Organ Perfusion for Uterus Transplantation in Non-Human Primates With Assumed Procurement of a Uterus From a Brain-Dead Donor

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.

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.

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.

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: 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.

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.