Chemotherapy and radiotherapy are essential in the treatment of cancers in children and youngadults; while, these therapies often result in testicular failure or reduced ovarian function. So far, thepriority is exclusively on the treatment of cancer, and these side effects have been under recognized. However, advances in the studies of ovarian cryopreservation are expected to correct the imbalance between the treatment effects and adverse reactions. Particularly for young women with cancer, ovarian cryopreservation before initiation of cancer treatment may give hope for the preservation of fertility. One of the problems in the study of cryopreservation techniques is that use of cryopreserved ovary yields only a very low rate of fertilization. We hypothesized that this is caused by instable blood flow during organ transplantation, so we conducted an experiment in a rat ovarian transplantation model, focusing on vascular anastomosis and cryopreservation. This study is based on the technique of vascular anastomosis, which we call "Super-Microsurgery". First, we examined the feasibility of the technique for ovarian transplantation. We removed vascularized ovaries from recipient rats and anastomosed the vessels of the ovaries to the subcutaneous vessels of donor recipient nude mice. A histological analysis of the group undergoing anastomosis and the group not undergoing anastomosis revealed that ovarian follicles and ovarian granulosa cells were better preserved in the group undergoing anastomosis, indicating the importance of vascular anastomosis in ovarian transplantation.

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A scientific approach towards organ preservation was initiated by Alexis Carrel, who was awarded the Nobel Prize in 1904. Subsequently, cryopreservation of organs gained momentum in the 1950s. However, organ cryopreservation has long been considered impossible, because the cells in the organs suffer from substantial damage due to ice-crystal formation and generation of osmotic-pressure gradients in the tissue. Meanwhile, in gynecology, freezing techniques for sperms, ova, fertilized eggs, etc., have been developed to ensure retention of fertility. Cells and tissue fragments can be frozen with a high probability of success. Some studies on the clinical applications of these approaches in humans have been published. In this study, we tried to cryopreserve organs, and not the cells or tissues, by using a freezing technology that employed a variable magnetic field. This freezing technology was principally developed by a Japanese company engaged in the development of food-freezing technologies. The combination of different techniques, i.e., the integration of this freezing technology with our technique, Super-Microsurgery, is expected to expedite basic experimental research on cryopreservation of small organs, particularly reproductive organs, which was hitherto considered impossible.

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Many cancer patients become infertile after treatment with anticancer drugs or radiotherapy. To restore fertility, cryopreservation of sperm, ova/fertilized ova, or ovarian tissue is considered as one of the available options; however, this method gives very low pregnancy rate due to cellular injury caused by freezing. Since it is impossible to collect sperm or ova prior to sexual maturity, there is no other treatment approach that can be applied in the case of children with cancer. In this paper, we propose anew transplantation procedure using rat models in which the function of the reproductive organs is preserved by temporarily transplanting them between living donors and recipients, without the requirement for cryopreservation of the ovarian tissue. These procedures are based on the plasticsurgery techniques that are aimed at restoration of amputated limbs. We removed the ovary from a recipient rat, temporarily transplanted it into a recipient rat, and finally retransplantated into the donor; this subsequently resulted in a successful natural pregnancy and delivery. Microscopic observation revealed that most ova that were transplanted to the ovary by vascular anastomosis survived. In addition, femoral bone mineral density analysis confirmed increased bone density compared with that measured prior to the ovarian transplantation. Furthermore, since mammals possess a pair of ovaries, the procedure developed in this study can also be applied to fields other than medicine. For example, the reproductive efficiency of animals after menopause can be increased through reproductive organ transplantation, which can be achieved by preservation of one of these ovaries for transplantation.

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Recently, research on the freezing of unfertilized eggs and ovaries aimed at preservation of fertility hasbeen advanced as a way to avoid iatrogenic infertility in young girls, whereas research in young boys is less emphasized due to the development of techniques the freeze sperm. A treatment for the preservation of fertility, however, has not been developed because sperm cannot be collected from prepubertal boys due to the immaturity of spermatogenesis. We developed an experimental model of vascularized testis transplantation with the aim of preserving fertility in prepubertal boys with childhood cancer and successfully achieved vascular anastomosis of a rat testicular artery and vein. We also found that when mouse testicular tissue was frozen under a magnetic field, tissue destruction is reduced as compared to the existing method of freezing. Combined application of super-microsurgery and a novel technique for freezing testis opened the way to long-term preservation of the testis and transplant studies.

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Recently, a therapy aimed to preserve fertility has been developed for patients with female genital cancer. However, carcinoma excision needs to be performed for cases of advanced disease stage at the expense of fertility. We have been conducting an ovarian cryopreservation study and uterus transplant study under immunosuppression in an attempt to reconstruct fertility in patients with a radical hysterectomy due to advanced disease. It may seem to be too early to expect clinical application of a uterus transplant study at this stage of development because many ethical and legal problems remain to be solved. However, we believe it is very important to raise the possibility for those patients undergoing radical hysterectomy to have babies by cryopreserving a part of the removed ovary so that IVM-IVF (in vitro maturation-in vitro fertilization) technique may be adopted in the future when the technology advances to the point of achieving a mature ovum from an oogonium.
We aim at safe fertility reconstruction in patients who had a hysterectomy due to uterine cancer by establishing a new uterus transplant based on an effort to integrate Super-Microsurgery, an advanced vascular anastomosis technique in the plastic surgery and reconstructive surgery field, and organ transplantation under immune tolerance, an advance in the transplantation surgery field. Considering studies of surrogate mothers and uterus transplants, cryopreservation of part of removed ovarian tissue (not used for pathological diagnosis) in patients with female genital cancer can be very important. We present the following report on the development of uterus transplant experiment model of pigs.

View full abstract

Chemotherapy and radiotherapy are essential in the treatment of cancers in children and youngadults; while, these therapies often result in testicular failure or reduced ovarian function. So far, thepriority is exclusively on the treatment of cancer, and these side effects have been under recognized. However, advances in the studies of ovarian cryopreservation are expected to correct the imbalance between the treatment effects and adverse reactions. Particularly for young women with cancer, ovarian cryopreservation before initiation of cancer treatment may give hope for the preservation of fertility. One of the problems in the study of cryopreservation techniques is that use of cryopreserved ovary yields only a very low rate of fertilization. We hypothesized that this is caused by instable blood flow during organ transplantation, so we conducted an experiment in a rat ovarian transplantation model, focusing on vascular anastomosis and cryopreservation. This study is based on the technique of vascular anastomosis, which we call "Super-Microsurgery". First, we examined the feasibility of the technique for ovarian transplantation. We removed vascularized ovaries from recipient rats and anastomosed the vessels of the ovaries to the subcutaneous vessels of donor recipient nude mice. A histological analysis of the group undergoing anastomosis and the group not undergoing anastomosis revealed that ovarian follicles and ovarian granulosa cells were better preserved in the group undergoing anastomosis, indicating the importance of vascular anastomosis in ovarian transplantation.

View full abstract

A scientific approach towards organ preservation was initiated by Alexis Carrel, who was awarded the Nobel Prize in 1904. Subsequently, cryopreservation of organs gained momentum in the 1950s. However, organ cryopreservation has long been considered impossible, because the cells in the organs suffer from substantial damage due to ice-crystal formation and generation of osmotic-pressure gradients in the tissue. Meanwhile, in gynecology, freezing techniques for sperms, ova, fertilized eggs, etc., have been developed to ensure retention of fertility. Cells and tissue fragments can be frozen with a high probability of success. Some studies on the clinical applications of these approaches in humans have been published. In this study, we tried to cryopreserve organs, and not the cells or tissues, by using a freezing technology that employed a variable magnetic field. This freezing technology was principally developed by a Japanese company engaged in the development of food-freezing technologies. The combination of different techniques, i.e., the integration of this freezing technology with our technique, Super-Microsurgery, is expected to expedite basic experimental research on cryopreservation of small organs, particularly reproductive organs, which was hitherto considered impossible.

View full abstract

Many cancer patients become infertile after treatment with anticancer drugs or radiotherapy. To restore fertility, cryopreservation of sperm, ova/fertilized ova, or ovarian tissue is considered as one of the available options; however, this method gives very low pregnancy rate due to cellular injury caused by freezing. Since it is impossible to collect sperm or ova prior to sexual maturity, there is no other treatment approach that can be applied in the case of children with cancer. In this paper, we propose anew transplantation procedure using rat models in which the function of the reproductive organs is preserved by temporarily transplanting them between living donors and recipients, without the requirement for cryopreservation of the ovarian tissue. These procedures are based on the plasticsurgery techniques that are aimed at restoration of amputated limbs. We removed the ovary from a recipient rat, temporarily transplanted it into a recipient rat, and finally retransplantated into the donor; this subsequently resulted in a successful natural pregnancy and delivery. Microscopic observation revealed that most ova that were transplanted to the ovary by vascular anastomosis survived. In addition, femoral bone mineral density analysis confirmed increased bone density compared with that measured prior to the ovarian transplantation. Furthermore, since mammals possess a pair of ovaries, the procedure developed in this study can also be applied to fields other than medicine. For example, the reproductive efficiency of animals after menopause can be increased through reproductive organ transplantation, which can be achieved by preservation of one of these ovaries for transplantation.

View full abstract

Recently, research on the freezing of unfertilized eggs and ovaries aimed at preservation of fertility hasbeen advanced as a way to avoid iatrogenic infertility in young girls, whereas research in young boys is less emphasized due to the development of techniques the freeze sperm. A treatment for the preservation of fertility, however, has not been developed because sperm cannot be collected from prepubertal boys due to the immaturity of spermatogenesis. We developed an experimental model of vascularized testis transplantation with the aim of preserving fertility in prepubertal boys with childhood cancer and successfully achieved vascular anastomosis of a rat testicular artery and vein. We also found that when mouse testicular tissue was frozen under a magnetic field, tissue destruction is reduced as compared to the existing method of freezing. Combined application of super-microsurgery and a novel technique for freezing testis opened the way to long-term preservation of the testis and transplant studies.

View full abstract

Recently, a therapy aimed to preserve fertility has been developed for patients with female genital cancer. However, carcinoma excision needs to be performed for cases of advanced disease stage at the expense of fertility. We have been conducting an ovarian cryopreservation study and uterus transplant study under immunosuppression in an attempt to reconstruct fertility in patients with a radical hysterectomy due to advanced disease. It may seem to be too early to expect clinical application of a uterus transplant study at this stage of development because many ethical and legal problems remain to be solved. However, we believe it is very important to raise the possibility for those patients undergoing radical hysterectomy to have babies by cryopreserving a part of the removed ovary so that IVM-IVF (in vitro maturation-in vitro fertilization) technique may be adopted in the future when the technology advances to the point of achieving a mature ovum from an oogonium.
We aim at safe fertility reconstruction in patients who had a hysterectomy due to uterine cancer by establishing a new uterus transplant based on an effort to integrate Super-Microsurgery, an advanced vascular anastomosis technique in the plastic surgery and reconstructive surgery field, and organ transplantation under immune tolerance, an advance in the transplantation surgery field. Considering studies of surrogate mothers and uterus transplants, cryopreservation of part of removed ovarian tissue (not used for pathological diagnosis) in patients with female genital cancer can be very important. We present the following report on the development of uterus transplant experiment model of pigs.

View full abstract