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.

Uterine Transplantation: Review of Livebirths and Reproductive Implications

Uterine transplantation (UTx) is a fertility restoring treatment for women with absolute uterine factor infertility. At a time when there is no question of the procedure's feasibility, and as the number of livebirths begins to increase exponentially, various important reproductive, fetal, and maternal medicine implications have emerged. Detailed outcomes from 17 livebirths following UTx are now available, which are reviewed herein, along with contextualized extrapolation from pregnancy outcomes in other solid organ transplants. Differences in recipient demographics and reproductive aspirations between UTx and other transplant recipients make extrapolating management strategies and outcomes in other solid organ transplants inappropriate. Whereas preterm delivery remains prominent, small for gestational age or hypertensive disorders do not appear to be as prevalent following UTx when compared to other solid organ transplants. Given the primary objective of undertaking UTx is to achieve a livebirth, publication of reproductive outcomes is essential at this early stage, to reflect on and optimize the management of future cases.

Uterine transplant: an ethical framework analysis from a Middle Eastern perspective

BACKGROUND

Significant advances in infertility treatment have been achieved over the past several decades, but women with uterine dysfunction, anomaly, or agenesis still need support to carry a pregnancy to term. Recently, advancements in surgical, anesthetic and immunosuppressive therapy have brought the idea of successful uterine transplant closer to reality, but many challenges must be overcome before uterine transplant can become more common, including ethical challenges related to the study and the conduct of this procedure.

METHODS

This was an updated ethical analysis of uterine transplant from a Middle Eastern perspective, using an established ethical framework that has been adapted for the analysis of research in non-Western cultures and developing countries.

RESULTS

Using the ethical framework, this analysis explored research developments in uterine transplant to date, using the following categories: collaborative partnership, social value, scientific validity, a fair selection of study population, favorable risk-benefit ratio, independent review, informed consent, and respect for recruited participants. The analysis revealed a significant need for region- and religion-specific ethical guidelines for uterine transplant procedures.

CONCLUSIONS

The horizons of research need to expand by addressing and researching the ethical issues related to uterine transplant trials and clinical procedures.

LIMITATIONS

Limitations included the challenges related to applying ethical analyses to work in developing countries, and the fact that this analysis was based on the views and interpretations of a single researcher.

Differential effects of the immunosuppressive calcineurin inhibitors cyclosporine-A and tacrolimus on ovulation in a murine model

STUDY QUESTION

Do therapeutic levels of cyclosporine-A and tacrolimus affect ovulation in a rat gonadotrophin-induced ovulation model?

SUMMARY ANSWER

Cyclosporine-A, but not tacrolimus, decreases ovulation rate when administered for 5 days before induced ovulation.

WHAT IS KNOWN ALREADY

The mainstays of immunosuppression in solid organ transplantation, to prevent rejection, are the calcineurin inhibitors cyclosporine-A or tacrolimus. These drugs could potentially affect fertility in transplanted patients. Since ovulation is an inflammation-like process with pivotal roles for several immune cells and modulators, it is possible that the calcineurin inhibitors, with broad effects on the immune system, could interfere with this sensitive, biological process.

STUDY DESIGN, SIZE, DURATION

Experimental design at university-based animal facilities. A total of 45 immature Sprague–Dawley rats were used. The study was carried out over 3 months.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Immature Sprague–Dawley rats (n = 45) were randomly assigned to receive equivalent doses of tacrolimus (0.5 mg/kg/day; TAC), cyclosporine-A (10 mg/kg/day; CyA) or vehicle (Control). Ovarian hyperstimulation was induced with 10 IU of equine chorionic gonadotrophin, and ovulation was triggered with 10 IU of hCG. Oocytes were retrieved from the oviducts and ovulation rates were calculated. Various subpopulations of white blood cells were counted in peripheral blood and ovarian tissue samples.

MAIN RESULTS AND THE ROLE OF CHANCE

Animals in the CyA group showed a lower ovulation rate when compared to the TAC and Control groups (CyA: mean 9 oocytes (range 0–22); TAC: 21 oocytes (8–41); Control: 22 oocytes (6–39); P = 0.03). Regarding counts of the white blood cell subpopulations and resident neutrophils in the ovary, no significant differences were observed between the groups.

LIMITATIONS, REASONS FOR CAUTION

Although the ovulation process is highly conserved within species, the differences between rodents and humans may limit the external translatability of the study.

WIDER IMPLICATIONS OF THE FINDINGS

These findings suggest that tacrolimus should be the preferred calcineurin inhibitor of choice in transplanted patients who are aiming for pregnancy.

STUDY FUNDING/COMPETING INTEREST(S)

Swedish Research Council and ALF of Sahlgrenska Academy, Sweden. Rio Hortega Grant from the Instituto de Salud Carlos III, Spain (CM09/00063). There are no conflicts of interest.

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.

Clinicopathologic Analysis of Uterine Allografts Including Proposed Scoring of Ischemia-reperfusion Injury and T Cell-mediated Rejection-Dallas UtErus Transplant Study: A Pilot Study

BACKGROUND

Uterus transplantation (UTx) enables pregnancy in infertile women. This study describes the histopathological changes of ischemia reperfusion injury and mostly acute T cell-mediated rejection (TCMR) in UTx and proposes modification toward a working formulation grading system with associated treatments.

METHODS

Protocol and indication biopsies from 11 living and 2 deceased donor UTx recipients were analyzed. Serving as a control were 49 age-matched nontransplanted uteri. All posttransplant histopathological specimens were evaluated in a blinded fashion by 3 pathologists. Response to treatment was assessed by follow-up biopsies. Serial serum donor-specific antibody (DSA) responses were also recorded.

RESULTS

Changes attributed to ischemia reperfusion resolved within 2 weeks of UTx in most of the patients. For TCMR grading, perivascular inflammation, focal capillary disruption, and interstitial hemorrhage were added to interface inflammation, intercellular edema, stromal inflammation, and epithelial apoptotic bodies. Of the 173 protocol biopsies, 98 were classified as negative for TCMR; 34, indeterminate-borderline; 35, mild; 3, moderate; and 3, severe, 1 of which occurred in a DSA-positive recipient and also showed microvascular injury. Corticosteroids successfully treated all moderate to severe TCMR episodes. Mild TCMR was treated by increasing existing baseline immunosuppression. Indeterminate-borderline episodes were not treated. Neither ischemia reperfusion injury nor TCMR with DSA adversely affected embryo transfer.

CONCLUSION

Relying on a modified histopathological grading system, we developed a treatment strategy resulting in resolution of TCMR and successful pregnancies.

Live birth after cervical ectopic uterus transplantation in mice

An ideal animal model is a prerequisite for the basic research of uterus transplantation. This study aimed to develop a new cervical ectopic uterus transplantation mice model, which was established by vascular anastomosis of the right common iliac artery and vein of the donor with the right common carotid artery and external jugular vein of the recipient, respectively, using the cuff method. The survival status of the transplanted uterus was assessed by macroscopic observation and histological examination after surgery, and the function of the graft uterus was tested by verifying whether the pregnancy is possible. A total of 40 transplants were performed, of which only 1 failed due to donor hemorrhage. After 26 transplants, the total operation time reduced to 52.4 ± 3.8 minutes, of which the total ischemia time took 6.6 ± 1.1 minutes. Sixty days after transplantation, all the graft uteri had a good blood supply and spontaneous contraction. The histology showed no significant difference between the transplanted uterus and the native. Embryo transfer experiments have proven that the transplanted uterus has uterine function. In conclusion, this new model is an effective and simple mice model for the studies of the scientific issues related to uterus transplantation.

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.

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.

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.

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.

The future of human uterus transplantation

The only untreatable subgroup of female infertility is absolute uterine factor infertility (AUFI), which is due to congenital or surgical absence of a uterus or presence of a nonfunctional uterus. The solitary option for a woman with AUFI to become a biological mother today is through a gestational surrogate mother, a procedure that is prohibited in Sweden and large parts of the world. Uterus transplantation (UTx) is a potential future treatment of AUFI. After extensive animal research, also involving non-human primates, a small number of human UTx cases have recently been performed. Here, we summarize the primate UTx experiments that have paved the way for the human UTx cases, which are described and analyzed in more detail. We also estimate how many women of fertile age are affected by AUFI and describe the causes. The ethics around UTx is complex and is also addressed.

Uterus transplantation: Experimental animal models and recent experience in humans

Uterus transplantation has been considered as an alternative management modality in the last few years for adoption or gestational surrogacy for women with absence of uterus due to congenital or acquired reasons. Surrogacy is legal in only a few countries because of ethical, social and legal issues. Up to date, a total of 11 uterus transplantation cases have been reported in which uteri were harvested from ten live donors and one donor with brain death. After unsuccessful attempt of first uterus transplantation, many studies have been conducted in animals and these experimental models enabled our knowledge to increase on this topic. First experimental studies were performed in rodents; later uterus transplantation was accomplished in sheep, pigs and rabbits. Recently, researches in non-human primates have led the experience regarding transplantation technique and success to improve. In this review, we reviewed the experimental animal researches in the area of uterus transplantation and recent experience in humans.

Uterus transplantation trial: 1-year outcome

OBJECTIVE

To report the 12-month outcome of seven patients with viable uteri after uterus transplantation (UTx).

DESIGN

Prospective observational study.

SETTING

University hospital.

PATIENT(S)

Seven patients with absolute uterine infertility and viable uteri for 12 months after live-donor UTx.

INTERVENTION(S)

Predetermined immunosuppression was with tacrolimus and mychophenolate mofetil (MMF) during 6 months, whereupon MMF should be withdrawn. Frequent ultrasound examinations were performed to assess uterine appearance and uterine artery blood flow. Cervical biopsies (for histological detection of rejection) were obtained at preset time points, with temporary adjustments of immunosuppression if there were signs of rejection. Menstruations were systematically recorded.

MAIN OUTCOME MEASURE(S)

Menstruation, uterine artery blood flow, histology of cervical biopsies, and blood levels of tacrolimus.

RESULT(S)

All patients showed regular menses after 1-2 months. Uterine artery blood flow was unchanged, with a median pulsatility index of 1.9 (range, 0.5-5.4). Blood levels of tacrolimus were approximately 10, 9, and 8 (μg/L) during months 2, 9, and 12, respectively. Four recipients showed mild inflammation in biopsies after MMF withdrawal and were treated with corticosteroids and azathioprine during the remainder of the 12 months. Subclinical rejection episodes were detected on ectocervical biopsies in five recipients. Histology showed apoptotic bodies and occasional spongiosis in the squamous epithelium. Moderate infiltration of lymphocytes and neutrophils was seen in the epithelial/stromal interface. All rejection episodes were successfully treated for 2 weeks with corticosteroids or dose increments of tacrolimus.

CONCLUSION(S)

We demonstrate long-term uterine viability after UTx, with continued menstruation and unaltered uterine artery blood flow. Subclinical rejection episodes were effectively reversed by temporary increase of immunosuppression.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01844362.

Risks for donors in uterus transplantation

Uterus transplantation (UTx) is an alternative to gestational surrogacy and adoption for patients with absolute uterine infertility. Studies have been conducted in animals, and UTx is now within the reach of clinical application in humans. Procedures in humans have been published, but many medical, ethical, and social problems and risks of UTx require discussion prior to widespread clinical application, from the perspectives of donors, recipients, families, and newborns. In this article, we summarize the burdens and risks of UTx, with a focus on donors who provide the uterus.

[Uterus transplantation. Current situation]

Except adoption, absolute uterine factor infertility lacks solution in case of motherhood desire. Gestational surrogacy is still not approved in France. Over the last decade, uterus transplantation experimentation made advances. Data from animal research, progress in immunosuppressive treatment and knowledge about pregnancy after transplantation provide a scenario in which a human allotransplantation project can become reality.

Preclinical report on allogeneic uterus transplantation in non-human primates

STUDY QUESTION

Is it possible to perform allogeneic uterus transplantation (UTx) with a donation from a live donor in a non-human primate species and what immunosuppression is needed to prevent rejection?

SUMMARY ANSWER

Allogeneic UTx in the baboon is a donor- and recipient-safe surgical procedure; immunosuppression with induction therapy and a triple protocol should be used.

WHAT IS KNOWN ALREADY

UTx may become a treatment for absolute uterine factor infertility. Autologous UTx models have been developed in non-human primates with reports on long-term survival of the uterine grafts. STUDY DESIGN, SIZEAND DURATION: This experimental study included 18 female baboons as uterus donors and 18 female baboons as uterus recipients. The follow-up time was 5-8 weeks.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

Uterus retrieval was performed with extended hysterectomy including bilateral uterine and internal iliac arteries and ovarian veins. After UTx, with vascular anastomoses unilateral to the internal iliac artery and the external iliac vein, the uterus recipients received one of the following: no immunosuppression (n = 4); monotherapy (oral slow release tacrolimus) (n = 4) or induction therapy (antithymocyte globulin) followed by triple therapy (tacrolimus, mycophenolate, corticosteroids; n = 10). Surgical parameters, survival, immunosuppression and rejection patterns were evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

The durations of uterus retrieval and recipient surgery were around 3 and 3.5 h, respectively. The total ischemic time was around 3 h. All the recipients and the donors survived the surgery. All the recipients presented rejection to some extent within the first weeks following UTx. In one recipient, the uterus was of normal appearance at the end of the study period. In spite of occasional high (>60 ng/ml) blood levels of tacrolimus, there was no evidence of nephrotoxicity.

LIMITATIONS AND REASONS FOR CAUTION

This initial non-human primate allogeneic UTx study indicates that further research is needed to optimize immunosuppression protocols in order to avoid uterine rejection.

WIDER IMPLICATIONS OF THE FINDINGS

The findings suggest that allogeneic UTx in primate species is feasible but continued work on this issue is needed.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the Swedish Research Council, ALF University of Gothenburg, Hjalmar Svensson Foundation and by Jane and Dan Olsson Research Foundation. The authors do not have any competing interest.

Uterus transplantation: animal research and human possibilities

Uterus transplantation research has been conducted toward its introduction in the human as a treatment of absolute uterine-factor infertility, which is considered to be the last frontier to conquer for infertility research. In this review we describe the patient populations that may benefit from uterus transplantation. The animal research on uterus transplantation conducted during the past two decades is summarized, and we describe our views regarding a future research-based human attempt.

Immunology of uterine transplantation: a review

The idea of using organ transplantation to solve quality-of-life issues was first introduced a century ago, with cornea transplants and thrusted before the world again in 1998, following a controversial hand transplant. Uterus transplantation (UTn) has been proposed as another quality-of-life transplant for the cure of permanent uterine factor infertility. In order to proceed in humans, a greater appreciation of the immunological mechanisms that underlie UTn is desirable. Allogeneic UTn (animal model) was first described by 2 studies in 1969. The first and only human UTn, performed in 2000, was an early attempt with limited use of animal model experiments prior to moving onto the human setting. Since then, work using rat, mouse, ovine, goat, and nonhuman primate models has demonstrated that the uterus is a very different but manageable organ immunologically compared to other transplanted organs. Therefore, specifically exploring immunological issues relating to UTn is a valuable and necessary part of the inevitable scientific process leading to successful human UTn.

Use of cyclosporine in uterine transplantation

Uterine transplantation has been proposed as a possible solution to absolute uterine factor infertility untreatable by any other option. Since the first human attempt in 2000, various teams have tried to clarify which immunosuppressant would be most suitable for protecting the allogeneic uterine graft while posing a minimal risk to the fetus. Cyclosporine A (CsA) is an immunosuppressant widely used by transplant recipients. It is currently being tested as a potential immunosuppressant to be used during UTn. Its effect on the mother and fetus and its influence upon the graft during pregnancy have been of major concern. We review the role of CsA in UTn and its effect on pregnant transplant recipients and their offspring.

Experimental uterus transplantation

BACKGROUND

Uterus transplantation (UTx) is developed in animal models as a future method to treat uterine factor infertility.

METHODS

All published studies in the area of UTx research were identified. Aspects relating to surgery, cold-ischemia/reperfusion, rejection, immunosuppression, pregnancy, ethics and institutional requirements were examined.

RESULTS

Uterus retrieval surgery has been solved in animals, including primates. Studies on cold-ischemia/reperfusion indicate an ischemic tolerance of >24 h. The transplantation procedure, with vascular anastomosis, has not been fully developed in animal models, indicated by frequent thrombosis formation. Pregnancies have only been reported in syngenic/auto-UTx animal models. Several ethical issues in relation to UTx, and requirements for a team that would be suitable to undertake human UTx, exist.

CONCLUSION

Much research on UTx has been performed in appropriate animal models. Several aspects of the procedure have been optimized but some remain to be solved. It is predicted that the research will soon reach a stage that could merit introduction of human UTx as an experimental procedure.