Follicular growth after xenotransplantation of cryopreserved/thawed human ovarian tissue in SCID mice: dynamics and molecular aspects

Purpose

To study the influence of xenotransplantation on follicular recruitment and growth in cryopreserved/thawed human ovarian tissue.

Method

Two 3-mm pieces of cryopreserved/thawed human ovarian tissue obtained from female cancer patients (n = 11) were xenotransplanted into a subcutaneous neck pouch of 6-week-old ovarectomized SCID mice (n = 33) for 4 (n = 18) and 12 (n = 15) weeks.

Result

Thirty-two out of 33 mice survived the entire observation periods. Graft recovery rate was 95.58 % (65 of 68 grafts). The percentages of primordial follicles after 4 weeks (P < 0.001) and 12 weeks (P = 0.009) of grafting were significantly lower in comparison to pregraft controls. The percentage of secondary follicle was significantly higher after 4 weeks of grafting (P = 0.018) and after 12 weeks (P = 0.001) of grafting in comparison to pregraft controls. Ki67 immunohistochemistry showed that proliferative follicles were significantly higher after 4 and 12 weeks of grafting compared to pregraft controls (P < 0.001). All follicles analyzed by TUNEL staining appeared healthy after xenotransplantation. The expression level of PTEN was reduced by 2.47-fold after 4 weeks of xenotransplantation, and this result was significant when 2^−ΔCt were analyzed (P = 0.042).

Conclusion

The higher proportion of growing follicles compared to resting follicles observed after xenotransplantation is most likely due to downregulation of PTEN gene expression followed by acceleration of follicular recruitment.

Electronic supplementary material

The online version of this article (doi:10.1007/s10815-016-0769-2) contains supplementary material, which is available to authorized users.

Fertility preservation in cancer survivors

Due to the increasing number of long-term cancer survivors, physicians of all specialties are confronted with the need to prevent side effects of the applied oncologic treatments. In the field of reproductive medicine fertility preservation has gained importance as most oncologic treatments have detrimental immediate or long-term impacts on male and female fertility. The American Society of Clinical Oncology and the American Society for Reproductive Medicine, as well as the recently founded International Society for Fertility Preservation propose several established and investigational options for fertility preservation. This review aims to summarize currently available techniques for fertility preservation and future perspectives in this field, as well as to provide recommendations for patient follow-up after cancer and during pregnancy.

Novel dynamic culture system to support initiation of primordial follicle growth in prepubertal mouse ovaries

OBJECTIVE

To evaluate the impact of dynamic in vitro culture on initiation of early follicular growth in prepubertal mouse ovaries.

DESIGN

Ovaries from 8-day-old BALB/c mice were cultured either in a dynamic system (n=28) or in a static system (n=20) for 4 days. Uncultured 8-day-old (n=9) or 12-day-old (n=17) ovaries served as baseline or in vivo controls, respectively.

SETTING

Academic research center.

ANIMAL(S)

Newborn female BALB/c mice (n=37).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Histologic follicle classification and counting and assessment of follicular viability via immunofluorescent staining.

RESULT(S)

The percentage of secondary follicles after dynamic culture was identical to the 12-day-old in vivo control. In contrast, after static culture ovaries showed a significantly higher percentage of secondary follicles. For immunofluorescent viability assessment 6.78 follicles per ovary could be isolated after dynamic culture, whereas only 3.8 follicles per ovary could be isolated after static culture.

CONCLUSION(S)

Dynamic in vitro culture supports physiologic follicular growth initiation, comparable to that observed in vivo. In contrast, accelerated follicular growth was observed after static culture. These findings add additional evidence to the idea that dynamic culture might be a beneficial first step to initiate follicle growth in vitro within the context of fertility preservation.

Female fertility loss and preservation: threats and opportunities

BACKGROUND

Ovarian aging and cytotoxic treatments are the most common causes for fertility loss in women. With increasing numbers of young female survivors following cytotoxic cancer treatments, the issue of fertility preservation has assumed greater importance.

METHODS

We review the literature on the causes of female fertility loss as well as the recent advances in fertility preservation options and strategies that might be of interest to oncologists. Currently, several methods and techniques exist for fertility preservation of female patients with cancer including embryo freezing, ovarian protection techniques, oocyte cryopreservation, ovarian tissue cryopreservation followed by autotransplantation, and recently in vitro culture of ovarian tissue, follicles, and oocytes. Each method or technique has advantages and disadvantages related to current success rate, required delay in cancer treatment, sperm requirement, and risk of reintroducing cancer cells.

RESULTS

To date, embryo freezing is the only established method successfully and widely used for fertility preservation of female patients with cancer. The other methods are promising but still considered experimental.

CONCLUSION

Patient awareness, physician knowledge, early counseling, costs management, international registry, interdisciplinary networks, and research development are necessary to improve the current care in the field of female fertility preservation.