antiapoptotic effects.

Live offspring from vitrified blastocysts derived from fresh and cryopreserved ovarian tissue grafts of adult mice

Ovarian tissue cryopreservation and transplantation can be used to preserve fertility for cancer patients. In this study, we assessed the viability and function of ovarian tissue from adult mice that was cryopreserved by solid surface vitrification or traditional slow-cooling using variousin vitroandin vivotechniques, including allotransplantation,in vitrooocyte maturation, embryo culturein vitro, blastocyst cryopreservation, embryo transfer, and development. The importance of cumulus cells for oocyte maturation, fertilization, and embryo development was investigated. Graft recovery, follicle survival, and oocyte retrieval was similar in control, vitrified, and slow-cooled groups. High rates of oocyte maturation, cleavage, and blastocyst formation were achieved, with no significant differences between the control, vitrified or slow-cooled ovarian tissue grafts. The presence of cumulus cells was important for oocyte maturation, fertilization, and subsequent development. Cumulus–oocyte complexes with no surrounding cumulus cells (N-COCs) or with an incomplete layer (P-COCs) had significantly lower rates of oocyte maturation and blastocyst formation than cumulus–oocyte complexes with at least one complete layer of cumulus cells (F-COCs; maturation rate: 63, 78 vs 94%; blastocyst rate: 29, 49 vs 80%). Live births were achieved using vitrified blastocysts derived from oocytes taken from vitrified and slow-cooled ovarian tissue heterotypic allografts. Successful production of healthy offspring from these vitrified blastocysts suggests that this technique should be considered as a useful stage to pause in the assisted reproduction pathway. This provides an alternative protocol for restoring fertility and offering cancer patients a better indication of their chances of pregnancy and live birth.

Abnormally low expression of connexin 37 and connexin 43 in subcutaneously transplanted cryopreserved mouse ovarian tissue

PURPOSE

To analyze the gap junction proteins connexin 37 (Cx37) and connexin 43 (Cx43) after subcutaneous transplantation of cryopreserved mouse ovarian tissue.

METHODS

Expression of gap junction genes was assessed by immunohistochemistry and real-time polymerase chain reaction (PCR) in transplanted cryopreserved ovarian tissue compared with that of normal ovarian tissue. Apoptosis of ovarian cells was evaluated by using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling method.

RESULTS

After subcutaneous transplantation, Cx37 and Cx43 mRNA and protein expression were significantly lower in cryopreserved than in normal ovarian tissue. Apoptosis was increased in granulosa cells from antral follicles of the cryopreserved tissue.

CONCLUSION

After cryopreservation and subcutaneous transplantation of ovarian tissue, proteins forming gap junctions between oocytes and granulosa cells are under-expressed compared with normal controls.

Normal developmental competence to the blastocyst stage is preserved in rabbit ovarian tissue following cryopreservation and autografting to the mesometrium

The aim of the present study was to evaluate mesometrial autotransplantation of frozen–thawed ovarian tissue in the adult rabbit and investigate the developmental competence of oocytes retrieved from grafts by in vitro maturation, fertilisation and blastocyst formation. Twenty-five rabbits were divided into control, fresh tissue transplantation and frozen–thawed tissue transplantation groups. Rabbits were stimulated with follicle-stimulating hormone (FSH) and oocytes were retrieved 3 months after transplantation. Oocytes matured in vivo or in vitro were then fertilised by conventional in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI), followed by observation and evaluation of fertilisation and blastocyst formation rates. No significant differences were found in the percentage of oocytes, maturation, fertilisation, cleavage and blastocyst formation among the three groups. Significantly higher fertilisation rates of in vitro-matured (IVM) oocytes were observed with ICSI compared with IVF in each group (81.1% v. 58.5%, 79.2% v. 59.6% and 80.4% v. 56.0% in the control, fresh tissue transplantation and frozen–thawed tissue transplantation groups, respectively). The blastocyst formation rate of IVM oocytes was significantly lower than that of in vivo-matured oocytes in each group (25.5% v. 65.7%, 22.4% v. 61.8% and 28.9% v. 63.0% in the control, fresh tissue transplantation and frozen–thawed tissue transplantation groups, respectively). In concusion, the mesometrium is a promising site for ovarian autografts in the rabbit. Oocytes retrieved from mesometrial grafts can develop to the blastocyst stage.

Preservation of female germ cells from ovaries of cat species

This review provides an overview on recent knowledge on female germ cell population within cat ovaries; on isolation, culture and cryopreservation of feline preantral follicles and on ovarian tissue preservation.