Ovarian tissue cryopreservation is cryopreservation

Cryopreservation

Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as 77 K or −196 °C . At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped...

 of tissue of the ovary

Ovary

The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...

 of a female.

Indications

Cryopreservation of ovarian tissue is of interest to women who want fertility preservation

Fertility preservation

Fertility preservation is the effort to help cancer patients retain their fertility, or ability to procreate. Research into how cancer affects reproductive health and preservation options are growing, sparked in part by the increase in the survival rate of cancer patients.-Indications:Fertility...

 beyond the natural limit, or whose reproductive potential is threatened by cancer therapy, for example in hematologic malignancies or breast cancer. It can be performed on prepubertal girls at risk for premature ovarian failure

Premature ovarian failure

Premature Ovarian Failure , also known as premature ovarian insufficiency, primary ovarian insufficiency , premature menopause, hypergonadotropic hypogonadism, is the loss of function of the ovaries before age 40...

, and this procedure is as feasible and safe as comparable operative procedures in children.

Procedure

The procedure is to take a part of the ovary and carry out slow freezing before storing it in liquid nitrogen whilst therapy is undertaken. Tissue can then be thawed and implanted near the fallopian, either orthotopic (on the natural location) or heterotopic (on the abdominal wall), where it starts to produce new eggs, allowing normal conception to take place. A study of 60 procedures concluded that ovarian tissue harvesting appears to be safe. The ovarian tissue may also be transplanted into mice that are immunocompromised (SCID mice) to avoid graft rejection, and tissue can be harvested later when mature follicles have developed.

Strips of cortical ovarian tissue can also be cryopreserved, but it must be re-implanted into the body to allow the encapsulated immature follicles to complete their maturation. Furthermore, ovarian tissue is fragile under hard freezing conditions and putting it back into the body carries the risk of re-introducing cancerous cells.

History

First ovarian transplant with cryopreserved ovarian tissue was performed by Dr Kutluk Oktay in 1999. In Sep 2004 Prof Donnez of Louvain in Belgium reported the first successful ovarian birth from slow, or controlled rate, frozen ovarian tissue. In 1997 samples of ovarian cortex were taken from a woman with Hodgkin’s lymphoma and cryo-preserved in a rate freezer (Planer, UK)and stored in liquid Nitrogen. Chemotherapy was initiated and after the patient had premature ovarian failure. In 2003, after freeze-thawing, orthotopic autotransplantation of ovarian cortical tissue was done by laparoscopy and five months after reimplantation signs indicated recovery of regular ovulatory cycles. Eleven months after re-implantation a viable intrauterine pregnancy was confirmed, which resulted in a live birth – Tamara.