Uterus Transplantation: the Translational Evolution of a Clinical Breakthrough

Women suffering from absolute uterine factor infertility (AUFI), due to either lack of a uterus or one unable to sustain neonatal viability, presented as one of the last frontiers in conquering infertility. Following systematic animal research for over a decade, uterus transplantation was tested as a treatment for AUFI in 2012, which culminated in the first human live birth in 2014. The development of uterus transplantation from mouse to human has followed both the Moore criteria for introduction of a surgical innovation and the IDEAL concept for evaluation of a novel major surgical procedure. In this article we review the important preclinical animal and human studies that paved the way for the successful introduction of human uterus transplantation a decade ago. We discuss this in the context of the Moore criteria and describe the different procedures of preparation, surgeries, postoperative monitoring, and use of assisted reproduction in human uterus transplantation. We review the worldwide activities and associated results in the context of the IDEAL concept for evaluation of surgical innovation and appraise the ethical considerations relevant to uterus transplantation. We conclude that rigorous application of the Moore criteria and strict alignment with the IDEAL concept have resulted in the establishment of uterus transplantation as a novel, safe, and effective infertility therapy that is now being used worldwide for the treatment of women suffering from AUFI.

Uterus transplantation: from research, through human trials and into the future

Women suffering from absolute uterine factor infertility (AUFI) had no hope of childbearing until clinical feasibility of uterus transplantation (UTx) was documented in 2014 with the birth of a healthy baby. This landmark accomplishment followed extensive foundational work with a wide range of animal species including higher primates. In the present review, we provide a summary of the animal research and describe the results of cases and clinical trials on UTx. Surgical advances for graft removal from live donors and transplantation to recipients are improving, with a recent trend away from laparotomy to robotic approaches, although challenges persist regarding optimum immunosuppressive therapies and tests for graft rejection. Because UTx does not involve transplantation of the Fallopian tubes, IVF is required as part of the UTx process. We provide a unique focus on the intersection between these two processes, with consideration of when oocyte retrieval should be performed, whether, and for whom, preimplantation genetic testing for aneuploidy should be used, whether oocytes or embryos should be frozen and when the first embryo transfer should be performed post-UTx. We also address the utility of an international society UTx (ISUTx) registry for assessing overall UTx success rates, complications, and live births. The long-term health outcomes of all parties involved-the uterus donor (if live donor), the recipient, her partner and any children born from the transplanted graft-are also reviewed. Unlike traditional solid organ transplantation procedures, UTx is not lifesaving, but is life-giving, although as with traditional types of transplantation, costs, and ethical considerations are inevitable. We discuss the likelihood that costs will decrease as efficiency and efficacy improve, and that ethical complexities for and against acceptability of the procedure sharpen the distinctions between genetic, gestational, and social parenthood. As more programs wish to offer the procedure, we suggest a scheme for setting up a UTx program as well as future directions of this rapidly evolving field. In our 2010 review, we described the future of clinical UTx based on development of the procedure in animal models. This Grand Theme Review offers a closing loop to this previous review of more than a decade ago. The clinical feasibility of UTx has now been proved. Advancements include widening the criteria for acceptance of donors and recipients, improving surgery, shortening time to pregnancy, and improving post-UTx management. Together, these improvements catalyze the transition of UTx from experimental into mainstream clinical practice. The procedure will then represent a realistic and accessible alternative to gestational surrogacy for the treatment of AUFI and should become part of the armamentarium of reproductive specialists worldwide.

Involving Animal Models in Uterine Transplantation

Background

Absolute uterine factor infertility affects 0. 2% women of childbearing age around the world. Uterine transplantation (UTx) is a promising solution for many of them since the first birth from UTx was described by the Swedish team in 2014. The success of Utx in humans has become possible after a systematic and meticulous approach involving years of research on animal models. To date, more than 80 UTx procedures have been performed worldwide and 30 children were born.

Material and Method

This review summarizes the research preparation conducted in animals before beginning UTx in humans. It focuses on the advantages and limits of each animal model, their place in surgical training, and current contribution in research to improve UTx successes in humans. The different steps in the process of UTx have been analyzed, such as imaging, surgery, ischemia-reperfusion effects, rejection markers, immunosuppressive treatment, and pregnancy.

Conclusion

Animal models have played an essential role in the implementation of UTx, which is a highly complex procedure. While respecting the 3R requirements (replacement, refinement, and reduction), the surgical training using large animal models, such as notably ewes remain irreplaceable for teams wishing to initiate a UTx program. Furthermore, animal models are still mandatory in current research to improve the success rates of UTx in humans as well as to reduce the morbidity associated with this experimental infertility treatment.

Keio Uterus Transplantation Research: From Basic Research toward Future Clinical Application

Uterus transplantation (UTx) is now a potential option to allow women with uterine factor infertility to give birth. However, UTx is still at an experimental stage, and basic animal studies, including in non-human primates, are needed for the accumulation of data prior to clinical application. Considering that UTx may provide new hope to Japanese women, we launched UTx research in 2009 and have since accumulated a large archive of results in the UTx research field. Furthermore, we have carried out various activities aimed at the implementation of clinical applications of UTx in Japan while clarifying the ethical and social issues involved. Currently, the clinical application of UTx in Japan is just around the corner, and it is expected that UTx research will develop further in the future. Herein, we summarize our basic experiences using non-human primates and our activities with the goal of future clinical applications.

Analysis of blood parameters and molecular endometrial markers during early reperfusion in two ovine models of uterus transplantation

The dissection of the veins is the trickiest step of Uterine transplantation (UTx). Performing the anastomosis of a single uterine vein could bring a therapeutic benefit and simplification of surgery and serve for managing unilateral venous thromboses. The objectives of this project were to evaluate the expression of early markers of ischemia-reperfusion and to compare findings following one or two vein anastomoses. Orthotopic uterine auto-transplantations were performed on an ovine model with anastomosis of either two (group 1) or one utero-ovarian veins (group 2). Blood gases, histology and ischemia- reperfusion markers transcripts (PTGS2, IL6, IL8, SOD2, C3, BAX/BCL2 and TLR4) were analyzed as well as PTGS2 protein expression using Western Blot and fluorescence immunolocalization on endometrial biopsies after 3h of reperfusion. Ten ewes were included in the experimentation, 4 were in group1, 3 in group 2, the others being sham operated controls. No significant differences were observed between the two phenotypes. Based on these results, the anastomosis of one single uterine vein appears to be an approach consistent with short-term graft survival. Further experiments will be needed to confirm the reliability of this approach, especially the long-term follow-up of the uterine graft including its ability to support gestation to term.

Uterine Transplantation: Scientific Impact Paper No. 65 April 2021

A uterine transplant, or womb transplant, provides a potential treatment for women who cannot become pregnant or carry a pregnancy because they do not have a womb, or have a womb that is unable to maintain a pregnancy. This is estimated to affect one in 500 women. Options for those who wish to start a family include adoption and surrogacy, but these are associated with legal, cultural, ethical and religious implications that may not be appropriate for some women and their families. A womb transplant is undertaken when the woman is ready to start a family, and is removed following the completion of their family. Womb transplants have been performed all over the world, with more than 70 procedures carried out so far. At least 23 babies have been born as a result, demonstrating that womb transplants can work. While the procedure offers a different option to adoption and surrogacy, it is associated with significant risks, including multiple major surgeries and the need to take medications that help to dampen the immune system to prevent rejection of the womb. To date there has been a 30% risk of a transplant being unsuccessful. Although the number of transplants to date is still relatively small, the number being performed globally is growing, providing an opportunity to learn from the experience gained so far. This paper looks at the issues that have been encountered, which may arise at each step of the process, and proposes a framework for the future. However, long term follow-up of cases will be essential to draw reliable conclusions about any overall benefits of this procedure.

The Fetal-Maternal Immune Interface in Uterus Transplantation

Uterus transplants (UTxs) have been performed worldwide. Overall frequencies have been low, but globally initiated UTx programs are expected to increase clinical implementation. The uterus constitutes a unique immunological environment with specific features of tissue renewal and a receptive endometrium. Decidual immune cells facilitate embryo implantation and placenta development. Although UTx adds to the complexity of immunity during pregnancy and transplantation, the procedure provides a unique clinical and experimental model. We posit that understanding the distinct immunological properties at the interface of the transplanted uterus, the fetus and maternal circulation might provide valuable novel insights while improving outcomes for UTx. Here, we discuss immunological challenges and opportunities of UTx affecting mother, pregnancy and healthy livebirths.

Uterus transplantation for fertility preservation in patients with gynecologic cancer

Cervical and endometrial cancer may impact women interested in future fertility in approximately 5-25% of cases. The recommended treatment for patients with early stage disease is hysterectomy and/or radiation leading to infertility. This is referred to as absolute uterine factor infertility. Such infertility was considered untreatable until 2014, when the first child was born after uterus transplantation. Thereafter, multiple births have been reported, mainly from women with Mayer-Rokitansky-Küster-Hauser syndrome, with congenital uterine absence, although also from a patient with iatrogenic uterine factor infertility caused by radical hysterectomy secondary to an early stage cervical cancer 7 years before uterus transplantation. A live birth after uterus transplantation may be considered promising for many who may not otherwise have this option.Uterus transplantation is a complex process including careful patient selection in both recipients and donors, in vitro fertilization, and complex surgery in the organ procurement procedure including harvesting the vessel pedicles with the thin-walled veins. Thereafter, the transplantation surgery with anastomosis to ensure optimal blood inflow and outflow of the transplanted organ. Knowledge regarding immunosuppression and pregnancy is essential. Lastly there is the hysterectomy component as the uterus must be removed. Multidisciplinary teams working closely are essential to achieve successful uterus transplantation and, ultimately, delivery of a healthy child. Both the living and deceased donor concept may be considered and we address both the advantages and disadvantages. This review summarizes the animal research thus far published on uterus transplantation, the suggested recipient selections including former gynecologic cancer patients, the living and deceased donor uterus transplantation concepts with reported results, and updated fertility outcomes.

Urogenital Lesions in Nonhuman Primates at 2 National Primate Research Centers

Given their genetic and anatomic similarities to humans, nonhuman primates (NHPs) may serve as animal models for urogenital diseases of humans. The purpose of this study was to examine the frequency of spontaneous urogenital lesions occurring over a 30-year period at the Yerkes and Southwest National Primate Research Centers and to compare and contrast lesions occurring in Old World versus New World primates. Lesions occurring in the chimpanzee (Pan troglodytes), baboon (Papio spp.), rhesus macaque (Macaca mulatta), cynomolgus macaque (Macaca fascicularis), pig-tailed macaque (Macaca nemestrina), sooty mangabey (Cercocebus atys), common marmoset (Callithrix jacchus), cotton-top tamarin (Sanguinus oedipus), and squirrel monkey (Saimiri sciureus) are discussed. The most common lesions of the kidney were medullary amyloidosis, renal cysts, renal tubular degeneration, glomerulonephritis or glomerulopathy, nephritis, nephrocalcinosis, pyelonephritis, and hydronephrosis. Specific causes of renal tubular disease included pigmentary nephrosis and tubular lipidosis. Renal tumors, including renal adenoma and carcinoma, lymphoma, and nephroblastoma, were infrequent diagnoses in all species. Endometriosis was the most frequently diagnosed lesion of the female genital tract. Of the animals examined in this study, it was most frequent in Old World primates. Leiomyoma was the most common uterine tumor. Granulosa cell tumor was the most frequently observed neoplasm of the ovaries, followed by teratoma. Of animals included in the study, most ovarian tumors occurred in baboons. Neoplasms of the male reproductive tract included interstitial cell tumor, seminoma, penile squamous cell carcinoma, penile papilloma, and histiocytoma. In New World monkeys, renal lesions were reported more frequently than genital lesions.

First Successful Delivery after Uterus Transplantation in MHC-Defined Cynomolgus Macaques

Delivery following uterus transplantation (UTx)—an approach for treating uterine factor infertility—has not been reported in nonhuman primate models. Here, six female major histocompatibility complex (MHC)-defined cynomolgus macaques that underwent allogeneic UTx were evaluated. Antithymocyte globulin and rituximab were administered to induce immunosuppression and a triple maintenance regimen was used. Menstruation resumed in all animals with long-term survival, except one, which was euthanized due to infusion associated adverse reaction to antithymocyte globulin. Donor-specific antibodies (DSA) were detected in cases 2, 4, and 5, while humoral rejection occurred in cases 4 and 5. Post-transplant lymphoproliferative disorder (PTLD) developed in cases 2 and 3. Pregnancy was attempted in cases 1, 2, and 3 but was achieved only in case 2, which had haploidentical donor and recipient MHCs. Pregnancy was achieved in case 2 after recovery from graft rejection coincident with DSA and PTLD. A cesarean section was performed at full-term. This is the first report of a successful livebirth following allogeneic UTx in nonhuman primates, although the delivery was achieved via UTx between a pair carrying haploidentical MHCs. Experimental data from nonhuman primates may provide important scientific knowledge needed to resolve unsolved clinical issues in UTx.

Experimental techniques for the development of a uterus transplantation model in cynomolgus macaques

Uterus transplantation (UTx) is now a treatment for women with uterine factor infertility to have a child. However, UTx is still largely at the experimental stage, and many medical issues remain unsolved. Therefore, adequate studies in large animals including non-human primates are required for validation of these issues. UTx research, especially in non-human primates, can provide important information for its full establishment in humans due to the anatomical and physiological similarities between the two. We accumulated data from UTx studies using cynomolgus macaques since 2009 and established autologous and allogeneic UTx models which led to deliveries after performing the procedure. In this paper, we summarized key points to develop UTx models in cynomolgus macaques based on our experience. UTx models in non-human primates can surely contribute new and beneficial knowledge in this field and can be useful for the further development of UTx in humans.

Human uterine vasculature with respect to uterus transplantation: A comprehensive review

Due to the novelty of uterus transplantation, data on preferable inflow and outflow of the graft are limited. This paper reviews the technique, type of vessels and the outcome. A systematic search of the PubMed database was conducted. We extracted and analyzed data on the arteries and veins utilized, types of anastomosis, types of donors, complications and the outcome. Thirty eight sources reported 51 human uterine transplantations, 10 graft thromboses and 25 live births. Inflow was established with two uterine arteries (UA) with/without the anterior division of the internal iliac artery in 62% (n = 31) of cases, two UA arteries with a segment/patch of the internal iliac artery in 34% (n = 17) of cases or two UA with a conduit in 4% of cases (n = 2). Both cases with a conduit developed thrombosis (n = 2). Arterial thrombosis/ischemia developed in 8 of the 51 cases. In 50% of cases with arterial thrombosis, atherosclerosis was identified as a possible cause. Outflow was established by two internal iliac veins with patches/segments in 27.5% of cases (n = 14) followed by two utero-ovarian veins in 25.5% (n = 13). Venous thrombosis occurred in 3 of the 51 cases. Uterine arteries with/without anterior division of the internal iliac artery were the most frequent arteries used for inflow and produced the highest patency rate. The presence of atherosclerosis and complex arterial reconstruction was associated with a high rate of arterial thrombosis. None of the veins utilized in the procedures appeared to be superior. There are insufficient data to draw a definite conclusion.

Metabolic alterations of uterine grafts after extended cold ischemic storage: experimental study in ewes

Uterine transplantation from a deceased donor could become an available option for widely treating uterine infertility. However, this procedure requires more precise knowledge about the graft's tolerance to extended cold ischemia. Here, we sought to assess the uterine metabolic alterations after extended cold ischemic storage in a model of auto-transplantation in ewe. A total of 14 uterine auto-transplantations were performed, divided into 2 groups: 7 after 3 h of cold ischemia time (CIT) and 7 after 24 h. Venous uterine blood was collected before uterus retrieval and during reperfusion (30, 60 and 90 min); thereafter, blood gases, lactate, glucose and amino acids (AAs) were analyzed. Apoptosis analyses were performed before uterus retrieval and following reperfusion in uterus biopsies. A total of 12 uterine auto-transplantations were successfully performed and 7 ewes were alive ≥8 days after transplantation. After reperfusion, a decrease in pH, a rise of lactate and lactate/glucose ratio and a delayed decrease of pO2 were found in the 3 h CIT group. No significant variation of these parameters was observed in the 24 h CIT group. Significant decreases of AAs were observed during reperfusion and these decreases were more pronounced and concerned a larger number of compounds in the 24 h CIT group than in the 3 h CIT group. There was no significant uterine apoptotic signal in either group. Overall, these results suggest that extended CIT storage delayed restoration of aerobic glycolysis and induced an increase in AA requirements of the uterus after reperfusion. However, this biochemical alteration did not reduce success rate for uterine transplantation.

Looking beyond the ovary for oncofertility care in women: uterine injury as a potential target for fertility-preserving treatments

Treatment for cancer has the potential to significantly diminish fertility and, further, to negatively impact the obstetrical outcomes of pregnancies that do occur. Cancer survivors have decreased rates of fertility and increased rates of pregnancy complications, such as preterm birth and low birth weight, after exposure to chemotherapy. To date, research on the impact of chemotherapy and radiotherapy on fertility and pregnancy outcomes has focused largely on the gonadotoxic effect of cancer treatments on ovaries, while the uterus and endometrium have not been extensively studied. It is intuitive, however, that decreased fertility and poorer obstetrical outcomes may be substantially mediated through injury to a highly mitotic tissue like the endometrium, which is also central to embryo implantation and utero-placental exchange. Pregnancy complications in cancer survivors might be due to compromised blood supply to the endometrium and myometrium affecting placentation or altered remodeling of the pregnant uterus secondary to radiation fibrosis. Alterations in endometrial receptivity at the molecular level could affect pregnancy implantation and early pregnancy loss, but later complications also can occur. This review focuses on understanding the unintended effects of chemotherapy and radiotherapy on uterine function in female cancer survivors and the impact on pregnancy, and summarizes mechanisms to protect and treat the uterus before and after cancer chemotherapy and radiotherapy.

Uterus transplantation: transition from experimental to clinical procedure

Uterus transplantation is a novel treatment to treat uterine factor infertility. This type of infertility is due to absence of an anatomical or functional uterus. This review covers important research findings in the field, and this research formed the base for introduction of uterus transplantation as an experimental clinical procedure. The basic animal-research investigated central facets such as surgery, immunosuppression, ischemia-reperfusion injury, rejection, and fertility. The first clinical uterus transplantation trial was started in 2013 and this was a live donor trial. The first live birth was reported in 2014 and this has been followed by a number of births from the initial trial in Sweden and in several other parts of the world. The uterus transplantations procedures and the live births that have been scientifically reported will be discussed in this review. Lastly, some aspects for an efficient transition from an experimental phase into a clinical phase of uterus transplantation will be discussed.

Global results of human uterus transplantation and strategies for pre-transplantation screening of donors

Absolute uterine factor infertility, due to absence or non-function of the uterus, is one of the few major subgroups of infertility that has remained without any treatment. Uterus transplantation has now been proposed as treatment for this type of infertility. The first attempt of human uterus transplantation was in 2000. This was a live donor case, but due to suboptimal surgical solutions it resulted in a necrotic uterus being removed after 99 days. This first human case, although a failure, inspired several research groups around the globe to initiate animal-based studies to investigate uterus transplantation in relation to surgery, immunosuppression, rejection and pregnancy outcome. The research was carried out in several animal species and advanced the field substantially. In 2011, the second uterus transplantation attempt was performed, and this involved a deceased donor procedure. Although the case was surgically successful, with resumed menstruations, clinical pregnancy with live birth could not be achieved. The first clinical trial of uterus transplantation was initiated in Sweden in 2013 and involved nine live donor procedures. The world's first live birth was reported from that trial in September 2014 and this was followed by two more births within that trial in November 2014. Births after uterus transplantation has since been reported from Sweden and other centers in Europe, North America, Latin America, and Asia. Thirty human uterus transplantation procedures have been reported in the scientific literature so far but by our personal knowledge the double number of procedures have been performed. The published cases will be reviewed in detail, and we will also describe the pregnancies of the live births that have been published. A small number of graft failures have occurred. These may in part be linked to suboptimal selection of donors, specifically concerning the quality of the uterine arteries. Consequently, we will also address the issue of strategies for pre-surgical screening of donors.

Long-Term Outcome and Rejection After Allogeneic Uterus Transplantation in Cynomolgus Macaques

Uterus transplantation (UTx) is an option for women with uterine factor infertility to have a child, but is still in the experimental stage. Therefore, allogeneic animal models of UTx are required for resolution of clinical issues. In this study, long-term outcomes were evaluated in four recipients (cases 1-4) after allogeneic UTx in cynomolgus macaques. Immunosuppression with antithymocyte globulin induction and a triple maintenance regimen was used. Postoperative ultrasonography and biopsy of the transplanted uterus and immunoserological examinations were performed. All four recipients survived for >3 months after surgery, but continuous menstruation did not resume, although temporary menstruation occurred (cases 1 and 2). All animals were euthanized due to irreversible rejection and no uterine blood flow (cases 1, 2 and 4) and post-transplant lymphoproliferative disorder (case 3). Donor-specific antibodies against MHC class I and II were detected in cases 1, 2 and 4, but not in case 3. Peripheral lymphocyte counts tended to elevate for CD3⁺, CD20⁺ and NK cells in conjunction with uterine rejection, and all animals had elevated stimulation indexes of mixed lymphocyte reaction after surgery. Establishment of allogeneic UTx in cynomolgus macaque requires further exploration of immunosuppression, but the clinicopathological features of uterine rejection are useful for development of human UTx.

Laparoscopic uterine graft procurement and surgical autotransplantation in ovine model

Currently, uterus transplantation (UTx) is a clinical option for infertile women. Over the past three decades, treating benign or malignant gynecological diseases with minimally invasive gynecological surgery has improved, providing significant advantages over conventional open surgery. This study addresses the method used for laparoscopic live-donor ovariohysterectomy and graft harvest from a sheep model. Using a microsurgical practice, ten grafts were autotransplanted after uterine perfusion. End-to-end anastomosis techniques were used to approximate veins and arteries. Follow-ups were carried out 2-months after surgery and postoperative studies included ultrasound scan, diagnostic hysteroscopy, vascular angiography, and exploratory laparoscopy. All transplants were completed without complications. After vascular anastomosis, total reperfusion of the tissue was accomplished in all animals without confirmation of arterial or venous thrombosis. Angiographic explorations did not show any statistically significant dissimilarity in the arterial diameters between the different examination times. 3-months after uterine transplantation all animals underwent assisted reproduction techniques. Patent uterine arteries were observed 4, 8 and 12 months after the transplant. 6-months after transplantation, six sheep (60%) became pregnant with assisted reproduction practices. We noticed an increase in the degree of fibrosis of the cervix samples in non-pregnant animals of the transplant group. Laparoscopic surgery can be an advantageous approach for the uterus retrieval procedure during uterine transplantation. However, larger sample sized reports are needed in order to accomplish validation, standardization and wider use of this route.

The Key Role of Warm and Cold Ischemia in Uterus Transplantation: A Review

Introduction: Uterus transplantation (UTx) is a promising treatment for uterine infertility that has resulted in several births since 2014. Ischemia is a key step in organ transplantation because it may lead to changes jeopardizing graft viability. Method: We performed a systematic review of animal and human studies relating to uterine ischemia. Results: We retained 64 studies published since 2000. There were 35 studies in animals, 24 in humans, and five literature reviews. Modest preliminary results in large animals and humans are limited but encouraging. In small animals, pregnancies have been reported to occur after 24 h of cold ischemia (CI). In ewes, uterine contractions have been detected after 24 h of CI. Furthermore, it has been shown in animals that uterine tolerance to CI and to warm ischemia (WI) can be increased by pharmacological products. In women, mean CI time in studies of births from uteri obtained from live donors was between 2 h 47 min and 6 h 20 min from a deceased donor; with only one birth in this case. Muscle contractions have also been demonstrated in myometrial samples from women, after six or more hours of CI. Conclusion: The uterus seems to be able to tolerate a prolonged period of CI, of at least six hours. Studies of the ischemia tolerance of the uterus and ways to improve it are essential for the development of UTx, particularly for procedures using grafts from deceased donors.

Uterine transplantation

Successful human uterine transplantation followed by subsequent pregnancy and live birth in a woman for whom this would otherwise have been impossible is a laudable goal. Research programs have been developed in several countries aimed at achieving this goal. The pioneering Swedish program has reported live births in six women, two of whom had a second pregnancy and birth. Five other live births have been reported from other countries. Most transplants were from a live donor, although recently a live birth has been reported following transplant from a deceased donor. The surgical procedure on a live donor is highly invasive, complex, hazardous, and long and may decrease her quality of life. The use of a deceased donor would partly simplify this issue and is being explored in several centers. Also explored are technical modifications to simplify the procedure and shorten the operating times. The American Society for Reproductive Medicine (ASRM) reminds us of the full array of options available to patients: 'including gestational carriers (surrogacy), adoption and child-free living'. The ASRM also recommends 55 years as the upper age limit for transfer of donor oocytes and embryos in healthy women. Would it not be more practical and less onerous for the prospective live donor to carry the pregnancy instead? Uterine transplantation remains an experimental procedure that requires the study and resolution of ethical, technical, financial, and social issues, all very important.

Intra- and Postoperative Blood Flow Monitoring in a Sheep Model of Uterus Transplantation

BACKGROUND

The introduction of the opportunity to transplant a viable uterus into women for fulfilling their desire to have a child has awakened high expectations worldwide.

MATERIALS AND METHODS

A sheep model was used to evaluate tools for optimizing measurement of blood flow in uterine transplantation. Intraoperatively, blood flow was measured using unidirectional Doppler and indocyanine green (ICG) fluorescence imaging. Postoperatively, an implantable Doppler probe served as a tool for clinical monitoring the patency of anastomosed vessels.

RESULTS

ICG imaging showed complete vascularization of the uterus before and in short-term evaluation after surgery. The implantable Doppler probe proved to be highly suitable for assessing patency of vessels in a non-invasive way. Results of histology, and real-time polymerase chain reaction demonstrated viability of the transplanted uterus.

CONCLUSION

Different methods to monitor vasculature patency have proven to be advantageous in supporting both surgeons and researchers in ensuring successful implementation of uterine transplantation.

Current Progress in Uterus Transplantation Research in Asia

Uterus transplantation (UTx) is now a possible approach for women with absolute uterine factor infertility to deliver a child, following the first successful delivery by Brännström et al. in Sweden in September 2014. This remarkable achievement attracted major attention worldwide and caused many countries to prepare for UTx, including countries in Asia. To date, three groups have performed UTx in humans in Asia, and many others are aiming for the clinical application of UTx with accumulation of basic experimental data. Therefore, it is likely that UTx will expand rapidly in Asia in the near future, although this will depend on ethical, social and religious views in each country. With this background, herein we summarize the current progress of UTx in East, Southeast and South Asia, with the purpose of increasing understanding of the current status of basic and clinical UTx research in each country and sharing progress and knowledge to ensure future development of UTx research in Asia.

Basic research on uterus transplantation in nonhuman primates in Japan

Uterus transplantation (UTx) is now a potential option for women with uterine factor infertility to have a child. However, UTx is still in an experimental stage and basic animal studies including in nonhuman primates are needed for accumulation of data that will provide important information for establishment of UTx in humans. Herein, we summarized our experiences using cynomolgus macaques, with the goal of promoting further development of UTx studies in nonhuman primates. Our basic studies using cynomolgus macaques were summarized, including the results of other teams in nonhuman primates. Our team in Japan launched UTx research in 2009 using cynomolgus macaques and has accumulated a large archive of results in the UTx research field, including examination of uterine blood flow, surgical procedures of autologous and allogeneic UTx, organ perfusion methods in deceased donor models, immunological response and rejection and ischemia/reperfusion injury. We achieved the first delivery after autologous UTx in primates and the first periodic recovery of menstruation after allogeneic UTx in nonhuman primate models. Results from animal studies, including those in nonhuman primates, provide the basis for clinical application of UTx. Therefore, our accumulated data since 2009 and our basic experience in cynomolgus macaque are meaningful for future UTx trials in Japan. In addition, more validation in nonhuman primate models is needed for resolution of medical issues and further development of UTx in humans, despite clinical application of UTx in several countries.

Allowable warm ischemic time and morphological and biochemical changes in uterine ischemia/reperfusion injury in cynomolgus macaque: a basic study for uterus transplantation

STUDY QUESTION

How long is the allowable warm ischemic time of the uterus and what morphological and biochemical changes are caused by uterine ischemia/reperfusion injury in cynomolgus macaques?

SUMMARY ANSWER

Warm ischemia in the uterus of cynomolgus macaques is tolerated for up to 4 h and reperfusion after uterine ischemia caused no further morphological and biochemical changes.

WHAT IS KNOWN ALREADY

Uterus transplantation is a potential option for women with uterine factor infertility. The allowable warm ischemic time and ischemia/reperfusion injury of the uterus in humans and non-human primates is unknown.

STUDY DESIGN, SIZE, DURATION

This experimental study included 18 female cynomolgus macaques with periodic menstruation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Animals were divided into six groups of three monkeys each: a control group and groups with uterine ischemia for 0.5, 1, 2, 4 and 8 h. Biopsies of uterine tissues were performed before blood flow blockage, after each blockage time, and after reperfusion for 3 h. Blood sampling was performed after each blockage time, and after reperfusion for 5, 15 and 30 min for measurement of biochemical data. Resumption of menstruation was monitored after the surgical procedure. Morphological, physiological and biochemical changes after ischemia and reperfusion were evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Mild muscle degeneration and zonal degeneration were observed in all animals subjected to warm ischemia for 4 or 8 h, but there were no marked differences in the appearance of specimens immediately after ischemia and after reperfusion for 3 h in animals subjected to 4 or 8 h of warm ischemia. There were no significant changes in any biochemical parameters at any time point in each group. Periodical menstruation resumed in all animals with warm ischemia up to 4 h, but did not recover in animals with warm ischemia for 8 h with atrophic uteri.

LIMITATIONS, REASON FOR CAUTION

Warm ischemia in actual transplantation was not exactly mimicked in this study because uteri were not perfused, cooled, transplanted or reanastomosed with vessels. Results in non-human primates cannot always be extrapolated to humans.

WIDER IMPLICATIONS OF THE FINDINGS

The findings suggest that the tolerable warm ischemia time in the uterus is expected to be longer than that in other vital organs.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant Number 26713050. None of the authors has a conflict of interest to declare.

Uterine Autotransplantation in the Nonhuman Primate With Preservation of the Uterine and Ovarian Vascular Pedicles

PURPOSE

To evaluate the technical feasibility of performing a uterine autotransplantation in the nonhuman primate while preserving the uterine and ovarian vascular pedicles.

METHODS

Eight (n = 8) female baboons at a primate research facility underwent a uterine autotransplant procedure with preservation of the vascular pedicles. The uterine arteries were separated from their amorphous tissue and skeletonized toward the internal iliac arteries bilaterally. A segment of the internal iliac artery was removed bilaterally along with both uterine arteries. Both ovarian veins were preserved to assist with the reperfusion of the uterine organ. Due to larger vascular pedicles in one of the primates, the uterine arteries were separated and reattached directly via end-to-end anastomosis. In another baboon, the deep uterine vein was used as a vascular pedicle rather than the ovarian vein on the left side due to adequate size and visualization.

RESULTS

Immediate tissue reperfusion occurred intraoperatively in 5 of the animals, with slower perfusion in 3 of the animals. Average warm ischemia time was 43.8 minutes while the average cold ischemia time was 174 minutes (2 hours, 54 minutes). Average total surgical time was 5.9 hours. All animals were sheltered into separate cages and monitored for behavior changes and food and drink consumption. Three of the primates expired immediately postoperatively, 2 from severe dehydration and 1 from gastric aspiration.

CONCLUSIONS

This pilot study describes a modified surgical approach for uterine transplants in the nonhuman primate. This surgical technique may be applicable to living and deceased donor uterine transplantation.

Uterus transplantation: From animal models through the first heart beating pregnancy to the first human live birth

Absolute uterine factor infertility affects 3-5% of the general population, and unfortunately this condition is untreatable. There are some available options, including surrogacy or adoption, but neither of these suits each and every woman who desires to have her own genetic child. With recent advances in surgery and transplant immunology, uterus transplantation may be a source of hope for these women with uterine infertility. In the last decade, a number of animal species including rats, mice, rabbits, pigs, sheep, and primates have been used as experimental models, and pregnancies were achieved in some of these. Human data consist of 11 subjects yielding positive pregnancy results with no live births in the second trial from Turkey and, more fortunately, live births from the latest trial from Sweden. In the light of all these studies, uterus transplantation has been proven to be a viable option for women with uterine factor infertility.

Uterus transplantation: Toward clinical application in Japan

Background

In recent years, uterus transplantation (UTx) has been applied as the treatment for patients with uterine factor infertility worldwide. Thus, the clinical application of UTx in Japan should be considered through both the history of UTx technology development in the world and future prospects.

Methods

Recent information on UTx was collected via a literature survey and the Internet.

Results

Basic research using various animals has been done mainly since 2000. In 2014, the world's first UTx baby was born in Sweden. In total, 24 UTx procedures have been performed at 10 institutes in nine countries and five births were obtained (as of May, 2017). In Japan, the "Project Team for Uterus Transplantation" initiated UTx experiments in 2008 and the "Japan Society for Uterus Transplantation" was organized in March, 2014. In the rest of the world, the "International Society for Uterus Transplantation" was established in January, 2016.

Conclusion

Uterus transplantation is still under development as a reproductive medicine tool and organ transplant procedure. A collaborative system that is not limited by facilities and specialties should strive to build an "all-Japan" team.

Womb transplants with live births: an update and the future

INTRODUCTION

Absolute uterine factor infertility, with a uterine absence or presence of a nonfunctional uterus, has during the last decades been the only remaining, major group of female infertility. Uterus transplantation (UTx) has now emerged as the first therapy for these women that have traditionally been regarded as unconditionally infertile. Areas covered: This review summarizes the research preparations in several experimental animal species that paved the way for the clinical introduction of UTx. The article also describes the human UTx attempts that have been reported up until today and the several live births that have occurred after the initial UTx baby was born in 2014. Future developments in human UTx and efforts to create a bioengineered uterus are also discussed. Expert opinion: UTx has already at this early phase of experimental introduction in the human setting proved to be a highly effective treatment for absolute uterine factor infertility. The UTx procedure has now been introduced at several centers worldwide within clinical research studies and with variations in techniques. The outcome and data from these studies will further optimize the UTx procedure to become a safe and highly effective infertility treatment.

Recent advances in the molecular mechanisms of Mayer-Rokitansky-Küster-Hauser syndrome

Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) is a disease caused by congenital absence of the uterus and two-thirds of the upper vagina. The pathogenic mechanism of MRKHS may involve gene abnormalities, and there are various case reports associating MRKHS with the Wnt family member 4 (Wnt4) mutation. Analysis of genes mapped to regions in which deletion and duplication are frequently detected in patients with MRKHS has shown involvement of LIM homeobox 1 (LHX1), HNF1 homeobox B (HNF1B) and T-box 6 (TBX6). In addition, there are case reports of MRKHS caused by chromosomal translocation and epigenetic function may be involved in MRKHS onset. Overexpression of HOXA and overexposure to estrogen may contribute to the onset and regulation of expression by methylation as a pathogenic mechanism. Determination of the molecular basis of MRKHS is in progress, but current treatment only includes vaginal enlargement and vaginoplasty for improved quality of life. Clinical application of uterine transplantation to allow childbearing by MRKHS patients is under investigation and clinical trials are underway around the world.

Bioengineering Strategies to Treat Female Infertility

Bioengineering strategies have demonstrated enormous potential to treat female infertility as a result of chemotherapy, uterine injuries, fallopian tube occlusion, massive intrauterine adhesions, congenital uterine malformations, and hysterectomy. These strategies can be classified into two broad categories as follows: (i) Transplantation of fresh or cryopreserved organs into the host and (ii) tissue engineering approaches that utilize a combination of cells, growth factors, and biomaterials that leverages the body's inherent ability to regenerate/repair reproductive organs. While whole organ transplant has demonstrated success, the source of the organ and the immunogenic effects of allografts remain challenging. Even though tissue engineering strategies can avoid these issues, their feasibilities of creating whole organ constructs are yet to be demonstrated. In this article we summarize the recent advancements in the applications of bioengineering to treat female infertility.

The history behind successful uterine transplantation in humans

This paper aimed to describe the basic aspects of uterine transplant (UTx) research in humans, including preliminary experiences in rodents and domestic species. Studies in rats, domestic species, and non-human primates validated and optimized the UTx procedure in terms of its surgical aspects, immunosuppression, rejection diagnosis, peculiarities of pregnancy in immunosuppressed patients, and patients with special uterine conditions. In animal species, the first live birth from UTx was achieved in a syngeneic mouse model in 2003. Twenty-five UTx procedures have been performed in humans. The first two cases were unsuccessful, but established the need for rigorous research to improve success rates. As a result of a controlled clinical study under a strictly designed research protocol, nine subsequent UTx procedures have resulted in six healthy live births, the first of them in 2014. Further failed UTx procedures have been performed in China, Czech Republic, Brazil, Germany, and the United States, most of which using living donors. Albeit still an experimental procedure in, UTx is the first potential alternative for the treatment of absolute uterine factor infertility (AUFI).

Uterus transplantation and beyond

Uterus transplantation is today the only available treatment for absolute uterine factor infertility which is caused by either congenital/surgical uterine absence or that a present uterus is non-functioning. Structured animal-based research, from rodents to nonhuman primates, was the scientific basis for a successful introduction of uterus transplantation as a clinical procedure. The patient groups for uterus transplantation, the preclinical research and data from the published human cases will be covered herein. During recent years the concept of bioengineering of organs and tissues has emerged. Creation of a bioengineered uterus is in the initial research state, with experiments performed in rodents. The research that has been performed to create a bioengineered uterus will be summarized. In conclusion, uterus transplantation is now a clinical experimental procedure for treatment of uterine factor infertility. In parallel to the establishment of this combined assisted reproduction technique and transplantation procedure as a routine clinical procedure, we predict that uterus bioengineering will develop further towards introduction within the human setting, but that this process will take several years.

Uterus Transplantation: Current State and Future Perspectives

Absolute uterine factor infertility (AUFI) has traditionally been regarded as untreatable. Gestational surrogacy (GS) is not permitted in most countries and societies in the world due to ethical, religious or legal reasons. The interest in uterus transplantation (UTx) as a treatment for AUFI started in the 1960s and, after some disappointing results, raised again in the new century, when our and other groups obtained live off-spring after UTx in the mouse, and here we review extensively the results of animal research. In September 2014, the first baby was born after human UTx and this proof-of-concept of UTx as an infertility treatment has been followed by several more births. All cases described in the literature are also reviewed.

The overall evidence suggests that the clinical introduction of UTx as the first available treatment for AUFI has been successful. However, UTx will stay at experimental stage for several years whilst optimizing the procedure and ensuring its safety from a medical and psychological perspective.

Surgical technique for allogeneic uterus transplantation in macaques

No study has reported an animal model of uterus transplantation (UTx) using cynomolgus macaques. We aimed to establish a surgical technique of allogeneic UTx assuming the recovery of a uterus from a deceased donor in cynomolgus macaques. Four allogeneic UTxs were performed in female cynomolgus macaques. Donor surgeries comprised en bloc recovery of organs with iliac vessels on both sides, and/or abdominal aorta/vena cava after sufficient perfusion from one femoral artery or external iliac artery. Before perfusion, 150 mL of whole blood was obtained from the donor for subsequent blood transfusion to the recipient. Four uterine grafts were orthotopically transplanted to recipients. End-to-side anastomosis was performed to the iliac vessels on one side in case 1 and iliac vessels on both sides in case 2; aorto-aorto/cavo-caval anastomosis was performed in cases 3 and 4. Arterial blood flow of the uterine grafts was determined by intraoperative indocyanine green (ICG) angiography. ICG angiography results showed sufficient blood flow to all uterine grafts, and anaemia did not progress. Under appropriate immune suppression, all recipients survived for more than 90 days post-transplantation, without any surgical complications. We describe a surgical technique for allogeneic UTx in cynomolgus macaques.

Use of nonhuman primates for the development of bioengineered female reproductive organs

Nonhuman primates (NHPs) have been widely used in reproductive biology, neuroscience, and drug development since a number of primate species are phylogenetically close to humans. In this review, we summarize the use of NHPs for nonclinical application in the reproductive system disorders including the loss or failure of an organ or tissue. Causes of infertility include congenital aplasia and acquired disorders of the reproductive organs. In addition, anti-cancer treatments can deplete ovarian follicles, leading to premature ovarian failure, infertility and long-term health risks. Along with a limited supply of human reproductive organs, anatomic/physiologic similarities to humans support the need for NHP models (New-World monkeys such as the common marmoset and Old-World monkeys such as cynomolgus and rhesus monkeys) to promote the advances in female infertility studies. For maintaining and executing animal studies using NHP, special protocols including animal care, anesthetic protocol, surgical technique, and immunosuppressive protocol are necessary. With a growing interest in the potential therapies such as endometrial tissue engineering, and ovary/follicle cryopreservation and grafting in Korea, this review can be useful in selecting appropriate animal models and can bridge between nonclinical studies and clinical applications by providing detailed information on the use of NHPs in the field of reproductive organ disorders.

Human uterus transplantation in focus

INTRODUCTION

Uterus transplantation (UTx) is introduced as the first treatment for absolute uterine factor infertility (AUFI), affecting 1:500 fertile aged women. This review presents potential patients, research and human UTx cases.

SOURCES OF DATA

Published articles and our research experience.

AREAS OF AGREEMENT

The first UTx live births in 2014 established UTx as a possible treatment for AUFI. This was proceeded by 15 years of systematic research.

AREAS OF CONTROVERSY

Is a deceased donor UTx as effective as the proven successful live donor UTx?.

GROWING POINTS

Human UTx trials will accumulate data on risks, effectiveness and long-term consequences for donors, recipients and children. These should also include aspects of quality of life, psychological well-being and cognitive/neuropsychiatric development of children.

AREAS TIMELY FOR DEVELOPING RESEARCH

All new activities in human UTx within the coming years should be conducted as prospective observational studies, and data should also be collected within an international registry.

Uterus transplantation: current progress and future prospects

Even if reproductive medicine has been remarkably successful during the past few decades, with the introduction of in vitro fertilization in the late 1970s and intracytoplasmic sperm injection in the early 1990s, it has been repeatedly mocked by infertility due to an absolute uterine factor. No treatment has been available for the women suffering from an absent or dysfunctional uterus, in terms of carrying a pregnancy. Approximately one in 500 women suffer from absolute uterine infertility, and the option so far to become a mother has been to either adopt or utilize gestational surrogacy. As of today, a total of eleven cases of human uterus transplantations have been reported worldwide, conducted in three different countries. The results of these initial experimental cases far exceed what might be expected of a novel surgical method. Many more uterus transplantations are to be expected in the near future, as other research teams' preparations are being ready to be put into clinical practice. In this review, we summarize the current worldwide experience of uterus transplantation as a treatment of absolute uterine factor infertility and the future prospects of human uterus transplantation.