Effect of different sites for cryopreserved ovarian tissue implantation in rabbit

Significance and Influence of Suturing for Ovarian Tissue Transplantation

The purpose of this animal study was to verify the effect of suturing on graft function in ovarian tissue transplantation. Ovaries from 2-week-old rats were transplanted orthotopically into the ovaries of 8-week-old female Wistar rats. The various transplantation methods used were insertion into the ovarian bursa without suturing (group A: control), suturing with a single 6-0 Vicryl stitch (group B: 6-0*1), suturing with a single 10-0 Vicryl stitch (group C: 10-0*1), and suturing with three 10-0 Vicryl stitches (group D: 10-0*3). Two weeks after transplantation, the transplanted ovaries were evaluated histologically and for gene expression. Engraftment rates of the donor ovaries 14 days after transplantation were 62.5%, 100%, 91.7%, and 100% in groups A, B, C, and D, respectively, significantly lower in group A than in the other groups. In terms of gene expression, TNFα levels were significantly higher in group D, and GDF9 and follicle-stimulating hormone receptor (FSHR) levels were significantly lower in group D than in groups A and B. The number of primordial follicles evaluated by HE staining was significantly lower in groups B, C, and D than in group A. Compared to orthotopic transplantation without sutures, direct suturing to the host improved the engraftment rate, although increasing the number of sutures increased inflammatory marker levels and decreased the number of primordial follicles. We believe that it is important to perform ovarian tissue transplantation using optimal suture diameter for good adhesion, but with a minimum number of sutures to preserve ovarian function.

Regenerative Medicine Approaches in Bioengineering Female Reproductive Tissues

Diseases, disorders, and dysfunctions of the female reproductive tract tissues can result in either infertility and/or hormonal imbalance. Current treatment options are limited and often do not result in tissue function restoration, requiring alternative therapeutic approaches. Regenerative medicine offers potential new therapies through the bioengineering of female reproductive tissues. This review focuses on some of the current technologies that could address the restoration of functional female reproductive tissues, including the use of stem cells, biomaterial scaffolds, bio-printing, and bio-fabrication of tissues or organoids. The use of these approaches could also be used to address issues in infertility. Strategies such as cell-based hormone replacement therapy could provide a more natural means of restoring normal ovarian physiology. Engineering of reproductive tissues and organs could serve as a powerful tool for correcting developmental anomalies. Organ-on-a-chip technologies could be used to perform drug screening for personalized medicine approaches and scientific investigations of the complex physiological interactions between the female reproductive tissues and other organ systems. While some of these technologies have already been developed, others have not been translated for clinical application. The continuous evolution of biomaterials and techniques, advances in bioprinting, along with emerging ideas for new approaches, shows a promising future for treating female reproductive tract-related disorders and dysfunctions.

Fertility preservation through gonadal cryopreservation

Fertility preservation is an area of immense interest in today's society. The most effective and established means of fertility preservation is cryopreservation of gametes (sperm and oocytes) and embryos. Gonadal cryopreservation is yet another means for fertility preservation, especially if the gonadal function is threatened by premature menopause, gonadotoxic cancer treatment, surgical castration, or diseases. It can also aid in the preservation of germplasm of animals that die before attaining sexual maturity. This is especially of significance for valuable, rare, and endangered animals whose population is affected by high neonatal/juvenile mortality because of diseases, poor management practices, or inbreeding depression. Establishing genome resource banks to conserve the genetic status of wild animals will provide a critical interface between ex-situ and in-situ conservation strategies. Cryopreservation of gonads effectively lengthens the genetic lifespan of individuals in a breeding program even after their death and contributes towards germplasm conservation of prized animals. Although the studies on domestic animals are quite promising, there are limitations for developing cryopreservation strategies in wild animals. In this review, we discuss different options for gonadal tissue cryopreservation with respect to humans and to laboratory, domestic, and wild animals. This review also covers recent developments in gonadal tissue cryopreservation and transplantation, providing a systematic view and the advances in the field with the possibility for its application in fertility preservation and for the conservation of germplasm in domestic and wild species.

Heterotopic ovarian transplantation results in less apoptosis than orthotopic transplantation in a minipig model

Background

Ovarian autotransplantation has shown increasing promise as a clinical method for the preservation of fertility and hormonal function. However, information regarding the success rate of this type of transplantation is limited. We hypothesized that results vary according to the site of the ovarian transplantation. To test this hypothesis, fresh or cryopreserved ovarian strips were autotransplanted to orthotopic or heterotopic sites. The strips were later collected, and the morphology and expression of selected markers of apoptosis were evaluated. We compared the Bax, Bcl-2 and cleaved caspase-3 staining levels and the morphometric aspects of autotransplanted fresh and cryopreserved ovarian strips placed at orthotopic and heterotopic sites in minipigs.

Methods

Forty female minipigs were allocated to the following five groups: group 1 (control), ovarian tissue removed during oophorectomy; group 2, transplantation of fresh ovarian strips to a heterotopic site; group 3, transplantation of fresh ovarian strips to an orthotopic site; group 4, transplantation of cryopreserved ovarian strips to a heterotopic site; and group 5, transplantation of ovarian trips to an orthotopic site. On day 7 after transplantation, ovarian strips were collected, and the morphology and expression of apoptosis markers were evaluated.

Results

In all groups, follicles across all stages of development were detected. The numbers of primordial, primary and secondary follicles were similar in all groups, but the numbers of antral follicles were lower in the cryopreserved groups in comparison with freshly derived ovarian tissue, with no significant differences observed between fresh and cryopreserved transplants. In all transplanted groups, Bcl-2 expression was lower and Bax expression was higher than in the control group. Furthermore, increased expression of apoptosis markers was detected in fresh intraperitoneal transplants. Lastly, the expression of cleaved caspase-3 was higher in the cryopreserved orthotopic group compared with the heterotopic group.

Conclusions

Orthotopic and heterotopic ovarian strip transplantations are feasible options using these techniques. Importantly, we found that heterotopic transplantation preserves ovarian follicle integrity to a greater degree (i.e., lower expression of apoptosis markers) than orthotopic transplantation, and cryopreservation does not exacerbate expression of apoptosis’s markers. These findings have major clinical applications and enhance the discussion regarding the heterotopic transplantation of ovarian tissue.

The root of reduced fertility in aged women and possible therapentic options: current status and future perspects

It is well known that maternal ageing not only causes increased spontaneous abortion and reduced fertility, but it is also a high genetic disease risk. Although assisted reproductive technologies (ARTs) have been widely used to treat infertility, the overall success is still low. The main reasons for age-related changes include reduced follicle number, compromised oocyte quality especially aneuploidy, altered reproductive endocrinology, and increased reproductive tract defect. Various approaches for improving or treating infertility in aged women including controlled ovarian hyperstimulation with intrauterine insemination (IUI), IVF/ICSI-ET, ovarian reserve testing, preimplantation genetic diagnosis and screening (PGD/PGS), oocyte selection and donation, oocyte and ovary tissue cryopreservation before ageing, miscarriage prevention, and caloric restriction are summarized in this review. Future potential reproductive techniques for infertile older women including oocyte and zygote micromanipulations, derivation of oocytes from germ stem cells, ES cells, and iPS cells, as well as through bone marrow transplantation are discussed.

Follicle development in cryopreserved bitch ovarian tissue grafted to immunodeficient mouse

The present study evaluated: (1) in vivo follicular development in canine ovarian tissue after slow freezing and xenotransplantation; and (2) the use of erythropoietin (EPO) as an angiogenic factor to optimise the transplantation procedure. Frozen-thawed ovarian tissue from five bitches was grafted into severe combined immunodeficient (SCID) mice (n=47) treated with or without EPO (500 IU kg(-1), once daily for 3 days) (Groups A and B, respectively) and analysed after 0, 1, 8 or 16 weeks. Follicle grade, follicle density, follicle morphology and stromal cells density were assessed by histological analysis, whereas vascularisation of the graft was quantified by immunohistochemistry with anti-α-smooth muscle actin antibody. Despite a massive loss of follicles after grafting, secondary follicle density was higher at 8 and 16 weeks than at 1 week regardless of EPO treatment. EPO significantly improved early follicle morphology and stromal cell density after 8 weeks and blood vessel density at 16 weeks after transplantation (P<0.05). Intact secondary follicles with more than three granulosa cells layers were observed 16 weeks after transplantation. The results suggest that canine ovarian tissue can be successfully preserved by our slow-freezing protocol because the tissue showed follicular growth after xenotransplantation. EPO treatment did not lessen the massive loss of follicles after transplantation.

Xenotransplantation of human ovarian tissue to nude mice: comparison between four grafting sites

BACKGROUND

This study was designed to assess the impact of different ovarian tissue transplantation sites on the follicular pool and ovarian tissue integrity after short-term grafting, since there is no consensus in the literature as to the optimal grafting site in experimental models.

METHODS

Frozen-thawed ovarian tissue from eight patients was grafted for 1 or 3 weeks to the peritoneum, inside the ovarian bursa, under the skin and into the muscle of 16 nude mice. Assessment of follicular density and follicle classification was carried out by histological analysis. Proliferative activity was evidenced by immunostaining with anti-Ki-67 antibodies, and fibrotic areas were analyzed by morphometry on histological slides.

RESULTS

One week post-transplantation, the proportion of Ki-67-positive primordial follicles was higher (20-42%) than in controls (1.7%), demonstrating follicular activation in all four sites. Despite this activation, primordial follicles were still found 3 weeks post-grafting, (34.1-66.9% of the follicle population), most of them quiescent, as indicated by the absence of Ki-67 immunostaining. Cryopreservation and grafting resulted in extensive fibrosis in the stroma. This fibrosis was significantly less pronounced in intramuscular (IM) grafts, representing 18.8% of the surface versus 44.7-60.5% for other sites, after 3 weeks of grafting.

CONCLUSIONS

All four grafting sites equally supported early follicular growth and preserved some quiescent follicles after short-term frozen-thawed human ovarian tissue transplantation. The extensive fibrosis observed does not appear to have a major impact on early follicle development, but its long-term effects must be investigated. The graft environment may be implicated in the preservation of the stroma, as suggested by a lower degree of fibrosis in the IM site.

Cryopreserved ovarian tissues can maintain a long-term function after heterotopic autotransplantation in rat

The functional longevity of cryopreserved ovarian grafts is one of the most challenging questions regarding ovarian transplantation at present. This study used a rat ovarian grafting model to investigate whether ovarian tissues from adult rats, which had been cryopreserved by vitrification and followed by heterotopic transplantation, could establish long-term hormone secretion and follicle development. Fresh and cryopreserved ovarian tissues were autologously transplanted under the kidney capsule. One-third of the animals in each group (sham-operated, fresh autografts, cryopreserved autografts, or castrated) were killed 5, 8, or 10 months after transplantation. Vaginal cytology, serum estradiol (E2), progesterone, and the morphology of the reproductive tract were used to assess ovarian function. Both fresh and cryopreserved ovarian grafts survived well in all the animal models with comparable proportion of follicles at each stage of folliculogenesis at all three time points. The serum E2 and progesterone concentrations in the groups with fresh or cryopreserved grafts remained comparable with those in sham-operated controls at all investigated time points. However, a loss of grafts and primordial follicles following heterotopic transplantation was noted. In conclusion, the heterotopic autotransplantation of vitrified ovarian tissues from adult rat without vascular anastomosis can maintain long-term ovarian function and exert endocrine function in target organs, in spite of the reduction in follicle pool.

Orthotopic and heterotopic ovarian tissue transplantation

BACKGROUND

Transplantation of ovarian tissue is, at present, the only clinical option available to restore fertility using cryopreserved ovarian tissue. More than 30 transplantations of cryopreserved tissue have been reported, and six babies have been born, worldwide, following this procedure. Despite these encouraging results, it is essential to optimize the procedure by improving the follicular survival, confirming safety and developing alternatives. Here, we review the different factors affecting follicular survival and growth after grafting.

METHODS

Relevant studies were identified by searching Pubmed up to January 2009 with English language limitation. The following key words were used: (ovarian tissue or whole ovary) AND (transplantation) AND (cryopreservation or pregnancy). Using the literature and personal experience, we examined relevant data on the different exogenous and clinical factors affecting follicular development after grafting.

RESULTS

Clinical factors such as the patient's age and the transplantation sites influenced the lifespan of the graft. A heterotopic transplantation site is not optimal but offers some advantages and it may also promote the hormonal environment after a combined heterotopic and orthotopic transplantation. Exogenous factors such as antioxidants, growth factors or hormones were tested to improve follicular survival; however, their efficiency regarding further follicular development and fertility potential remains to be established.

CONCLUSION

Additional evidence is required to define optimal conditions for ovarian tissue transplantation. Alternatives such as whole ovary or isolated follicles transplantations require further investigation but are likely to be successful in humans in the future.

Developmental competence and chromosomal aneuploidy of preimplantation embryos derived from rabbit oocytes grown in ovarian mesometrial grafts

The quality of oocytes derived from rabbit ovarian grafts after cryopreservation and mesometrial autotransplantation was assessed according to the capacity to develop into offspring and the incidence of chromosome abnormalities of blastocyst embryos after fertilization. Ovarian cryopreservation and mesometrial transplantation do not affect the chromosome complement of blastocysts derived from oocytes grown in ovarian grafts, and oocytes retrieved from mesometrial grafts produce live offspring after fertilization.

Normal developmental competence to the blastocyst stage is preserved in rabbit ovarian tissue following cryopreservation and autografting to the mesometrium

The aim of the present study was to evaluate mesometrial autotransplantation of frozen–thawed ovarian tissue in the adult rabbit and investigate the developmental competence of oocytes retrieved from grafts by in vitro maturation, fertilisation and blastocyst formation. Twenty-five rabbits were divided into control, fresh tissue transplantation and frozen–thawed tissue transplantation groups. Rabbits were stimulated with follicle-stimulating hormone (FSH) and oocytes were retrieved 3 months after transplantation. Oocytes matured in vivo or in vitro were then fertilised by conventional in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI), followed by observation and evaluation of fertilisation and blastocyst formation rates. No significant differences were found in the percentage of oocytes, maturation, fertilisation, cleavage and blastocyst formation among the three groups. Significantly higher fertilisation rates of in vitro-matured (IVM) oocytes were observed with ICSI compared with IVF in each group (81.1% v. 58.5%, 79.2% v. 59.6% and 80.4% v. 56.0% in the control, fresh tissue transplantation and frozen–thawed tissue transplantation groups, respectively). The blastocyst formation rate of IVM oocytes was significantly lower than that of in vivo-matured oocytes in each group (25.5% v. 65.7%, 22.4% v. 61.8% and 28.9% v. 63.0% in the control, fresh tissue transplantation and frozen–thawed tissue transplantation groups, respectively). In concusion, the mesometrium is a promising site for ovarian autografts in the rabbit. Oocytes retrieved from mesometrial grafts can develop to the blastocyst stage.