Ovarian Tissue Transplantation: Experience From Germany and Worldwide Efficacy

Abstract

Extraction of ovarian tissue prior to oncologic therapy and subsequent transplantation is being performed increasingly often to preserve fertility in women. The procedure can be performed at any time of the cycle and, therefore, generally does not lead to any delay in oncological therapy. Success rates with transplantation of cryopreserved ovarian tissue have reached promising levels. More than 130 live births have been reported worldwide with the aid of cryopreserved ovarian tissue and the estimated birth rate is currently approximately 30%. In Germany, Austria, and Switzerland, the FertiPROTEKT consortium has successfully achieved 21 pregnancies and 17 deliveries generated after 95 ovarian tissue transplantations by 2015, one of the largest case series worldwide confirming that ovarian tissue cryopreservation and transplantation are successful. Approximately, more than 400 ovarian tissue cryopreservation procedures are performed each year in the FertiPROTEKT consortium, and the request and operations for ovarian tissue transplantation have increased in recent years. Therefore, recommendations for managing transplantation of ovarian tissue to German-speaking reproductive medicine centers were developed. In this overview, these recommendations and our experience in ovarian tissue transplantation are presented and discussed with international procedures.

Modulating hypoxia and oxidative stress in human xenografts using adipose tissue-derived stem cells

“…In the transplanted ovarian tissues, major follicle loss occurs during the hypoxic period, as proven by the widely documented decrease in follicle density (4-7) and large-scale primordial follicle activation caused by the triggering of signaling pathways involved in cell survival and proliferation (7,30,31). Despite the early follicle loss, grafted ovarian tissue results in endocrine resumption in around 90% of the cases (1,32) and fertility restoration, yielding live birth rates of up to 30%-41% (3,32) after OTT. A number of tissuespecific characteristics may explain the ovarian tissue resilience, namely, the ability to restore its function despite hypoxic or ischemic injury, including the capacity to physiologically boost the tissue vasculature both from existing vessels (33) and by vascular progenitor cells (34) that sustain follicle growth and corpus luteum formation; rapid growth of granulosa cells in the antral follicles in relatively hypoxic conditions, while ensuring an aerobic metabolism for oocytes (35); and quiescence of primordial follicles in a sparse vascular network with low metabolic demands (36,37).…”

Long-Term Advantages of Ovarian Reserve Maintenance and Follicle Development Using Adipose Tissue-Derived Stem Cells in Ovarian Tissue Transplantation

“…Endocrine resumption is observed in more than 90% of women 3–6 months after OTT, with some variation in the duration of endocrine activity and subsequent follicle growth, depending on the ovarian reserve [ 29 , 30 , 31 ]. In our group, the mean duration of transplanted tissue function is 5–6 years [ 4 , 29 ], contingent on a number of factors: (i) the age of patients at the time of tissue cryopreservation and their baseline ovarian reserve; (ii) the quality of freezing, thawing, and transplantation procedures; (iii) the amount of grafted tissue present; (iv) the degree of ischemia and hypoxia post-transplantation [ 4 , 32 ].…”

Is Ovarian Tissue Transplantation Safe in Patients with Central Nervous System Primitive Neuroectodermal Tumors?

“…The current study has a small sample size, so further well-designed and conducted research is needed to confirm the quality of our data. While there is currently no evidence to suggest that ovarian tissue transplantation causes reseeding of the primary cancer [ 14 , 44 ], the risk of ovarian metastasis cannot be completely ruled out for any type of tumor, because of the lack of highly specific detection methods at the time of grafting and the possibility of sampling error due to bias [ 45 ].…”