Melatonin increases superoxide dismutase 2 (SOD2) levels and improves rat ovarian graft function after transplantation.

BACKGROUND: Ovarian cryopreservation is a promising technique despite being hindered by damage from freezing and thawing. Melatonin can mitigate this outcome. OBJECTIVE: This study aimed to evaluate the effect of melatonin on the follicular dynamics of ovarian tissue in a cryopreserved cell culture. METHODS: Three-month-old adult female Wistar rats (n = 24) weighing approximately 250 g were oophorectomized and divided into two groups (n = 12): the control group (CG) and the melatonin group (MG). In the CG, slow cryopreservation was performed according to the standard protocol with Medium M2 and dimethyl sulfoxide (DMSO). In MG, melatonin diluted in ethyl alcohol vehicle at a concentration of 0.1 µm was added to the culture medium. In both groups, the ovaries were cryopreserved by slow freezing and kept in liquid nitrogen for 24 h. Subsequently, after thawing, the ovaries were reimplanted in the retroperitoneum, one on each side of the great vessels (inferior vena cava and aorta). After 30 days, the animals were euthanized during the diestrus phase; then, the grafts were removed and processed for histomorphometric and immunohistochemical analyses, whereas the blood was subjected to biochemical analysis. Student's t test was used to assess the difference between the groups. RESULTS: The FSH levels in MG (83.79 ± 32.37) were lower than those in CG (120.52 ± 36.59), p = 0.03. The FSH/AMH ratios were also lower in MG (3.53 ± 1.13) than in CG (6.52 ± 2.85), p = 0.001. The SOD2 immunoexpression was higher in MG than in CG regarding all parameters except for the degenerated follicles (follicular cells and internal thecal cells): CG (16.80 ± 4.80 [13.36-20.24]) and MG (14.91 ± 4.04 [12.01-17.79]) p = 0.351. Statistically, the difference in intact follicles (theca + interstitium) between CG (6.60 ± 2.59 [4.75-8.45]) and MG (9.31 ± 3.09 [7.09-11.51]) was significant (p = 0.049), with a small difference in the expression of regular antral follicles. CONCLUSIONS: Melatonin can improve the quality of cryopreserved tissues, as evidenced in this study, and the evaluation of cryopreserved ovarian grafts, as shown in the melatonin group with better hormonal parameters and greater immunohistochemical expression of the SOD2 antioxidant. Thus, damage is reduced during cryopreservation and transplantation is improved.

Investigation of the Effects of Curcumin and Gallic Acid in the Liver and Kidneys of Rat Ovarian Transplant Recipients.

OBJECTIVES: Recent studies have shown that oxidative stress, inflammation, and apoptosis play substantial roles in the pathogenesis of tissue damage and distant organ damage during ovarian transplantation. Because of their potential antioxidant and anti-inflammatory properties, investigating natural compounds like curcumin and gallic acid is crucial. This study investigated the effects of curcumin, gallic acid, and their combination on liver and kidney tissues in a rat model of ovarian transplantation. MATERIALS AND METHODS: For this study, we used 42 adult female Sprague-Dawley rats aged 11 to 12 weeks, which we randomly divided into 6 groups. After the transplant procedures, we performed histopathological analysis, biochemical examinations, and statistical analysis. RESULTS: Significant damage was shown in the liver and kidney tissues of the ovarian transplant only and transplant plus corn oil groups compared with the control group, as evidenced by histopathological evaluation, increased BAX/BCL-2 intensity indicating apoptotic activity, and elevated interleukin 6 levels. However, treatment with curcumin, gallic acid, or their combination attenuated these adverse effects, suggesting potential protective effects against transplant-induced injury. CONCLUSIONS: Our findings highlight the therapeutic potential of these compounds in mitigating tissue damage and inflammation associated with ovarian transplant.

Ovarian tissue cryopreservation and transplantation as a natural means to delay menopause.

Ovarian tissue cryopreservation and transplantation (OTCT) offers hope for preserving fertility and endocrine functions in patients undergoing gonadotoxic treatments. Advancements in techniques for the procedure have transformed OTCT from an experimental procedure into a viable option. There is a growing interest in utilizing OTCT to delay menopause and alleviate associated health issues. Menopausal transition affects women globally, leading to symptoms and long- term health risks. OTCT has the potential to restore endocrine functions, reducing menopause-related symptoms while mitigating health consequences such as osteoporosis and cardiovascular diseases. Although the use of OTCT for delaying menopause is not clinically proven, the discussion around shows potential for future utilization. In essence, the remarkable advancements in OTCT have bestowed upon us the ability to safeguard fertility and sustain the delicate endocrine functions of the ovaries. However, it is the tantalizing prospect of utilizing this technique to postpone menopause and alleviate its associated symptoms that truly captivates the imagination. Further research is imperative to substantiate the clinical efficacy of OTCT; nonetheless, its potential in menopausal therapy is both promising and warrants comprehensive exploration. This review highlights advancements and the feasibility of OTCT to postpone menopause as an alternative approach to currently used conventional menopause therapy methods.

Generation of rat offspring from ovarian oocytes by xenotransplantation.

The idea of utilizing unused oocytes present in the ovaries has been tested in various ways to produce offspring. However, only a limited number of studies succeeded in offspring generation. They include transplantation of ovaries into autologous or allogeneic animals, and acquisition of pups from oocytes obtained by transplanting mouse ovaries into immunodeficient rats. Here we report successful production of rat oocytes by transplanting rat ovaries under the kidney capsule of immunodeficient mice with addition of hormone administration to the mice. In addition, these oocytes were developed by in vitro fertilization, and transplanted into the oviducts of pseudopregnant rats, resulting in successful delivery of pups. The modified gene of the donor rat was confirmed to be correctly inherited to the pups. These results show that xenotransplantation of ovarian tissue makes it possible to leave offspring, beginning a new phase in developmental engineering.

Exploring the effect of platelet-rich plasma on vascularization and survival of follicles in xenotransplanted human ovarian tissue.

RESEARCH QUESTION: Do platelet-rich plasma (PRP) products, specifically human platelet lysate (hPL) and umbilical cord plasma, enhance vascularization and follicular survival in human ovarian tissue transplanted to immunodeficient mice? DESIGN: Human ovarian tissue was transplanted to subcutaneous pockets in nude mice, followed by daily injections for 6 days of PRP or saline at the transplantation sites. After a grafting period of 3 and 6 days, vascularization was assessed using CD-31 quantification, and gene expression of angiogenic markers (VEGF/Vegf) together with apoptosis-related genes (BAX/BCL-2), oxidative stress markers (HMOX-1/Hmox-1) and pro-inflammatory markers (Il-1ß/Il-6/Tnf-α) was quantitively analysed. Follicle density was analysed in the grafts after 4 weeks. Additionally, a pilot study was conducted exploring the suitability of ultrasound scanning for assessing survival and vascularization in ovarian tissue xenografted to mice. RESULTS: Although there was a significant increase in the CD-31 area from day 3 to day 6 post-grafting, there were no significant differences between the hPL and control groups. Gene expression analysis revealed significant down-regulation of VEGF from day 3 to day 6 for both the hPL and control groups, and significant up-regulation of BAX/BCL-2 in the hPL group compared with the controls. The follicle density showed no significant differences in the hPL group and UCP groups compared with the controls. Furthermore, ultrasound biomicroscopy provided valuable insights into graft morphology, necrotic areas and blood flow, suggesting its potential as a monitoring tool. CONCLUSIONS: Despite the angiogenic properties of PRP, this study was unable to demonstrate a significant impact of hPL on vascularization or of hPL and UCP on follicular survival in xenotransplanted human ovarian tissue.

Utility and Outcomes of Ovarian Tissue Cryopreservation and Transplantation for Gynecologic Cancers: A Systematic Review and Meta-analysis.

OBJECTIVE: To evaluate the utility, success, and safety of ovarian tissue cryopreservation and autologous cryopreserved ovarian tissue transplantation for fertility preservation in patients with gynecologic cancers. DATA SOURCES: A comprehensive search was performed of the MEDLINE, EMBASE, ClinicalTrials.gov , and Cochrane Library databases to identify relevant studies on the utility and outcomes of ovarian tissue cryopreservation and autologous cryopreserved ovarian tissue transplantation for gynecologic cancers from inception until January 23, 2024. METHODS OF STUDY SELECTION: Two reviewers independently performed the study selection, data extraction, and risk-of-bias assessment, and the results were then reviewed together. Twenty-three studies were included in the current systematic review. TABULATION, INTEGRATION, AND RESULTS: The resultant data were meta-analyzed to produce a pooled-effect estimate of the utility of ovarian tissue cryopreservation and autologous transplantation in gynecologic cancers as a proportion of all indications. We found that 7.5% and 9.6% of women undergoing ovarian tissue cryopreservation and autologous transplantation, respectively, had gynecologic cancers. In comparison, hematologic malignancies and breast cancer accounted for approximately 66.0% of all indications for these procedures. The return rate for autologous cryopreserved ovarian tissue transplantation in gynecologic cancers (6.0%) was not statistically different from those for other indications. Among women with gynecologic cancer who underwent ovarian stimulation, 27.3% had at least one child, and the ovarian endocrine function was restored in 78.1% of the women after autologous transplantation. The median graft longevity was 32 months, and no graft-site recurrence was reported after autologous transplantation in women with gynecologic cancer. CONCLUSION: Our results suggest that ovarian tissue cryopreservation and autologous transplantation are feasible options for preserving ovarian function in women with gynecologic cancers, although ovarian tissue cryopreservation is underutilized, and further studies are needed to determine the longer-term outcomes of autologous transplantation. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, CRD42024498522.

Prospective solutions to ovarian reserve damage during the ovarian tissue cryopreservation and transplantation procedure.

Birth rates continue to decline as more women experience fertility issues. Assisted reproductive technologies are available for patients seeking fertility treatment, including cryopreservation techniques. Cryopreservation can be performed on gametes, embryos, or gonadal tissue and can be used for patients who desire to delay in vitro fertilization treatment. This review focuses on ovarian tissue cryopreservation, the freezing of ovarian cortex containing immature follicles. Ovarian tissue cryopreservation is the only available treatment for the restoration of ovarian function in patients who undergo gonadotoxic treatments, and its wide adoption has led to its recent designation as "no longer experimental" by the American Society for Reproductive Medicine. Ovarian tissue cryopreservation and subsequent transplantation can restore native endocrine function and can support the possibility of pregnancy and live birth for the patient. Importantly, there are multiple steps in the procedure that put the ovarian reserve at risk of damage. The graft is highly susceptible to ischemic reperfusion injury and mass primordial follicle growth activation, resulting in a "burnout" phenomenon. In this review, we summarize current efforts to combat the loss of primordial follicles in grafts through improvements in freeze and thaw protocols, transplantation techniques, and pharmacologic adjuvant treatments. We conducted a review of the literature, with emphasis on emergent research in the last 5 years. Regarding freeze and thaw protocols, we discuss the widely accepted slow freezing approach and newer vitrification protocols. Discussion of improved transplantation techniques includes consideration of the transplantation location of the ovarian tissue and the importance of graft sites in promoting neovascularization. Finally, we discuss pharmacologic treatments being studied to improve tissue performance postgraft. Of note, there is significant research into the efficacy of adjuvants used to reduce ischemic injury, improve neovascularization, and inhibit hyperactivation of primordial follicle growth activations. Although the "experimental" label has been removed from ovarian tissue cryopreservation and subsequent transplantation, there is a significant need for further research to better understand sources of ovarian reserve damage to improve outcomes. Future research directions are provided as we consider how to reach the most hopeful results for women globally.

Thawing fertility: a view of ovarian tissue cryopreservation processes and review of ovarian transplant research.

Individuals with a disease or treatment that increases their risk of premature gonadal insufficiency may opt to undergo fertility preservation. Those who are postpubertal can often cryopreserve gametes, sperm, or eggs to expand their biologic family using assisted reproductive technologies. Ovarian tissue cryopreservation (OTC) and testicular tissue cryopreservation may be an option for individuals who are unable to use standard fertility preservation techniques. The development of OTC was critical for many patients, including prepubertal children with ovaries that do not yet produce eggs, adolescents who make few good-quality eggs, and adult women with ovaries who cannot undergo ovarian stimulation. The only option to restore fertility and hormone production after OTC is through ovarian tissue transplantation (OTT). Ovarian tissue cryopreservation and OTT have been successful for some patients. Although OTC is no longer considered experimental by the American Society for Reproductive Medicine, the process is far from standardized. Significant research needs to be done, especially at the point of OTT, to improve the success and longevity of ovarian tissue function. This article lists the main steps from surgical procurement of the ovarian tissue to transplantation and restoration of function. Our pediatric hospital program has had to decide which options in procurement, processing, cryopreservation, and warming will be used in our clinical laboratory. The options and limitations within the research and analyses are briefly discussed. Literature focusing on techniques to improve OTT effectiveness and longevity was reviewed. Ovarian tissue transplantation studies that performed xenograft experiments after pretreatment of the tissue graft by a ligand or drug, treatment of the host, or encapsulation of the ovarian tissue were identified. The intended effects of the treatments include increasing vascularization, reducing apoptosis, and directing activation or suppression of primordial follicles. Robust research in this area must continue with rigorous analyses to make strides in improving fertility preservation and restoration options for patients.

Heterotopic ovarian transplantation instead hormonal replacement therapy after radical hysterectomy for cervical cancer: case report and review of literature.

PURPOSE: Only a few case reports have described heterotopic ovarian tissue transplantation (OTT) with the only objective of restoring ovarian function. METHODS: Case report and review of the literature for reporting cases of heterotopic OTT with the only aim of restoring ovarian endocrine function. In a cancer survivor woman with a history of hysterectomy and bilateral oophorectomy for cervical cancer and because she poorly tolerated hormone replacement therapy (HRT), we performed a heterotopic OTT in a pelvic subcutaneous "pocket" after an OT cryostorage of 17 years. RESULTS: A cyclic ovarian endocrine function started 3 months after OTT with an immediate patient self-described improvement of her quality of life. A second OTT was performed 19 months after, due to hot flushes recurrence and FSH increase. Despite a cyclic endocrine function, progesterone levels have always been low, resulting in a relative hyperoestrogenism state. CONCLUSION: In the future, the indications of heterotopic OTT could be spread in alternative to HRT. However, our data suggest that the heterotopic graft environment is less favorable to corpus luteum development, and further studies are needed to assay the best site of heterotopic graft, the optimal number of ovarian cortex fragments to graft, and the potential risk of relapse in case of malignant residual disease.

Clinical dilemmas in ovarian tissue cryopreservation.

Ovarian tissue cryopreservation (OTC) is increasingly offered globally as a fertility preservation strategy for both postpubertal women and prepubertal girls, with subsequent reimplantation of cryopreserved ovarian cortex resulting in a rapidly growing number of live births. There remains very limited evidence of efficacy from tissue stored when the patient was prepubertal or from conditions affecting the ovary directly, e.g., Turner syndrome. Although OTC is becoming a more established practice, several clinical dilemmas remain from a practical and ethical standpoint. This review discusses the challenges regarding optimal patient selection for the procedure, the use of OTC in patients with a poor prognosis, the potential of reimplantation of tissue contaminated with malignant cells, and the role of OTC in those with an intrinsic ovarian disorder.

The impact of heterotopic ovarian tissue transplantation with varied volumes on reproductive endocrine function in oophorectomized rats.

BACKGROUND: This study aimed to investigate the effects of different volumes of ovarian tissue transplantation on the reproductive endocrine function of rats after oophorectomy. METHODS: Female rats were selected to establish a castration model and then underwent different volumes of ovarian tissue transplantation. Group I served as the sham operation group. The transplantation group was divided into five subgroups based on the calculated ratio of ovarian weight to body weight in normal female rats, δ = (2.52 ± 0.17) ×10-4: Group II: transplanted ovarian volume was δ; Group III: 0.75δ; Group IV: 0.5δ; Group V: 0.25δ; Group VI: without ovarian transplantation. The post-transplant oestrous cycle recovery was observed, and blood samples were collected every 2 weeks to measure serum hormone levels. Histological evaluation was performed at the end of the observation period. RESULTS: Rats in Group V exhibited disrupted oestrous cycles after transplantation, which were significantly longer than those in Group I. Rats in Groups II, III, and IV showed no cyclic changes. At 6 weeks post-transplantation, rats in Group V had lower E2 and AMH levels and higher FSH levels compared to Group I. The uterine wet weight and the number of normal follicles in Group V were significantly lower than those in Group I, but the number of atretic follicles was higher than in Group I. CONCLUSION: The larger ovarian tissue transplantation resulted in a faster recovery with a higher survival rate of the uterus and normal follicles, compared to smaller ovarian tissue transplantation.

With advancements in science and technology, ovarian transplantation techniques have become increasingly mature. However, there are still many questions that need to be addressed. For instance, the large size of the transplanted ovarian tissues may cause over-recruitment of the primordial follicles. When the transplanted ovarian tissue is too small, it can only exert limited functionality and may not meet the patient's needs. This study aimed to investigate the effects of different volumes of ovarian tissue transplantation on the reproductive endocrine function in rats after oophorectomy, and to provide a theoretical basis for determining the minimum effective volume of heterotopic ovarian tissue transplantation.

Heterotopic ovarian allotransplantation in a caprine model: Effects of implant site on morphological parameters.

This study aimed to investigate a new implantation site (intra-auricular subcutaneous - IA) compared to intramuscular (IM) in the cervical portion (cervical splenius muscle) of the neck for ovarian transplantation in goats. Morphological aspects of the implant, follicular activation and morphology, and type I and III collagen deposits of the transplanted tissue were evaluated. Four fragments of the ovarian cortex were allotransplanted at the IA and IM sites in all goat recipients and recovered 7 (IA-7; IM-7) or 15 (IA-15; IM-15) days later and submitted to histological analysis. Two fragments/animal were separated for the fresh control (FC) group. There was a higher percentage of normal and developing primordial follicles at the IA-7 site (P < 0.05) compared to the other treatments, with similar values to the fresh control. Type I and III collagen fibers differed between the groups (P < 0.05), showing a considerable decrease in type I collagen fibers at the IA-7 site compared to the FC. However, the IM-7 and IA-15 sites showed higher values of type I collagen fibers, showing similarity to the FC. Therefore, we conclude that the IA site in goats is an effective site for ovarian tissue transplantation, as it is easily accessible, low invasive and has presented satisfactory rates of morphology and follicular activation.

Maximizing Success: An Overview of Optimizing the Ovarian Tissue Transplantation Site.

Ovarian tissue cryopreservation and transplantation (OTCT) has emerged in recent years as a potential method for reversing abnormal endocrine and reproductive functions, particularly in patients receiving gonadotoxic cancer treatments having longer survival rates. From its first rodent experiments to human trials, OTCT has evolved tremendously, opening new windows for further utilization. Since then, significant progress has been achieved in terms of techniques used for surgical removal of the tissue, optimal fragment size, freezing and thawing procedures, and appropriate surgical sites for the subsequent reimplementation of the graft. In addition, various approaches have been proposed to decrease the risk of ischemic injury, which is the leading cause of significant follicle loss during neo-angiogenesis. This review aims to discuss the pros and cons of ovarian and retroperitoneal transplantation sites, highlighting the justifications for the viability and efficacy of different transplantation sites as well as the potential advantages and drawbacks of retroperitoneal or preperitoneal area.

First report on successful delivery after retransplantation of vitrified, rapid warmed ovarian tissue in Europe.

RESEARCH QUESTION: Cryopreservation of ovarian tissue is one feasible option to preserve female fertility prior to cancer treatment. The slow freezing protocol represents the current standard approach, while vitrification has been suggested as a promising alternative. This paper reports the follow-up and first successful delivery after retransplantation of vitrified, rapid warmed ovarian tissue in Europe. DESIGN: After the patient received a diagnosis of breast cancer, ovarian tissue was removed laparoscopically and sent via overnight transportation to University Hospital Bonn for vitrification on site. The patient was treated with chemotherapy, leading to ovarian failure. After 2 years, retransplantation of the vitrified, rapid warmed tissue was conducted on site. RESULTS: Two months after grafting, the patient reported regular menstrual cycles. After 1 further month a clinical pregnancy occurred, which ended in a spontaneous abortion at the 8th week of pregnancy. Six months after grafting, another naturally conceived pregnancy was determined, resulting in the birth of a healthy boy 14 months after retransplantation of the ovarian tissue. CONCLUSIONS: Complementing the successful deliveries reported by the groups of Suzuki (Japan) and Silber (USA) regarding vitrified tissue, the current results confirm the high potential of this cryopreservation method in a clinical routine setting as an alternative approach to the widespread slow freezing method.

Perinatal outcomes of pregnancies following autologous cryopreserved ovarian tissue transplantation: a systematic review with pooled analysis.

OBJECTIVE: This study aimed to synthesize the existing evidence on perinatal outcomes after autologous cryopreserved ovarian tissue transplantation, concurrently identifying key factors influencing these outcomes. DATA SOURCES: A comprehensive search was performed on MEDLINE, Embase, and Cochrane Library databases to identify relevant studies on the effect of autologous cryopreserved ovarian tissue transplantation on perinatal outcomes from inception to October 22, 2023. Where there was missing information, the authors were contacted for updated data. STUDY ELIGIBILITY CRITERIA: Observational studies, such as cohort studies, case series, and case reports that reported a live birth after autologous cryopreserved ovarian tissue transplantation, were considered eligible. Studies lacking data on women's demographic characteristics, autologous cryopreserved ovarian tissue transplantation procedure details, or perinatal outcomes were excluded. In addition, cases involving fresh or nonautologous transplantations and those addressing primary ovarian insufficiency were excluded. METHODS: Two reviewers (M.E. and E.U.) independently performed the study selection, data extraction, and risk of bias assessment, and the results were then reviewed together. The PRISMA guidelines were followed, and the protocol was registered on PROSPERO (CRD42023469296). RESULTS: This review included 58 studies composed of 122 women with 162 deliveries (154 singletons and 8 twins) after autologous cryopreserved ovarian tissue transplantation, resulting in 170 newborns. Of note, 83.6% of the women had a malignant disease. Moreover, most of these women (51.0%) were exposed to some form of chemotherapy before ovarian tissue cryopreservation. Of the 162 childbirths, 108 (66.7%) were conceived naturally, and 54 (33.3%) were conceived through assisted reproductive techniques. The birthweight of 88.5% of newborns was appropriate for gestational age, whereas 8.3% and 3.1% were small for gestational age and large for gestational age, respectively. The preterm birth rate was 9.4%, with the remaining being term deliveries. Hypertensive disorders of pregnancy were noted in 18.9% of women, including pregnancy-induced hypertension in 7.6%, preeclampsia in 9.4%, and hemolysis, elevated liver enzymes, and low platelet count in 1.9%. The incidences of gestational diabetes mellitus and preterm premature rupture of membranes were 3.8% for each condition. Neonatal anomalies were reported in 3 transplant recipients with 4 newborns: arthrogryposis, congenital cataract, and diaphragmatic hernia in a twin. Finally, among the recipients' characteristics, not receiving chemotherapy before ovarian tissue cryopreservation (odds ratio, 0.23; 95% confidence interval, 0.07-0.72; P=.012) and natural conception (odds ratio, 0.29; 95% confidence interval, 0.09-0.92; P=.035) were associated with a lower perinatal complication rate. CONCLUSION: On the basis of low certainty evidence from observational studies, perinatal complication rates did not increase after autologous cryopreserved ovarian tissue transplantation compared with the general pregnant population, except for preeclampsia. This could be due to chemotherapy exposure, underlying medical conditions, and the common use of assisted reproductive techniques. Further larger studies are needed to explore the causes of increased preeclampsia incidence in autologous cryopreserved ovarian tissue transplantation pregnancies.

Research progress on mechanism of follicle injury after ovarian tissue transplantation and protective strategies. / 移植卵巢组织卵泡损伤机制及保护策略.

Ovarian tissue cryopreservation and transplantation is the only way to preserve fertility for female cancer patients in prepubertal ages and those who cannot delay radiotherapy or chemotherapy. However, the success rate of cryopreservation and transplantation of ovarian tissue is still low at present due to the risk of ischemia and hypoxia of the grafted tissues. Abnormal activation of primordial follicles and ischemia-reperfusion injury after blood supply recovery also cause massive loss of follicles in grafted ovarian tissues. Various studies have explored the use of different drugs to reduce the damage of follicles during freezing and transplantation as well as to extend the duration of endocrine and reproductive function in patients with ovarian transplantation. For example, melatonin, N-acetylcysteine, erythropoietin or other antioxidants have been used to reduce oxidative stress; mesenchymal stem cells derived from different tissues, basic fibroblast growth factor, vascular endothelial growth factor, angiopoietin 2 and gonadotropin have been used to promote revascularization; anti-Müllerian hormone and rapamycin have been used to reduce abnormal activation of primordial follicles. This article reviews the research progress on the main mechanisms of follicle loss after ovarian tissue transplantation, including hypoxia, ischemia-reperfusion injury and associated cell death, and abnormal activation of follicles. The methods for reducing follicle loss in grafted ovarian tissues are further explored to provide a reference for improving the efficiency of ovarian tissue cryopreservation and transplantation.

Current Fertility Preservation Steps in Young Women Suffering from Cancer and Future Perspectives.

Childhood cancer incidence, especially in high-income countries, has led to a focus on preserving fertility in this vulnerable population. The common treatments, such as radiation and certain chemotherapeutic agents, though effective, pose a risk to fertility. For adult women, established techniques like embryo and egg freezing are standard, requiring ovarian stimulation. However, for prepubescent girls, ovarian tissue freezing has become the primary option, eliminating the need for hormonal preparation. This review describes the beginning, evolution, and current situation of the fertility preservation options for this young population. A total of 75 studies were included, covering the steps in the current fertility preservation protocols: (i) ovarian tissue extraction, (ii) the freezing method, and (iii) thawing and transplantation. Cryopreservation and the subsequent transplantation of ovarian tissue have resulted in successful fertility restoration, with over 200 recorded live births, including cases involving ovarian tissue cryopreserved from prepubescent girls. Despite promising results, challenges persist, such as follicular loss during transplantation, which is attributed to ischemic and oxidative damage. Optimizing ovarian tissue-freezing processes and exploring alternatives to transplantation, like in vitro systems for follicles to establish maturation, are essential to mitigating associated risks. Further research is required in fertility preservation techniques to enhance clinical outcomes in the future. Ovarian tissue cryopreservation appears to be a method with specific benefits, indications, and risks, which can be an important tool in terms of preserving fertility in younger women.

The role of the indoleamine 2,3-dioxygenase gene in preventing ovarian transplant rejection in rats†.

Indoleamine 2,3-dioxygenase (IDO) plays important roles in maternal immune tolerance. Female Sprague Dawley rats (9-11 weeks old) were randomly divided into an autoplastic transplantation group (n = 75) and an allograft transplantation group (n = 300) was further divided into subgroups of ovarian transplantation, allograft ovarian transplantation, allograft ovarian transplantation with cyclosporine A treatment, allograft ovarian transplantation and transfection with IDO-expressing lentiviruses, and allograft ovarian transplantation and transfection with control lentiviruses. IDO was successfully transfected into the transplanted ovarian tissue. The survival rate, success rate of ovarian transplantation, period until estrous cycle restoration, and estrogen levels of rats that received IDO-expressing lentiviruses were significantly different from those of rats that underwent allograft transplantation and with control transfection (all P < 0.05), but not significantly different from those rats that received autoplastic transplantation (all P > 0.05). The number of ovarian follicles in the transplanted ovarian tissue of rats that received IDO-expressing lentiviruses was also significantly higher. The expression level of IDO protein detected by immunohistochemistry and western blotting was especially high in ovaries that had received IDO-containing lentiviruses. Naturally pregnant rats were found in each group postoperatively. These results indicated that IDO-expressing lentiviruses were successfully transfected into transplanted ovarian tissues of rats and that IDO was stably expressed within a certain time. These findings suggest that the expression level of IDO protein is associated with an enhanced success rate of ovarian tissue transplantation and a short restoration period of endocrine function.

Quantification of follicles in human ovarian tissue using image processing software and trained artificial intelligence†.

Cancer survival rates in prepubertal girls and young women have risen in recent decades due to increasingly efficient treatments. However, many such treatments are gonadotoxic, causing premature ovarian insufficiency, loss of fertility, and ovarian endocrine function. Implantation of donor ovarian tissue encapsulated in immune-isolating capsules is a promising method to restore physiological endocrine function without immunosuppression or risk of reintroducing cancer cells harbored by the tissue. The success of this approach is largely determined by follicle density in the implanted ovarian tissue, which is analyzed manually from histologic sections and necessitates specialized, time-consuming labor. To address this limitation, we developed a fully automated method to quantify follicle density that does not require additional coding. We first analyzed ovarian tissue from 12 human donors between 16 and 37 years old using semi-automated image processing with manual follicle annotation and then trained artificial intelligence program based on follicle identification and object classification. One operator manually analyzed 102 whole slide images from serial histologic sections. Of those, 77 images were assessed by a second manual operator, followed with an automated method utilizing artificial intelligence. Of the 1181 follicles the control operator counted, the comparison operator counted 1178, and the artificial intelligence counted 927 follicles with 80% of those being correctly identified as follicles. The three-stage artificial intelligence pipeline finished 33% faster than manual annotation. Collectively, this report supports the use of artificial intelligence and automation to select tissue donors and grafts with the greatest follicle density to ensure graft longevity for premature ovarian insufficiency treatment.