Fertility preservation PDF Print E-mail

Cryopreservation of human sperm has been practiced for several decades.

Its medical indications are specific: self-preservation before sterilizing treatment (chemotherapy, radiotherapy,…) with the view to carrying out an A.R.T. procedure, in case of sperm deficit after a vasectomy surgery or some methods of male contraception.

he possibility of women having the same opportunity as men to preserve their fertility has been made possible through more recent techniques such as oocyte freezing through vitrification and ovarian tissue cryopreservation. Fertility preservation.

The concept of ovarian tissue cryopreservation:

Oncology diagnosis and therapy has become more effective, increasing the survival rate of patients after treatment. Nevertheless cancer treatment involves aggressive therapies causing long-term physical and physiologic side-effects. Paediatric oncological treatment with chemotherapeutic agents is likely to result in gonadal toxicity. Both the testis and the ovaries are vulnerable to radiation damage. While in male children these gonadotoxic therapies can lead to subfertility, these treatments can provoke permanent damage in female children inciting an irreversible gonadal failure leading to a future infertility. Similar concerns are raised for adult women that are submitted to radiotherapy and/or chemotherapy. Those women are likely to suffer consequences from such treatments which can lead to premature menopause and threatened fertility. 

Ovarian tissue cryopreservation has the potential to be an important adjunct to oncological treatments for female children and for women in their reproductive phase of life. Cancer survivors that undergo ovarian tissue retrieval prior their oncological therapy have the possibility to autograph this tissue later on to recuperate impaired hormonal responses and restore their fertility.

A part from being a consequence of the oncological treatment, premature ovarian failure may occur also in women with genetic diseases, in recurrent ovarian diseases or after bilateral oophorectomy. The cryopreservation of ovarian tissue could serve its purpose to restore female fertility in these patients.

Patient selection:

Patients requiring cryopreservation of ovarian tissue should be selected on the basis of a multidisciplinary staff discussion (oncologists, gynecologists, reproductive biologists, pediatrician and radiotherapist) after informed counseling and consent from the patient.

The indications to proceed with ovarian tissue retrieval and cryopreservation includes hemato-oncological indications; solid tumors in pelvic region; extra-pelvic region disease; bilateral oophorectomy; Turner syndrome mosaicism; and benign condition requiring alkylating agents.

Methodologies used and follow up of ovarian grafts:

Ovaries or ovarian cortical tissue is in most cases removed by laparoscopy. Prior to cryopreservation an evaluation of the follicular pool density is imperative for decision making in later transplantation. Most of the methodologies involves cryopreservation of the cortical layers of the ovary.

This picture shows a whole ovary being prepared for cryopreservation: the ovarian cortex is removed from the ovary and divided into small pieces that are frozen following a well stablished procedure.

The ovary can be divided into two parts: the ovarian cortex where the follicle develops and the medula. This section of the ovarian stromal layer contains the primordial follicles, the follicular reserve of a woman. For cryopreservation we will dissect the cortex to obtain the section of the layer that contains the primary and primordial follicles.

Ethical considerations:

Technically, ovarian tissue cryopreservation is a very promising technique to preserve fertility for several indications. However, ovarian freezing and autotransplantation should be considered experimental procedures because of the uncertain risks associated with these technologies. Data concerning the maximum lifespan of frozen ovarian cortical grafts is limited. More and more centers worldwide offer ovarian tissue preservation technology, and some have already succeed in restoring ovulatory cycles in patients following autographs and several pregnancies have been obtained.

Although experimental, the results obtained on humans and animals are reassuring, and no abnormalities of the offspring born after ovarian tissue transplantation have been observed so far.