Ovarian Tissue Transplant May Restore Fertility After Cancer Treatment
NEW YORK (Reuters Health) Jun 26 - Even after highly gonadotoxic cancer treatment, long-term ovarian function and fertility can be restored by repeated heterotopic ovarian tissue autotransplantation, researchers in Korea and the US report in the June issue of Fertility and Sterility.
In cryopreserved ovarian tissue, ischemia after orthotopic 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 heterotopic transplantation have been reported.
Their current report is a prospective clinical case series of four young women who had completed cancer chemotherapy /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, stored the cortical 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 placed into a space between the rectus sheath and the rectus muscle.
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.
Dr. 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 heterotopic transplantation of ovarian tissue, including vascularity and accessibility of the site, as well as environmental factors, including "temperature, pressure, space for follicular growth, peritoneal fluid, cytokines, angiogenic factors, and hormonal milieu."
Fertil Steril 2009;91:2349-2354.