Today we talk about death, cellular death in early development. Don't worry, it's not as scary as it sounds. Or is it? I'm Doctor Mark Ammols and this is taco. About fertility Tuesday. There are several things in life. Life I don't understand. One, how can you put a perfectly normal EU ploy, genetically normal embryo, into a, uterus that has been tested and looked at and not get pregnant?
And two, how my wife can remember something from six months ago to be upset with me about, but forgot where she put her keys just five minutes ago. Both are mysteries to me, but we're going to tackle the first one today. In today's episode, I'm not going to explain every single reason why Nambryo doesn't work. That's podcasts I've done before, and there are podcasts I may do in the future. But today I want to focus on one specific
type of reason. There could be failure, or reasons that the ECG might be very low and drop down right away. And, that is death. Specifically speaking, cellular death. See, one thing that's very interesting is that there are embryos that we thought that were going to transfer, and they appear alive and they are. They are completely viable. But at the cellular level, things may not be what it appears that we are seeing with our own
eyes. And there are certain cells that are actually undergoing death even though everything looks normal. So what do I mean by this? Let's take me, for example. If I'm going to die in ten days and you freeze me for ten years, I'm still going to die once you thaw me. Ten days later, you just postponed my death by freezing me. But you haven't stopped the death process I was going to go through no matter what. Well, the same thing can happen to embryos. We don't know which embryos are going to keep
growing. And there are many embryos that are never planning on moving forward. But we don't know that. And we postpone that death by freezing them. And later we find out that there was something wrong with them. We actually see this all the time. There are, embryos on day three that look amazing. They're the literal Brad pit of embryos. They're just beautiful. And yet they never keep growing. They stop. That's because the cells have died and they're not going to grow
anymore. Now, we don't wait past day five at the blastocyst stage, so we don't know if those blastocysts will keep going on. So today I want to talk a little bit about the signs of that and explain why is it that we can't know this? Why is this always going to be a limitation, or at least for now, a limitation of our ability to know if it's going to work or not? Because one of the things that happens and when it doesn't work is we are striving for answers, trying to figure
out why this didn't work. Because they just put a living baby in me and I didn't come away pregnant. Now, when you look at a human like myself, or a dog or cat, whatever you want, you can tell it's alive by looking at certain parameters. So with a cat and dog, you can sit there and listen to its heart. See, that's breathing. Maybe it's panting. With a human, you can talk to them so you know they're not doing well. But even if you couldn't talk to them, you can look
at certain signs, you can check their temperature. So there's a lot of things that we're able to look at to be able to tell if death is coming. But that's different when it comes to cells. With a cell, there isn't really an obvious sign until after the fact. And this becomes very difficult, because if you can't tell, the cells are having problems. How would you know when you
put the embryo back? What if there was a way for us to know before we put the embryo back, that something was already wrong and not put that embryo back, or at least give the person the foreknowledge, then, no, it may not work. To be able to do this, we would have to have some type of signal, something that would let us know, because there is no heartbeat with that cellular organism. There is no discussion to have with it. We can't tell if it's not doing
well. We have to look at things like proteins and cascades that occur within the cytoplasm of those cells that tell us death is occurring. Now, when we're talking about cellular death, it's basically broken into two parts. One is called apoptosis, and the other one is called necrosis. Apoptosis is a programmed cell death, meaning the cell is itself triggering the death, whereas necrosis would be an unplanned death. It's going to be more like when you think of
something, a cell exploding. And that's exactly what we see. So most of the time when an embryo stalls on, let's say, day three and doesn't keep growing, it's apoptosis, a programmed cell death, where something, let's say with the DNA is bad and causes that embryo to not move forward. It's a very clean death, and there's actually very little inflammatory factors there versus
in necrosis cell death. It's unplanned, which can be due to, let's say, outside factors that then cause the cell to rupture and release all of its contents. Now, it's important to understand that apoptosis isn't just through genetic problems. There can be other things that could be wrong that can cause self destruction. Sometimes some of the cells in an embryo are undergoing apoptosis, but the other cells are not. And the purpose of apoptosis then is to not harm
the other cells. Once apoptosis has started, the cell starts to shrink, its DNA gets cut up. The cell eventually breaks down to small little packages that are quickly removed by the immune system without causing any type of inflammation. But the process is very energy dependent, meaning the cell requires energy to carry out its own death. We'll get back to this a little bit later because this is where mito
scores come into play. Necrosis, on the other hand, is more violent and uncontrolled form of cell death. It usually happens when a cell is injured or deprived of essential nutrients or oxygen. Usually the cells will swell and they burst, like I said, spelling their contents into the surrounding area. And this causes inflammation and can actually damage cells nearby. If you had to think of these two in kind of less like human terms, imagine a building that we wanted to take down.
Apoptosis would be taking each brick, brick by brick, taking the building down, very controlled, whereas necrosis would be like an uncontrolled explosion that made the whole building collapse. Now, when it comes to embryos not growing or stalling, most of the time that's going to be apoptosis. It's not the necrosis form of cell death. The necrosis form of cell death is usually going to happen due to extreme conditions, such as when the culture environment has ph
issues or toxic environment. Apoptosis, can also occur from those things, but it's definitely associated with DNA issues or an environment where it's not able to thrive. Now, it's important to understand, when an, embryo is uploid means genetically normal, that uploid means overall, from the big picture, the chromosomes are normal. That doesn't mean at
the low level that the DNA is normal. There are times that the embryo can be considered euploid, but still have small DNA issues inside it that could potentially cause things like apoptosis, or I can cause problems with energy production and that energy production can sometimes cause issues with a cell continuing to grow, leading then to apoptosis. What would be ideal is if there were markers that we could look at, such as biomarkers, to help us figure out which embryos are undergoing cellular
death. Now, at this time, there is no way to look at this in the form of being able to determine which embryo to transfer. This is because there's a short amount of time from the point when you thaw the embryo and then when you transfer it. A lot of this testing takes more time and is very difficult, to do because you would have to take the cells of the embryo and lyse them to find these different biomarkers. So what some people have looked at is what is called spent media. This is the
media the embryo is in. And it may be releasing certain proteins into that media that may show there are some issues, such as markers of apoptosis. One of those things can be cat spaces. Caspase three is one of the markers of apoptosis. So we were able to see that in the media. We would be able to know that something
is happening. Other things that we'd be able to look at are things like DNA fragments, nexin five, lactose dehydrogenase, reactive oxygen species, S 100 proteins, hiegshop proteins and even mitochondrial dysfunction markers. Next. And five is a molecule thats usually in the cellular membrane. And gets everted out whenever there are problems, such as apoptosis. That gives a signal for the embryo to
be cleared away. Whereas lactate dehydronase, reactive oxygen species and S 100 proteins and heat shock proteins are going to be indicators of stress. And the fact that the cell is undergoing apoptosis and necrosis. Now, although we don't currently check myochondrial dysfunction markers, there is a test called a mitoscore. The mitoscore is actually looking at the DNA in the mitochondria, which are
the powerhouse of the cells. If there is a higher amount of mitochondrial DNA, then it means there's more mitochondria there, which means the cell needed more energy. And so the times the cell would need more energy are either going to be in very fast development or when it's being stressed. What they do is they take that mitochondrial DNA and then they look at comparing it to the normal DNA within the nuclear DNA. And then they can come up with a score that
tells if it's higher than normal. Not every company has a midoscore, but if your company does, what's important to understand is, yes, it does tell us that there is more mitochondrial DNA inside the cell, but what we don't know yet is there is no absolute correlation between that. Admitting the embryo is not doing well. Now, if you have two embryos that are equal, so let's say embryo one and two, both are the same grade, everything looks the same,
and you have to then have a tiebreaker. That's where the minus score comes in. And so you'd want to use the one that has the lowest mile score that would never take over for choosing which embryo to put back. So what I mean by that, what I'm saying is that you would never pick an embryo just because of a minor score. You would only use a minor score to
help pick an embryo. But it is the last thing we look at, because there's just not good evidence yet to show that it's going to mean that the embryo will not work. It just means that it may have lower implantation potential because of the fact that it's requiring more energy, meaning it might be under more stress. Unfortunately, all of the factors I was talking about looking at, apoptosis and cellular death, cannot be seen. Unfortunately, we just
don't have the ability to do that this time. And so we're limited. And unfortunately, that limit limits us to knowing the next day, which is too late, or we're able to look at things like mitoscores, which are just not that good at, ah, correlating between which embryos will be the best and which ones will not. What this means is there are embryos that we are transferring into the body that never had a chance. And unfortunately,
there's no way for us to know this. This is why some people get zero implantation, no hcg, not because the embryo couldn't find a good place to park implant, but because the embryo wasn't even alive by the time it was ready to implant. If we were able to watch the embryo, maybe another day later, we would have seen it wouldn't grow. This is what we see
in culture environments. Many embryos that look like they're going amazing all of a sudden stall, and then after the fact, we can go, oh, I guess that embryo wasn't growing anymore. It was on its way to death. The reason why this is important is because cellular death is common and it's not preventable. And unfortunately, it can lead to a normal embryo to not implant. And the problem is, we
blame ourselves. We assume it has to be something wrong with us, that maybe someone did something wrong or that there's some other factor, and there can be. But it could also be something as simple as the embryo never kept growing. This is why if someone puts back a euploid embryo and it doesn't implant, I don't get scared yet. And most clinics don't. Most will actually say, wait till your second transfer with a euploid embryo before we start hitting the panic button
and start looking at some of those other causes. Not everyone has the fortunability to be able to have multiple transfers. They might only have one or two embryos. And in that situation, obviously you do
the testing you need before your transfer. But the important point of this podcast is I wanted you to know about at least this one specific type of cause that they may not be implanting, that in that situation the embryo may have never even been alive by the time it was ready to implant, and unfortunately, there is no way to know that before transferring the embryo. Maybe you're going through IVF and this was helpful. Maybe you have
a friend who's going through it. The important part is it's very difficult when you put back an embryo and it doesn't work, and it's so easy to go down rabbit holes. And so if you know someone or this is you, please let this episode give you at least some comfort in knowing that it isn't something you did wrong, it isn't something you missed, but that there is a natural cellular death that occurs, and that unfortunately, we have no way to know which embryos are undergoing it even prior to the
transfer. And that is very possible, although it seems very unlikely and it doesn't happen often, that the embryo that was put back, even though it looked beautiful, may have been on its way out due to cellular death. I hope this episode was helpful to you or someone you know. As always, if you like this podcast, please give us a five star review on your favorite medium. Tell your friends about us, and if you can even let me know, it only
encourages me to do it more. If you have topics you want me to go over, please send me a message either through Facebook, Instagram, or to tbftirectionfertility.com and let me know what you would like me to do. The most important part, though, is keep coming back, and I look forward to talking again next week on Taco Bell fertility Tuesday.