This type of tissue transplant has been around for a long time, but was thought to be impractical for ovarian tissue until better survival rates for young cancer patients generated new interest, said Dr. John Schnorr, lead author of a study presented here at the annual meeting of the American Society for Reproductive Medicine.
His team at Eastern Virginia Medical School in Norfolk, Virginia, restored ovarian function, menstrual cycles and egg production in monkeys whose ovaries had been surgically removed.
The investigators divided 16 monkeys into three groups--the first group had ovarian tissue transplanted into the arms, the second had ovarian tissue placed in the arm and a growth factor was administered, the third set, the control group, had only fat tissue placed in the arm. This group's ovaries were frozen and the tissue was transplanted back into the upper arm at the end of the study.
Five of the six monkeys in the first group had functioning ovarian transplants, meaning that stimulation of the transplants produced mature eggs that could be used to produce offspring.
Two of the five monkeys in the group treated with the growth factor had functioning transplants as did two of the monkeys receiving the frozen ovarian tissue.
The researchers said hormone levels were also measured and confirmed their results.
"This study demonstrates that the transplantation of both fresh and frozen ovarian tissue can restore ovarian function and produce mature eggs in primates," Schnorr said.
In a separate study, a team at Cornell University Weill Medical College successfully transplanted a 35-year-old cancer patient's ovarian tissue in her forearm, restoring egg development and hormone production.
The researchers said they were able to retrieve eggs from the woman's arm for in-vitro fertilization, although they have so far been unsuccessful in achieving fertilization.
Schnorr noted that the success of the transplants in primates with menstrual cycles offered promise for the development of procedures to remove and transplant a woman's own ovarian tissue if she is at risk of becoming sterile from chemotherapy, radiation therapy or other causes.
The technique could also be useful for women at high risk for ovarian cancer or who anticipate delaying childbearing, Schnorr said.
"We are still trying. It is very exciting to be able to utilize ovarian tissue in such a simple fashion," said Dr. Kutluk Oktay, author of the Cornell study.
Oktay said a second patient, with a benign ovarian cyst, has also undergone the graft procedur