The impact of culture conditions on early follicle recruitment and growth from human ovarian cortex biopsies in vitro

New Insights on In Vitro Maturation of Oocytes for Fertility Preservation

In the last decade, the evolution of oncofertility has sparked a resurgence of interest in in vitro maturation (IVM) due to its suitability in certain oncological scenarios where controlled ovarian hyperstimulation may not be feasible. The retrieval of immature cumulus-oocyte complexes from small antral follicles, regardless of the menstrual cycle phase, presents a swift opportunity to vitrify mature oocytes or embryos post-IVM in urgent situations or when stimulation is not advisable. Harvesting immature cumulus-oocyte complexes and immature oocytes can be achieved transvaginally or directly in the laboratory from extracorporeal ovarian tissue. Although IVM has transitioned from an experimental status due to safety validations, it relies on the intricate process of oocyte maturation. Despite successful live births resulting from IVM in fertility preservation contexts, the comparatively lower developmental competence of in vitro matured oocytes highlights the necessity to enhance IVM culture systems. Recent advancements in IVM systems hold promise in bolstering oocyte competence post-IVM, thereby narrowing the gap between IVM and outcomes from ovarian stimulation. Additionally, for optimizing the chances of conception in cancer survivors, the combination of IVM and ovarian tissue cryopreservation stands as the favored choice when ovarian stimulation is unfeasible.

Enhanced solute transport and steady mechanical stimulation in a novel dynamic perifusion bioreactor increase the efficiency of the in vitro culture of ovarian cortical tissue strips

Introduction: We report the development and preliminary evaluation of a novel dynamic bioreactor to culture ovarian cortical tissue strips that leverages tissue response to enhanced oxygen transport and adequate mechanical stimulation. In vitro multistep ovarian tissue static culture followed by mature oocyte generation, fertilization, and embryo transfer promises to use the reserve of dormant follicles. Unfortunately, static in vitro culture of ovarian tissue does not promote development of primordial to secondary follicles or sustain follicle viability and thereby limits the number of obtainable mature oocytes. Enhancing oxygen transport to and exerting mechanical stimulation on ovarian tissue in a dynamic bioreactor may more closely mimic the physiological microenvironment and thus promote follicle activation, development, and viability. Materials and Methods: The most transport-effective dynamic bioreactor design was modified using 3D models of medium and oxygen transport to maximize strip perifusion and apply tissue fluid dynamic shear stresses and direct compressive strains to elicit tissue response. Prototypes of the final bioreactor design were manufactured with materials of varying cytocompatibility and assessed by testing the effect of leachables on sperm motility. Effectiveness of the bioreactor culture was characterized against static controls by culturing fresh bovine ovarian tissue strips for 7 days at 4.8 × 10-5 m/s medium filtration flux in air at -15% maximal total compressive strain and by assessing follicle development, health, and viability. Results and Conclusions: Culture in dynamic bioreactors promoted effective oxygen transport to tissues and stimulated tissues with strains and fluid dynamic shear stresses that, although non-uniform, significantly influenced tissue metabolism. Tissue strip culture in bioreactors made of cytocompatible polypropylene preserved follicle viability and promoted follicle development better than static culture, less so in bioreactors made of cytotoxic ABS-like resin.

In Vitro Growth of Human Follicles: Current and Future Perspectives

Ovarian tissue cryopreservation is gaining importance as a successful method to restore fertility to girls and young women at high risk of sterility. However, there are concerns regarding the safety of transplantation after ovarian tissue cryopreservation due to the high risk of reintroducing cancer cells and causing disease recurrence. In these cases, the development of culture systems that support oocyte development from the primordial follicle stage is required. Notable achievements have been reached in human follicle in vitro growth in the past decade. Currently, systems for the in vitro culture of ovarian tissue are based on two-dimensional substrates that do not support the survival of follicles or recapitulate the mechanical heterogenicity in the mammalian ovary. Recognition of the importance of special arrangements between cells has spurred research in three-dimensional culture systems, and the provision of a precise culture system that maximizes the diffusion of nutrients and gases through the follicles has raised interest in advanced biomimetic models. The current review critically examines various culture systems employed for the in vitro development of follicles, with a particular focus on solutions utilizing Organ-on-a-Chip (OOC) technology. The emphasis on OOC technology underscores its role as a promising avenue in ensuring the successful cultivation and maintenance of follicular structures during the culture period.

Dynamic in vitro culture of bovine and human ovarian tissue enhances follicle progression and health

In vitro ovarian cortical tissue culture, followed by culture of isolated secondary follicles, is a promising future option for production of mature oocytes. Although efforts have been made to improve the culture outcome by changing the medium composition, so far, most studies used static culture systems. Here we describe the outcome of 7 days cultures of bovine and human ovarian cortical tissue in a dynamic system using a novel perifusion bioreactor in comparison to static culture in conventional and/or gas permeable dishes. Findings show that dynamic culture significantly improves follicle quality and viability, percentage and health of secondary follicles, overall tissue health, and steroid secretion in both species. Model predictions suggest that such amelioration can be mediated by an enhanced oxygen availability and/or by fluid-mechanical shear stresses and solid compressive strains exerted on the tissue.

Co-culture of human cryopreserved fragmented ovarian tissue with theca progenitor cells derived from theca stem cells

PURPOSE

Despite the significant advances in the in vitro development of human primordial follicles, it is still a challenging approach with great potential for improvements. Therefore, the present study aimed to investigate the effect of a feeder layer of human theca progenitor cells (hTPCs) on the development of primordial follicles embedded in human ovarian tissue.

METHODS

Fragments of frozen-thawed ovarian tissue were activated using the vanadate-derivative dipotassium bisperoxo (5-hydroxy-pyridine-2-carboxylic) oxovanadate (V) and kit ligand for 24 h. Then, the specimens were divided into the co-culture and mono-culture groups and were cultured with and without a hTPC feeder layer for 6 days, respectively. Afterward, the follicles were counted and classified, and the hormone levels and expression levels of apoptosis- and folliculogenesis-related genes were assessed.

RESULTS

Both culture groups showed significant follicle growth (P < 0.05). However, the co-culture group had a significantly higher number of growing follicles compared to the other group (P < 0.05). Moreover, the expression levels of ZP1, ZP2, ZP3, BMP-7, AMH, and GDF9 were significantly higher in the co-culture group compared to the other group (P < 0.05), while the expression levels of P53 and CASP3 were significantly lower (P < 0.05). Also, the concentrations of estradiol, progesterone, testosterone, and androstenedione were significantly higher in the co-culture group compared to the other group (P < 0.05).

CONCLUSION

The present study results provided novel evidence on the direct role of hTPCs in the growth and development of human primordial follicles. However, there is a need for future studies to illustrate the underlying mechanisms. Schematic summary of the results. According to our results, the expression of ZP1, ZP2, ZP3, and GDF9 in the oocytes, AMH in the granulosa cells, and BMP4 in the theca cells of the co-culture group were significantly higher than those of the mono-culture and non-culture groups, while the expression of apoptotic genes (BAX, CASP3, and P53) was significantly lower. Moreover, the co-culture group showed significantly increased levels of estradiol, progesterone, testosterone, and androstenedione in its culture media compared to the mono-culture groups.

Human ovarian tissue in-vitro culture: primordial follicle activation as a new strategy for female fertility preservation

Cryopreservation and transplantation of ovarian tissue is the only fertility preservation option used for prepubertal girls and women who don't have a chance for embryo or oocyte vitrification. For women with aggressive cancer, hormone-responsive malignancies, autoimmune diseases, etc. ovary transplantation cannot be performed so an alternative technology called in-vitro follicle activation is thinkable. In this method, dormant primordial follicles are activated from the resting primordial pool by in-vitro culture and enter their growth phase. Different in-vitro culture media and supplements in addition to various culturing methods have been conducted for activating these dormant follicles. Furthermore, several signaling pathways such as Hippo, phosphatidylinositol-3-kinase, and mTOR influence follicle activation. Therefore, the addition of different activators of these signaling pathways can beneficially regulate this culture system. This review summarizes the findings on different aspects of human ovarian tissue culture strategies for in-vitro follicular activation, their medium, and different factors involved in this activation. Afterward, signaling pathways important for follicle activation and their clinical applications towards improving activation in culture are also reviewed.

High cryo-resistance of SARS-CoV-2 virus: Increased risk of re-contamination at transplantation of cryopreserved ovarian tissue after COVID-19 pandemic

Cryopreservation and re-transplantation of ovarian tissue after anticancer treatment is important medical technology. Today, during a pandemic, the risk of contamination of transplanted cells with SARS-CoV-2 virus is extremely high. Data about cryo-resistance (virulence and/or infectivity) of SARS-CoV-2 are limited. Analysis and systematization of literature data allow us to draw the following conclusions: 1) The cytoplasmic membrane of somatic cell, like envelope of corona viruses, consists of lipid bilayer and this membrane, like envelope of corona virus, contains membrane proteins. Thus, we can consider the cytoplasmic membrane of an ordinary somatic cell as a model of the envelope membrane of SARS-CoV-2. It is expected that the response of the virus to cryopreservation is similar to that of a somatic cell. SARS-CoV-2 is more poor-water and more protein-rich than somatic cell, and this virus is much more cryo-resistant. 2) The exposure of somatic cells at low positive temperatures increases a viability of these cells. The safety of the virus is also in direct proportion to the decrease in temperature: the positive effect of low temperatures on SARS-CoV-2 virus has been experimentally proven. 3) Resistance of SARS-CoV-2 to cryoprotectant-free cryopreservation is extremely high. The high viability rate of SARS-CoV-2 after freezing-drying confirms its high cryo-resistance. 4) The risk of SARS-CoV-2 infection after transplantation of cryopreserved ovarian tissues that have been contaminated with this virus, increases significantly. Our own experimental data on the increase in the viability of cancer cells after cryopreservation allow us to formulate a hypothesis about increasing of viability (virulence and/or infectivity) of SARS-CoV-2 virus after cryopreservation.

Long-time low-temperature transportation of human ovarian tissue before cryopreservation

RESEARCH QUESTION

Can the low-temperature transport time of removed human ovarian tissue be prolonged until cryopreservation?

DESIGN

Fresh ovarian cortex from nine premenopausal patients was either slow-frozen immediately or stored at 4°C for 24 or 48 h before slow-freezing. The fresh and frozen-thawed biopsies were evaluated by follicle counting via calcein staining, histologic analyses via haematoxylin and eosin staining, and apoptosis via terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL). The fresh cortex was assessed by reactive oxygen species (ROS) and total antioxidant capacity (TAC) assay to detect oxidative stress. The frozen-thawed cortex biopsies were also evaluated by quantitative PCR for messenger RNA (mRNA) expression of BCL-2, BAX, TNFa, HIF-1a, BMP15 and GDF9, and Western blot for detection of BCL-2, BMP15, GDF9 and CASPASE-3. The frozen-thawed cortex was cultured in vitro for 4 days, anti-Müllerian hormone and glucose were assessed in the supernatant, and ROS and TAC assay detected any oxidative stress in the cortex.

RESULTS

In the fresh cortex, there were no significant differences between the three groups. In the frozen-thawed cortex, there were no significant differences between the three groups regarding follicle viability, TUNEL, mRNA expression of TNFa, HIF-1a or BMP15. GDF9 mRNA and BAX/BCL-2 were lower and higher at 48 h than at 0 h, respectively. However, the protein expression of BCL-2, CASPASE-3, GDF9 and BMP15 were no different. In the cultured cortex, ROS, TAC and glucose uptake were no different across the three groups.

CONCLUSION

Ovarian tissue transportation was validated for 24 h in the procedure used in clinical practice. This study showed that 4-8°C transportation for 24 or 48 h does not seem to damage the ovarian tissue. However, ovarian tissue transportation beyond 48 h needs to be further studied for conclusions to be made.

The effect of agar substrate on growth and development of cryopreserved-thawed human ovarian cortical follicles in organ culture

OBJECTIVE

To preserve human ovarian tissue structure and improve follicular growth and survival during in-situ culture, various biomaterials are used. In this study we aimed to compare agar as a cultivation substrate with matrigel-coated insert in order to achieve an optimum system for in-situ human follicle culture.

STUDY DESIGN

Frozen-thawed human ovarian cortical tissues were cultured on either matrigel-coated inserts or agar-soaked substrates. The proportion of morphologically viable and degenerated follicles at different developmental stages, secreted hormonal levels, and apoptotic and proliferation gene expressions were compared between the cultured groups after 7-days of culture.

RESULTS

The follicular growth was not significantly different between the two cultured groups, although showing higher percentage of growing follicles in agar cultured group. The secreted hormonal levels didn't have any difference between two cultured groups. Although the apoptotic gene expressions didn't show any difference between the cultured groups, the apoptotic index was lower in agar cultured group. In addition, Ki67 gene expression, a proliferative marker, showed a significantly higher expression in agar cultured group.

CONCLUSION

Based on the results, agar is as suitable as matrigel-coated inserts for the survival and growth of follicles during culture. Therefore, agar can be an inexpensive alternative substrate for culturing frozen-thawed human ovarian cortical strips.

Serum anti-Mullerian hormone (AMH) concentration has limited prognostic value for density of primordial and primary follicles, questioning it as an accurate parameter for the ovarian reserve

OBJECTIVES

To evaluate the prognostic value of anti-Mullerian hormone (AMH) levels in estimating the ovarian density of primordial and primary follicles, which can be assumed to reflect the real ovarian reserve.

STUDY DESIGN

A total of 537 women, average age 30.4 years (range 8.0-43.7 years), underwent ovarian tissue cryopreservation prior to gonadotoxic therapies due to malignant diseases which do not affect ovarian reserve parameters. Standardized ovarian biopsies were obtained, and follicular density was analysed. The prognostic accuracy of serum AMH in estimating ovarian follicle density was evaluated.

MAIN OUTCOME MEASURES

Histologically determined follicle density, AMH serum concentration and their correlation.

RESULTS

In children, follicle density was high but AMH concentration was low. AMH concentration was predicted to be maximum at the age of 15.5 years. In women aged over 15.5 years, the relationship between AMH concentration and follicle density was evaluated. Crude analysis revealed that serum AMH levels and follicular density were moderately correlated (r = 0.34, p < 0.001). From the adjusted regression model the predicted value of follicle density of women aged 20, 30 and 40 years as well as the associated 50 % and 95 % prediction intervals (50 % PI and 95 % PI, respectively) were calculated. For example, for women aged 40 years with a serum AMH level of 1 ng/ml, a follicle density of 2.3/mm³ (50 %PI: [1.1, 4.6]; 95 %PI: [0.3, 18]) was predicted. These large prediction intervals demonstrate the low predictive value of serum AMH for the ovarian follicle density.

CONCLUSIONS

Serum AMH levels have limited prognostic value for the follicle density and therefore for the real ovarian reserve.

Serum anti-Müllerian hormone concentration and follicle density throughout reproductive life and in different diseases—implications in fertility preservation

STUDY QUESTION

How do anti-Müllerian hormone (AMH) serum concentrations and follicle densities (FDs) change with age and disease and what are the implications for fertility preservation?

SUMMARY ANSWER

AMH concentrations and FD do not correlate in young women, and AMH but not FD is reduced in some diseases, limiting the value of AMH as a predictive parameter of ovarian tissue transplantation.

WHAT IS KNOWN ALREADY

AMH is widely used as a parameter to estimate the ovarian reserve. However, the reliability of AMH to predict total number of follicles and the FD is questionable. Women with lymphoma and leukaemia have been shown to have reduced AMH concentrations, but it is unknown if the FD is also reduced. In fertility preservation it is essential to estimate the correct total number of follicles and the FD, as ovarian tissue should only be cryopreserved if ovarian reserve is high. Furthermore, the amount of tissue to be transplanted should be based on the estimation of the real FD.

STUDY DESIGN, SIZE, DURATION

This retrospective observational study included 830 women (mean ± SD age, 28.2 ± 6.81 years; range, 4–43 years) with malignant (n = 806) and benign (n = 24) diseases who cryopreserved tissue in a single centre as part of a national fertility preservation programme. Females with ovarian surgery or known predispositions for a reduced ovarian reserve were excluded. AMH concentrations and FD were evaluated from March 2011 to September 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

AMH concentrations were analysed before gonadotoxic therapies. Standardized biopsies, obtained from different areas of ovarian cortex, were collected. FD was analysed after tissue digestion and calcein staining and was expressed as average number of primordial and primary follicles count per 3 mm biopsy and per cubic millimeter tissue. AMH concentrations and FD were analysed in relation to age and diagnosis group. Both parameters were age adjusted, and associations between the different diagnosis groups and AMH versus FD were assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

Mean ± SD AMH concentration was 3.1 ± 2.81 g/ml, mean FD per 3 mm biopsy was 137 ± 173.9 and 19.4 ± 24.60 per mm3. Maximum AMH concentrations were found in children and teenagers at the age of 6–10 years (5.71 ng/ml) and in adults at the age of 21–25 years (3.33 ng/ml). FD was highest in young children up to an age of 15 years and decreased with increasing age. AMH and FD were not correlated in women ≤20 years and weakly to moderately correlated in women 21–40 years (r = 0.24–0.39). Age-adjusted correlations between AMH and FD were demonstrated in several diagnosis groups such as breast cancer, leukaemia, sarcoma, gastrointestinal cancer and gynaecological cancer but not in the groups exhibiting Hodgkin’s and non-Hodgkin’s lymphoma, cerebral cancer, other types of malignancies and other types of benign diseases. Further statistical analysis supported the finding that, in some diagnosis groups such as Hodgkin’s lymphoma and in gynaecological cancer, AMH concentrations but not FDs are reduced, questioning the prognostic accuracy of AMH for the FD in these diseases.

LIMITATIONS, REASONS FOR CAUTION

Even though biopsies were taken from different sites, heterogenous distribution of follicles might have had some effect on the accuracy of the analysis.

WIDER IMPLICATION OF THE FINDINGS

AMH should be used with care to estimate the total ovarian reserve and FD of cancer patients in young women in some diseases. Therefore, calculating the amount of ovarian tissue to be transplanted based solely on AMH might be inaccurate whereas FD might be a better parameter.

STUDY FUNDING/COMPETING INTEREST(S)

The study did not receive any exterior funding.

Spectroscopic monitoring of transport processes during loading of ovarian tissue with cryoprotective solutions

There is an increasing demand for female fertility preservation. Cryopreservation of ovarian cortex tissue by means of vitrification can be done ad-hoc and for pre-pubertal individuals. Obtaining a homogeneous distribution of protective agents in tissues is one of the major hurdles for successful preservation. Therefore, to rationally design vitrification strategies for tissues, it is needed to determine permeation kinetics of cryoprotective agents; to ensure homogeneous distribution while minimizing exposure time and toxicity effects. In this study, Fourier transform infrared spectroscopy (FTIR) was used to monitor diffusion of different components into porcine ovarian cortex tissue. Water fluxes and permeation kinetics of dimethyl sulfoxide (DMSO), glycerol (GLY), ethylene glycol (EG), and propylene glycol (PG) were investigated. Diffusion coefficients derived from FTIR data, were corroborated with differential scanning calorimetry and osmometer measurements. FTIR allowed real-time spectral fingerprinting of tissue during loading with mixtures of protective agents, while discriminating between different components and water. Exposure to vitrification solutions was found to cause drastic initial weight losses, which could be correlated with spectral features. Use of heavy water allowed distinguishing water fluxes associated with dehydration and permeation, both of which were found to precede permeation of cryoprotective agents. Overall, DMSO and EG were found to permeate faster than GLY and PG. In mixtures, however, solutes behave differently. The non-invasive spectroscopic method described here to study permeation of vitrification solution components into ovarian tissue can be applied to many other types of engineered constructs, tissues, and possibly organs.

In vitro survival of follicles in prepubertal ewe ovarian cortex cryopreserved by slow freezing or non-equilibrium vitrification

PURPOSE

Vitrification is a well-accepted fertility preservation procedure for cryopreservation of oocytes and embryos but little is known regarding ovarian tissue, for which slow freezing is the current convention. The aim of the present study was to assess the efficiency of non-equilibrium vitrification compared to conventional slow freezing for ovarian cortex cryopreservation.

METHODS

Using prepubertal sheep ovaries, the capacity of the tissue to sustain folliculogenesis following cryopreservation and in vitro culture was evaluated. Ovarian cortex fragments were cultured in wells for 9 days, immediately or after cryopreservation by conventional slow freezing or non-equilibrium vitrification in straws. During culture, follicular populations within cortex were evaluated by histology and immunohistochemistry for PCNA and TUNEL. Steroidogenic activity of the tissue was monitored by assay for progesterone and estradiol in spent media.

RESULTS

No significant differences in follicle morphology, PCNA, or TUNEL labeling were observed between cryopreservation methods at the initiation of culture. Similar decreases in the proportion of primordial follicle population, and increases in the proportion of growing follicles, were observed following culture of fresh or cryopreserved ovarian tissue regardless of cryopreservation method. At the end of culture, PCNA and TUNEL-positive follicles were not statistically altered by slow freezing or vitrification in comparison to fresh cultured fragments.

CONCLUSIONS

Overall, for both cryopreservation methods, the cryopreserved tissue showed equal capacity to fresh tissue for supporting basal folliculogenesis in vitro. Taken together, these data confirm that both non-equilibrium vitrification and slow-freezing methods are both efficient for the cryopreservation of sheep ovarian cortex fragments.

Do Bioreactor Designs with More Efficient Oxygen Supply to Ovarian Cortical Tissue Fragments Enhance Follicle Viability and Growth In Vitro?

Background: Autotransplantation of cryopreserved ovarian tissue is currently the main option to preserve fertility for cancer patients. To avoid cancer cell reintroduction at transplantation, a multi-step culture system has been proposed to obtain fully competent oocytes for in vitro fertilization. Current in vitro systems are limited by the low number and health of secondary follicles produced during the first step culture of ovarian tissue fragments. To overcome such limitations, bioreactor designs have been proposed to enhance oxygen supply to the tissue, with inconsistent results. This retrospective study investigates, on theoretical grounds, whether the lack of a rational design of the proposed bioreactors prevented the full exploitation of follicle growth potential. Methods: Models describing oxygen transport in bioreactors and tissue were developed and used to predict oxygen availability inside ovarian tissue in the pertinent literature. Results: The proposed theoretical analysis suggests that a successful outcome is associated with enhanced oxygen availability in the cultured tissue in the considered bioreactor designs. This suggests that a rational approach to bioreactor design for ovarian tissue culture in vitro may help exploit tissue potential to support follicle growth.

Implications from early life stress on the development of mouse ovarian follicles: Focus on oxidative stress

AIM

The early life stress has significant long-term effects on the development of the offspring. This study was undertaken to verify if maternal separation as a stressor agent affects the oxidative status and developmental competence of mouse pre-antral follicles (PF) during in vitro culture period.

METHODS

Female litters of National Medical Research Institute mice were divided into two groups: maternally separated group (MS), separated from the mothers for 6 h per day from postnatal days 2-16; and the rest considered as the control group, which left undisturbed over the 14 days. The litters were sacrificed and the ovarian tissue was harvested to isolate the PF. The PF were in vitro cultured up to 12th day when ovulation was induced. The developmental parameters and oxidative status (i.e., total antioxidant capacity and Malondialdehyde levels, as well as the activities of superoxide dismutase, glutathione peroxidase and catalase) were assessed.

RESULTS

The rates of survival, antrum formation, ovulation and oocyte maturation of PF derived from the MS group were significantly lower compared with those of the control group. Furthermore, the Malondialdehyde level of the MS group was significantly higher than that of the control group. By contrast, the total antioxidant capacity level was lower in the MS group with respect to the control group. Also, the activity of superoxide dismutase, glutathione peroxidase and catalase of PF, derived from the MS group, was significantly lower compared with those of the control group.

CONCLUSION

Early life stress damages the developmental competence of mouse PF through induction of oxidative stress.

Panax ginseng Extract Improves Follicular Development after Mouse Preantral Follicle 3D Culture

Objective

Panax ginseng is a popular traditional herb that has been used in complementary and alternative medicine in eastern Asia, and it possesses pharmacologically active compounds like ginsenosides (GSs). This study aimed to investigate the impact of Panax ginseng extract (PGE) at different concentrations on in vitro follicular function and development in a three-dimensional (3D) culture system fabricated using sodium alginate after 12 days of culture.

Materials and Methods

In this experimental study, preantral follicles (n=661) were mechanically isolated from the ovaries of 14-day-old female NMRI mice using 29-gauge insulin syringes. Follicles were individually capsulated within sodium alginate, and divided into four groups including control and experimental groups 1, 2, and 3. Then, they were cultured for 12 days in the medium supplemented with different concentrations of PGE (0, 50, 100, and 500 µg/ mL, for control groups and groups 1, 2 and 3, respectively). At the end of the culture period, the mean diameter and maturation of follicles, follicular steroid production, mRNA expression level of proliferating cell nuclear antigen (PCNA) and follicle stimulating hormone receptor (FSH-R), and reactive oxygen species (ROS) levels in collected metaphase-II (MII) oocytes were determined.

Results

The mean diameter of follicles in group 2 was significantly increased as compared to other groups (P<0.001). The percentages of the survival and maturation rate and levels of secreted hormones were higher in group 2 than the other groups (P<0.05). Follicles cultured in the presence of PGE 100 µg/mL had higher levels of proliferation cell nuclear antigen (PCNA) and follicle stimulating hormone receptor (FSH-R) mRNA expression in comparison to other groups (P<0.05). Moreover, oocytes collected from groups 2 and 3 had lower levels of ROS as compared to other groups (P<0.05).

Conclusion

Our results suggest that PGE at the concentration of 100 µg/mL induces higher follicular function and development in the 3D culture system.

Overnight ovarian tissue transportation for centralized cryobanking: a feasible option

RESEARCH QUESTION

Is overnight transportation of ovarian tissue before cryopreservation in a centralized cryobank from the FertiPROTEKT network feasible?

DESIGN

Data from 1810 women with cryopreserved ovarian tissue after overnight transportation from December 2000 to December 2017 were analysed with a focus on transportation, tissue activity parameters and pregnancy, and delivery rates after transplantation.

RESULTS

A total of 92.4% of tissue samples arrived at ideal temperatures of 2-8°C, 0.4% were transported at temperatures lower than ideal and 6.4% were transported at temperatures that were too high, generally due to mishandling of the inlayed cool packs of the transportation boxes. In 62 women, 78 tissue transplantations were carried out. A subgroup of 30 women who underwent a single orthotopic transplantation with fulfilled criteria of a complete follow-up after transplantation until the end of study, a premature ovarian insufficiency after gonadotoxic therapy as well as the absence of pelvic radiation, was further analysed. In this group, transplantations into a peritoneal pocket accounted for 90%. Transplants were still active at 1 year and above after transplantation in 93.3%. Pregnancy and delivery rates were 46.7% and 43.3%, respectively, with one ongoing pregnancy at the end of the study.

CONCLUSIONS

Overnight transportation for central cryobanking is a feasible concept that results in high reproducible success rates through standardized professional tissue freezing and storage.

Evaluation of an ovary-on-a-chip in large mammalian models: Species specificity and influence of follicle isolation status

The ability to grow oocytes from immature ovarian follicles in vitro has significant potential for fertility preservation; yet, it has proved challenging in large mammalian species due to the complex metabolic needs and long-term culture requirements. Currently, follicular incubations are based on a "static" system with manual exchange of medium. Despite the numerous advantages of conventional culturing approaches, recapitulating the native microenvironment and supporting the survival of ovarian follicles from large mammalian species still represent challenges. In this study, we utilized an innovative, dynamic microfluidic system to support the in vitro survival of domestic cat and dog follicles enclosed within the ovarian cortex or isolated from ovarian cortex. Results indicate both species-specific and tissue type-specific differences in response to microfluidic culture. Domestic cat but not dog ovarian cortical tissues maintained viability under flow similar to conventional agarose gel controls. Preantral stage isolated follicles from both species that grew most favourably in conventional alginate bead culture, but overall, there was no influence of culture system on expression of follicle development or oocyte health markers. This system represents an important exploration toward the development of an improved ovarian in vitro culture system of large mammalian species (e.g., cats and dogs), which has potential applications for fertility preservation, reproductive toxicology, and endangered mammal conservation efforts.

A transportation network for human ovarian tissue is indispensable to success for fertility preservation

PURPOSE

The purpose of this study was to examine the efficacy of an ovarian tissue transportation network for fertility preservation (FP) for cancer patients in Japan.

METHODS

PubMed was searched for papers on transportation of human ovarian tissue for FP. We analyzed population, area, number of cancer patients for ovarian tissue cryopreservation (OTC), quality control/assessment and safety, cost of a cryopreservation center for the building for 30 years, and medical fees of cancer patients (operation, cryopreservation, and storage of ovarian tissue).

RESULTS

More than twenty babies have been born in Denmark and Germany through a transportation system. Up to 400 new patients a year need OTC. The fees for removal, cryopreservation, and storage for 5 years, and transplantation of ovarian tissue are around €5,000, €4,000, and €5,000, respectively. It costs more than €5 million to establish and maintain one cryopreservation center for 30 years. If we have a few cryopreservation centers in Japan, we can cryopreserve 400 patients' ovarian tissue per year by safer slow freezing and maintain quality control/assessment. We need to lighten the patients' burden for easy to use FP by a government subsidy and medical insurance coverage.

CONCLUSIONS

This model has been termed the Danish model ("the woman stays - the tissue moves"). This is truly patient-centered medicine. We can have maximum effects with the minimum burden. A transportation network like those of Denmark and Germany is the best strategy for FP in Japan. It may be the best system for cancer patients, medical staff, and the Ministry of Health, Labor, and Welfare.

Chapter 15 Development of a Nationwide Network for Ovarian Tissue Cryopreservation

Ovarian tissue cryopreservation is gaining much interest since the publication of the first live birth after retransplantation of frozen-thawed tissue in 2004 (Donnez et al., Lancet 364:1405-1410, 2004). In contrast to cryopreservation of gametes and embryos, ovarian tissue freezing is a complex requiring a proper approach in order to make this a viable option for fertility preservation of cancer patients. Due to the need in terms of laboratory space, equipment, personnel, and adequate logistics, an ovarian tissue cryobank is most economic if managed as a centralized service unit that interacts with numerous clinics covering the surgical part. Transportation of ovarian tissue under appropriate conditions from the surgical unit to the cryobank for subsequent preparation and freezing has been shown to have no impact on cryo-survival (Schmidt et al., Hum Reprod 18:2654-2659, 2003; Isachenko et al., Fertil Steril 91:1556-1559, 2009). Several children have been born after retransplantation of such tissue that was derived from the cryobank in Bonn, Germany (Homepage FertiPROTEKT. http://www.fertiprotekt.de ). This cryobank is one of the largest in the world with more than 1300 tissue samples that were frozen from 2003 until today. It is integrated in the network FertiPROTEKT (Homepage FertiPROTEKT. http://www.fertiprotekt.de ) and is served by 108 surgical centers that are located all over Germany. The concept of this cryobank is a blueprint for success and has recently been used for another regionally centralized cryobank in Beijing, China. In this chapter the most important topics that need to be considered while creating a centralized cryobank within a national or regional network are highlighted.

Ovarian tissue culture in the presence of VEGF and fetuin stimulates follicle growth and steroidogenesis

Ovarian tissue cryopreservation together with follicle culture provides a promising technique for fertility preservation in cancer patients. The study aimed to evaluate follicle parameters in a culture medium supplemented with VEGFA165 and/or fetuin. Vitrified-warmed ovarian cortical pieces were divided randomly into four culture groups consisting of basic culture medium (control), and the basic culture medium supplemented with VEGFA165, fetuin or both. After six days of culture, we evaluated the following: percentage of resting, primary and secondary growing follicles; survival rate; steroid hormones production; levels of reactive oxygen species, lipid peroxidation and total antioxidant capacity; and developmental and antioxidant gene expression. The addition of VEGFA165 alone or in combination with fetuin to the culture medium caused resting follicle activation and increased the number of growing follicles. In the VEGFA165 group, we found a significant increase in the concentrations of 17β-estradiol at day 6 and progesterone from 4th day of the culture period. In the VEGFA165 + fetuin group, the concentration of 17β-estradiol rose at day 4 of the culture period. The levels of BMP15, GDF9 and INHB mRNAs were increased in all treated groups. In the fetuin and fetuin + VEGFA165 groups, we observed a high level of total antioxidant capacity and expression of SOD1 and CAT genes, low reactive oxygen species and lipid peroxidation levels and increased number of viable follicles. In conclusion, the present study provides useful evidence that supplementation of culture medium with VEGFA165 + fetuin leads to primordial follicle activation and development and increased percentage of healthy secondary growing follicles.

Expression of Folliculogenesis-Related Genes in Vitrified Human Ovarian Tissue after Two Weeks In Vitro Culture

OBJECTIVE

This study was designed to evaluate the effects of vitrification and in vitro culture of human ovarian tissue on the expression of oocytic and follicular cell-related genes.

MATERIALS AND METHODS

In this experimental study, ovarian tissue samples were obtained from eight transsexual women. Samples were cut into small fragments and were then assigned to vitrified and non-vitrified groups. In each group, some tissue fragments were divided into un-cultured and cultured (in α-MEM medium for 2 weeks) subgroups. The normality of follicles was assessed by morphological observation under a light microscope using hematoxylin and eosin (H&E) staining. Expression levels of factor in the germ line alpha (FIGLA), KIT ligand (KL), growth differentiation factor 9 (GDF-9) and follicle stimulating hormone receptor (FSHR) genes were quantified in both groups by real-time reverse transcriptase polymerase chain reaction (RT-PCR) at the beginning and the end of culture.

RESULTS

The percentage of normal follicles was similar between non-cultured vitrified and non-vitrified groups (P>0.05), however, cultured tissues had significantly fewer normal follicles than non-cultured tissues in both vitrified and non-vitrified groups (P<0.05). In both cultured groups the rate of primary and secondary follicles was significantly higher than non-cultured tissues (P<0.05). The expression of all examined genes was not significantly altered in both non-cultured groups. Whiles, in comparison with cultured tissues non-cultured tissues, the expression of FIGLA gene was significantly decreased, KL gene was not changed, GDF-9 and FSHR genes was significantly increased (P<0.05).

CONCLUSION

Human ovarian vitrification following in vitro culture has no impairing effects on follicle normality and development and expression of related-genes. However, in vitro culture condition has deleterious effects on normality of follicles.

Effect of Human Ovarian Tissue Vitrification/Warming on the Expression of Genes Related to Folliculogenesis

Background:

Ovarian tissue cryopreservation is an alternative strategy to preserve the fertility of women predicted to undergo premature ovarian failure. This study was designed to evaluate the expression of folliculogenesis-related genes, including factor in the germline alpha (FIGLA), growth differentiation factor-9 (GDF-9), follicle-stimulating hormone receptor (FSHR), and KIT LIGAND after vitrification/warming of human ovarian tissue.

Methods:

Human ovarian tissue samples were collected from five transsexual women. In the laboratory, the ovarian medullary part was removed by a surgical blade, and the cortical tissue was cut into small pieces. Some pieces were vitrified and warmed and the others were considered as non-vitrified group (control). Follicular normality was assessed with morphological observation by a light microscope, and the expression of FIGLA, KIT LIGAND, GDF-9,, and FSHR genes was examined using real-time RT-PCR in both the vitrified and non-vitrified groups.

Results:

Overall, 85% of the follicles preserved their normal morphologic feature after warming. The percentage of normal follicles and the expression of FIGLA, KIT LIGAND, GDF-9, and FSHR genes were similar in both vitrified and non-vitrified groups (P > 0.05).

Conclusion:

Vitrification/warming of human ovarian tissue had no remarkable effect on the expression of folliculogenesis-related genes.

Effects of neutral red assisted viability assessment on the cryotolerance of isolated bovine preantral follicles

PURPOSE

Fertility preservation strategies warrant non-invasive viability assessment of preantral follicles (PAF) such as staining with Neutral Red (NR) that is incorporated by viable follicles. To optimize the procedure, we firstly determined the lowest concentration and shortest exposure time needed for optimal viability screening of isolated bovine PAF. Secondly, we combined this protocol to a vitrification procedure to assess cryotolerance of the stained follicles.

METHODS

Isolated PAF (900, divided over 6 replicates) were cultured in DMEM/Ham's F12 (Culture Medium - Cm) for 4 days (38.5 °C, 5% CO2). On D0, D2 and D4, follicles were stained, by adding NR medium (NRm = Cm with different concentrations NR) after which viability was assessed by counting stained/non-stained PAF every 30 min for a period of 2 h.

RESULTS

Following a binary logistic regression analysis with staining as a result (yes/no) versus log-concentration, a probability model could be fitted, indicating that the proportion of stained follicles remained stable after 30 min when 15 μg/ml NR was used, without compromising follicular health and viability. Consequently, using this protocol, no significant effect of staining prior to vitrification, was found on PAF viability immediately after warming or following 4 days of culture.

CONCLUSIONS

In conclusion, we propose NR staining as a non-invasive, non-detrimental viability assessment tool for PAF, when applied at 15 μg/ml for 30 min, being perfectly compatible with PAF vitrification.

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.

Efficacy of ovarian tissue cryopreservation in a major European center

PURPOSE

To evaluate the effect of cryopreservation and thawing of ovarian tissue from oncological patients opting for fertility preservation on ovarian tissue viability.

METHODS

In this prospective cohort study, the ovarian tissue viability before and after cryopreservation and thawing was measured for 25 newly diagnosed oncological patients who had their ovarian tissue cryopreserved. Outcome measures were follicle integrity (histology), follicle viability (Calcein viability assay), steroid hormone production (estradiol and progesterone production in vitro) and overall tissue viability (glucose uptake in vitro). This study was conducted at a Cryobank for storage of ovarian tissue in a university hospital.

RESULTS

Cryopreserved/thawed ovarian tissue showed a decreased glucose uptake when compared to tissue that had not been cryopreserved. In addition, a diminished E2 and P4 production was observed after cryopreservation and thawing, despite the fact that numbers of viable follicles as determined by the Calcein viability assay were comparable. Histological examination revealed a higher percentage of degenerated follicles after cryopreservation and thawing.

CONCLUSIONS

Ovarian tissue cryopreservation and thawing impairs the viability of ovarian tissue in oncological patients opting for fertility preservation.