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

Pregnancy management and outcome after uterus transplantation

Uterus transplantation is a novel approach in women whose uterus is absent or severely abnormal. However, it is still an experimental procedure that poses risks to both mother and baby. To date, 32 live births after uterus transplantation have been reported in peer-reviewed journals, with several maternal, fetal and neonatal complications. The most common complications were preterm delivery, hypertensive disorders and placenta previa. Four patients experienced episodes of transplant rejection during pregnancy. The appropriate management of complicated and non-complicated pregnancies following uterus transplantation is still unresolved. In this review, obstetric outcomes after uterus transplantation and optimal management during pregnancy are discussed in light of the available data. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Anatomic characteristics and novel transplantation model of the canine uterus

Background

In Vietnam, the rate of absolute uterine factor infertility is increasing, but no study has been published on uterine transplantation. The present study was designed to comprehensively observe the canine uterine anatomy and to examine the possibility of using a living canine donor for uterine transplantation training and further research.

Methods

Ten female Vietnamese mixed-breed dogs were sacrificed for anatomical research, and 15 additional pairs were used to evaluate the novel uterine transplant model.

Results

The anatomic features of the canine uterus differed considerably from those of the human uterus, with the uterine vessels originating from branches of the pudendal vessels (also known as the vaginal vessels). The uterine vascular pedicle had a small diameter (1 to 1.5 mm for arteries and 1.2 to 2.0 mm for veins) and required manipulation under a microscope. To perform uterine transplantation, the donor specimen's artery and vein lengths were successfully reconstructed by anastomosis between both sides of the vasculature using autologous Y-shaped subcutaneous veins. The living-donor uterine transplantation model constructed in this study was feasible, with the transplanted uterus surviving in 86.7% of cases (13/15).

Conclusions

Uterine transplantation was successfully performed in a Vietnamese canine living donor model. This model could be helpful in uterine transplantation training and improve the transplantation success rate in humans.

Uterus transplantation - donor and recipient work-up

PURPOSE OF REVIEW

Uterus transplantation (UTx) is transitioning from an experimental procedure to a clinical treatment for absolute uterine factor infertility (AUFI). Standardized protocols for the evaluation and selection of donors and recipients that maximize chances of success - a healthy live birth - are needed.

RECENT FINDINGS

To date, recipient eligibility has been limited to otherwise healthy women with AUFI who are of childbearing age and are good candidates for in-vitro fertilization (IVF). For donors (living or deceased), selection criteria vary, apart from basic requirements of blood-type compatibility and freedom from critical infectious diseases, but generally require a term birth and a uterus free from uterine pathologies. The stepwise evaluation process for candidate recipients and living donors moves through health screening (medical and psychosocial); initial selection committee review; IVF (recipients only); and final selection committee review. This eliminates candidates with poor chances of success before exposure to unnecessary risks.

SUMMARY

The currently stringent selection criteria for prospective recipients and donors will likely broaden, as UTx becomes more widely available. Continued research is needed to define the donor, recipient and uterine graft factors associated with successful outcomes, and to support the development of standardized selection criteria.

Evolution and Transformation of Uterine Transplantation: A Systematic Review of Surgical Techniques and Outcomes

BACKGROUND

 Uterine transplantation (UTx) is acknowledged to be on the second (2A) of five steps of development in accordance with the staging system for the evaluation of surgical innovations. Accordingly, we aimed to systematically review the available evidence of the surgical techniques and outcomes of UTx in terms of graft survival.

METHODS

 A comprehensive search was conducted across PubMed Medline, Cochrane-EBMR, Scopus, Web of Science, and CENTRAL through November 2020.

RESULTS

 Forty studies, reporting 64 recipients and 64 donors, satisfied inclusion criteria. The surgical time and the estimated blood loss were 515 minutes and 679 mL for graft procurement via laparotomy, 210 minutes and 100 mL for laparoscopic-assisted graft harvest, and 660 minutes and 173 mL for robotic-assisted procedures, respectively. Urinary tract infections (n = 8) and injury to the urinary system (n = 6) were the most common donor complications. Using the donor's internal iliac system, two arterial anastomoses were performed in all cases. Venous outflow was accomplished through the uterine veins (UVs) in 13 cases, a combination of the UVs and the ovarian/uteroovarian veins (OVs/UOVs) in 36 cases, and solely through the OVs/UOVs in 13 cases. Ischemia time was 161 and 258 minutes when using living donors (LD) and deceased donors (DD), respectively. Forty-eight uteri were successfully transplanted or fulfilled the purpose of transplantation, 41 from LDs and 7 from DDs. Twenty-five and four live childbirths from LDs and DDs have been reported, respectively.

CONCLUSION

 UTx is still experimental. Further series are required to recommend specific surgical techniques that best yield a successful transplant and reduce complications for donors and recipients.

Uterine Tissue Engineering: Where We Stand and the Challenges Ahead

Tissue engineering is an innovative approach to develop allogeneic tissues and organs. The uterus is a very sensitive and complex organ, which requires refined techniques to properly regenerate and even, to rebuild itself. Many therapies were developed in 20th century to solve reproductive issues related to uterus failure and, more recently, tissue engineering techniques provided a significant evolution in this issue. Herein we aim to provide a broad overview and highlights of the general concepts involved in bioengineering to reconstruct the uterus and its tissues, focusing on strategies for tissue repair, production of uterine scaffolds, biomaterials and reproductive animal models, highlighting the most recent and effective tissue engineering protocols in literature and their application in regenerative medicine. In addition, we provide a discussion about what was achieved in uterine tissue engineering, the main limitations, the challenges to overcome and future perspectives in this research field.

Methods for neovagina creation in women with Mayer-Rokitansky-Küster-Hauser syndrome for subsequent uterus transplantation

Mayer-Rokitansky-Küster-Hauser syndrome is a rare female congenital anomaly that presents with an inability to have coital sexual intercourse and absolute uterine factor infertility. Both surgical and nonsurgical approaches have been described for the treatment of vaginal agenesis to allow satisfactory coitus. Transplantation of the uterus has the challenge of achieving pregnancy and delivery of her own genetic and biological children in a woman without a natural uterus. Women of reproductive age with a congenital form of absolute uterine factor infertility are considered appropriate recipients of a uterus in the experimental phase of uterus transplantation trials. A neovagina in the normal anatomic position covered by natural non-keratinized mucosa is one of the main assumptions for surgical and reproductive success in transplant recipients. More than 70 uterine transplants have been performed to date, and more than 25 childbirths have been achieved by several research centers in the recipients of a uterus with uterine agenesis. In women with Mayer-Rokitansky-Küster-Hauser syndrome, skin-graft neovagina, Vecchietti's vaginoplasty, and self-dilation using Frank's and Ingram's methods are appropriate techniques to create a neovagina if transplantation of the uterus is intended in the future.

Melatonin and Glycine Reduce Uterus Ischemia/Reperfusion Injury in a Rat Model of Warm Ischemia

Ischemia/reperfusion injury (IRI) remains a significant problem to be solved in uterus transplantation (UTx). Melatonin and glycine have been shown to possess direct cytoprotective activities, mainly due to their antioxidative and anti-inflammatory properties. The aim of this study was to investigate the protective effects of melatonin and glycine and their combination on IRI in a rat model of warm ischemia. In this study, Sprague-Dawley rats were assigned to eight groups, including sham and IRI (n = 80). Melatonin and glycine alone or their combination were administered prior to 1 h of uterus ischemia followed by 1 h of reperfusion. Melatonin (50 mg/kg) was administered via gavage 2 h before IRI and glycine in an enriched diet for 5 days prior to intervention. Uterus IRI was estimated by histology, including immunohistochemistry, and biochemical tissue analyses. Histology revealed that uterus IRI was significantly attenuated by pretreatment with melatonin (p = 0.019) and glycine (p = 0.044) alone as well as their combination (p = 0.003). Uterus IRI led to increased myeloperoxidase expression, which was significantly reduced by melatonin (p = 0.004), glycine (p < 0.001) or their combination (p < 0.001). The decline in superoxide dismutase activity was significantly reduced in the melatonin (p = 0.027), glycine (p = 0.038) and combined treatment groups (p = 0.015) when compared to the IRI control group. In conclusion, melatonin, glycine and their combination significantly reduced oxidative stress-induced cell damage after IRI in a small animal warm ischemia model, and, therefore, clinical studies are required to evaluate the protective effects of these well-characterized substances in uterus IRI.

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.

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.

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.

Deceased Donation Uterus Transplantation: A Review

Uterus transplantation (UTx) offers women with absolute uterine factor infertility the option to gestate and birth their own biologically related child. The first birth following living donation UTx happened in 2014. The first birth following deceased donation happened in December 2017, with further successes since. Interest in deceased donation UTx is increasing. The authors established a database to track UTx clinical trials and outcomes. Utilising this database and existing literature, this article reviews the first reported cases of deceased donation UTx and outcomes, and drawing upon comparisons with living donor UTx, comments upon the future for this area of reproductive transplantation research. This is the first article to bring together the literature on deceased donation UTx procedures and outcomes.

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.

A New Approach for Treatment of Woman With Absolute Uterine Factor Infertility: A Traditional Review of Safety and Efficacy Outcomes in the First 65 Recipients of Uterus Transplantation

Uterine transplantation restores fertility 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 dramatically, with detailed outcomes from 65 cases now available. Pregnancies achieved through uterus transplantation and following in vitro fertilization (IVF) are associated with an increased risk for further mother and newborn babies. This traditional review is focused on the safety and efficacy features of the treatment. However, it is associated with significant risk, with approximately one-quarter of grafts are removed because of complications. Uterine transplantation is realizable in women with uterine factor infertility but is associated with a significant complication risk. The risk of the procedure and gestational and delivery complications deserve important consideration before receiving such treatments. Nevertheless, these observations are preliminary and should be revised after a larger series of data are published. 

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.

Uterine transplantation and IVF for congenital or acquired uterine factor infertility: A systematic review of safety and efficacy outcomes in the first 52 recipients

Uterine transplantation (UTx) associated with IVF restores fertility in women affected by absolute uterine factor infertility (AUFI). Pregnancies achieved both in women undergoing any solid organ transplantation and following IVF are associated with an increased risk of maternal and neonatal complications. This systematic review evaluated this risk in UTx-IVF treated women focusing on the safety and efficacy features of the treatment. Twenty-two studies and three press releases reporting on 52 UTx-IVF treatments were identified. Regarding the safety of treatment, 38/52 (73,1%) of surgical procedures led to the restoration of uterine function in recipients, 12/52 (23,1%) of recipients experienced post-operative complications requiring hysterectomy, and 2/52 (3,8%) of procedures failed before uterine recipients’ surgery due to intra-operative complications. Regarding the efficacy of treatment, results focused on transplanted patients showing full recovery of organ functioning: 16/38 (42,1%) of patients achieved a pregnancy, including two women who gave births twice. UTx-IVF pregnancies led to 16 deliveries and all new-borns were healthy. Six out of 16 (37,5%) UTx pregnancies faced major complications during gestation. Preterm births occurred in 10/16 (62,5%) UTx deliveries. Our data indicates that the risk of gestational and delivery complications deserves important consideration in AUFI women receiving UTx-IVF treatments. However, these observations are preliminary and need to be revised after larger series of data are published.

The vaginal microbiome in uterine transplantation

Women with congenital absolute uterine factor infertility (AUFI) often need vaginal restoration to optimise sexual function. Given their lack of procreative ability, little consideration has previously been given to the resultant vaginal microbiome (VM). Uterine transplantation (UTx) now offers the opportunity to restore these women's reproductive potential. The structure of the VM is associated with clinical and reproductive implications that are intricately intertwined with the process of UTx. Consideration of how vaginal restoration methods impact VM is now warranted and assessment of the VM in future UTx procedures is essential to understand the interrelation of the VM and clinical and reproductive outcomes. TWEETABLE ABSTRACT: The vaginal microbiome has numerous implications for clinical and reproductive outcomes in the context of uterine transplantation.

What will the future hold for artificial organs in the service of assisted reproduction: prospects and considerations

Assisted reproduction provides a wide spectrum of treatments and strategies addressing infertility. However, distinct groups of infertile patients with unexplained infertility, congenital disorders, and other complex cases pose a challenge in in vitro fertilization (IVF) practices. This special cohort of patients is associated with futile attempts, IVF overuse, and dead ends in management. Cutting edge research on animal models introduced this concept, along with the development of artificial organs with the aim to mimic the respective physiological functions in reproduction. Extrapolation on clinical application leads to the future use of infertility management in humans. To date, the successful clinical application of artificial reproductive organs in humans is not feasible because further animal model studies are required prior to clinical trials. The application of these artificial organs could provide a solution to infertility cases with no other options. This manuscript presents an overview on the current status, future prospects, and considerations on the potential clinical application of artificial ovary, uterus, and gametes in humans. This paper presents how the IVF practice landscape may be shaped and challenged in the future, along with the subsequent concerns in assisted reproductive treatments.

Revaluation and lessons learned from the first 9 cases of a Czech uterus transplantation trial: Four deceased donor and 5 living donor uterus transplantations

Although uterus transplantation is still in the experimental stage, it has promising potential as a treatment for women with absolute uterine factor infertility based on the childbirths from living donor trials conducted in Sweden and the United States. We report the main characteristics and perioperative and postoperative courses of both recipients and donors following 4 deceased donor and 5 living donor uterus transplantations. Three main priorities differentiate this study from the previously reported uterus transplantations. First, clinical experience with the largest worldwide group of deceased donor uterine transplants is described. Second, in the majority of living donor uterine recipients, only 2 ovarian veins were used for venous blood outflow. All of these recipient procedures were surgically successful, and follow-up posttransplant ultrasound examinations revealed normal uterine blood supply and outflow. Third, in only one living and one deceased donor recipient, the transplanted uterus relied on only 2 uterine veins for venous outflow with a 50% surgical success rate. In all other recipients, 2 uterine and 2 ovarian veins were utilized. Although a successful pregnancy has not yet been achieved, the presented surgical and functional results of our trial are promising.

Technical, Immunological, and Ethical Similarities and Differences Between Vascularized Composite Allotransplantation and Solid Organ Transplantation in Current Practice

Solid organ transplantation (SOT) is a surgical method used as the gold standard in end-term organ failure. Following SOT, successful results have also been achieved in vascularized composite tissue transplantation, which improves the quality of life with the success of solid organ transplants and the development of modern immunosuppressive regimens. This review discusses the preoperative, operative, postoperative, and immunological differences between vascularized tissue transplantation and SOT.

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.

Robotics in reproduction, fertility preservation, and ovarian transplantation

Robotic technology is one of the most promising and rapidly developing advancements of the twenty-first century with a potential to make significant contributions to reproductive surgery and preservation of fertility. Along with the major advances in cancer therapy, the number of female cancer survivors of reproductive age has dramatically increased. As a consequence, fertility preservation has gained more emphasis in reproductive science in the last few decades. A broad range of surgical procedures such as tubal reanastomosis, ovarian transposition, radical trachelectomy, and ovarian transplantation has been introduced to restore or preserve fertility in selected patients. These procedures can be accomplished through various surgical routes, including open surgery and minimally invasive approaches. In this review, we aim to present the current applications, advantages, and disadvantages of robotic technology in the field of reproductive surgery with a special interest in ovarian transplantation for fertility preservation.