Evaluation of Liberase, a purified enzyme blend, for the isolation of human primordial and primary ovarian follicles

Mesenchymal Stem Cells Facilitate In Vitro Development of Human Preantral Follicle

Biological folliculogenesis is a lengthy and complicated process, and follicle growth microenvironment is poorly understood. Mesenchymal stem cells (MSCs) have been shown to establish a supportive microenvironment for wound repair, autoimmune diseases amelioration, and tumor development. Therefore, this study is aimed to investigate whether MSCs could help to reconstruct a microenvironment to facilitate the in vitro follicle development. Here we show human MSCs significantly promote the survival rates, increase the growth velocity, and improve the viability of preantral follicles in a dose-dependent manner. Further analyses reveal that growth differentiation factor 9 and bone morphogenetic protein 15 in oocytes and inhibin βA and transforming growth factor β1 in granulose cells within the follicles cocultured with MSCs express notably higher than those in the follicles cultured without MSCs. In summary, our findings demonstrate a previously unrecognized function of MSCs in promoting preantral follicle development and provide a useful strategy to optimize fertility preservation and restoration by facilitating in vitro follicle growth.

Is transplantation of a few leukemic cells inside an artificial ovary able to induce leukemia in an experimental model?

PURPOSE

To evaluate the tumor-inducing ability of a few leukemic cells xenotransplanted inside an artificial ovary.

METHODS

Ten and 100 BV-173 leukemic cells were embedded in a fibrin matrix along with 50,000 human ovarian stromal cells, and grafted to the peritoneal bursa of 5 and 5 SCID mice respectively. Four mice grafted with 3x10(6) leukemic cells in fibrin served as positive controls. At 20 weeks post-transplantation, the grafts, liver, spleen, blood and bone marrow were analyzed for the presence of leukemia by anti-CD79α IHC, flow cytometry (FC) and PCR.

RESULTS

All mice grafted with 3x10(6) cells developed peritoneal masses 4 weeks after xenotransplantation, and systemic disease was confirmed by IHC, PCR and FC. Among mice grafted with 10 or 100 leukemic cells, none showed any sign of leukemia after 20 weeks, and IHC, FC and PCR on the different recovered tissues all proved negative.

CONCLUSION

This study investigates the tumor-inducing potential of a few leukemic cells grafted inside an artificial ovary. Transplantation of 100 leukemic cells appears to be insufficient to induce leukemia after 20 weeks. These results in an immunodeficient xenografting model are quite reassuring. However, for clinical application, follicle suspensions must be purged of leukemic cells before grafting, as even the slightest risk should be avoided.

Follicles of various maturation stages react differently to enzymatic isolation: a comparison of different isolation protocols

Isolation of human follicles is based on digestion of the tissue by combinations of enzymes. Follicle vitality and morphology are often based on the analysis of pooled follicles of different maturation stages. Information is therefore lacking on the effect of the isolation protocol to individual follicles of different maturation stages. A study was conducted using five protocols combining different enzymes and varying concentrations. Isolated follicles were classified according to their maturation stages, counted and characterized for vitality, morphology, early apoptosis and organization of transzonal projections. No statistical differences were found between the protocols when outcome parameters were analysed on a pool of follicles regardless of their maturation status. Differences were observed in quality when the follicles were analysed separately according to their maturation status. Combining morphologic characteristics and vitality, both Liberase DH and Liberase TM combined with collagenase IV were better at isolating high-quality primordial follicles, compared with collagenase IV. No statistical difference between the isolation protocols was found for primary follicles. If only high-quality isolated secondary follicles are needed, collagenase IV is found to be most advantageous. Follicles of different maturation stages react differently when enzymatic isolation protocols are compared.

Oxygen consumption rate of early pre-antral follicles from vitrified human ovarian cortical tissue

The study of human ovarian tissue transplantation and cryopreservation has advanced significantly. Autotransplantation of human pre-antral follicles isolated from cryopreserved cortical tissue is a promising option for the preservation of fertility in young cancer patients. The purpose of the present study was to reveal the effect of vitrification after low-temperature transportation of human pre-antral follicles by using the oxygen consumption rate (OCR). Cortical tissues from 9 ovaries of female-to-male transsexuals were vitrified after transportation (6 or 18 h). The follicles were enzymatically isolated from nonvitrified tissue (group I, 18 h of transportation), vitrified-warmed tissue (group II, 6 and 18 h of transportation) and vitrified-warmed tissue that had been incubated for 24 h (group III, 6 and 18 h of transportation). OCR measurement and the LIVE/DEAD viability assay were performed. Despite the ischemic condition, the isolated pre-antral follicles in group I consumed oxygen, and the mean OCRs increased with developmental stage. Neither the transportation time nor patient age seemed to affect the OCR in this group. Meanwhile, the mean OCR was significantly lower (P < 0.05) in group II but was comparable to that of group I after 24 h of incubation. The integrity of vitrified-warmed primordial and primary follicles was clearly corroborated by the LIVE/DEAD viability assay. These results demonstrate that the OCR can be used to directly estimate the effect of vitrification on the viability of primordial and primary follicles and to select the viable primordial and primary follicles from vitrified-warmed follicles.

Characterization of freshly retrieved preantral follicles using a low-invasive, mechanical isolation method extended to different ruminant species

Due to the increased interest in preantral follicular physiology, non-invasive retrieval and morphological classification are crucial. Therefore, this study aimed: (1) to standardize a minimally invasive isolation protocol, applicable to three ruminant species; (2) to morphologically classify preantral follicles upon retrieval; and (3) to describe morphological features of freshly retrieved follicles compared with follicle characteristics using invasive methods. Bovine, caprine and ovine ovarian cortex strips were retrieved from slaughterhouse ovaries and dispersed. This suspension was filtered, centrifuged, re-suspended and transferred to a Petri dish, to which 0.025 mg/ml neutral red (NR) was added to assess the viability of the isolated follicles. Between 59 and 191 follicles per follicle class and per species were collected and classified by light microscopy, based on follicular cell morphology. Subsequently, follicle diameters were measured. The proposed isolation protocol was applicable to all three species and showed a significant, expected increase in diameter with developmental stage. With an average diameter of 37 ± 5 μm for primordial follicles, 47 ± 6.3 μm for primary follicles and 67.1 ± 13.1 μm for secondary follicles, no significant difference in diameter among the three species was observed. Bovine, caprine and ovine follicles (63, 59 and 50% respectively) were graded as viable upon retrieval. Using the same morphological characteristics as determined by invasive techniques [e.g. haematoxylin–eosin (HE) sections], cumulus cell morphology and follicle diameter could be used routinely to classify freshly retrieved follicles. Finally, we applied a mechanical, minimally invasive, follicle isolation protocol and extended it to three ruminant species, yielding viable preantral follicles without compromising further in vitro processing and allowing routine follicle characterization upon retrieval.

Fibrin-mediated delivery of an ovarian follicle pool in a mouse model of infertility

The cryopreservation and autotransplantation of ovarian tissue is emerging as a powerful approach for preserving fertility. However, for cancer patients, it may not be possible to transplant ovarian tissue due to the risk of re-seeding disease. We investigated strategies for transplantation of individually isolated follicles to minimize the risk of re-introducing cancer cells present within the vasculature of ovarian stroma. Procedures for large-scale isolation of early-stage follicles and their encapsulation into fibrin hydrogels were developed. For in vivo validation studies, mice were ovariectomized and transplanted with encapsulated follicles into the ovarian bursa. A substantial increase in the number of secondary follicles was observed in the graft at 9 days after transplantation, and antral follicles by day 21, demonstrating primordial follicle recruitment into the growing pool. Initially, elevated follicle-stimulating hormone levels declined substantially by day 21, indicating feedback from the graft; presence of corpora lutea showed the graft's capability of restoring hormone cyclicity. Taken together, the transplanted follicles were able to engraft, mature, and restore ovarian function in an infertile mouse. This biomaterial may, thus, provide a platform for follicle transplantation with a low risk of cancer contamination and for developing strategies that preserve fertility for women facing a cancer diagnosis.

Combined use of N-acetylcysteine and Liberase improves the viability and metabolic function of human hepatocytes isolated from human liver

Background aims

Successful hepatocyte isolation is critical for continued development of cellular transplantation. However, most tissue available for research is from diseased liver, and the results of hepatocyte isolation from such tissue are inferior compared with normal tissue. Liberase and N-acetylcysteine (NAC) have been shown separately to improve viability of isolated hepatocytes. This study aims to determine the effect of Liberase and NAC in combination on human hepatocyte isolation from normal and diseased liver tissues.

Methods

Hepatocytes were isolated from 30 liver specimens through the use of a standard collagenase digestion technique (original protocol) and another 30 with the addition of NAC and standard collagenase substituted by Liberase (new protocol). Viability and success, defined as maintenance of cell adhesion and morphology for 48 hours, were assessed. Metabolic function was assessed by means of albumin and urea synthesis.

Results

Baseline factors were similar for both groups. The delay to tissue processing was slightly shorter in the new protocol group (median, 2 versus 4 hours; P = 0.007). The success rate improved from 12 of 30 (40.0%) to 21 of 30 (70.0%) with the use of the new protocol (P = 0.037), and median viable cell yield increased from 7.3 × 10⁴ to 28.3 × 10⁴ cells/g tissue (P = 0.003). After adjusting for delay, success rate (P = 0.014) and viable cell yield/g tissue (P = 0.001) remained significantly improved. Albumin and urea synthesis were similar or superior in the new protocol group.

Conclusions

NAC and Liberase improve the success of hepatocyte isolation, with a significantly higher yield of viable cells. The use of these agents may improve the availability of hepatocytes for transplantation and laboratory research.

Basic fibroblast growth factor promotes the development of human ovarian early follicles during growth in vitro

STUDY QUESTION

What is the effect of basic fibroblast growth factor (bFGF) on the growth of individual early human follicles in a three-dimensional (3D) culture system in vitro?

SUMMARY ANSWER

The addition of 200 ng bFGF/ml improves human early follicle growth, survival and viability during growth in vitro.

WHAT IS KNOWN ALREADY

It has been demonstrated that bFGF enhances primordial follicle development in human ovarian tissue culture. However, the growth and survival of individual early follicles in encapsulated 3D culture have not been reported.

STUDY DESIGN, SIZE, DURATION

The maturation in vitro of human ovarian follicles was investigated. Ovarian tissue (n= 11) was obtained from 11 women during laparoscopic surgery for gynecological disease, after obtaining written informed consent. One hundred and fifty-four early follicles were isolated by enzymic digestion and mechanical disruption. They were individually encapsulated into alginate (1% w/v) and randomly assigned to be cultured with 0, 100, 200 or 300 ng bFGF/ml for 8 days.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Individual follicles were cultured in minimum essential medium α (αMEM) supplemented with bFGF. Follicle survival and growth were assessed by microscopy. Follicle viability was evaluated under confocal laser scanning microscope following Calcein-AM and Ethidium homodimer-I (Ca-AM/EthD-I) staining.

MAIN RESULTS AND THE ROLE OF CHANCE

After 8 days in culture, all 154 follicles had increased in size. The diameter and survival rate of the follicles and the percentage with good viability were significantly higher in the group cultured with 200 ng bFGF/ml than in the group without bFGF (P < 0.05). The percentage of follicles in the pre-antral stage was significantly higher in the 200 ng bFGF/ml group than in the group without bFGF (P < 0.05), while the percentages of primordial and primary follicles were significantly lower (P < 0.05).

LIMITATIONS, REASONS FOR CAUTION

The study focuses on the effect of bFGF on the development of individual human early follicles in 3D culture in vitro and has limited ability to reveal the specific effect of bFGF at each different stage. The findings highlight the need to improve the acquisition and isolation of human ovarian follicles.

WIDER IMPLICATIONS OF THE FINDINGS

The in vitro 3D culture of human follicles with appropriate dosage of bFGF offers an effective method to investigate their development. Moreover, it allows early follicles to be cultured to an advanced stage and therefore has the potential to become an important source of mature oocytes for assisted reproductive technology; particularly as an option for fertility preservation in women, including patients with cancer.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Basic Research Program of China (2011|CB944504, 2011CB944503) and the National Natural Science Foundation of China (81200470, 81000275, 31230047, 8110197). There are no conflicts of interest to declare.

Vitamin E-analog Trolox prevents endoplasmic reticulum stress in frozen-thawed ovarian tissue of capuchin monkey (Sapajus apella)

Ovarian fragments were exposed to 0.5 M sucrose and 1 M ethylene glycol (freezing solution; FS) with or without selenium or Trolox. Histological and ultrastructural analyses showed that the percentages of normal follicles in control tissue and in tissue after exposure to FS + 50 μM Trolox were similar. Trolox prevented endoplasmic reticulum (ER)-related vacuolization, which is commonly observed in oocytes and stromal tissue after exposure to FS. From the evaluated stress markers, superoxide dismutase 1 (SOD1) was up-regulated in ovarian tissue exposed to FS + 10 ng/ml selenium. Ovarian fragments were subsequently frozen-thawed in the presence of FS with or without 50 μM Trolox, followed by in vitro culture (IVC). Antioxidant capacity in ovarian fragments decreased after freeze-thawing in Trolox-free FS compared with FS + 50 μM Trolox. Although freezing itself minimized the percentage of viable follicles in each solution, Trolox supplementation resulted in higher rates of viable follicles (67 %), even after IVC (61 %). Furthermore, stress markers SOD1 and ERp29 were up-regulated in ovarian tissue frozen-thawed in Trolox-free medium. Relative mRNA expression of growth factors markers was evaluated after freeze-thawing followed by IVC. BMP4, BMP5, CTGF, GDF9 and KL were down-regulated independently of the presence of Trolox in FS but down-regulation was less pronounced in the presence of Trolox. Thus, medium supplementation with 50 μM Trolox prevents ER stress and, consequently, protects ovarian tissue from ER-derived cytoplasmic vacuolization. ERp29 but not ERp60, appears to be a key marker linking stress caused by freezing-thawing and cell vacuolization.

In vitro development of human primordial follicles to preantral stage after vitrification

PURPOSE

The aim was to culture primordial follicles in vitro to reach preantral stage in vitrified human ovarian tissue.

METHODS

Ovarian tissue samples were obtained from six women. Tissue strips were vitrified by infiltration with a cryoprotectant followed by mounting on a stainless steel carrier. After culturing for 7 days the morphology and developmental stages of follicles enclosed in fresh and vitrified groups were analyzed.

RESULTS

High proportion of viable follicles in vitrified ovarian strips was obtained. After culturing for 7 days the percentage of secondary and preantral follicles increased significantly (P < 0.05) whereas primordial and transitory follicles showed a significant decrease (P < 0.05) compared to their respective counterparts at day 0 of culture.

CONCLUSIONS

Vitrification of ovarian strips with an improved carrier device and culturing of follicles in ovarian strips after warming yielded developed follicles with high viability and morphological integrity that may be suitable for use in fertility preservation among cancer patients.

Ovarian follicle culture: advances and challenges for human and nonhuman primates

The removal and cryostorage of ovarian cortical biopsies is now offered as a fertility preservation option for young women. The only available option to restore fertility using this tissue is by transplantation, which may not be possible for all patients. The full potential of this tissue to restore fertility could be achieved by the development of in vitro systems that support oocyte development from the most immature stages to maturation. The techniques of in vitro growth (IVG) combined with in vitro maturation (IVM) are being developed with human tissue, but comparing different systems has been difficult because of the scarcity of tissue so nonhuman primates are being used as model systems. There are many challenges to developing a complete culture system that would support human oocyte development, and this review outlines the approaches being taken by several groups using tissue from women and nonhuman primate models to support each of the stages of oocyte development.

Risk of transferring malignant cells with transplanted frozen-thawed ovarian tissue

Ovarian tissue cryopreservation and transplantation is a real option to preserve and restore fertility in young cancer patients. However, there is a concern regarding the possible presence of malignant cells in the ovarian tissue, which could lead to recurrence of the primary disease after reimplantation. A review of the existing literature was done to evaluate the risk of transplanting malignant cells in case of the main malignant indications for ovarian tissue cryopreservation. For ovarian tissue from patients with hematologic malignancies, it is of paramount importance to identify minimal residual disease before ovarian tissue transplantation. Indeed, these pathologies, reviewed here in detail, are considered to be most at risk of ovarian metastasis.

Vitreous cryopreservation of human preantral follicles encapsulated in alginate beads with mini mesh cups

To completely avoid ice crystal formation and thus get a higher survival rate, vitrification methods have been commonly used for cryopreservation of oocytes and embryos. However, currently used vitrification methods for oocytes and embryos are not suitable for the cryopreservation of preantral follicles (PFs). In the present study, stainless steel mesh was fabricated into mini mesh cups to vitrify isolated PFs. Moreover, isolated follicles were encapsulated and then subjected to vitreous cryopreservation to facilitate in vitro culture/maturation of follicles after warming. The results showed that the percentages of viable follicles did not differ significantly between the vitrification group and fresh group soon after warming (81.25% vs. 85.29%, P>0.05) and after a 7-day culture period (77.78% vs. 83.33%, P>0.05). No difference in mean follicular diameter was observed between cryopreserved and fresh follicles when cultured in vitro. Transmission electron microscopic analysis revealed that vitreous cryopreservation could maintain the ultrastructure of follicles in alginate beads. In conclusion, the present vitrification method could efficiently cryopreserve isolated human ovarian follicles encapsulated by calcium alginate, which could be put into immediate use (in vitro culture/ maturation) after warming. However, more follicles and some detailed biochemical analyses are required to further investigate the effects of vitrification on the long-term growth of human encapsulated PFs.

In vitro activation of dormant follicles for fertility preservation

Recent advances in radiotherapy and chemotherapy have led to higher cure rates for female children and adolescents with cancer. However, these treatments adversely affect germ cell survival, and ovarian failure is thus a probable side effect of these anticancer therapies. Moreover, an increasing number of women are choosing to postpone childbearing until later in life, but their primordial follicle reserves degenerate with advancing age. Thus there is a pressing need for the development of fertility preservation methods for these individuals. Ovarian tissue cryopreservation prior to loss of the primordial follicle population either due to cancer treatments or normal aging is a promising option for safeguarding fertility. A complete in vitro maturation (IVM) system could help generate mature eggs for later use without the patient having to undergo the cumbersome process involved in current assisted reproduction methods to generate mature eggs. Cryopreserved ovarian cortical tissues have attracted the attention of reproductive biologists and clinicians because of the large number of safely frozen primordial follicles in them, and it is theoretically possible to use these follicles for in vitro activation (IVA) and subsequent IVM. Ovarian tissue collection is independent of patient age and social or personal conditions. Despite being widely accepted potential techniques for fertility preservation, IVA and IVM of human primordial follicles to obtain fertilizable eggs remains far from reality. This chapter highlights the current achievements and obstacles in obtaining growing follicles through activation of dormant follicles.

Memoir of fertility preservation

Fertility preservation has been practiced for at least 50 years using semen banking, pelvic surgery, and radiation shields, but in the past 20 years it has emerged as a rapidly growing subspecialty of reproductive medicine. A dramatic rise in survivorship of young cancer patients and the widespread postponement of family building to the later years of the female reproductive lifespan have been major driving forces. Throughout the history of fertility preservation, low temperature banking has played a pivotal role, first for gametes and later for embryos and immature germ cells, while ovarian transplantation recently began to contribute and spermatogonial stem cell transfer holds future promise for men and prepubertal boys. But there are significant risks with some diseases from reimplanting residual disease, which hopefully can be eliminated by new methods for purging the tissue and germ cell culture. Since all technologies are interim, cryopreservation as a mainstay in this field will likely be swept aside eventually by a stream of progress aimed at managing fertility preservation in vivo.

Purified enzymes improve isolation and characterization of the adult thymic epithelium

The reproducible isolation and accurate characterization of thymic epithelial cell (TEC) subsets is of critical importance to the ongoing study of thymopoiesis and its functional decline with age. The study of adult TEC, however, is significantly hampered due to the severely low stromal to hematopoietic cell ratio. Non-biased digestion and enrichment protocols are thus essential to ensure optimal cell yield and accurate representation of stromal subsets, as close as possible to their in vivo representation. Current digestion protocols predominantly involve diverse, relatively impure enzymatic variants of crude collagenase and collagenase/dispase (col/disp) preparations, which have variable efficacy and are often suboptimal in their ability to mediate complete digestion of thymus tissue. To address these issues we compared traditional col/disp preparations with the latest panel of Liberase products that contain a blend of highly purified collagenase and neutral protease enzymes. Liberase enzymes revealed a more rapid, complete dissociation of thymus tissue; minimizing loss of viability and increasing recovery of thymic stromal cell (TSC) elements. In particular, the recovery and viability of TEC, notably the rare cortical subsets, were significantly enhanced with Liberase products containing medium to high levels of thermolysin. The improved stromal dissociation led to numerically increased TEC yield and total TEC RNA isolated from pooled digests of adult thymus. Furthermore, the increased recovery of TEC enhanced resolution and quantification of TEC subsets in both adult and aged mice, facilitating flow cytometric analysis on a per thymus basis. We further refined the adult TEC phenotype by correlating surface expression of known TEC markers, with expression of intracellular epithelial lineage markers, Keratin 5 and Keratin 8. The data reveal more extensive expression of K8 than previously recognized and indicates considerable heterogeneity still exists within currently defined adult TEC subsets.

Ovarian tissue and follicle transplantation as an option for fertility preservation

OBJECTIVE

To review and summarize data from the scientific literature on ovarian tissue and follicle transplantation as an option for fertility preservation.

DESIGN

Review of pertinent literature.

SETTING

University hospital.

PATIENT(S)

Women having undergone ovarian tissue transplantation.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Review of the literature.

RESULT(S)

Over the last decade, the field of ovarian transplantation and cryopreservation has significantly progressed, becoming applicable in humans. Indeed, fresh and frozen cortical ovarian tissue transplantations have been successfully reported worldwide, resulting in around 28 healthy babies. Although ovarian-tissue harvesting seems to be safe, the risk of reimplantation of cancer from ovarian cortical transplants cannot be estimated at this time. As a consequence, auto-transplantation of ovarian tissue in women having suffered from systemic hematological malignancies is not recommended. In these situations, reimplantation of isolated ovarian follicles might represent an interesting option in the future.

CONCLUSION(S)

Although the clinical experience is limited, the robust results obtained open new perspectives for the management of premature ovarian failure resulting or not from gonadotoxic treatments.

Viability assessment of fresh and frozen/thawed isolated human follicles: reliability of two methods (Trypan blue and Calcein AM/ethidium homodimer-1)

PURPOSE

To assess the reliability of trypan blue (TB) and calcein AM/ethidium homodimer-1 (CaAM/EthD-1) staining to evaluate the viability of fresh and thawed human ovarian follicles.

METHODS

Isolated follicles from fresh and thawed cortex were stained using TB versus CaAM/EthD-1 methods (n = 10 patients). Measurements were performed by two independent observers. The reliability was evaluated by intraclass correlation coefficient (ICC) and the differences between paired measurements were tested by the Wilcoxon test.

RESULTS

Inter-observer reliability was excellent for each method. Nevertheless, it was even better with the TB method (ICC = 0.83) compared with CaAM/EthD-1 (ICC = 0.75). Moreover, the ICCs for viability measurements using the two methods were good for each observer (observer 1: ICC = 0.49; observer 2: ICC = 0.40).

CONCLUSION

Compared with CaAM/EthD-1, TB appears to be more reliable as a staining method for follicle viability evaluation. TB staining is a quick and useful method, complementary to histological analysis for quality control in ovarian tissue cryopreservation.

In vitro growth and steroidogenesis of dog follicles are influenced by the physical and hormonal microenvironment

The present study examined the influences of the physical and hormonal microenvironment on in vitro growth and steroidogenesis of dog follicles. Follicles were enzymatically isolated and individually encapsulated in 0.5% (w/v; n=17) or 1.5% (n=10) alginate and cultured with 0.5 IU/ml equine chorionic gonadotropin for 192 h. In a separate experiment, follicles were encapsulated in 0.5% alginate and cultured with 0 (n=22), 1 (n=23), 10 (n=20) or 100 (n=21) μg/ml FSH for 240 h. Follicle diameter and steroid production were assessed every 48 h in both studies. Follicles encapsulated in the 0.5% alginate grew faster (P<0.05) than those cultured in the 1.5% concentration. Oestradiol (E(2)) and progesterone (P(4)) increased consistently (P<0.05) over time, and follicles in the 1.5% alginate produced more (P<0.05) P(4) than those in the 0.5% solution. Follicles cultured in the highest FSH concentration (100 μg/ml) increased 100% in size after 240 h compared with 50 to 70% in lower dosages. E(2) concentration remained unchanged over time (P>0.05) across FSH dosages. However, P(4) increased (P<0.05) as culture progressed and with increasing FSH concentration. Results demonstrate that dog follicles cultured in alginate retain structural integrity, grow in size and are hormonally active. Lower alginate and increasing FSH concentrations promote in vitro follicle growth. However, the absence of an E(2) rise in follicles cultured in FSH alone suggests the need for LH supplementation to support theca cell differentiation and granulosa cell function.

Cryopreservation and transplantation of ovarian tissue

Cryopreservation and autotransplantation of ovarian tissue for fertility preservation is considered an experimental technique. However, in some clinical situations it remains the only option. Eleven pregnancies have been reported worldwide from this procedure. Transplantation of ovarian tissue pieces without a vascular pedicle requires the establishment of a new blood supply that takes 5 days. This leads to a substantial loss of follicles in the graft that may limit the longevity of the graft.

Pregnancy and live birth after autotransplantation of frozen-thawed ovarian tissue in a patient with metastatic disease undergoing chemotherapy and hematopoietic stem cell transplantation

OBJECTIVE

To report a live birth after orthotopic transplantation of cryopreserved ovarian tissue.

DESIGN

Case report.

SETTING

Department of Gynecology, Cliniques Universitaires Saint-Luc, Brussels.

PATIENT(S)

Woman with metastatic cancer who had her ovarian tissue cryopreserved in 2001 before undergoing chemotherapy and hematopoietic stem cell transplantation, resulting in premature ovarian failure.

INTERVENTION(S)

Orthotopic reimplantation of ovarian cortex performed 7 years after cryopreservation.

MAIN OUTCOME MEASURE(S)

Restoration of ovarian activity.

RESULT(S)

Restoration of ovarian activity was observed 3.5 months after reimplantantation, and ongoing pregnancy was diagnosed 9 months after grafting. The patient delivered a healthy baby weighing 2.830 kg.

CONCLUSION(S)

Our patient represents the thirteenth live birth to occur after orthotopic reimplantation of cryopreserved tissue, but the first in a woman treated for metastatic disease.

Isolation of pre-antral follicles from human ovarian medulla tissue

BACKGROUND

Cryopreservation of ovarian tissue for fertility preservation is based on the ovarian cortex that contains the vast majority of the follicular reserve, while the remaining tissue, the medulla is discarded. The present study describes the development of a gentle method for isolating pre-antral follicles from human ovarian medulla and evaluating its follicular content.

METHODS

Medulla was collected from 40 girls/women aged 3-35 years undergoing cryopreservation of the ovarian cortex. Follicle density was assessed for all patients and pre-antral follicles were isolated from 22 patients. On the basis of the neutral red (NR) staining of follicles and enzymatic digestion with a mixture of Collagenase IV and Liberase Thermolysin Medium, viable pre-antral follicles were isolated.

RESULTS

NR accumulated in follicles resulting in a distinct red staining within the medulla. Follicle density of the medulla varied from 0 to 9824 follicles/gram of medulla and was significantly higher (P< 0.001) in the 3-9-year age group when compared with older groups (10-35 years). Enzymatic digestion combined with follicle identification by NR yielded a high output of isolated and viable pre-antral follicles from medulla, of which, 3607 follicles were collected and classified. The percentage of primordial and growing follicles decreased and increased, respectively, with age (P< 0.0001 and <0.0007).

CONCLUSIONS

Discarded medulla contained a considerable pool of pre-antral follicles, especially in young girls. Our new method allowed the isolation of viable pre-antral follicles from human ovarian medulla and provides a unique opportunity for basic scientific studies and for culture and grafting purposes.

Reimplantation of cryopreserved ovarian tissue from patients with acute lymphoblastic leukemia is potentially unsafe

Ovarian tissue cryopreservation is currently proposed to young cancer patients to preserve their fertility before radiochemotherapy. The potential risk is that the tissue might harbor malignant cells that could induce disease recurrence. We therefore decided to evaluate the presence of leukemic cells in cryopreserved ovarian tissue from 18 leukemic patients: 6 with chronic myeloid leukemia (CML) and 12 with acute lymphoblastic leukemia (ALL). In each case, histology, quantitative reverse-transcribed polymerase chain reaction (RT-PCR) and long-term (6 months) xenografting to immunodeficient mice were used. Histology did not identify any malignant cells in the ovarian tissue. By quantitative RT-PCR, 2 of 6 CML patients were positive for BCR-ABL in their ovarian tissue. Among the 12 ALL patients, 7 of the 10 with available molecular markers showed positive leukemic markers in their ovarian tissue (translocations or rearrangement genes). Four mice grafted with ovarian tissue from ALL patients developed intraperitoneal leukemic masses. In conclusion, this study demonstrates, by quantitative RT-PCR, ovarian contamination by malignant cells in acute as well as chronic leukemia, whereas histology fails to do so. Moreover, chemotherapy before ovarian cryopreservation does not exclude malignant contamination. Finally, reimplantation of cryopreserved ovarian tissue from ALL and CML patients puts them at risk of disease recurrence.

Whole sheep ovary cryopreservation: evaluation of a slow freezing protocol with dimethylsulphoxide

PURPOSE

To evaluate a slow freezing method for whole ovary cryopreservation by evaluating effects of added cryoprotectant.

METHODS

Sheep ovaries were isolated during surgery, flushed with either Ringer-Acetate or dimethylsulphoxide and cryopreserved by slow freezing. After rapid thawing, viability was assessed by ovarian in vitro perfusion, cell culture, histology and fluorescent live-dead assay.

RESULTS

Production of cyclic AMP and progesterone was slightly higher in the dimethylsulphoxide group. Cultured ovarian cells from dimethylsulphoxide-preserved ovaries secreted larger amounts of progesterone than cells from Ringer-Acetate preserved. Light microscopy of ovarian biopsies obtained after perfusion, revealed well-preserved tissue in the dimethysulphoxide group but not in the Ringer-Acetate group. The density of small follicles and ovarian cell viability were higher in dimethysulphoxide ovaries compared to Ringer-Acetate ovaries.

CONCLUSIONS

Equilibrium with its protective effect can be achieved by slow freezing protocol, with an additional protective effect by the presence of dimethylsulphoxide.

Current achievements and future research directions in ovarian tissue culture, in vitro follicle development and transplantation: implications for fertility preservation

BACKGROUND Female cancer patients are offered 'banking' of gametes before starting fertility-threatening cancer therapy. Transplants of fresh and frozen ovarian tissue between healthy fertile and infertile women have demonstrated the utility of the tissue banked for restoration of endocrine and fertility function. Additional methods, like follicle culture and isolated follicle transplantation, are in development. METHODS Specialist reproductive medicine scientists and clinicians with complementary expertise in ovarian tissue culture and transplantation presented relevant published literature in their field of expertise and also unpublished promising data for discussion. As the major aims were to identify the current gaps prohibiting advancement, to share technical experience and to orient new research, contributors were allowed to provide their opinioned expert views on future research. RESULTS Normal healthy children have been born in cancer survivors after orthotopic transplantation of their cryopreserved ovarian tissue. Longevity of the graft might be optimized by using new vitrification techniques and by promoting rapid revascularization of the graft. For the in vitro culture of follicles, a successive battery of culture methods including the use of defined media, growth factors and three-dimensional extracellular matrix support might overcome growth arrest of the follicles. Molecular methods and immunoassay can evaluate stage of maturation and guide adequate differentiation. Large animals, including non-human primates, are essential working models. CONCLUSIONS Experiments on ovarian tissue from non-human primate models and from consenting fertile and infertile patients benefit from a multidisciplinary approach. The new discipline of oncofertility requires professionalization, multidisciplinarity and mobilization of funding for basic and translational research.

Solid-surface vitrification is an appropriate and convenient method for cryopreservation of isolated rat follicles

BACKGROUND

Cryopreservation of isolated follicles may be a potential option to restore fertility in young women with cancer, because it can prevent the risks of cancer transmission. Several freezing protocols are available, including slow-rate freezing, open-pulled straws vitrification (OPS) and solid-surface vitrification (SSV, a new freezing technique). The purpose of our study was to investigate the effects of these freezing procedures on viability, ultrastructure and developmental capacity of isolated rat follicles.

METHODS

Isolated follicles from female Sprague-Dawley rats were randomly assigned to SSV, OPS and slow-rate freezing groups for cryopreservation. Follicle viability assessment and ultrastructural examination were performed after thawing. In order to study the developmental capacity of thawed follicles, we performed in vitro culture with a three-dimensional (3D) system by alginate hydrogels.

RESULTS

Our results showed that the totally viable rate of follicles vitrified by SSV (64.76%) was slightly higher than that of the OPS group (62.38%) and significantly higher than that of the slow-rate freezing group (52.65%; P < 0.05). The ultrastructural examination revealed that morphological alterations were relatively low in the SSV group compared to the OPS and slow-rate freezing groups. After in vitro culture within a 3D system using alginate hydrogels, we found the highest increase (28.90 +/- 2.21 microm) in follicle diameter in follicles from the SSV group. The estradiol level in the SSV group was significantly higher than those in the OPS and slow-rate freezing groups at the end of a 72-hr culture period (P < 0.05).

CONCLUSIONS

Our results suggest that the SSV method is an appropriate and convenient method for cryopreservation of isolated rat follicles compared with the conventional slow-rate freezing method and the OPS method.

A simple and efficient method for preparation of isolated ovarian follicles for transmission electron microscopy

OBJECTIVE

A simple method for preparation of isolated ovarian follicles for transmission electron microscopy (TEM) using transwell inserts is described.

MATERIALS AND METHODS

Pre-antral follicles were enzymatically isolated from mouse ovaries and cultured overnight on transwell insert polyester membranes. The following day, isolated ovarian follicles were processed for TEM by moving the transwell insert through successive wells containing the fixation and embedding reagents. After polymerization of the resin, the polyester membrane with the follicles embedded in the resin was disengaged from the transwell unit. The resin was sectioned. Semi-thin sections were stained with toluidine blue while ultra-thin sections were stained by uranyl acetate and examined by light microscopy and TEM, respectively.

RESULTS

Isolated ovarian follicles were easily processed in groups for TEM. Follicles were well embedded and there appeared to be no loss of tissue during processing. The ultra-structure of processed isolated ovarian follicles was well preserved with little evidence of processing artifacts.

CONCLUSIONS

In situ processing and preparation of isolated ovarian follicles by first allowing attachment on transwell insert membranes was shown to be a simple, rapid and effective method for TEM.

Malignant cells are not found in ovarian cortex from breast cancer patients undergoing ovarian cortex cryopreservation

BACKGROUND

Breast cancer is a frequent indication for ovarian cortex cryopreservation due to its high incidence. The main concern of this procedure is the possibility of reintroducing metastatic cells within the implant, an issue that has not been addressed systematically. Thus, a study was designed to analyse the presence of ovarian metastases in breast cancer patients undergoing ovarian tissue cryopreservation.

METHODS

Morphological and immunohistochemical studies following the concept of the sentinel lymph node (SLN) were performed on 100 cortical ovarian biopsies obtained from 63 patients and on six frozen-thawed entire cortex from patients with the diagnosis of infiltrating ductal breast carcinoma undergoing ovarian cortex extraction and cryopreservation. The antibody panel included Cytokeratin CAM 5.2, Gross Cystic Disease Fluid Protein-15 (GCDFP15), Wilms' tumour antigen-1 (WT1) and Mammaglobin 1.

RESULTS

Employing only morphologic criteria, suspicious neoplastic cells were detected in five biopsies, but in none of the six entire cortex analysed. These five cases were reclassified as hyperplasic surface epithelium-inclusion cysts (CAM 5.2+, WT1+) or apoptotic granulosa cells (CAM 5.2-, GCDFP15+, WT1-).

CONCLUSIONS

Using the methodology of the SLN our data suggest the absence of tumour cells in biopsies obtained from patients undergoing ovarian cortex cryopreservation to preserve their fertility potential, although future methods of cancer screening may change our perception of this procedure.

Viability and function of the cryopreserved whole ovary: in vitro studies in the sheep

BACKGROUND

Cryopreservation of whole ovaries followed by vascular transplantation may improve long-term function in comparison to conventional cryopreservation of ovarian cortex and avascular transplantation. The aim of this study was to assess methods for the evaluation of viability and function of frozen-thawed whole ovaries.

METHODS

Ewe ovaries were flushed with either cryoprotectant (propandiol: FROZEN-PROH) or Ringer Acetate (FROZEN-RA) followed by slow freezing. Some ovaries were assessed fresh after flushing with Ringer Acetate (FRESH-RA). Assessment was done by light microscopy, biochemical response (cyclic adenosine 3',5'-monophosphate (cAMP) and steroids) during in vitro perfusion with forskolin, viability assay and cell culture.

RESULTS

Microscopy showed well-preserved morphology with the presence of small follicles in all groups before perfusion. Stromal oedema was seen after in vitro perfusion of FROZEN ovaries, and shrunken small follicles were seen only in FROZEN-RA at the end of perfusion. During in vitro perfusion, FRESH-RA ovaries responded with large increase in levels of cAMP after stimulation with forskolin. FROZEN-PROH and FROZEN-RA ovaries exhibited lower production of cAMP. Progesterone concentrations in cell cultures of dispersed ovarian cells were higher in FRESH-RA when compared with FROZEN groups. Addition of hCG to cell cultures resulted in higher progesterone levels in the FROZEN-PROH compared with FROZEN-RA. Cell viability assay showed overall viability of 60-75% with no significant difference between groups.

CONCLUSION

In vitro perfusion may prove to be a suitable method to test viability and function of frozen-thawed whole ovaries contributing to the optimization of current cryopreservation protocols.

Cryopreservation/transplantation of ovarian tissue and in vitro maturation of follicles and oocytes: challenges for fertility preservation

Cryopreservation of ovarian tissue and in vitro follicle maturation are two emerging techniques for fertility preservation, especially in cancer patients. These treatment regimes are opening up more options and allow for more suitable choices to preserve fertility according to the patient's specific circumstances. If these technologies are to become widely accepted, they need to be safe, easy to perform and must obtain favorable results. The generation of healthy eggs with the normal genetic complement and the ability to develop into viable and healthy embryos requires tight regulation of oocyte development and maturation. Novel freezing techniques such as vitrification, along with whole ovary cryopreservation and three-dimensional follicle cultures, have shown favorable outcomes. The scope of this article is to take a comprehensively look at the challenges still faced in order for these novel technologies to be routinely employed with the aim of successful fertility preservation.

Preservation of fertility in young cancer patients: contribution of transmission electron microscopy

During the last decade, new technologies in reproductive medicine have emerged to preserve the fertility of women whose gonadal function is threatened by premature menopause or gonadotoxic treatments. To offer an individualized approach to these patients, different experimental procedures are under investigation, including oocyte cryopreservation and cryopreservation and transplantation of ovarian tissue in the form of cortical fragments, whole ovary or isolated follicles. This review shows that transmission electron microscopy (TEM), combined with other in-vivo and in-vitro analysis techniques, is a valuable tool in the establishment of new experimental protocols to preserve female fertility. Ultrastructural studies allow in-depth evaluation of the oocyte's unique morpho-functional characteristics, which explain its low cryotolerance, and provide essential information on follicular, stromal and endothelial cell integrity, as well as cellular interactions crucial for normal folliculogenesis. In order to be able to offer appropriate and efficient options in every clinical situation, oocyte in-vitro maturation and ovarian tissue transplantation need to be optimized. Further development of new approaches, such as follicular isolation and whole ovary transplantation, should be encouraged. Fine ultrastructural details highlighted by TEM studies will be useful for the further optimization of these emerging technologies.

Demande de préservation de la fertilité chez la femme en cas de maladie auto-immune: possibilités et pratiques en France

Cancer is not the only disease where the question of the female fertility preservation is asked. In autoimmune diseases, alkylating agents are also used and it is now established that 20 g as a cumulative dose of cyclophosphamide is associated with premature ovarian failure in 50% of 20-year-old patients. Several strategies are discussed and offered to these patients to prevent the ovarian failure: GnRH agonist treatment, in vitro fertilization and embryos cryopreservation, oocytes cryopreservation and ovarian cortex cryopreservation. These techniques might also be associated one with the other. A survey was conducted in France in order to assess the practices realised in these diseases. Four centres were asked for these diseases, concerning 17 patients (mean age: 26.2 +/- 1.8 SEM [15-43]) and systemic lupus erythematosus was the most frequent disease (7/17). Ovarian cortex cryopreservation was realised for 6 patients. Embryos or oocytes cryopreservation was realised for 2 patients including one where ovarian cortex cryopreservation was associated. In 10 cases, considering the treatment and the patient's wish no fertility preservation was realised. Female fertility preservation in autoimmune diseases is a difficult question and a national registry, such as the one conducted by the GRECOT, can help to answer this question.

Short-term transplantation of isolated human ovarian follicles and cortical tissue into nude mice

This study was designed to evaluate follicular survival and growth after short-term transplantation of fresh isolated human follicles and ovarian cortical tissue to nude mice. Ovarian biopsies were obtained from nine women undergoing laparoscopy. Twelve nude mice were xenografted with an ovarian cortical fragment in the right ovarian bursa, and a clot containing isolated follicles in the left, for a period of 7 days. One ungrafted fragment was used as a control. Histological sections were analyzed to determine follicle number and stage. The proliferative status of follicular cells was assessed by Ki-67 immunostaining. A total of 659 follicles was analyzed by histology and 545 follicles by immunohistochemistry. The percentage of primordial follicles was found to be markedly reduced 1 week post-grafting when compared with ungrafted tissue, while the percentage of primary follicles had significantly increased. Only 8% of follicles showed Ki-67-positive granulosa cells before grafting, whereas 1 week after grafting, 71% of follicles in fragments and 67% of isolated follicles were Ki-67-positive (P<0.001). Moreover, the histological aspect of isolated follicle grafts was similar to that of grafted fragments: follicles were surrounded by vimentin-positive stroma-like tissue of human origin, as confirmed by fluorescent in situ hybridization with human-specific probes. Our results demonstrate, for the first time, that isolated human follicles are able to survive and grow after xenografting. This study also shows massive in vivo follicular activation after transplantation of grafted fragments and isolated follicles. One week after grafting, well-structured stroma-like tissue of human origin was observed around the isolated follicles. The potential origin of this stroma is discussed.

Engineering the follicle microenvironment

In vitro ovarian follicle culture provides a tool to investigate folliculogenesis, and may one day provide women with fertility-preservation options. The application of tissue engineering principles to ovarian follicle maturation may enable the creation of controllable microenvironments that will coordinate the growth of the multiple cellular compartments within the follicle. Three-dimensional culture systems can preserve follicle architecture, thereby maintaining critical cell-cell and cell-matrix signaling lost in traditional two-dimensional attached follicle culture systems. Maintaining the follicular structure while manipulating the biochemical and mechanical environment will enable the development of controllable systems to investigate the fundamental biological principles underlying follicle maturation. This review describes recent advances in ovarian follicle culture, and highlights the tissue engineering principles that may be applied to follicle culture, with the ultimate objective of germline preservation for females facing premature infertility.

Ovarian tissue cryopreservation and transplantation: a review

The review covers current options for ovarian tissue cryopreservation and transplantation and provides a systematic review of the existing literature from the last 10 years, taking into account all previously published reviews on the subject. The different cryopreservation options available for fertility preservation in cancer patients are embryo cryopreservation, oocyte cryopreservation and ovarian tissue cryopreservation. The choice depends on various parameters: the type and timing of chemotherapy, the type of cancer, the patient's age and the partner status. The different options and their results are discussed, as well as their putative indications and efficacy. The review concludes that advances in reproductive technology have made fertility preservation techniques a real possibility for patients whose gonadal function is threatened by premature menopause, or by treatments such as radiotherapy, chemotherapy or surgical castration.