Today we talk about vitrification. I'm, Doctor Mark Ammels, and this is taco. About fertility Tuesday. In the world of science, there are some amazing things that have been discovered. Well, one of those amazing things that wasn't originally created for the fertility world is vitrification. Vitrification is the flash freezing of cells without forming crystallization, which occurs when water
freezes. What's important about this process is it allows us to do things such as freezing foods and still keep the taste and the texture normal and allows us to freeze cells without damage to them. The term vitrification itself comes from the latin word vitrum, meaning glass, and originally referred to the process of turning materials into a glass like state. The original reason for vitrification was to preserve tissues such
as cells. However, after fertility and research has taken over, it now allows us to do things such as freeze eggs, freeze embryos, and freeze stem cells. Now, to truly understand vitrification, you have to understand what came before it, and that was slow freezing. Slow freezing was where you very slowly would freeze tissues by making the temperature colder and colder very slow. And the purpose of that was to reduce the crystalline structure of water when it freezes.
See, water has these things called hydrogen bonds. And when it freezes, these hydrogen bonds cause the water molecules to range in a hexagonal crystal structure that takes up more space in the actual liquid form, which then causes it to become less dense, which is why ice floats on water. But more important, it expands. And so if you imagine when you put a soda in the freezer or some other drink cause you want to get cold fast, sometimes you forget about it. Sure. That's happened
to all of us. What happens? The container ruptures, just like foods. Foods. When the water molecules in the foods freezes too fast, what happens is it expands and kills the cells in the food. That crystalline structure is what is killing the cells. Now, with slow freezing, they're able to reduce it down. So the crystalline structure still formed, but it didn't form as well, and so allowed the structure to be less damaged. And so we were able to have fairly decent thaw
rates. But then came vitrification. And vitrification is a, flash freezing. You are taking the tissue and plunging it into liquid nitrogen, and it's freezing immediately. This prevents the water to create that hexagonal shape with a crystallization. And instead, the material becomes more amorphous, like glass. So it's not in this perfect arranged, but instead, it's in an amorphous phase. This then leads to less crystallization and less damage to the cells. So why do we say it's a glass state?
Well, because that's actually what happens with glass. Glass, when it becomes a solid, actually more like a liquid, because it doesn't make those structures in a uniform way versus, like, a diamond. But because glass is technically not a solid, over years and years and years, it will start to move, but it moves so slow, you don't see it. That's kind of what's going on with an embryo or eggs that are
frozen. I would make the argument that egg freezing probably benefited much more than even embryo freezing, because eggs have a huge water volume. So with slow freezing, they had a very poor thaw rate. Matter of fact, you didn't see things like egg banks in the past, but now you see them all the time. And that's because with vitrification, things got better. So, in summary, think of the vitrified state
as the molecules of the embryo. are not arranged in a regular repeating pattern like you would find in a crystal. Instead, they are disordered amorphous state, similar to how glass is structured. Imagine a piece of glass in your window. In this glass state, the molecular movement is extremely slow, almost like hitting the pause button on the cell's activity. And this is crucial because this is what prevents the formation of ice crystals, which can damage the
cells. And just like glass, the molecules in a vitrified embryo are locked in place. But if we looked over an incredibly long period of time, we see some minimal movement. This state keeps the embryo safe and viable for future use, making vitrification a, revolutionary advancement over the older, slow freezing methods we used to use. Let's just talk about the survival rates. So using slow freezing in the past, we would be happy if we saw survival rates of around 55% to
65%. The best clinics in the country were getting close to 90% survival rate, but even that wasn't very common, and that was only when they would freeze it as a PN, which is the very first cell structure after it fertilizes. And this is because of those crystal formations that occurred to versus. Vitrification has a much higher survival rate after the thaw, exceeding well above 90%. Most clinics can boast around a 98 99% chance of the embryo
surviving the thaw. Even at our clinic, we usually go six months between having an embryo and not survive the thaw. Once a while, we'll get two in a row, but then we don't see it again for many, many months, because it's just very unlikely. The embryo is not going to survive the thaw because
of crystal formation. Now, embryos could not survive the thaw for other reasons, such as mechanical failure in the straws or a nature of popping, where sometimes when they go the thaw, the embryo, it can pop. But the point is, it's still very, very rare. And this was a huge advancement because now we weren't scared to freeze them. See, prior to vitrification, everyone had the fresh transfer because everyone
was afraid to freeze them. You froze embryos, but the chances weren't that good in the past, but when vitrification occurred, now we could freeze embryos. And that made so many changes. For example, when people used to have ovarian hyperstimulation, you would have to do a freeze all. But you were always worried about it because
it wouldn't thaw as well. There was a higher rate of ovarian hyperstimulation syndrome because you had to either just cancel patients or you had to take the risk of them getting ovarian hyperstimulation. Now, with ventrification, we just freeze everything, and we reduce the risk of them developing ovarian hyperstimulation syndrome as well as secondary ovarian hyperstimulation. Once again, pregnant, the donor pool
exploded. In the past, if you wanted to use a donor egg, you basically had to have someone who would go through the ivf cycle for you, and then you would take those eggs and fertilize them with the sperm and then do a fresh transfer. That meant the donor had to be available whether they were in school or not, you had to be available. It was literally a nightmare. And that's how
all donors had to be done. But then once we were able to freeze eggs, then we realized we could put donors through and build up these large reservoirs of donor eggs, and then people could pick them, making it first much faster, because now you don't have to wait for someone to go through a process. But two have a broader span of, donors that you can look at that maybe have different cultural aspects or physical characteristics that you want, whereas before, you just found the
person who'd be willing to do it for you. But even beyond that, the implantation rates became much higher. With slow freezing, we were seeing implantation rates as low as 18%, but with vitrification, we were seeing 40% and above even. Pregnancy rates were only 23% with slow freezing, but with vitrification, we're seeing 50%. Now, some of that could be due to when the embryo was frozen versus, day three versus day five. But the point is, it really advanced our
field. It allowed transfers now to be done at the right time for the patient versus having to do fresh, because with a fresh transfer, the lining wasn't perfect. Too bad. You were still doing the transfer. But with vitrification, we can now freeze the embryo with no fear and then do the transfer and we can make sure the lining is perfect. I just had a recent patient who only had one embryo. That was their only chance, and I would see them
and their lining was good. It wasnt great, it was good. And id tell them, listen, we get one shot at this. I think we should cancel the cycle. Lets wait till next month. So we did, and eventually that lining looked perfect and we did the transfer. Im happy to say. I just spoke to them about a week or two ago, and they told me that they had their baby that wouldnt have been possible without
vitrification. When my wife and I went through, we had at best, a 30% to 40% chance putting back two embryos that were fresh. Today, a single vitrified embryo being thawed and transferred into your body has a higher rate than two embryos did when we did it. Another area is egg freezing. For lecta purposes, prior to vitrification, you could freeze your eggs, but the chances that you would actually thaw them and be
usable were almost zero. But now with, vitrification, we have people freezing their eggs when they're young or freezing their eggs maybe when they're dealing with cancer and able to postpone having a child later in life. It also allows people to synchronize cycles. So if a donor can only go through at one point, but the recipient can only go through another time, things can be frozen until
they're ready. Even beyond human fertility, it is loud, the animal world, to be able to have better breeding programs, because now they can preserve the genetic materials of some of the best animals. And as I mentioned in the beginning, even beyond the medical industry, it has allowed the food industry to improve quality of the food and extend its shelf life. Even some of the drugs and vaccines that are sensitive to temperature changes are preserved using vitrification techniques to
maintain their efficiency. Vitrification has truly transformed the fertility industry, bringing about remarkable improvements in access rate of ivf treatments. The benefits of vitrification extend beyond even fertility and has revolutionized the way we preserve materials. It truly is fascinating clinically, but also as a scientist, it's quite amazing. It's, in my mind, one of the greatest advancements in science. what's even crazier is that we haven't stopped
there. There are future techniques coming out using nanotechnology, magnetic freezing, and even high pressure freezing to get the same results. By reducing crystal formation with the nanoparticles, it would help enhance the cryoprotective properties of the freezing materials. So then that way, it will protect the cells from being damaged. With magnetic freezing, what they'll do is, using magnetics, they can adjust the mag fields of the water molecules to reduce the crystallized
formation. And with the hydrostatic pressure, they can build up the pressure that also prevent ice crystal formulation from happening. As you can see, no one's stopping at just vitrification. But we're always looking for better ways to be able to improve the freezing and thawing process. I know this wasn't a clinical episode today, but I do love the sciences of our field. And I thought many of you may wonder,
what is this whole vitrification thing? Because whenever most of us think of freezing, we think, oh, they just put them in their freezer and then they take them out later. But as you see, we don't do that. There's actually a very specific scientific method to be able to freeze these and be able to thaw them with high efficiency, as usual. If you like this episode, tell a friend about it. Maybe you have a kid who's in science and might find this interesting.
But if you like it, please give us a five star review on your favorite medium. And as always, I look forward to talking to you again next week on m talk about fertility Tuesday.