Ovarian tissue transplant may restore fertility
Even after highly concentrated cancer treatment of the ovaries, long-term ovarian function and fertility can be restored by repeated ovarian transplant with tissue taken from the patient before treatment, researchers in Korea and the US report in the current issue Fertility and Sterility.
In frozen ovarian tissue, a lack of oxygen after ovarian grafting causes a substantial loss of follicles, shortening the life span of the tissue, so repeated transplantation may be required, Dr. S. Samuel Kim at the University of Kansas, Kansas City, and his co-investigators note.
Until now, the authors note, no successful pregnancies after transplantation have been reported.
They report a clinical case series of four young women who had completed cancer chemotherapy and radiotherapy. Before treatment, the team collected a whole ovary from each patient, and after sectioning (up to 10 x 10 x 2 mm in size) and processing, and storing the tissue samples in liquid nitrogen.
For transplantation, 8 to 10 thawed sections were threaded onto suture material. Through a 1-2 cm skin incision in the abdomen, the tissue was transplanted.
After the first transplant, hormone levels and follicular development indicated that ovarian function returned between 12 and 20 weeks but lasted only 3 to 5 months.
A second attempt in three patients who remained in cancer remission produced a faster return of function (between 2 and 4 months), which lasted for 15 to 36 months. At times, patients’ symptoms and elevated progesterone levels indicated spontaneous ovulation.
Kim’s team reports that four of six oocytes retrieved from two patients were fertilized and cultured in vitro for 2 to 3 days, and cryopreserved. Plans are to thaw the embryos and transfer them to surrogates in the near future.
Still, they note, researchers have yet to determine the optimal conditions for transplantation of ovarian tissue, including the accessibility of the site, as well as environmental factors, such as temperature, space for follicular growth, peritoneal fluid and hormonal milieu.
SOURCE: Fertility and Sterility, June, 2009.
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