Dr. Kaylen Silverberg of the Texas Fertility Center in Austin Speaks to the Greater Los Angeles Reproductive Endocrine Society (GLARES)
Today’s embryologist has the unenviable task of selecting the best embryo to achieve pregnancy. Their job to choose which embryo has the best chance of growing into a baby is strictly based on morphology, what the embryologist can see through the microscope. This leaves the decision down to a kind of Petri dish beauty pageant. “When it comes right down to it, it’s like we only get to see the embryos in the “evening gown competition”. However, just as in the Miss America pageant, the one that looks the best in an evening gown may not end up becoming Miss America”, Dr Kaylen Silverberg said in addressing the Greater Los Angeles Reproductive Endocrine Society. “What we need is a more quantitative way to approach embryo selection.” Scientists today are beginning to develop more sophisticated ways to determine which embryos will win the contest based on a variety of measureable factors other than physical appearance.
The Greater Los Angeles Reproductive Endocrine Society (GLARES) gathered on June 10th at the beachside restaurant Shutters in Santa Monica to listen to Dr. Kaylen Silverberg of the Texas Fertility Center in Austin, Texas speak on advances in the field of Metabolomic, Proteomic and Genomic science. “There is a 65 to 70% chance that perfectly normal appearing embryos obtained from a 35 year old woman will have a chromosomal abnormality. By the age of 40 that number increases to over 90%. If we can find a non invasive way to help embryologists select the best embryos for transfer, we may be able to exponentially increase pregnancy rates while simultaneously controlling the risks of multiple birth and increased cost.”
Dr Silverberg, one of the country’s leading experts in the area of advanced reproductive technology and embryo selection explained the current research to a packed room of Southern California’s best IVF programs including Dr. Richard Paulson of the University of Southern California and Dr. Mark Surrey of the Southern California Reproductive Center. “It is our specialty’s challenge to limit the number of multiple pregnancies yet maintain high pregnancy rates. The only way to ensure both is to be able to better determine which embryos will result in healthy singleton births.” There is extreme pressure not only within the medical community but in the court of public opinion to limit the number of multiples born to couples undergoing fertility treatments. High order multiples, such as triplets or higher, result in increased medical risks to the mother as well as to the babies. Some studies have shown an increase in morbidity rates for the mother as high as 15% compared to only 5% for single births.1 In addition to the physical risks to the health of mother and baby, the cost to society of high order multiples is exponential with studies showing a 10 fold increase in medical costs from singleton birth to triplets or higher. 2
Fertility clinics nationwide are doing everything in their power to decrease the percentage of multiple births in their programs and the need to find better ways to grade embryos is pushing science in new directions other than the conventional method of morphology grading. “Visually grading embryos is not a very effective way of giving a couple the best possible chance for a successful cycle.” With a room full of nodding heads, Dr Silverberg went on to say “we have all been surprised by the “ugly embryo” that turns into the most beautiful of babies”.
Scientists and embryologists are now looking at choosing embryos based on “Omics”. Omics is the study of the more measurable qualities of an embryo’s development and health.
Genomics employs scientific methodology to determine which genes are expressed in an embryo and whether or not they are “normal”. Preimplantation Genetic Screening (PGS) is a type of Genomics that is used today in larger IVF centers. It is a very promising scientific advance, as it can effectively diagnose many chromosomal abnormalities before an embryo is transferred into a woman’s uterus. This benefit is somewhat offset by the fact that PGS requires the removal of one of the embryo’s cells during the growth process, potentially reducing the chance for pregnancy. Although PGS can very effectively determine the presence of a specific gene defect such as Down’s syndrome, it cannot speak to the complete health of the embryo, as the number of genes that can be screened in any one embryo is limited by current technology.
Proteomics is a method in which proteins produced by an embryo are analyzed at various stages of the embryo’s development. Embryologists have found differences in protein production between healthy and unhealthy embryos. A major advantage of the science of proteomics is that proteins can be retrieved from the liquid containing the growing embryos without having to risk damaging the embryo in the process.
Metabolomics studies the way embryos use the nutrients provided to them in the culture dish by the embryologist. It has been shown that healthy embryos use certain nutrients differently than their ill or failing counterparts. By evaluating levels of nutrients provided to the embryos as well as waste products generated by the embryos, embryologists may be able to determine which embryos will successfully produce a baby.
Although the fields of genomic, proteomic and metabolomic science are years away from utilization in IVF centers across the nation it is only a matter of time before science levels the playing field between the evening gown competition and the final question round.
1El-Toukhy T, et al. Am J Obstet Gynecol 2006;194:322
2Callahan et al. New Engl J Med 1994;331:244
ABOUT THE TEXAS FERTIITY CENTER
The Texas Fertility Center is one of the nation’s leading infertility practices, providing advanced reproductive endocrinology services for patients throughout Texas and the Southwestern United States for over 30 years. With over 60 years of combined medical experience TFC has been recognized nationally for unprecedented pregnancy rates, cutting edge laboratory procedures and innovative research programs. For more information please visit www.txfertility.com
Press release GLARES Santa Monica, CA June 2009AH