Transplantation Of Human Ovarian Tissue Research Articles

Hormonal Stimulation of Human Ovarian Xenografts in Mice: Studying Folliculogenesis, Activation, and Oocyte Maturation.

Ovarian tissue cryopreservation and banking provides a fertility preservation option for patients who cannot undergo oocyte retrieval; it is quickly becoming a critical component of assisted reproductive technology programs across the world. While the transplantation of cryopreserved ovarian tissue has resulted in over 130 live births, the field has ample room for technological improvements. Specifically, the functional timeline of grafted tissue and each patient's probability of achieving pregnancy is largely unpredictable due to patient-to-patient variability in ovarian reserve, lack of a reliable method for quantifying follicle numbers within tissue fragments, potential risk of reintroduction of cancer cells harbored in ovarian tissues, and an inability to control follicle activation rates. This review focuses on one of the most common physiological techniques used to study human ovarian tissue transplantation, xenotransplantation of human ovarian tissue to mice and endeavors to inform future studies by discussing the elements of the xenotransplantation model, challenges unique to the use of human ovarian tissue, and novel tissue engineering techniques currently under investigation.

Role of the PI3K and Hippo pathways in follicle activation after grafting of human ovarian tissue.

Our aim was to elucidate the mechanisms involved in follicle activation of the ovarian reserve after human ovarian tissue transplantation, with specific focus on the role of the effectors of the PI3K (mTOR and FOXO1) and Hippo (YAP) signaling pathways and whether they are somehow altered. Frozen-thawed ovarian tissue was collected from six women (age 25-35 years) undergoing surgery for non-ovarian pathologies and divided into 4 fragments in each case: one for non-grafted controls and three for grafting to immunodeficient mice for 3, 7 and 21 days. The tissue was processed for hematoxylin and eosin staining, immunohistochemistry and immunofluorescence at different timepoints before and after grafting. Activation of the PI3K and Hippo signaling pathways was investigated by analysis of mTOR phosphorylation, FOXO1 cytoplasmic localization and YAP nuclear localization. No change in mTOR levels was observed in primordial follicles post-transplantation, but a significant upturn was recorded in growing follicles compared with primordial follicles, irrespective of grafting time. A higher percentage of primordial follicles was also found with FOXO1 in the cytoplasm after 3 days of transplantation than in non-grafted controls. Finally, a greater proportion of primordial follicles was detected with YAP in the nucleus at all timepoints after grafting. This study supports the hypothesis that follicle activation may occur as an early event after transplantation, with follicle growth and death both contributing to the burnout phenomenon. This is the first time that the effectors of the PI3K and Hippo pathways have been investigated in grafted human ovarian tissue and their role in burnout documented.

In vitro Activation Prior to Transplantation of Human Ovarian Tissue: Is It Truly Effective?

Research Question: What are the true benefits, if any, of disrupting the Hippo signaling pathway and stimulating the Akt pathway in xenotransplanted human ovarian tissue using an in vitro activation (IVA) approach?Design: Human ovarian tissue was retrieved from 18 young patients by laparoscopy and grafted to 54 severe combined immunodeficient mice. The experiment was conducted using fresh ovarian tissue (group I; n = 6 women), slow-frozen-thawed ovarian tissue (group II; n = 6 women), and vitrified-warmed ovarian tissue (group III; n = 6 women). Slow-freezing and vitrification procedures were performed according to Gosden's and Kawamura's protocols, respectively. The tissue (fresh, slow-frozen, and vitrified) was fragmented into small cubes (1 × 1 × 1 mm) to disrupt the Hippo signaling pathway and cultured or not in IVA medium for 48 h with Akt stimulators (PI3K stimulator and PTEN inhibitor), before being transplanted to the mice. All the grafts were maintained for 28 days.Results: (1) Follicular density: Follicular density decreased in all groups after transplantation, most significantly in the vitrification group. Culture with IVA had no impact. (2) Follicle activation: Addition of PI3K stimulator and PTEN inhibitor for 48 h prior to grafting did not significantly change the proportion of primordial follicles in any of the groups (fresh, slow-frozen, or vitrified tissue) compared to 48 h of control culture without these molecules. Particularly, vitrification and culture in IVA medium yielded no benefits in terms of growing follicle percentages or follicle proliferation rates. The large proportion of growing follicles in the vitrified tissue group after grafting may have been responsible for the higher rate of atresia.Conclusion: We were unable to demonstrate any significant benefits of cutting ovarian tissue into small cubes and applying IVA with Akt stimulators. The association of vitrification and transplantation was actually found to be the most deleterious combination with respect to the follicle reserve, and even worse when culture with Akt stimulators was performed.

Evaluation of Z-VAD-FMK as an anti-apoptotic drug to prevent granulosa cell apoptosis and follicular death after human ovarian tissue transplantation.

To evaluate the efficiency of ovarian tissue treatment with Z-VAD-FMK, a broad-spectrum caspase inhibitor, to prevent follicle loss induced by ischemia/reperfusion injury after transplantation. In vitro, granulosa cells were exposed to hypoxic conditions, reproducing early ischemia after ovarian tissue transplantation, and treated with Z-VAD-FMK (50μM). In vivo, cryopreserved human ovarian fragments (n = 39) were embedded in a collagen matrix containing or not Z-VAD-FMK (50μM) and xenotransplanted on SCID mice ovaries for 3days or 3weeks. In vitro, Z-VAD-FMK maintained the metabolic activity of granulosa cells, reduced HGL5 cell death, and decreased PARP cleavage. In vivo, no improvement of follicular pool and global tissue preservation was observed with Z-VAD-FMK in ovarian tissue recovered 3-days post-grafting. Conversely, after 3weeks of transplantation, the primary follicular density was higher in fragments treated with Z-VAD-FMK. This improvement was associated with a decreased percentage of apoptosis in the tissue. In situ administration of Z-VAD-FMK slightly improves primary follicular preservation and reduces global apoptosis after 3weeks of transplantation. Data presented herein will help to guide further researches towards a combined approach targeting multiple cell death pathways, angiogenesis stimulation, and follicular recruitment inhibition.

Robot-assisted Laparoscopic Transplantation of Frozen-thawed Ovarian Tissue

Study ObjectiveTo show a new approach for orthotopic human ovarian tissue transplantation via robot-assisted laparoscopic surgery. DesignA step-by-step video explanation of the surgical technique (Canadian Task Force classification III). SettingAcademic medical center. InterventionsThe robot-assisted transplantation approach consisted of 3 steps: (1) reconstruction of the ovarian tissue graft, (2) preparation of the contralateral menopausal ovary as the recipient site, and 3) transplantation of the reconstructed graft to the bivalved contralateral ovary. Institutional review board approval was obtained. Measurements and Main ResultsAlthough still experimental, cryopreservation and subsequent transplantation of frozen-thawed ovarian tissue are currently the only available methods for prepubertal girls and young women with cancer who are not eligible for established fertility preservation options such as oocyte or embryo cryopreservation [1]. We performed the first reported autologous ovarian transplantation with a conventional laparoscopic technique [2]. To date, over 60 babies have been born after the orthotopic transplantation of cryopreserved ovarian tissue, and this number is growing [3,4]. Until recently, all of these children were born from ovarian transplants that were performed via laparotomy or conventional laparoscopy [5]. We have recently developed a robot-assisted ovarian transplantation procedure that uses an extracellular matrix scaffold to facilitate ovarian reconstruction, handling, and revascularization. Both of the procedures resulted in robust ovarian function and births [6]. The purpose of this video reports the surgical technique in detail, which uses the da Vinci Xi (Intuitive Surgical Inc, Sunnyvale, CA) robotic system for transplantation, and a decellularized human extracellular tissue matrix (Alloderm; LifeCell Corp, Branchburg, NJ) for graft reconstruction. ConclusionRobotic ovarian transplantation may have several advantages, which include precision, more delicate graft handling, and reduced time from tissue thawing to transplantation. The collective usefulness of the extracellular tissue matrix may enhance this technique by enabling a niche for ovarian reconstruction and potentially enhanced revascularization. The feasibility and comparative advantages of this technique are currently being studied in ongoing trials.

Mesenchymal Stem Cells Enhance Angiogenesis and Follicle Survival in Human Cryopreserved Ovarian Cortex Transplantation.

Transplantation of cryopreserved ovarian tissue is a novel technique to restore endocrine function and fertility especially for cancer patients. However, the main obstacle of the technique is massive follicle loss as a result of ischemia in the process of transplantation. Mesenchymal stem cells (MSCs) have been acknowledged to play an important role in supporting angiogenesis and stabilizing long-lasting blood vessel networks through release of angiogenic factors and differentiation into pericytes and endothelial cells. This study is aimed to investigate whether MSCs could be applied to overcome the above obstacle to support the ovarian tissue survival in the transplantation. Here we show that human MSCs could enhance the expression level of VEGF, FGF2, and especially the level of angiogenin, significantly stimulate neovascularization, and increase blood perfusion of the grafts in the cryopreserved ovarian tissue transplantation. Further studies reveal that MSCs could notably reduce the apoptotic rates of primordial follicles and decrease follicle loss in the grafted ovarian tissues. In summary, our findings demonstrate a previously unrecognized function of MSCs in improving human ovarian tissue transplantation and provide a useful strategy to optimize fertility preservation and restoration.

Gene expression in human ovarian tissue after xenografting

Cryobanking and transplantation of ovarian tissue is a promising approach to restore fertility in cancer patients. However, ischemic stress following avascular ovarian cortex grafting is known to induce stromal tissue fibrosis and alterations in follicular development. The aim of the study was to analyze the impact of freeze-thawing and grafting procedures on gene expression in human ovarian tissue. Frozen-thawed ovarian tissue from 14 patients was xenografted for 7 days to nude mice and one ungrafted fragment was used as a control. Immediately after recovery, grafts were processed for RNA extraction and histological analysis. Their expression profile was screened by whole-genome oligonucleotide array (n = 4) and validated by reverse-transcriptase polymerase chain analysis (n = 10). After data filtering, the Limma package was used to build a linear regression model for each gene and to compute its fold change between tissues on Days 0 and 7. After adjusting the P-value by the Sidak method, 84 of the transcripts were significantly altered after 7 days of grafting, including matrix metalloproteinase-9 and -14 and angiogenic factors such as placental growth factor and C-X-C chemokine receptor type 4 (CXCR4). Major biological processes were related to tissue remodeling, including secretory processes, cellular adhesion and response to chemical and hormonal stimuli. Angiopoietin signaling, the interleukin-8 pathway and peroxisome proliferator-activated receptor activation were shown to be differentially regulated. On Day 7, overexpression was confirmed by PCR for interleukin-8, transforming growth factor-beta 1, matrix metalloproteinase-14 and CXCR4, compared with ungrafted controls. In conclusion, new as well as known genes involved in tissue restructuring and angiogenesis were identified and found to play a key role during the first days after human ovarian tissue transplantation. This will facilitate the development of strategies to optimize grafting techniques.

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.

Xenotransplantation of human ovarian tissue to nude mice: comparison between four grafting sites

This study was designed to assess the impact of different ovarian tissue transplantation sites on the follicular pool and ovarian tissue integrity after short-term grafting, since there is no consensus in the literature as to the optimal grafting site in experimental models. Frozen-thawed ovarian tissue from eight patients was grafted for 1 or 3 weeks to the peritoneum, inside the ovarian bursa, under the skin and into the muscle of 16 nude mice. Assessment of follicular density and follicle classification was carried out by histological analysis. Proliferative activity was evidenced by immunostaining with anti-Ki-67 antibodies, and fibrotic areas were analyzed by morphometry on histological slides. One week post-transplantation, the proportion of Ki-67-positive primordial follicles was higher (20-42%) than in controls (1.7%), demonstrating follicular activation in all four sites. Despite this activation, primordial follicles were still found 3 weeks post-grafting, (34.1-66.9% of the follicle population), most of them quiescent, as indicated by the absence of Ki-67 immunostaining. Cryopreservation and grafting resulted in extensive fibrosis in the stroma. This fibrosis was significantly less pronounced in intramuscular (IM) grafts, representing 18.8% of the surface versus 44.7-60.5% for other sites, after 3 weeks of grafting. All four grafting sites equally supported early follicular growth and preserved some quiescent follicles after short-term frozen-thawed human ovarian tissue transplantation. The extensive fibrosis observed does not appear to have a major impact on early follicle development, but its long-term effects must be investigated. The graft environment may be implicated in the preservation of the stroma, as suggested by a lower degree of fibrosis in the IM site.

L’oncofertilité : vers une nouvelle spécialité ?

Although treatment and survival are the primary focus of health-care patients, with cancer survivors living longer it is now appropriate to consider their quality of life after treatment, including the possibility of becoming parents. There are several options for fertility preservation in cancer patients. Even though most of them are still experimental and their efficacy and reliability have not been determined, especially in women. The most successful alternative for female survivors is embryo cryopreservation, an approach not suitable for many single or virgin women or even possible for prepubertal girls. Reports of live birth after transplantation of human ovarian tissue have reinforced the clinical potential of ovarian tissue banking for fertility preservation. Many exciting studies are underway to improve the efficacy and solve the problems with current fertility preservation strategies, especially for in vitro culture of cryopreserved tissue or follicles. Continuous efforts to improve current strategies and to develop new strategies will benefit many women and children who are facing premature ovarian failure and sterility.

ORIGINAL ARTICLE: Development of Human Graafian Follicles Following Transplantation of Human Ovarian Tissue into NOD/SCID/γcnull Mice

Problem Transplantation of human ovarian cortex into host mice may permit various kinds of challenges in reproductive medicine. A novel immunodeficient mouse strain (NOD/SCID/γcnull: NOG) has been developed as a host of transplantation of human tissue.Method of study Human ovarian cortex was transplanted into various sites of NOG mice and human follicular development was examined by immunohistochemistry.Results Transplantation of human ovarian tissue into NOG mice resulted in approximately similar tissue survival and follicle growth as did transplantation into non‐obese diabetic‐severe combined immunodeficient mice. The human Graafian follicule from NOG mouse expressed the same steroidogenic enzymes as observed in human Graafian follicles, which developed in the human body. The NOG mice’s ovarian bursa was better placed for transplantation than the back skin or kidney capsule.Conclusion These results represent the successful generation and biological confirmation of the human Graafian follicles from the human ovarian cortex in the NOG mice.

Chick embryo chorioallantoic membrane (CAM) model: a useful tool to study short-term transplantation of cryopreserved human ovarian tissue

To investigate the chorioallantoic membrane (CAM) model for the study of short-term transplantation of frozen human ovarian tissue. Prospective study. Academic research unit. Ovarian tissue was obtained from three women. Frozen-thawed human cortical fragments were grafted onto traumatized CAM or beneath the CAM of 10-day-old chick embryos. Grafts were retrieved after 1, 2, 3, 4, and 5 days in ovo. Viability was assessed by calcein-AM and ethidium homodimer I. Tissue integrity, ischemic injury, and neovascularization were evaluated by histology. Cell proliferation was analyzed by Ki-67 immunohistochemistry. All the grafts showed adhesion when placed onto CAM, compared with only 30.4% beneath the CAM. Follicles were healthy, apart from a few degenerated follicles in necrotic and fibrotic areas. After 5 days, the majority of follicles were intermediate (32%) or primary (45.7%). Ki-67 immunohistochemistry revealed 12.5% proliferative follicles on day 2, reaching 20.7% on day 5. Fibrosis appeared on day 1; necrosis, follicular degeneration and follicular proliferation on day 2; and neovascularization and stromal cell proliferation on day 3. The present study showed that the CAM model provides a new approach to study human ovarian tissue transplantation in its first ischemic stages, yielding information on the timing of tissue changes before the establishment of neovascularization.

Resumption of ovarian function in a patient with premature ovarian failure (pof) after human fresh, heterologous, heterotopic ovarian transplantation

Objective: The recent advances in gonadal tissue cryobiology and transplantation enable physicians to offer preservation of gonadal function and prevention of fertility problems. Not only before chemo or radiotherapy but also in women at risk of POF. Most of the studies were performed with animals, xenografting and human autologous models, but a close hormonal follow up was not reported. To the best of our knowledge, this is the first case of a fresh, heterologous hystocompatible human ovarian tissue transplantation in an heterotopic location to a POF patient.

The Evidence of Follicle Maturation and Subsequent Ovulation in Human Ovarian Tissue Xenografted into Severe Combined Immunodeficient (SCID) Mice

Objectives: Transplantation of human ovarian tissue into immunodeficient host animals appears to be a promising method to grow and mature primordial follicles and to eliminate the potential risk of reintroducing cancer cells which can occur with autotransplantation. Our primary aim was to evaluate the efficacy and practicability of the SCID mouse xenograft model for human follicle maturation and its potential for ovulation.

Restoration of Ovarian Function After Autologous Transplantation of Human Ovarian Tissue in the Forearm

Objectives: Transplantation of both fresh and frozen-banked parathyroid glands in the forearm has been successfully performed for decades (NEJM 1976;29:57). In this trial, we sought to determine whether a similar technique could be adapted to auto-transplant ovarian tissue to salvage ovarian functions in case of radical surgery or cancer therapy.