Breakthrough in Egg Freezing
Ten years after achieving the first human births in the Western Hemisphere conceived using previously frozen eggs (cryopreserved oocytes), Reproductive Biology Associates (RBA), is seeing unprecedented success rates in a clinical study. Since 1997, when RBA announced their initial results, egg freezing has continued to be classified as 'experimental' due to low birth rates. To date there have been only 200 births worldwide using the various egg freezing methods.
Now, in a clinical study of the efficiency of egg donation using egg cryo-banking, Dr. Peter Nagy, Scientific Director at RBA, and his team have modified the egg freezing technique, significantly improving success rates.
As a result of the RBA study Dr. Nagy and his team is reporting that laboratory and clinical outcomes using fresh or frozen eggs for egg donor IVF treatment are similar. Out of the 20 patients involved in the study, 17 have achieved clinical pregnancy as confirmed by ultrasound. To date, twenty-eight babies have been born. Prior to this success, egg donation programs have been strongly limited in their efficiency by factors including availability of qualifying donors, expense, delay in synchronization, FDA regulations and ethical concerns regarding embryo disposition.
Dr. Nagy explains that this new modification in egg freezing will significantly expand treatment options available to infertile couples. Recipients can benefit from the donors without the difficulty of synchronization and risk of contamination. Another advantage is that IVF patients who live in countries where embryo freezing is prohibited will now have a viable option to pursue.
"As this technology is further developed our hope in the future is that egg cryo-banking will provide an important benefit to women wishing to defer their reproductive choices until they are older, thus avoiding the inevitable loss of viability of their eggs with aging. Also, some women, prior to certain forms of cancer therapy, may wish to preserve their own eggs before any damage arises from their treatment. In addition to women storing their own frozen eggs, we at RBA have been studying the feasibility of cryostorage of donated eggs for use by recipients suffering from ovarian failure or dysfunction," said Dr. Nagy.
Consisting of more than 90% water, previous egg freezing techniques resulted in the formation of ice crystals, destroying cell membranes and contributing to the low success rates. In this study, the RBA scientists treated the eggs in a cryoprotectant solution formulated in the RBA laboratory prior to the vitrification process. Vitrification was the preferred method, and is a fast-freezing technique that cools the egg at a rate of 10,000° C/minute. In comparison, the slow-freezing technique previously used cooled the egg at a rate of 0.3° C/minute. The difference in freeze time was dramatic. This meticulous and precise handling throughout the egg freezing process by the RBA scientists significantly contributed to the results that were achieved.
Dr. Nagy concludes, "Two distinct advantages in establishing egg banks are reduced costs and increased flexibility. Egg cryo-banking will allow the flexibility of storing unfertilized eggs that can be thawed and fertilized as needed. Through our ongoing studies and continued success, our hope is that egg cryo-banking will soon be available to a broader range of patients and become another valuable tool in our Assisted Reproductive Technologies (ART) program. We're also encouraged in the fact that this technology will help preserve a woman's fertility potential, and dramatically reduce frozen embryo storage and mitigate related moral and ethical concerns."