Optimizing Decellularization of Bovine Ovarian Tissue: Toward a Transplantable Artificial Ovary Scaffold with Minimized Residual Toxicity and Preserved Extracellular Matrix Morphology.

INTRODUCTION: The decellularized extracellular matrix (dECM) from ovarian tissue could be the best scaffold for the development of a transplantable artificial ovary. Typically, dECM from ovarian tissue has been obtained using sodium dodecyl sulfate (SDS), at a concentration of 1% for 24 h. However, SDS can leave residues in the tissue, which may be toxic to the seeded cells. This study aimed to obtain dECM from bovine ovarian tissue using SDS and NaOH at a minimum concentration in the shortest incubation time. METHODS: The respective SDS and NaOH concentrations investigated were 1% and 0.2M; 0.5% and 0.1M; 0.1% and 0.02M, and 0.05% and 0.01M, with 24, 12, and 6 h incubation periods. After the incubation time the tissue was washed in 50 mL of distilled water for 6 h. RESULTS: Histological analysis confirmed decellularization and showed the conservation of collagen fibers in all samples following treatment. Furthermore, the lowest SDS and NaOH concentrations that showed no DNA remaining during electrophoresis analysis were 0.1% and 0.02M when incubated for 24 and 12 h. DNA quantification resulted in ˂ 0.2 ng DNA/mg ovarian tissue using these protocols. Additionally, the coculture of dECM (obtained by 0.1% SDS and 0.02M NaOH for 12 h) with ovarian cells showed that there was no toxic effect for the cells for up to 72 h. CONCLUSION: The protocol involving 0.1% SDS and 0.02M NaOH for 12 h incubation decellularizes bovine ovarian tissue, generating a dECM that preserves the native ECM morphology and is non-toxic to ovarian cells.

Cancer cell contamination and decontamination methods for ovaries and testes: special focus on prepubertal gonads with a view to safe fertility restoration.

Fertility restoration in patients that survived a hematological cancer during childhood is a core part of their care pathway. Nonetheless, there might be a risk of contamination of the gonads by cancer cells, especially in patients presenting with leukemia and lymphoma. When only a few cancer cells have reached the gonad, they may not be detected by routine histological examination, and therefore more sensitive techniques are required before being confident of the safety of transplanting cryostored testicular and ovarian tissues or cells back to the patient after recovery. Furthermore, if neoplastic cells are identified in the gonadal tissue, methods to eliminate such cells are urgently awaited as the presence of only a few cancer cells may induce disease relapse in these patients. In this review, contamination rates of human gonadal tissue in the case of leukemia or lymphoma as well as decontamination methods applied to both adult and prepubertal testicular and ovarian tissues are presented. Prepubertal gonads will be the main focus as we aim to show how far we have come in establishing safe approaches to fertility restoration. Advances have been made using animal tissue that is usually artificially contaminated by the addition of cancer cell lines to the gonadal cells or tissue, but these techniques need to be improved and still await development in the case of in vivo cancer cell invasion of 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.

Rescuing fertility during COVID-19 infection: exploring potential pharmacological and natural therapeutic approaches for comorbidity, by focusing on NLRP3 inflammasome mechanism.

The respiratory system was primarily considered the only organ affected by Coronavirus disease 2019 (COVID-19). As the pandemic continues, there is an increasing concern from the scientific community about the future effects of the virus on male and female reproductive organs, infertility, and, most significantly, its impact on the future generation. The general presumption is that if the primary clinical symptoms of COVID-19 are not controlled, we will face several challenges, including compromised infertility, infection-exposed cryopreserved germ cells or embryos, and health complications in future generations, likely connected to the COVID-19 infections of parents and ancestors. In this review article, we dedicatedly studied severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) virology, its receptors, and the effect of the virus to induce the activation of inflammasome as the main arm of the innate immune response. Among inflammasomes, nucleotide oligomerization domain-like receptor protein, pyrin domain containing 3 (NLRP3) inflammasome pathway activation is partly responsible for the inflicted damages in both COVID-19 infection and some reproductive disorders, so the main focus of the discussion is on NLRP3 inflammasome in the pathogenesis of COVID-19 infection alongside in the reproductive biology. In addition, the potential effects of the virus on male and female gonad functions were discussed, and we further explored the potential natural and pharmacological therapeutic approaches for comorbidity via NLRP3 inflammasome neutralization to develop a hypothesis for averting the long-term repercussions of COVID-19. Since activation of the NLRP3 inflammasome pathway contributes to the damage caused by COVID-19 infection and some reproductive disorders, NLRP3 inflammasome inhibitors have a great potential to be considered candidates for alleviating the pathological effects of the COVID-19 infection on the germ cells and reproductive tissues. This would impede the subsequent massive wave of infertility that may threaten the patients.

A Draft Map of the Human Ovarian Proteome for Tissue Engineering and Clinical Applications.

Fertility preservation research in women today is increasingly taking advantage of bioengineering techniques to develop new biomimetic materials and solutions to safeguard ovarian cell function and microenvironment in vitro, and in vivo,. However, available data on the human ovary are limited and fundamental differences between animal models and humans are hampering researchers in their quest for more extensive knowledge of human ovarian physiology and key reproductive proteins that need to be preserved. We therefore turned to multi-dimensional label-free mass spectrometry to analyze human ovarian cortex, as it is a high-throughput and conclusive technique providing information on the proteomic composition of complex tissues like the ovary. In-depth proteomic profiling through two-dimensional liquid chromatography-mass spectrometry, Western blotting, histological and immunohistochemical analyses, and data mining helped us to confidently identify 1508 proteins. Moreover, our method allowed us to chart the most complete representation so far of the ovarian matrisome, defined as the ensemble of extracellular matrix proteins and associated factors, including more than 80 proteins. In conclusion, this study will provide a better understanding of ovarian proteomics, with a detailed characterization of the ovarian follicle microenvironment, in order to enable bioengineers to create biomimetic scaffolds for transplantation and three-dimensional in vitro, culture. By publishing our proteomic data, we also hope to contribute to accelerating biomedical research into ovarian health and disease in general.

New insights into the GDF9-Hedgehog-GLI signaling pathway in human ovaries: from fetus to postmenopause.

RESEARCH QUESTION: Are glioma-associated oncogene homolog 1, 2, and 3 (GLI1, 2, and 3) and protein patched homolog 1 (PTCH1) specific markers for precursor theca cells in human ovaries as in mouse ovaries? DESIGN: To study the GDF9-HH-GLI pathway and assess whether GLI1 and 3 and PTCH1 are specific markers for precursor theca cells in the human ovary, growth differentiation factor 9 (GDF9), Indian Hedgehog (IHH), Desert Hedgehog (DHH), Sonic Hedgehog (SHH), PTCH1 and GLI1, 2 and 3 were investigated in fetal (n=9), prepubertal (n=9), reproductive-age (n=15), and postmenopausal (n=8) human ovarian tissue. Immunohistochemistry against GDF9, IHH, DHH, SHH, PTCH1, GLI1, GLI2, and GLI3 was performed on human ovarian tissue sections fixed in 4% formaldehyde and embedded in paraffin. Western blotting was carried out on extracted proteins from the same samples used in the previous step to prove the antibodies' specificity. The quantitative real-time polymerase chain reaction was performed to identify mRNA levels for Gdf9, Ihh, Gli1, Gli2, and Gli3 in menopausal ovaries. RESULTS: Our results showed that, in contrast to mice, all studied proteins were expressed in primordial follicles of fetal, prepubertal, and reproductive-age human ovaries and stromal cells of reproductive-age and postmenopausal ovaries. Intriguingly, Gdf9, Ihh, and Gli3 mRNA, but not Gli1 and 2, was detected in postmenopausal ovaries. Moreover, GLI1, GLI3, and PTCH1 are not limited to a specific population of cells. They were spread throughout the organ, which means they are not specific markers for precursor theca cells in human ovaries. CONCLUSION: These results could provide a basis for understanding how this pathway modulates follicle development and ovarian cell steroidogenesis in human ovaries.

Evidence of metabolic activity during low-temperature ovarian tissue preservation in different media.

PURPOSE: Although ovarian tissue transportation has been validated for up to 24 h, there is no standard protocol to date. We aimed to elucidate how existing media currently used for ovarian tissue transportation affect ovarian tissue metabolism and cell viability. METHODS: Cow ovarian fragments were immersed in 0.9% NaCl solution, IVF medium, Leibovitz 15 medium (L-15), or PBS for 1, 4, or 24 h at 4 °C. Media were analyzed for pH, lactate dehydrogenase (LDH) activity, and glucose, pyruvate, and lactate concentrations, while apoptosis was assessed by TUNEL assays in fixed fragments. Viability rates were assessed by flow cytometry (FACS). RESULTS: There were lower pH levels in NaCl at all time points compared with other media. LDH activity increased with time and was lowest in NaCl at 1 and 4 h. There was no significant difference in glucose levels, but a significant pyruvate decrease in L-15 and a significant lactate increase in all media. TUNEL showed apoptosis rates ranging from 0 to 5%. FACS showed a mean of 4% necrotic cells and 15-19% apoptotic cells after 1 h of incubation, but less than 1% necrotic cells and 2-6% apoptotic cells after 24 h in all media. CONCLUSION: Our results indicate marked metabolic activity in ovarian tissue at 4 °C and suggest that cells use internal sources of energy, which may influence transplantation outcomes. This highlights the importance of better understanding whole tissue dynamics to develop a standard protocol for ovarian tissue transportation. Graphical abstract.

Divide-and-Conquer Matrisome Protein (DC-MaP) Strategy: An MS-Friendly Approach to Proteomic Matrisome Characterization.

Currently, the extracellular matrix (ECM) is considered a pivotal complex meshwork of macromolecules playing a plethora of biomolecular functions in health and disease beyond its commonly known mechanical role. Only by unraveling its composition can we leverage related tissue engineering and pharmacological efforts. Nevertheless, its unbiased proteomic identification still encounters some limitations mainly due to partial ECM enrichment by precipitation, sequential fractionation using unfriendly-mass spectrometry (MS) detergents, and resuspension with harsh reagents that need to be entirely removed prior to analysis. These methods can be technically challenging and labor-intensive, which affects the reproducibility of ECM identification and induces protein loss. Here, we present a simple new method applicable to tissue fragments of 10 mg and more. The technique has been validated on human ovarian tissue and involves a standardized procedure for sample processing with an MS-compatible detergent and combined centrifugation. This two-step protocol eliminates the need for laborious sample clarification and divides our samples into 2 fractions, soluble and insoluble, successively enriched with matrisome-associated (ECM-interacting) and core matrisome (structural ECM) proteins.

Long-term follow-up of vitrified and autografted baboon (Papio anubis) ovarian tissue.

STUDY QUESTION: Can vitrified baboon ovarian tissue survive >5 months after autotransplantation and subsequently restore fertility? SUMMARY ANSWER: Our results show that ovarian tissue grafts can survive at least 18 months, but fertility restoration could not be confirmed due to lack of pregnancy. WHAT IS KNOWN ALREADY: Ovarian function in baboons can be re-established after autografting of vitrified-warmed ovarian tissue fragments. STUDY DESIGN, SIZE, DURATION: Ovaries from five adult female baboons were used for this study. Unilateral ovariectomy was performed in each animal, followed by vitrification of ovarian fragments. Orthotopic autotransplantation of the vitrified-warmed ovarian fragments was carried out 1 day after ovariectomy. One month later, the other ovary was removed from each animal and vitrified. The next day, the ovarian samples were warmed and orthotopically autografted. Biopsies of grafted tissues were taken after 12 and 18 months for stromal tissue and follicle evaluation. Control samples were collected before vitrification. PARTICIPANTS/MATERIALS, SETTING, METHODS: After grafting, follicle survival, growth and function and also the quality of stromal tissue were assessed histologically and by immunohistochemistry. Estrogen levels were measured, and cyclicity was monitored. All five animals were mated several times. Male baboons used in the mating experiments were not of proven fertility. MAIN RESULTS AND THE ROLE OF CHANCE: After vitrification, warming and long-term grafting, follicles were able to grow. However, their function may have been negatively affected by vitrification and/or transplantation, as expression of kit ligand and c-kit differed from fresh ungrafted tissue (P < 0.05). Corpora lutea and/or ovulation stigma were observed in grafts, indicating successful ovulation in all the baboons, with estrogen levels comparable to those in adult female baboons. LARGE SCALA DATA: Not applicable. LIMITATIONS, REASONS FOR CAUTION: Despite our promising findings on ovarian function restoration, the vitrification procedure could not be validated. Moreover, male baboons used for mating were not of proven fertility. WIDER IMPLICATIONS OF THE FINDINGS: Our protocol of ovarian tissue vitrification successfully re-established ovarian function in a baboon model of autotransplantation. While more studies are required to determine whether this approach can indeed restore fertility, it may prove an easy way of cryopreserving ovarian tissue with a view to recovering ovarian function. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by grants from the Fonds National de la Recherche Scientifique (FNRS) (C.A.A. is an FRS-FNRS Research Associate; grant 5/4/150/5 awarded to M.M.D.), Fonds Spéciaux de Recherche, Fondation Saint Luc, Stichting tegen Kanker (Fondation contre le Cancer), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil; grant # 013/14 CAPES/WBI awarded to C.M.L.), Wallonie-Bruxelles International (awarded to C.A.A.), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; grant awarded to Sarah R. Scalercio) and donations from the Ferrero family. None of the authors have any competing interests to declare.

FERTILITY PRESERVATION: Construction and use of artificial ovaries.

Increasing numbers of patients are now surviving previously fatal malignant diseases, so for women of childbearing age, fertility concerns are paramount once they are cured. However, the treatments themselves, namely chemo- and radiotherapy, can cause considerable damage to endocrine and reproductive functions, often leaving these women unable to conceive. When such gonadotoxic therapy cannot be postponed due to the severity of the disease or for prepubertal girls, the only way to preserve fertility is cryobanking their ovarian tissue for future use. Unfortunately, with some types of cancer, there is a risk of reimplanting malignant cells together with the frozen-thawed tissue, so it is not recommended. A safer approach involves grafting isolated preantral follicles back to their native environment inside a specially created transplantable artificial ovary for their protection. This bioengineered ovary must mimic the natural organ and therefore requires an appropriate scaffold to encapsulate not only isolated follicles, but also autologous ovarian cells, which are needed for follicles to survive and develop. Here we review the indications for use of this artificial ovary and advances in the field that are bringing us ever closer to clinical implementation.

Translational research aiming to improve survival of ovarian tissue transplants using adipose tissue-derived stem cells.

There is now sufficient evidence to support the feasibility and efficacy of ovarian tissue (OT) cryopreservation and transplantation for both fertility preservation and restoration purposes. However, there are still issues to address regarding the grafting procedure itself, since transplanted tissue suffers massive follicle loss in the early post-grafting period. To improve follicle survival after transplantation, our group recently developed a two-step transplantation technique for OT transplantation in a xenografting model using adipose tissue-derived stem cells (ASCs). The aim of this narrative review is to describe and discuss the previously reported findings. ASCs were initially characterized by flow cytometry as positive for CD29, CD44, CD73, CD90, CD105 and CD166 (>95%) and negative for CD34, CD14, CD31, CD45 and Lin1. ASCs were used in a model of xenotransplantation, were they were embedded in a fibrin scaffold and transplanted to the peritoneum of immunodeficient mice. The goal of the first step was to increase levels of partial pressure of oxygen (pO2 ) and revascularization in the peritoneal transplantation site for further OT transplantation. As ASCs showed the ability to differentiate into endothelial-like cells and vessels in our model, OT transplantation was then performed with ASC grafts in a controlled experiment. At 7 days post-transplantation, the ASC group showed: (1) significantly higher pO2 levels; (2) significantly greater human and murine CD34-positive endothelial areas; (3) significantly higher primordial follicle survival rates; (4) and significantly lower numbers of apoptotic follicles compared with the control group. Our research model demonstrates that by adding ASCs to a fibrin scaffold before OT transplantation, faster and better graft reoxygenation and revascularization may be obtained, resulting in increased follicle survival and reduced follicle apoptosis.

Cryopreservation of Human Ovarian Tissue: A Review.

BACKGROUND: Cryopreservation of human ovarian tissue has been increasingly applied worldwide to safeguard fertility in cancer patients, notably in young girls and women who cannot delay the onset of their treatment. Moreover, it has been proposed to patients with benign pathologies with a risk of premature ovarian insufficiency. So far, more than 130 live births have been reported after transplantation of cryopreserved ovarian tissue, and almost all patients recovered their ovarian function after tissue reimplantation. SUMMARY: This review aims to summarize the recent results described in the literature regarding human ovarian tissue cryopreservation in terms of methods and main results obtained so far. To cryopreserve human ovarian tissue, most studies describe a slow freezing/rapid thawing protocol, which is usually an adaptation of a protocol developed for sheep ovarian tissue. Since freezing has been shown to have a deleterious effect on ovarian stroma and granulosa cells, various research groups have been vitrifying ovarian tissue. Despite promising results, only 2 babies have been born after transplantation of vitrified/warmed ovarian tissue. Optimization of both cryopreservation strategies as well as thawing/warming protocols is therefore necessary to improve the survival of follicles in cryopreserved ovarian tissue. KEY MESSAGES: Human ovarian tissue cryopreservation has been successfully applied worldwide to preserve fertility in patients with malignant or nonmalignant pathologies that have a detrimental effect on fertility. Human ovarian tissue cryopreservation could also be applied as an alternative to postpone pregnancy or menopause in healthy women. Slow freezing and vitrification procedures have been applied to cryopreserve human ovarian tissue, but both alternatives require optimization.

The Human Ovary and Future of Fertility Assessment in the Post-Genome Era.

Proteomics has opened up new avenues in the field of gynecology in the post-genome era, making it possible to meet patient needs more effectively and improve their care. This mini-review aims to reveal the scope of proteomic applications through an overview of the technique and its applications in assisted procreation. Some of the latest technologies in this field are described in order to better understand the perspectives of its clinical applications. Proteomics seems destined for a promising future in gynecology, more particularly in relation to the ovary. Nevertheless, we know that reproductive biology proteomics is still in its infancy and major technical and ethical challenges must first be overcome.

Safety of ovarian tissue transplantation in patients with borderline ovarian tumors.

STUDY QUESTION: Is transplantation of cryopreserved ovarian tissue from patients with borderline ovarian tumors (BOTs) a safe procedure? SUMMARY ANSWER: BOT cells were found in frozen-thawed and xenografted ovarian tissue in 1 of 11 BOT patients. WHAT IS KNOWN ALREADY: The risk of reintroducing malignant cells upon ovarian tissue transplantation has been subject of debate for many years. Reimplantation of cryopreserved ovarian tissue from leukemia patients is unsafe, while results from studies of cryopreserved ovarian tissue from other forms of cancer, such as Hodgkin's lymphoma, are reassuring. STUDY DESIGN, SIZE, DURATION: Prospective experimental study conducted in an academic research unit using ovarian tissue from 11 patients undergoing cryopreservation for BOTs. PARTICIPANTS/MATERIALS, SETTING, METHODS: Histology, immunohistochemistry (IHC) for mucin 1 (MUC1) and cytokeratin 7 (CK7) and molecular analysis by reverse transcription quantitative polymerase chain reaction (RT-qPCR) for CK7 and MUC1 were performed on frozen-thawed ovarian tissue from 11 patients. Long-term (5 months) xenografting of ovarian tissue in immunodeficient mice was performed. The xenografts were analyzed by histology, IHC and RT-qPCR, furthermore IHC for CD10, a marker of endometriosis, was performed on a selected sample. MAIN RESULTS AND THE ROLE OF CHANCE: Analysis by histology, IHC and RT-qPCR indicated 10 of the ovarian tissue samples were negative. Analysis of the xenograft samples indicated nine were negative for malignant cells but in two xenografts glandular lesions were detected by histology. In these two xenografts, CK7 and MUC1 markers were demonstrated by IHC and CK7 expression also by RT-qPCR. A BOT was confirmed in the xenograft in which the original ovarian tissue was positive, while in the other case IHC demonstrated expression of endometriosis marker CD10. LIMITATIONS, REASONS FOR CAUTION: Cryopreserved ovarian fragments cannot be tested before transplantation, therefore the preimplantation analysis cannot guarantee that all cryopreserved fragments will be free of BOT cells. WIDER IMPLICATIONS OF THE FINDINGS: BOT cells can be found in cryopreserved ovarian tissue from BOT patients, therefore preimplantation analysis is an absolute prerequisite. Endometriosis can also be detected in cryopreserved ovarian tissue and caution should also be exercised in this scenario. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by grants from the Fonds National de la Recherche Scientifique de Belgique (FNRS-PDR Convention T.0077.14, Télévie Grant 7.4590.16 awarded to Rossella Masciangelo, and Grant 5/4/150/5 awarded to Marie-Madeleine Dolmans), the Fonds Speciaux de Recherche, and the Foundation Against Cancer. None of the authors have any conflicting interests to declare.

Evaluation of a new freezing protocol containing 20% dimethyl sulphoxide concentration to cryopreserve human ovarian tissue.

RESEARCH QUESTION: Could a modification in the ovarian tissue freezing protocol improve follicle survival after cryopreservation and xenotransplantation? DESIGN: Ovarian tissue was used from 13 adult patients, frozen either with our original protocol, or a modified version involving a higher concentration of dimethyl sulphoxide (DMSO), larger volume of cryopreservation solution and lower seeding temperature. After thawing, the ovarian fragments were xenotransplanted to six mice with severe combined immunodeficiency (SCID) for 3 weeks. RESULTS: The proportion of primordial follicles decreased, and the proportion of growing follicles increased significantly (all P < 0.01) after cryopreservation and xenografting compared with fresh controls for both protocols. Follicle density, development, ultrastructure and function were similar between treatments. CONCLUSIONS: This study showed that, although the higher DMSO concentration did not improve survival of preantral follicles, it did not seem to induce any major toxicity in the follicle population either.

Ovarian tissue cryopreservation by stepped vitrification and monitored by X-ray computed tomography.

Ovarian tissue cryopreservation is, in most cases, the only fertility preservation option available for female patients soon to undergo gonadotoxic treatment. To date, cryopreservation of ovarian tissue has been carried out by both traditional slow freezing method and vitrification, but even with the best techniques, there is still a considerable loss of follicle viability. In this report, we investigated a stepped cryopreservation procedure which combines features of slow cooling and vitrification (hereafter called stepped vitrification). Bovine ovarian tissue was used as a tissue model. Stepwise increments of the Me2SO concentration coupled with stepwise drops-in temperature in a device specifically designed for this purpose and X-ray computed tomography were combined to investigate loading times at each step, by monitoring the attenuation of the radiation proportional to Me2SO permeation. Viability analysis was performed in warmed tissues by immunohistochemistry. Although further viability tests should be conducted after transplantation, preliminary results are very promising. Four protocols were explored. Two of them showed a poor permeation of the vitrification solution (P1 and P2). The other two (P3 and P4), with higher permeation, were studied in deeper detail. Out of these two protocols, P4, with a longer permeation time at -40 °C, showed the same histological integrity after warming as fresh controls.

Eliminating malignant cells from cryopreserved ovarian tissue is possible in leukaemia patients.

Reimplantation of cryopreserved ovarian tissue (OT) can successfully restore ovarian function in young cancer patients after gonadotoxic treatment. However, for patients with leukaemia, there is a risk of malignant cell transmission. Our objective was to evaluate minimal disseminated disease in OT from leukaemia patients and test a follicle isolation technique to obtain disease-free follicle suspensions. Cryopreserved OT from 12 leukaemia patients was thawed and analysed by histology and long-term xenografting in immunosuppressed mice. In 10 patients, follicles were isolated from OT, and polymerase chain reaction (PCR) was performed on tissue, digested ovarian suspensions and isolated follicle suspensions to investigate leukaemic cell presence. Mean patient age was 17·1 years. An average of 3·2 follicles were isolated per mm² of cortex. Xenografting of OT induced leukaemic masses in 2/12 mice. PCR identified leukaemic cell presence in 66% of OT. Malignant cells were also detected in digested ovarian suspensions. However, none of the follicle samples (>2300 follicles tested) showed any malignant cell presence after washing. This study demonstrates that it is possible to recover large numbers of viable follicles from cryopreserved OT of leukaemia patients. All isolated and washed follicle suspensions tested negative for leukaemic cells, giving leukaemia patients genuine hope of fertility restoration.

Survival and growth of human preantral follicles after cryopreservation of ovarian tissue, follicle isolation and short-term xenografting.

In women, chemotherapy and radiotherapy can be harmful to the ovaries, causing loss of endocrine and reproductive functions. When gonadotoxic treatment cannot be delayed, ovarian tissue cryobanking is the only way of preserving fertility. This technique, however, is not advisable for patients with certain types of cancer, because of the risk of reintroducing malignant cells present in the cryopreserved tissue. Our objective is therefore to develop a transplantable artificial ovary. To this end, cryopreserved human preantral follicles were isolated and embedded in fibrin formulations prepared with 50 mg/ml fibrinogen and 10 IU/ml thrombin supplemented or not with 3% hyaluronic acid, and respectively xenografted to specially created right and left peritoneal pockets in eight nude mice. On days 0 and 7, the animals were killed and the matrices retrieved. On day 7, no difference was observed in the recovery rate of follicles embedded in fibrin alone (23.4%) or fibrin-hyaluronic acid (20.5%). Ki67 staining confirmed growth of the grafted follicles and terminal deoxynucleotidyl transferase)-mediated dUDP nick-end labelling assay revealed 100% of the follicles to be viable in both groups on day 7. In conclusion, fibrin seems to be a promising material for creation of an artificial ovary, supporting follicle survival and development.

The artificial ovary: current status and future perspectives.

Cryopreservation and transplantation of ovarian tissue has proved to be a promising technique to safeguard fertility in cancer patients. However, with some types of cancer, there is a risk of transmitting malignant cells present in the cryopreserved tissue, so transplantation after disease remission is not advisable. To restore fertility in these patients, some research teams have been developing a transplantable artificial ovary, whose main goal is to mimic the natural organ. It should be composed of a matrix that encapsulates and protects follicles, as well as ovarian cells, which are necessary for follicle survival and development. This article reviews progress made in the creation of a transplantable artificial ovary and discusses future trends for its development.