Experimental uterus transplantation

The protective effects of tacrolimus on rat uteri exposed to ischemia-reperfusion injury: a biochemical and histopathologic evaluation

OBJECTIVE

To evaluate the effects of the immunosuppressant tacrolimus as an antioxidant and analyze the histopathologic changes in rat uteri exposed to experimental ischemia-reperfusion (I/R) injury.

DESIGN

Experimental study.

SETTING

Experimental surgery laboratory in a university.

ANIMAL(S)

Twenty-eight female rats exposed to experimentally induced uterine I/R injury.

INTERVENTION(S)

Group I: control group; group II: uterine I/R injury-induced group; group III: pre-ischemia tacrolimus group; group IV: post-ischemia tacrolimus group.

MAIN OUTCOME MEASURE(S)

Uterine tissue malondialdehyde (MDA) level as a marker of lipid peroxidation and glutathione (GSH) level and superoxide dismutase (SOD) and catalase (CAT) activities as markers of tissue antioxidant capacity; histopathologic examination of all uterine rat tissue.

RESULT(S)

Following aortic I/R injury, MDA levels were significantly increased whereas GSH levels and CAT and SOD activities were found to be decreased compared with control animals. MDA levels were found to recover prominently after the administration of tacrolimus in both groups III and IV. Administration of tacrolimus improved uterine GSH levels and CAT activity in the tacrolimus-treated groups.

CONCLUSION(S)

Our results indicate that tacrolimus reduces oxidative damage in rat uteri exposed to I/R injury induced by distal abdominal aortic occlusion. Histologic evaluation reveals that tacrolimus attenuates the inflammatory response and protects the tissue damage induced by I/R injury.

Porcine uterus cryopreservation: an analysis of contractile function using different uterotonics

Cryopreservation of whole organs has become increasingly successful in recent years, and establishing reliable methods for confirming the success of specific cryopreservation procedures has therefore become extremely important. On the assumption that methods such as histological evaluation do not provide definitive evidence of long-term cryopreservation and that clear signs of conserved function in an organ are good evidence of its viability, contractile function was analysed in porcine uteri (n=60), either after long-term (group A) or short-term (group B) cryopreservation and post-thaw treatment with three different uterotonics. A slow freezing protocol was used to preserve the organs. Fifteen fresh uteri were analysed similarly for contractile function, which was evaluated by measuring intrauterine pressure after administration of oxytocin, prostaglandin E(1) (PGE(1)), and carbachol. After cryopreservation, all but three uteri (95%) showed rhythmic contractions similar to those in fresh uteri except for differences in the heights of contraction peaks, with lower contractions in PGE(1) subgroup B (P<0.05). With the exception of three nonresponsive uteri in group A, there were no differences in contractility between uteri after long-term cryopreservation and fresh uteri. The results of this study thus contribute to the debate on whether slow freezing or vitrification techniques are best for whole-organ cryopreservation. In summary, (1) preservation of muscular function in porcine uteri is feasible with a slow freezing protocol; (2) measurement of contractile function following administration of uterotonics is a useful method of confirming functionality; and (3) long-term cryopreservation does not significantly impair post-thaw contractibility in comparison with fresh uteri.

Endometrial reconstruction from stem cells

Adult stem cells have been identified in the highly regenerative human endometrium on the basis of their functional attributes. They can reconstruct endometrial tissue in vivo suggesting their possible use in treating disorders associated with inadequate endometrium. The identification of specific markers for endometrial mesenchymal stem cells and candidate markers for epithelial progenitor cells enables the potential use of endometrial stem/progenitor cells in reconstructing endometrial tissue in Asherman syndrome and intrauterine adhesions.

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.

The effect of collagen-binding vascular endothelial growth factor on the remodeling of scarred rat uterus following full-thickness injury

Serious injuries of uterine which lead to scar formation will finally result in infertility or pregnancy complications. There are few effective methods to treat such damages because of the shortage of native tissues. Vascular endothelial growth factor (VEGF) is important for the formation of new vessels and re-epithelialization of endometrium. Here we produced a collagen-binding VEGF by fusing a collagen-binding domain to the N-terminal of native VEGF. After injection into a rat scarred uterus model (partial of rat uterine horn was excised and left for scar formation) the collagen targeting VEGF promoted remodeling of the scarred uterus including the regeneration of endometrium, muscular cells, and vascularization and improved pregnancy outcomes. Thus, collagen-binding VEGF may be a pragmatic solution for the treatment of severe uterine damages.

Regeneration of uterine horns in rats by collagen scaffolds loaded with collagen-binding human basic fibroblast growth factor

Severe damages of uterine endometrium which prevent embryos from implantation and placentation finally often result in infertility or pregnant complications. There is lack of effective treatments due to the limitation of native materials available and complexity of the function and internal environment of uterus. In the present study, a collagen targeting basic fibroblast growth factor (bFGF) delivery system was constructed by a collagen membrane loaded with bFGF fused a collagen-binding domain (CBD) to the N-terminal which limits the diffusion of bFGF from collagen. We tested the bFGF delivery system in rats under the severe uterine damage model (partial rat uterine horn excision/reconstruction), and found this delivery system improved regeneration abilities of uterine endometrium and muscular cells, improved vascularization, as well as better pregnancy outcomes in rats. Therefore, this targeting delivery system may be an effective strategy for uterine tissue regeneration.

A new surgical technique of uterine auto-transplantation in cynomolgus monkey: preliminary report about two cases

OBJECTIVE

Uterine transplantation experiments have been performed in various animal species for future clinical applications of uterine transplantation for permanent uterine factor infertility in humans. The aim of this study was to confirm the feasibility of uterine auto-transplantation in cynomolgus monkeys by developing new surgical techniques.

METHODS

Two female cynomolgus monkeys underwent surgery under general anesthesia. The uterus with vascular grafts and the vaginal wall was removed, and back-table preparation was performed using heparinized saline. The uterus with vascular grafts and the vaginal wall was anastomosed with the vaginal stump and blood vessels in the pelvis, respectively. The auto-transplant uterine function was evaluated by confirming engraftment of the uterus by laparotomy, endometrial proliferation by transabdominal ultrasonography and periodical menstruation.

RESULTS

The first animal died due to acute renal failure 2 days after the operation. Second-look laparotomy in the second animal at 40 days after the operation indicated there was no congestion in the uterus, and the uterus showed the typical red color of a normal uterus. Thereafter, endometrial proliferation was observed by transabdominal ultrasonography and periodical menstruation was confirmed, indicating re-established uterine function.

CONCLUSION

This is the preliminary report of uterine auto-transplantation in cynomolgus monkeys. This study demonstrates the feasibility of uterine auto-transplantation by using new surgical technique in cynomolgus monkeys. Accumulation of basic experimental data in non-human primates is required prior to performing the procedure in humans.