July 24, 2009

Preserving Fertility in Cancer Patients

The vast improvement in cancer treatment and increased survival rates have created a challenge for young cancer patients, since the chemotherapy and radiation treatments that save lives often threaten fertility. Techniques to safeguard fertility, such as freezing eggs for later embryo development, have low odds of success, leaving patients with limited reproductive options.

That is beginning to change, as researchers improve techniques, mature human eggs in the laboratory, and discover cellular mechanisms that could help preserve and even restore fertility. Summaries of the findings are as follows.

Growing egg cells in the lab:  Researchers at Northwestern University are developing a method they hope will be a new fertility option for young cancer patients who have undergone radiation and chemotherapy. During a 30-day experiment, a team led by Teresa K. Woodruff, Ph.D., grew human follicles -- tiny sacs that contain immature eggs -- until the eggs they contained were nearly mature. Dr. Woodruff is quoted as saying this is the first step in developing a fertility option for young cancer patients.

Freezing eggs for later fertilization:  Cryopreservation, the process of freezing eggs for later fertilization, has played a major role in assisted reproductive technology for the past two decades. Unfortunately, however, a mere half of the eggs survive the freezing and thawing processes required to develop a viable embryo, and of these, only 20 percent, once fertilized, result in the birth of a baby. David Albertini, Ph.D., University of Kansas Medical Center, is quoted as saying that clinicians may be waiting too long "“ three hours "“ after thawing eggs to initiate fertilization. His research team used confocal microscopy to discover that the structures needed to make the embryo's chromosomes align and divide were in place after only an hour, indicating a shorter thawing time could have greater potential for success.
Restoring fertility from the bottom up:  Researchers at Stanford University, led by Renee A. Reijo Pera, Ph.D., have identified several genes involved in the formation of germ cells that give rise to eggs and sperm. These genes, DAZ and DAZL, form the basis of human embryo and germ cell growth and may be key to understanding human reproductive failure. While continued progress in developing germ cells capable of making embryos renders fertility restoration feasible, it also raises significant ethical questions, Dr. Reijo Pera is quoted as saying.

SOURCE:  Researchers reported these and other findings at the annual meeting of the Society for the Study of Reproduction (SSR), July 18 to 22, Pittsburgh, PA