Cryopreservation of intact human ovary with its vascular pedicle--or cryopreservation of hemiovaries?

Successful fertility following optimized perfusion and cryopreservation of whole ovary and allotransplantation in a premature ovarian insufficiency rat model

Background

Fertility preservation by whole ovary cryopreservation and transplantation (WOCP&TP) with vascular anastomosis requires successful cryopreservation. In this study, we investigated the possibility of restoring ovarian function and natural fertility after WOCP&TP in a premature ovarian insufficiency (POI) rat model. The influence of cryopreservation on the offspring of rats following WOCP&TP was also explored.

Method

Rats aged 8-10 weeks were used as donors and recipients for allotransplantation. Fifteen rat whole ovaries were divided into three groups: the optimized group, the conventional group, and the fresh group. Different perfusion modes were used before cryopreservation and after thawing. Whole ovaries were observed by morphologic analysis, immunohistochemical staining, and transferase-mediated deoxyuridine triphosphate nick end-labeling assay. Ovarian function and fertility after WOCP&TP were then observed in 25 cyclophosphamide-induced POI rats for 8 months. Ovarian function was assessed by vaginal smears and blood hormone levels. Fertility restoration was quantified as the live birth rate after mating. The filial generation of rats was mated at 8-10 weeks of age. Offspring were observed for birth defect.

Results

Histological evaluation demonstrated intact morphology of follicles in all groups, with 77.6% of the total number of follicles identified as intact in the optimized group. The apoptotic rates of ovarian cells in the optimized group were significantly lower than that in the conventional group. Of the 20 live POI rats, 14 (70%) began to recover ovarian function after 2 weeks of transplantation, with normal hormone levels achieved 4 weeks after transplantation. Four of 14 rats were pregnant and delivered live offspring. One rat had a second pregnancy and delivered a second litter of live offspring. When the offspring matured, they were mated, and second and third generations of rats were born. All offspring had no abnormalities in appearance.

Conclusions

High rates of restoration of ovarian function and natural fertility with multiple generations of offspring were obtained following WOCP&TP in a cyclophosphamide-induced POI rat model by utilizing optimized perfusion. Cryopreservation did not affect the viability of successive generations.

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.

Restoration of ovarian function and natural fertility following the cryopreservation and autotransplantation of whole adult sheep ovaries

STUDY QUESTION

Is it possible to restore ovarian function and natural fertility following the cryopreservation and autotransplantation of whole ovaries, complete with vascular pedicle, in adult females from a large monovulatory animal model species (i.e. sheep)?

SUMMARY ANSWER

Full (100%) restoration of acute ovarian function and high rates of natural fertility (pregnancy rate 64%; live birth rate 29%), with multiple live births, were obtained following whole ovary cryopreservation and autotransplantation (WOCP&TP) of adult sheep ovaries utilizing optimized cryopreservation and post-operative anti-coagulant regimes.

WHAT IS KNOWN ALREADY

Fertility preservation by WOCP&TP requires successful cryopreservation of both the ovary and its vascular supply. Previous work has indicated detrimental effects of WOCP&TP on the ovarian follicle population. Recent experiments suggest that these deleterious effects can be attributed to an acute loss of vascular patency due to clot formation induced by damage to ovarian arterial endothelial cells.

STUDY DESIGN, SIZE, DURATION

Study 1 (2010–2011; N = 16) examined the effect of post-thaw perfusion of survival factors (angiogenic, antioxidant, anti-apoptotic; n = 7–8) and treatment with aspirin (pre-operative versus pre- and post-operative (n = 7–9)) on the restoration of ovarian function for 3 months after WOCP&TP. Study 2 (2011–2012; N = 16) examined the effect of cryoprotectant (CPA) perfusion time (10 versus 60 min; n = 16) and pre- and post-operative treatment with aspirin in combination with enoxaparine (Clexane^®; n = 8) or eptifibatide (Integrilin^®; n = 8) on ovarian function and fertility 11–23 months after WOCP&TP.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Both studies utilized mature, parous, Greyface ewes aged 3–6 years and weighing 50–75 kg. Restoration of ovarian function was monitored by bi-weekly blood sampling and display of behavioural oestrus. Blood samples were assayed for gonadotrophins, progesterone, anti-Müllerian Hormone and inhibin A. Fertility restoration in Study 2 was quantified by pregnancy rate after a 3 month fertile mating period and was confirmed by ultrasound, hormonal monitoring and live birth. Ovarian function was assessed at sacrifice by ovarian appearance and vascular patency (Doppler ultrasound) and by follicular histology.

MAIN RESULTS AND THE ROLE OF CHANCE

In Study 1, survival factors were found to have no benefit, but the inclusion of pre-operative aspirin resulted in four ewes showing acute restoration of ovarian function within 3 weeks and a further six ewes showing partial restoration. The addition of post-operative aspirin alone had no clear benefit. In Study 2, combination of aspirin with additional post-operative anti-coagulants resulted in total acute restoration of ovarian function in 14/14 ewes within 3 weeks of WOCP&TP, with 9/14 ewes becoming pregnant and 4/14 giving birth to a total of seven normal lambs. There was no difference between anti-coagulants in terms of restoration of reproductive function and fertility. In contrast, the duration of CPA perfusion was highly significant with a 60 min perfusion resulting in ovaries of normal appearance and function with high rates of primordial follicle survival (70%) and an abundant blood supply, whereas ovaries perfused for 10 min had either resorbed completely and were vestigial (7/14) or were markedly smaller (P < 0.01). It is concluded that both the degree of CPA penetration and the maintenance of post-operative vascular patency are critical determinants of the success of WOCP&TP.

LIMITATIONS, REASONS FOR CAUTION

Before application of this technology to fertility preservation patients, it will be critical to optimize the CPA perfusion time for different sized human ovaries, determine the optimum period and level of anti-coagulant therapy, and confirm the normality of offspring derived from this procedure.

WIDER IMPLICATIONS OF THE FINDINGS

This technology holds promise for the preservation of fertility in women. It could also potentially be applied to the cryopreservation of other reproductive or even major organs (kidneys) where there are considerable difficulties in storing donated tissue.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was received from the Medical Research Council, University of Nottingham. The authors confirm that they have no conflict of interest in relation to this work.

Cancer and fertility preservation: Barcelona consensus meeting

Improvements in early diagnosis and treatment strategies in cancer patients have enabled younger women with cancer to survive. In addition to the stressful event of the diagnosis, patients with malignant diseases face the potential loss of the opportunity to have children. Preservation of fertility has become a challenging issue and it is still surrounded by controversies. On the basis of available evidence, a group of experts reached a consensus regarding the options for trying to preserve fertility in women with cancer: among established methods, in postpubertal women, oocyte cryopreservation is the preferred option, whereas ovarian tissue cryopreservation is the only possibility for prepubertal girls. Combining several strategies on an individual basis may improve the chances of success. Realistic information should be provided before any intervention is initiated. Counseling should offer support for patients and provide better care by understanding emotional needs, psychological predictors of distress and methods of coping. Early referral to the fertility specialist is essential as fertility preservation (FP) may improve quality of life in these patients. The information summarized here is intended to help specialists involved in the treatment of cancer and reproductive medicine to improve their understanding of procedures available for FP in young cancer patients.

Concise review: fertility preservation: an update

Fertility preservation is an emerging field in medicine that enables men, women, and children to maintain reproductive health when it is threatened by gonadotoxic treatment. Patients affected by other nononcologic malignancies that can impair spermatogenesis and ovogenesis can also benefit from fertility preservation treatments. Age-related infertility can also be overcome by cryopreserving gametes or embryos. The only established methods for fertility preservation in male patients are sperm cryopreservation in postpubertal age and experimental testicular tissue cryopreservation in prepubertal age. In adult women, oocyte cryopreservation is the preferred option, whereas ovarian tissue cryopreservation is the only possibility for prepubertal girls. Fertility preservation treatments must be addressed through a multidisciplinary approach that involves gynecologists, urologists, oncologists, pediatricians, and professionals in the field of medically assisted reproduction to work in coordination to provide patients with counseling and comprehensive information about fertility issues.

Orthotopic and heterotopic ovarian tissue transplantation

BACKGROUND

Transplantation of ovarian tissue is, at present, the only clinical option available to restore fertility using cryopreserved ovarian tissue. More than 30 transplantations of cryopreserved tissue have been reported, and six babies have been born, worldwide, following this procedure. Despite these encouraging results, it is essential to optimize the procedure by improving the follicular survival, confirming safety and developing alternatives. Here, we review the different factors affecting follicular survival and growth after grafting.

METHODS

Relevant studies were identified by searching Pubmed up to January 2009 with English language limitation. The following key words were used: (ovarian tissue or whole ovary) AND (transplantation) AND (cryopreservation or pregnancy). Using the literature and personal experience, we examined relevant data on the different exogenous and clinical factors affecting follicular development after grafting.

RESULTS

Clinical factors such as the patient's age and the transplantation sites influenced the lifespan of the graft. A heterotopic transplantation site is not optimal but offers some advantages and it may also promote the hormonal environment after a combined heterotopic and orthotopic transplantation. Exogenous factors such as antioxidants, growth factors or hormones were tested to improve follicular survival; however, their efficiency regarding further follicular development and fertility potential remains to be established.

CONCLUSION

Additional evidence is required to define optimal conditions for ovarian tissue transplantation. Alternatives such as whole ovary or isolated follicles transplantations require further investigation but are likely to be successful in humans in the future.

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.