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

Abstract

BackgroundOvarian 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.MethodsForty 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.ResultsIn 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.ConclusionsOrthotopic 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.

State of the Art in Fertility Preservation for Female Patients Prior to Oncologic Therapies

“…Improving techniques led to an estimated 35%-40% live birth [49], since the first alive human baby, obtained as a result of ovarian cortex auto-transplant, was reported in 2004, and there were more than 100 live births worldwide; however, global reach of the procedure remains low, limiting further progress [49]. There are growing numbers of studies trying to discern how the best results can be obtained, by ovarian strip vitrification, or slow freezing, whole ovary versus ovarian strip, or the best place to insert the implant as one study concluded that implant location could significantly affect the results [50]. One group [51] compared whole ovary vitrification vs. slow freezing and concluded that the efficacy of whole ovaries cryopreservation by vitrification was higher than those by conventional freezing and rapid freezing, and that conventional freezing of ovarian cortical strips was more effective than cryopreservation of whole ovaries, independent of the way of whole ovary cryopreservation.…”

A new possibility in fertility preservation: The artificial ovary

“…Nevertheless, heterotopic transplantation has benefits such as easier access, relatively simpler transplantation procedure, and cost‐effectiveness in cases of repeated transplantations (J. Donnez et al, ). Heterotopic grafts' long‐term restoration of endocrine function has been demonstrated, and a recent study reported that heterotopic grafts cause less apoptosis than orthotopic grafts (Damasio et al, ; S. S. Kim, ). More studies are needed to identify the appropriate transplantation sites; however, orthotopic transplantation is deemed to satisfy the ideal concept of the artificial ovary as it allows natural ovulation and pregnancy.…”

“…Donnez et al, 2013). Heterotopic grafts' long-term restoration of endocrine function has been demonstrated, and a recent study reported that heterotopic grafts cause less apoptosis than orthotopic grafts (Damasio et al, 2016;S. S. Kim, 2012).…”

Natural hormone replacement therapy with a functioning ovary after the menopause: dream or reality?

“…According to Kim (2012;2014), the heterotopic graft produced progesterone secretion. A recent paper (Damásio et al, 2016) reported that heterotopic transplantation was able to preserve ovarian follicle integrity in an animal model, but the manuscript failed to report endocrine secretion. In a study by Suzuki et al (2012), it was reported that heterotopic autografts can give rise to long-term ovarian function, with progesterone values over 10 mg/ml during the luteal phase.…”