Ovarian tissue transplantation:

Author: Prof Claus Yding Andersen

The European Tissue Directive, established several decades ago, outlines the accreditation conditions for the in vitro manipulation of cells. This regulatory framework was created in response to the contamination of blood products with HIV in the mid-1980s, which led to significant political and public health repercussions. Although the politicians involved obviously did not directly cause these issues, it became evident that robust regulations were necessary to prevent similar incidents in the future, resulting in the implementation of the EU Tissue Directive.

Ovarian tissue cryopreservation and transplantation are emerging methods that are gaining widespread acceptance for fertility preservation across various diagnoses and conditions. There is substantial evidence supporting the clinical effectiveness of transplanting frozen/thawed ovarian tissue, as women can regain folliculogenesis, resume menstrual cycles, achieve fertility, and most importantly, give birth to healthy children.

However, once the ovarian tissue is exhausted and no follicles remain, the transplanted tissue persists within the patient. Often, ovarian tissue is transplanted not only into the remaining in situ ovary but also into ectopic sites, such as a peritoneal pocket, which is not its natural location. Additionally, this tissue has been exposed to cryoprotectants and non-physiological in vitro conditions.

A critical question arises regarding long-term safety and quality assurance: ‘Does previously frozen and transplanted ovarian tissue carry an increased risk of malignant transformation over time?’

It is essential to clarify that any potential transformation is most likely not be linked to the original disease necessitating fertility preservation. Furthermore, there is no preliminary data, which suggests such a direct connection.

To date, more than 1,500 patients have undergone ovarian tissue transplantation, with many women having had their frozen/thawed tissue transplanted for over a decade. Gathering data on this long-term aspect of ovarian tissue transplantation would be reassuring for clinicians, researchers, legislators, and society at large.

In summary, while ovarian tissue cryopreservation and transplantation present promising opportunities for fertility preservation, ongoing evaluation of their long-term safety is crucial to ensure patient well-being and inform future clinical practices.

Key question:

Does previously frozen and transplanted ovarian tissue carry an increased risk of malignant transformation over time? 

 

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