Deborah Howell (Host): You know, as of late, there's been so many advancements in reproductive medicine, it can be hard to keep up. Today, Fertility Centers of Illinois Laboratory Director, Dr. Juergen Liebermann, dives into his groundbreaking research that could revolutionize the world of frozen embryo transfer, or FET, protocols. Dr. Liebermann will tell us about his latest study, Fast and Furious: Pregnancy Outcome with a Rapid Warming Protocol, where he and his team explore the efficacy of a novel, one-step rapid warming protocol for thawing embryos.

This is the Time to Talk Fertility Podcast. I'm your host, Deborah Howell. Dr. Liebermann, it's so nice to have you back with us again today.

Dr. Juergen Liebermann: Yeah, good morning, Deborah. I'm happy to be back.

Host: For those of us who hadn't heard it the first time, what inspired you to become an embryologist?

Dr. Juergen Liebermann: It's the science behind and always evolving development to improve embryo growth, the quality of the embryos, and also number of embryos we can make available for biopsy and cryopreservation to improve patient's care and outcome. As a fertility patient, you probably want to get to meet an embryologist these days. But I can assure you that the scientists working in an IVF lab are taking care of your gametes and embryos. We are a part of every patient's IVF journey, and we want to be releasing patients from our practice with success, that means getting pregnant.

Host: Sure. And what's a typical day like for you and your team?

Dr. Juergen Liebermann: So, on any day, the embryologists are reviewing paperwork, preparing and doing egg collection, preparing the sperm samples, inseminating the eggs that could be via conventional IVF or ICSI; checking for fertilization, for cell division and embryo growth and development; cryopreservating, that means freezing oocytes and embryos; thawing them; and then checking, scoring, and classifying, and creating embryos to choose the embryos for the transfer, or for biopsy, or finally freezing.

For example, we have 10 to 15 egg collections each day, there is a lot to keep track of. We need to prepare paperwork and dishes and tubes and labels for these 10 to 15 cases. Then, we do fertilization check on day one for another 12 cases. Day five for another number of patients. We need to check embryo if you get to a fresh transfer or if they get biopsied or simply frozen. On certain days, we biopsy and freeze about 70 or more embryos. When we have embryos, they need to be thawed for transfer, or we're thawing oocytes, inseminating them and culture them to embryos. Well, the lab is a busy place to be.

Host: I was going to say, what a busy day. And you not only lead a team of embryologists, but you also contribute ongoing research to the world of embryology. Can you give us an overview of your recent study, Fast and Furious: Pregnancy Outcome with a Rapid Warming Protocol?

Dr. Juergen Liebermann: Well, in May of 2022, I started again with research on the cryopreservation of oocytes and embryos. In the past, I published already two books with the help of many other contributors worldwide on freezing and warming of embryos. Freezing and warming protocols were well established over 15 years, not much have changed. So, they are time-consuming, they are labor-intensive. And for example, freezing embryos, it took us 10 minutes, but before we develop these protocols, it took like two and a half hours, and warming takes now about 11 minutes. So, freezing oocytes takes about 16 minutes, and warming another 11 minutes.

The reasons are that we require stepwise removal of the cryoprotectant and need to rehydrate the cells in a series of osmotic solutions to prevent osmotic shock, which can destroy the cells. This thinking has been a fundamental principle in cryobiology for decades. And the theory behind this approach is to gradually eliminate the cryoprotectant and rehydrate the embryos to minimize damage during the vitrification warming procedure. It is evident that a protocol with 90% or 100% survival using a single-step solution without stepwise procedure could be challenged for the central dogma of cryobiology. Encouraged by other groups and their already reported publications on rapid warming, we started on an intensive in-house trial on embryos as well as oocytes donated for research beginning in May of '22.

Target was to improve the hypothesis that warming of embryos can be done in one step. If that worked, we would be able to cut down the time for warming one embryo from 11 minutes to one minute. After four months of research, our data were so convincing that we implemented the new warming protocol in our clinical setting. That was September 21 in 2022. We warm embryos now in one minute instead of 11 minutes, and we freeze embryos in five minutes instead of nine minutes.

Parallel to the embryos, I started freezing and warming oocytes, with the purpose to cut down time of freezing as well, and for warming. In November '22, after 6 months of research, I developed a new protocol, which allows us to freeze oocytes in two minutes, whereas before it was 16 minutes, and to warm them in two minutes as well, before it was 11 minutes. Both findings on embryos as well as oocytes, I was able to publish in a top ranked peer-reviewed English journal specialized for our field.

The pregnancy outcomes so far are very consistent, over 70% for patients up to 40 and about 65% for older patients over 40. And when I summarize this step, the short warming protocol makes laboratory technique for warming blastocysts simpler. It reduces unnecessary time blastocysts are exposed to room temperature and, in turn, reduces stress to the blastocyst. There is less time for radical oxygen species creation. They can have a negative impact on embryo development.

Host: Well, this is great news at every step. Could you explain the difference between the one-step rehydration protocol and the standard multi-step rehydration protocol?

Dr. Juergen Liebermann: A one-step means we're using one solution only to rehydrate warm embryos for one minute at room temperature. The multi-step protocol usually require three steps to rehydrate embryos.

Host: And let's talk a little bit about survival rates, and discuss the survival rates observed between the one-step and the multi-step protocols.

Dr. Juergen Liebermann: The survival rates between both protocols are not significantly different.

Host: Fair enough. And what were the clinical pregnancy rates for both protocols? And why are these results significant?

Dr. Juergen Liebermann: So, clinical pregnancy is important to define what it means. It's observing via ultrasound and embryonic sac. So, clinical pregnancy rate between both protocols were also not significantly different.

Host: All right. Now, your findings indicated a higher ongoing pregnancy rate with the one-step protocol. Can you elaborate on this a little bit?

Dr. Juergen Liebermann: This is correct. An ongoing pregnancy is now defined as observing an embryonic sac plus fatal heartbeat. And the ongoing pregnancy were about 40% before the one-step warming. Now, we are 50% with an implantation of 60%, which was 40% before. The live birth rate, also called baby take home rate, went up from 30% to 51%.

Host: And there's more good news. The miscarriage rate was lower with one-step rehydration protocol. Can you discuss the potential reasons for this finding?

Dr. Juergen Liebermann: Yeah. As I already laid out in the previous question, the improvement with the protocol and the ongoing pregnancy is a result of lowering the miscarriage rate. We believe that the reduced time of warming at room temperature from 11 to 1 minute improves the quality of the warm embryos and increases their potential to implant and to stay in the uterus.

Host: We've been talking about a lot of numbers and findings, but what do these findings mean for clinical practice and patients at Fertility Centers of Illinois?

Dr. Juergen Liebermann: Our outcome using frozen-warmed embryos in the past was always top. But with this protocol, we were able to increase, even we changed  our results and more consistent and we can provide parenthood to patients faster.

Host: Love it. Now, did the outcomes differ for embryos that had undergone pre-implantation genetic testing, or PGT, compared to those that had not?

Dr. Juergen Liebermann: The outcome of embryos undergoing genetic testing, pre-implantation genetic testing, will always differ, better than using untested embryos, especially in women with advanced age, that would be 38 and up. The change in the protocol from three to one-step improved the outcome for both embryos, but the main impact comes from the genetic testing when you transfer a known duplicate embryos versus an unknown embryo.

Host: Got it. Now, were there any unexpected findings in your study?

Dr. Juergen Liebermann: Yes. That one step for warming is sufficient to successfully warm embryos without compromising their survival and chance to achieve pregnancies. This is shaking up one of the keystones of cryobiology. In addition, working also with eggs, I found that a short rehydration and dehydration, means shorter time for freezing as well as for warming, is beneficial for the egg survival, because they can retake their meiotic activity. There's potential to fertilize and to develop into good quality embryos. Time is essence, and less time outside their physiological temperature of 37 degrees Celsius is a key. In addition, also retaking up faster water, which in turn allows faster regaining of cell activities.

Host: Sure. Now, what are the potential implications of your findings for the future of assisted reproductive technologies?

Dr. Juergen Liebermann: So, reducing the time necessary to complete those freezing warming steps leads to better development and pregnancy rates, as well as cost savings. Short rehydration is easy to implement in your daily routine and standardize your blastocyst cryopreservation procedure, and its outcome even more successful. So, one-step warming protocol is superior to the multi-step protocol in terms of pregnancy outcome, supporting an optimized workflow by reducing the labor to about 95% as well as cost effective about 40% in any IVF laboratory.

Host: And how might the one-step rehydration protocol improve the workflow in clinical settings?

Dr. Juergen Liebermann: Before we had this one-step protocol and we always have like 10 to 15 transfers per day, we needed two embryologists to follow these cases, because it was 11 minutes per embryo to fall. Now, with the one-minute protocol, we are only in need of one embryologist. That means we can free up one embryologist for other tasks, which helps us to make our daily work more smoother and more efficient.

Host: Are there challenges, Dr. Liebermann, for implementing the one-step rehydration protocol in different clinics?

Dr. Juergen Liebermann: We did our homework for doing a trial using embryos patients donated to research and then there was no challenge for us, as it is not for many other clinics following already our protocol.

Host: Understood. Now, how do you see the one-step rehydration protocol evolving over the next few years?

Dr. Juergen Liebermann: It will simply replace a multi-step warming protocol and will be beneficial for every IV laboratory in terms of cost effectiveness and time saving.

Host: This is fascinating and such good news for patients. Is there anything you'd like to add to our conversation?

Dr. Juergen Liebermann: The interest in my studies is so intense that since the beginning of putting my results on LinkedIn, even before they were published, my posts usually reach 300 comments and 35,000 impressions and many reposts. I was invited since then holding lectures in Los Angeles, Orlando, Denver, Toronto, Spain, Italy, Las Vegas, San Diego, and Chicago.

My next lectures are planned for Amsterdam, Brazil, and Morocco. I gave webinars for clinics in Dubai, Japan and for the international IVF Initiative with 43 countries joining my presentation as well for EMR 4 for India, and the International Society for IVF. And today, I will have a scheduled webinar for embryologists in Argentina.

Host: Well, best of luck on your travels. This is such wonderful information, Dr. Liebermann. We thank you so much for being with us today to share your expertise and all your great success.

Dr. Juergen Liebermann: Thank you very much, Deborah, for having me.

Host: That was Dr. Juergen Liebermann, Director of Laboratories here at FCI. To schedule an appointment to talk to a fertility specialist, call 877-324-4483 or visit fcionline.com for more info. And if you enjoyed this podcast, you can find more like it in our podcast library, and make sure to give us a like and a follow if you do.

This has been the Time to Talk Fertility Podcast. I'm your host, Deborah Howell. Have yourself a terrific day.