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

Registry of the International Society of Uterus Transplantation: First Report

BACKGROUND

Uterus transplantation (UTx) is a novel type of transplantation to treat infertility in women with an absent or nonfunctioning uterus. The International Society of Uterus Transplantation (ISUTx) has developed a registry to monitor worldwide UTx activities while serving as a repository for specific research questions.

METHODS

The web-based registry has separate data fields for donor, recipient, surgeries, immunosuppression, rejections, pregnancies with live birth(s), and transplant hysterectomies. Data are prospectively registered.

RESULTS

A total of 45 UTx procedures have been registered; the majority (78%) of those procedures were live donor (LD) transplants. Median age of the LDs, deceased donors, and recipients were 50 y (range 32-62), 38.5 y (19-57), and 29 y (22-38), respectively. The duration of LD surgery was approximately twice as long as the recipient surgery. Postoperative complications of any Clavien-Dindo grade were registered in 20% of LDs and 24% of recipients. Rejection episodes were more frequent (33%) early after transplantation (months 1-5) compared with later time points (months 6-10; 21%). Healthy neonates were delivered by 16 recipients, with 3 women giving birth twice. The total live birth rate per embryo transfer was 35.8%. Median length of pregnancy was 35 gestational weeks. Twelve uteri were removed without childbirth, with 9 transplant hysterectomies occurring during the initial 7 mo post-UTx.

CONCLUSIONS

A mandatory registry is critical to determine quality and process improvement for any novel transplantation. This registry provides a detailed analysis of 45 UTx procedures performed worldwide with a thorough analysis of outcomes and complications.

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.

Uterus transplantation: state of the art in 2021

PURPOSE

To provide a comprehensive review of uterus transplantation in 2021, including a discussion of pregnancy outcomes of all reported births to date, the donor and recipient selection process, the organ procurement and transplant surgeries, reported complications, postoperative monitoring, preimplantation preparation, and ethical considerations.

METHODS

Literature review and expert commentary.

RESULTS

Reports of thirty-one live births following uterus transplantation have been published from both living and deceased donors. The proper selection of donors and recipients is a labor-intensive process that requires advanced planning. A multidisciplinary team is critical. Reported complications in the recipient include thrombosis, infection, vaginal stricture, antenatal complications, and graft failure. Graft rejection is a common occurrence but rarely leads to graft removal. While most embryo transfers are successful, recurrent implantation failures in uterus transplant patients have been reported. Rates of preterm delivery are high but appear to be declining; more data, including long-term outcome data, is needed.

CONCLUSIONS

Uterus transplantation is an emerging therapy for absolute uterine factor infertility, a condition previously without direct treatment options. It is paramount that reproductive health care providers are familiar with the uterus transplantation process as more patients seek and receive this treatment.

Uterus transplantation: state of the art in 2021

PURPOSE

To provide a comprehensive review of uterus transplantation in 2021, including a discussion of pregnancy outcomes of all reported births to date, the donor and recipient selection process, the organ procurement and transplant surgeries, reported complications, postoperative monitoring, preimplantation preparation, and ethical considerations.

METHODS

Literature review and expert commentary.

RESULTS

Reports of thirty-one live births following uterus transplantation have been published from both living and deceased donors. The proper selection of donors and recipients is a labor-intensive process that requires advanced planning. A multidisciplinary team is critical. Reported complications in the recipient include thrombosis, infection, vaginal stricture, antenatal complications, and graft failure. Graft rejection is a common occurrence but rarely leads to graft removal. While most embryo transfers are successful, recurrent implantation failures in uterus transplant patients have been reported. Rates of preterm delivery are high but appear to be declining; more data, including long-term outcome data, is needed.

CONCLUSIONS

Uterus transplantation is an emerging therapy for absolute uterine factor infertility, a condition previously without direct treatment options. It is paramount that reproductive health care providers are familiar with the uterus transplantation process as more patients seek and receive this treatment.

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.

Operative and Clinical Outcomes of Minimally Invasive Living-Donor Surgery on Uterus Transplantation: A Literature Review

BACKGROUND

The surgical approach and choice of drainage veins for uterus transplantation living-donor surgery have been investigated to reduce invasiveness.

METHODS

A thorough search of the PubMed database was conducted. The search was not limited by language or date of publication. The data were collected on 13 October 2020. Two reviewers independently assessed each article and determined eligibility for inclusion in the review article. Inclusion criteria were English peer-reviewed articles reporting surgical information or postoperative course, articles regarding animal research on UTx, UTx on deceased donors, or not original articles.

RESULTS

Of the 51 operations within 26 articles reviewed, the mean operative time was shortest in the laparoscopic approach, and longest in the robot-assisted approach. The mean blood loss was less in the laparoscopic and robot-assisted approaches than in the open approach. In cases where the uterine veins were not preserved, the mean operative time was shortened by each approach and the mean blood loss decreased with the laparoscopic and robot-assisted approaches.

CONCLUSIONS

These procedures may contribute to less invasive living-donor surgery.

Single bilateral ovarian venous return in uterine transplant: Validation in an orthotopic auto-transplant model in the Yucatan minipig

BACKGROUND

Uterine transplant (UT) represents an opportunity to treat absolute uterine infertility. However, the use of uterine veins for venous return, in addition to ovarian veins, significantly increases the risk of ureteral wounds in the living donor and UT time for the recipient. Our aim was to demonstrate that dual ovarian venous return is sufficient for graft viability and survival.

METHODS

Uterine orthotopic auto-transplant was performed under general anaesthesia in six Yucatan minipig sows. The uterus graft was implanted with termino-lateral anastomoses between the ovarian and external iliac veins, and between the uterine and external iliac arteries, respectively.

RESULTS

The macroscopic physical aspect of the graft was adequate in 83 % of the sows (5/6) 30 min after reperfusion with a surgical time of 439±54 min (mean anastomosis time: 153±49 min). Two sows died the day after surgery. In the four remaining sows, two uteri were necrotic and two were adequately vascularized on Day 7.

CONCLUSIONS

the learning curve was relatively fast, the sole use of bilateral ovarian venous return is possible and might reduce post-surgery morbidity in human living donors as well as UT time for the recipient.

Targeting connexins with Gap27 during cold storage of the human donor uterus protects against cell death

Uterus transplantation is an experimental infertility treatment for women with uterine factor infertility. During donor uterus retrieval and subsequent storage, ischemia and other stressors are likely to occur, resulting in the delayed restoration of organ function and increased graft rejection. The uterus expresses connexin-based hemichannels, the opening of which can promote ischemic cell death, as well as gap junctions that may expand cell death by bystander signaling. We investigated if connexin channel inhibition with connexin channel inhibitor Gap27 could protect the uterus against cell death during the storage period. The study involved 9 female patients undergoing gender-change surgery. Before uterus removal, it was exposed to in situ warm ischemia with or without reperfusion. Uterus biopsies were taken before, during, and after ischemia, with or without reperfusion, and were subsequently stored under cold (4ᵒC) or warm (37ᵒC) conditions. TUNEL cell death assay was done at various time points along the combined in vivo/ex vivo experimental timeline. We found that Gap27 protected against storage-related cell death under cold but not warm conditions when the uterus had experienced in situ ischemia/reperfusion. For in situ brief ischemia without reperfusion, Gap27 reduction of cell death was delayed and significantly less, suggesting that protection critically depends on processes initiated when the organ was still in the donor. Thus, the inclusion of the connexin channel inhibitor Gap27 during cold storage protects the uterus against cell death, and the degree of protection depends on the history of exposure to warm ischemia. Gap27 protection may be indicated for uteri from deceased donors, in which ischemia is likely because life-saving organs have retrieval priority.

Uncontrollable uterine atony after replacement of uterine inversion managed by hysterectomy: a case report

Background

Uterine inversion may cause massive hemorrhage, resulting in maternal deterioration and death. Replacement of the inverted uterus must be performed as soon as possible. As time passes, the inverted uterus becomes atonic and necrotic, and a surgical approach may be required.

Case presentation

A 27-year-old Japanese woman was admitted to our hospital 4 hours postpartum with increased hemorrhage after the replacement of an inverted uterus. Recurrent inversion was diagnosed, and though the atonic uterus was replaced again by the Johnson maneuver, hemorrhage persisted. Balloon tamponade was not successful in stopping the hemorrhage, and uterine artery embolization was performed. Bleeding resumed the next day on removal of the balloon, and hysterectomy was performed. Massive hemorrhage, coagulopathy, and uterine necrosis caused uterine atony, and the reperfused blood flow on replacement of the ischemic uterus increased hemorrhage.

Conclusions

Cases of uterine inversion with coagulopathy lasting for more than 4 hours may require a surgical intervention, and uterine replacement may have to be delayed until the maternal hemodynamic condition is stabilized. Uterine replacement under laparotomy may be also be considered due to the risk of increased hemorrhage.

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.

Propagation of spontaneous electrical activity in the ex vivo human uterus

Contractions of the non-pregnant uterus play a key role in fertility. Yet, the electrophysiology underlying these contractions is poorly understood. In this paper, we investigate the presence of uterine electrical activity and characterize its propagation in unstimulated ex vivo human uteri. Multichannel electrohysterographic measurements were performed in five freshly resected human uteri starting immediately after hysterectomy. Using an electrode grid externally and an electrode array internally, measurements were performed up to 24 h after hysterectomy and compared with control. Up to 2 h after hysterectomy, we measured biopotentials in all included uteri. The median root mean squared (RMS) values of the external measurements ranged between 3.95 μV (interquartile range (IQR) 2.41–14.18 μV) and 39.4 μV (interquartile range (IQR) 10.84–105.64 μV) and were all significantly higher than control (median RMS of 1.69 μV, IQR 1.13–3.11 μV), consisting of chicken breast meat. The RMS values decreased significantly over time. After 24 h, the median RMS (1.27 μV, IQR 0.86–3.04 μV) was comparable with the control (1.69 μV, IQR 1.13–3.11 μV, p = 0.125). The internal measurements showed a comparable pattern over time, but overall lower amplitude. The measured biopotentials propagated over the uterine surface, following both a plane-wave as well as an erratic pattern. No clear pacemaker location nor a preferred propagation direction could be identified. These results show that ex vivo uteri can spontaneously generate propagating biopotentials and provide novel insight contributing to improving our understanding of the electrophysiology of the human non-pregnant uterus.

Ischemia and reperfusion injury in uterus transplantation: A comprehensive review

Uterus transplantation (UTx) is the only available treatment for human beings who cannot carry children out to term. However, despite several clinical studies with a very limited number of UTx many issues have to be addressed. Up to date, there is a limited number of successful UTx with livebirth and the majority was achieved with live donors. Wide clinical application is inherently limited by the lack of organs, ischemia/reperfusion injury (IRI) as well as immunosuppression after UTx. The objective of this comprehensive literature review is to discuss these arising limitations of UTx with main focus on strategies to reduce IRI. This review showed, that usage of immunosuppressants, opioids or supplements, like amino acids, protects uterus from IRI, improving rising level of antioxidants and decreasing level of oxidative stress markers. The available data of experimental and clinical studies was compiled and will be discussed.

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.

Human uterine transplantation: a review of outcomes from the first 45 cases

Uterine transplantation restores reproductive anatomy in women with absolute uterine factor infertility and allows the opportunity to conceive, experience gestation, and acquire motherhood. The number of cases being performed is increasing exponentially, with detailed outcomes from 45 cases, including nine live births, now available. In light of the data presented herein, including detailed surgical, immunosuppressive and obstetric outcomes, the feasibility of uterine transplantation is now difficult to refute. However, it is associated with significant risk with more than one-quarter of grafts removed because of complications, and one in ten donors suffering complications requiring surgical repair. TWEETABLE ABSTRACT: Uterine transplantation is feasible in women with uterine factor infertility, but is associated with significant risk of complication.

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.

The development of an extended normothermic ex vivo reperfusion model of the sheep uterus to evaluate organ quality after cold ischemia in relation to uterus transplantation

INTRODUCTION

Uterus transplantation has recently proved that infertility in women with uterine factor infertility can be cured. It is still an experimental procedure with numerous critical details remaining to be established, including tolerance to warm and cold ischemic insults. In preparation for human uterus transplantation trials, most teams use the sheep as a model system for research and team training, since the vasculature and the uterus is of similar size as in the human. We, therefore, aimed to develop an ex vivo sheep uterus reperfusion platform that mimics the reperfusion situation so that initial assessments and comparisons can be performed without the need for costly and labor-intensive in vivo transplantation experiments.

MATERIAL AND METHODS

Isolated sheep uteri were perfused with the preservation solution IGL-1 and were then exposed to cold ischemia for either 4 (n = 6) or 48 hours (n = 7). Uteri were then reperfused for 48 hours under normothermic conditions with an oxygenated recirculating perfusate containing growth factors and synthetic oxygen carriers. Histological and biochemical analysis of the perfusate was conducted to assess reperfusion injury.

RESULTS

Quantification of cell density indicated no significant edema in the myometrium or in the endometrium of uteri exposed to 4 hours cold ischemia and then a normothermic ex vivo reperfusion for 48 hours. Only the outer serosa layer and the inner columnar luminal epithelial cells were affected by the reperfusion. However, a much faster and severe reperfusion damage of all uterine layers were evident during the reperfusion experiment following 48 hours of cold ischemia. This was indicated by major accumulation of extracellular fluid, presence of apoptotic-labeled glandular epithelial layer and vascular endothelium. A significant accumulation of lactate was measured in the perfusate with a subsequent decrease in pH.

CONCLUSIONS

We developed a novel ex vivo sheep uterus model for prolonged perfusion. This model proved to be able to distinguish reperfusion injury-related differences associated to organ preservation. The experimental setup is a platform that can be used to conduct further studies on uterine ischemia- and reperfusion injury that may lead to improved human uterus transplantation protocols.

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.