Scientist Stories: Mathew Blurton-Jones, Stem Cell Therapies for Alzheimer's Disease

Our next presenter, I've actually heard speak a number of times on the topic, but I'm going to refer to my notes because at my age, frankly, I forget things. Matthew, although that is not necessarily endemic to the aging process. Matthew Blerton-Jones has a PhD. He's the assistant professor in the Department of Neurobiology and Behavior. His lab uses stem cells to examine the underlying molecular mechanisms that drive the development of Alzheimer's and Parkinson's disease and develop novel therapeutic approaches to treat these disorders. His studies have shown that neural stem cells can improve cognitive and motor functions by elevating levels of critical neurotropic— excuse me, neurotropic factors and enhancing endogenous? Endogenous. Hey, I got a Master's of Public Administration. What do you want? Structural plasticity. And he holds the world record for underwater basket weaving. So without further ado, we invite Dr. Matthew Blerton-Jones, a really nice guy, up for his presentation. Thanks.

Thank you, Jim, for that very kind introduction. I didn't know you knew about the basket weaving. I kind of keep that on the lowdown, but I appreciate you acknowledging that. So it's a real pleasure to be here today to tell you guys about some more research we're doing with stem cells. And I should tell you, when the organizers of this first approached me, they said, you know, maybe you could give a talk about how stem cells are offering a new hope for treating Alzheimer's disease. And at first I thought, well, that sounds a little dramatic. But, well, I kind of do think that stem cells could offer a new hope. But probably more importantly, having grown up in the '70s, I thought at last I finally had an excuse to use my Star Wars-themed introductory title slide. So for those of you who don't remember, that first Star Wars movie was called A New Hope. So what I'm going to tell you about today is a number of things. I'm going to start by just trying to tell you a bit about stem cells. What are stem cells? There are actually many different types of stem cells. I'm trying to explain to you why I think certain stem cells might be more useful for Alzheimer's disease than others. I'm then going to tell you about some of our data that we've generated over the last few years, looking at neural stem cell transplantation in a transgenic model of Alzheimer's disease. And then I'm going to tell you about what we think are some of the key challenges that we're trying to tackle now to move these findings towards an eventual clinical application and testing. And then I'll end by telling you about some really ingenious new technology. I wish I invented it. I didn't. But, in fact, the guy who did just got the Nobel for it. But how a new type of stem cell called induced pluripotent stem cells may help us to understand or perhaps even treat Alzheimer's disease. So, what is a stem cell? Well, a stem cell can be very broadly defined as having two key characteristics. A stem cell is a cell that can replicate itself over and over, so make exact copies of itself over and over again. But a stem cell also has to be able to what we call differentiate, which means it matures, it can change into other more specialized cell types.. So a stem cell could give rise to a blood cell, stem cell could potentially give rise to skin cells or brain cells such as neurons. Another way to think about stem cells is that they're really the raw material from which a body is built. And we can even look back at the earliest stages of development and start to see stem cells. So soon after fertilization, around 5 days post-fertilization, The embryo forms something called a blastocyst, and within this blastocyst are a group of cells that we refer to as pluripotent stem cells. Now, what do we mean by pluripotent? Pluripotent means that these cells are capable of giving rise to any cell type in the body. They could make bone, they could make blood, they could make brain cells. There's also another type of stem cell, which are referred to as multipotent stem cells. They're also referred to as somatic stem cells.. And these cells have become a little more specialized. They're only capable of giving rise to a smaller subset of cells. And it turns out these multipotent stem cells actually reside within all of us within different organs. So, for instance, in the brain, we all have what are referred to as neural stem cells. And these neural stem cells can only make copies of themselves or produce the 3 principal brain cells that reside in our brain. So probably you guys have all heard about stem cells in the news, and a lot of that news is focused on some very promising therapies. A lot of that news is also focused on the ethical and moral debate about the use of stem cells. I want to point out that the ethical moral debate really focuses on the use of these cells, these pluripotent stem cells, because they're derived from a very early stage embryo. These multipotent stem cells can be derived from a variety of sources, including organ donors. And so, that aside, there's another reason why we've chosen to focus on multipotent stem cells, which is we're studying Alzheimer's disease. We're studying a brain disease. It sort of makes our life easier if we work with cells that belong in the brain. So neural stem cells belong in the brain. We don't need to be putting blood cells in the brain. That wouldn't make a lot of sense. So, I just want to bring up one other point about stem cells, because you, again, have probably heard a lot about the hope of stem cells, as my title implied. Any of you think that stem cells have ever been used to treat someone with a disease? Hands up if you think they have. Any? Just 2, 3 hands, right? Well, that means most of you are wrong. For over 40 years, stem cells have been saving many, many lives. We just didn't know they were stem cells. So you guys have heard of bone marrow transplantation, right, for blood cancers? Well, the reason that works is within the bone marrow, are hemopoietic stem cells, and these are the stem cells that give rise to all of the blood lineages. Nowadays, they actually often don't take whole bone marrow, they actually isolate these stem cells and put those directly in, and that actually works better. So that's just an example that it's not all hype. There really is some real medical rationale for why stem cells could be incredibly powerful. So as I mentioned earlier, our focus is on these cells, neural stem cells. Because we're studying Alzheimer's disease. So one of the first questions when you think about stem cells is this idea that stem cells can make new neurons. We know that in Alzheimer's disease, you've lost a lot of neurons. Here's a healthy brain on the right. Here is a person who passed away from advanced Alzheimer's, and you can see this huge loss of neurons. One of the sort of simple ways to think about this is, well, maybe if we could replace these neurons, Maybe we could help improve this patient before they had died, or maybe we could reverse Alzheimer's disease. But when you really think a bit about it and you look at this amount of loss and how widespread this loss is, it really leads most researchers to conclude this, that it's really unlikely that this idea of replacing cells is going to be a good approach for Alzheimer's disease. Maybe that might be more useful for a disease like Parkinson's, where there's a more restricted population of cells that have degenerated.. But in Alzheimer's, that would be very difficult. The reason it would be so difficult is, for this kind of a paradigm to work, first you'd need to make the appropriate stem cells, and there'd need to be lots of different kinds, because there's lots of different neurons that are dying in Alzheimer's disease. You then would have to transplant them using this big stereotactic injection system, and you'd have to deliver them to all the different regions of the brain that are affected, which is virtually everywhere. You then need those cells to grow and produce what are called axons. These are these big processes that neurons grow and use to connect with each other. And then the cells have to form these connections, which we refer to as synapses. Really, these synapses are what forms the basis of our ability for our brain to think. It's the way our neurons communicate together. So you can see there's a lot of steps that will be involved to have a cell replacement strategy work. And it turns out that in the adult, and even the aged brain even more so, there's a lot of mechanisms that kind of prevent a lot of this. So, I think this approach of cell replacement therapy with stem cells for Alzheimer's would be extremely challenging. I think this is probably why this recent review showed this, which is, if you look down— up here at the top, this talks about the prevalence of these various diseases: Alzheimer's, Parkinson's, Huntington's. On the bottom is the number of articles that have looked at stem cells in relation to those diseases. So you can see that Alzheimer's disease is way behind the pack in terms of the number of studies. And I really think it comes down to this idea that if you think of stem cells in terms of cell replacement, it makes sense that stem cells are not going to be really helpful for Alzheimer's disease. Okay, so why am I up here talking to you about stem cells for Alzheimer's? I just told you all the reasons we shouldn't use them, right? Well, as a scientist, I often have to go back to the literature, to the other papers that are published, and even other fields, and try and understand clues as to what might be a good approach to pursue. And there was actually a lot of work on stem cells in terms of Parkinson's disease. But those studies that looked at those, at the use of stem cells for Parkinson's, that really looked at the mechanisms behind what they were seeing, found that the cells weren't working by replacing neurons. They were working by some sort of more indirect effects. They seemed to be helping promote the health of the brain, promote the survival and the connectivity of the cells that are already in the brain. And that's something that we thought, well, maybe stem cells could be beneficial in terms of Alzheimer's disease. If we can use stem cells to keep the cells alive, keep them functioning, maybe get them to connect a bit better. And so that was our rationale for actually going forward with this crazy experiment. So, the— what I'm going to tell you about now is a set of data we've developed over the last couple years asking this question: whether these neural stem cells, if you transplant them into a brain of an animal that models Alzheimer's disease, does that either affect the pathology or does it affect the cognitive phenotype, the impairments that you see in these mice? So, we started our studies with mouse neural stem cells. We actually harvested these mouse neural stem cells from this green mouse. Scientists have a clever trick of making these green mice by taking a jellyfish protein, putting it into the mouse, and now all the cells in that mouse fluoresce green. So why, why would we do that, other than that they're pretty to look at? Well, if we start with cells that are green, after we put them into another mouse that's not green, we can find those cells and see what they're doing and what they're becoming.. And as I mentioned before, these neural stem cells can become 3 main cell types. Neurons, which we think of as the main brain cell that do a lot of the work. But then these 2 other cell types are probably equally, if not more important, some would argue. Astrocytes are a really critical support cell. They provide nourishment to these neurons. They help take away bad things. These oligodendrocytes, they serve a very important function too. They essentially wrap around these axons that neurons make, they serve much the same function as insulation would on a wire, and they speed up the conduction that neurons communicate with. So all three of these cell types are important. All three of them can be generated from these neural stem cells. So you may also ask, well, why did we choose the green mice instead of these nice red ones? And there I'll have to return to my little Star Wars theme. It seems quite obvious. Having grown up in the '70s, that we would, of course, want to take the good side of the force. So, I just want to introduce you a little bit to Alzheimer's neuropathology. You've obviously heard this morning about quite a few aspects of pathology. I think everyone has heard much about amyloid plaques that we can image in various modalities, we think is driving a lot of the progression— initiation of the disease. There's neurofibrillary tangles, which are an accumulation of a different protein, a protein called tau, that actually occurs within the neurons. And that is certainly contributing to the progression of the disease as well. And the other thing I want to point out, though, that you maybe haven't heard as much about so far, is that there's a great deal of synaptic loss in Alzheimer's disease. So, what are synapses? I briefly mentioned earlier. Synapses is our name for these connections between brain cells. Up here in this picture, there's in green two brain cells grown in a little dish, and hopefully— it may be difficult to make out— you can make out some of these little red dots on these green cells. Each of those red dots represents a synapse. When you're growing these cells in culture, each cell will make maybe about 100 to 1,000 of these synapses. In the brain, you can actually get anywhere from 100 up to about 10,000 synapses. And so this is really what makes the complexity of our brain and the ability for these neurons to communicate and thought to occur. The reason I'm bringing this up is that there's some very good studies that have been replicated many times saying that synapse loss is the very best correlate to dementia and Alzheimer's disease. So when you quantify each of these pathologies and look at how badly demented a patient was, the synapse loss comes out on top as the best correlate. Okay, so I'm going to come back to that point in a little bit. So, you've also heard from Dr. Tanner's talk about these mice, the triple transgenic mice that were generated by Frank LaFerla. These are a model that's been very widely used around the world now. And the reason is that this model is really the only model that exhibits these two key pathologies of Alzheimer's, the plaques and tangles. And I should add, they also exhibit synapse loss with age. Our approach was to take some of these mice at a fairly old age. 18 months doesn't sound that old to humans, but for a mouse, that's pretty old. They only live for about 24 months or so. We decided to use old mice because at this stage they have a lot of pathology. You can— some of you guys may remember from some of the talks earlier that the amyloid seems to be accumulating for up to 17 years before anyone shows any symptoms. So, by the time a patient's diagnosed, they already have a lot of plaques and even a lot of tangles. And so, for us, it was very important to ask, could we have effects in the presence of this very established pathology? So, that's why we started with these old animals. We decided, and we thought a lot about this, how are we going to get the stem cells in the brain? And there were lots of discussions, but really the most straightforward for us for these studies was to go ahead and inject them straight into the brain. And that sounds like an invasive thing, and it certainly is, but you'll be surprised to hear that neurosurgeons will tell you that brain surgery in a human is actually safer than an appendectomy, and it's actually quite routinely done in patients with Parkinson's disease. So this is a plausible approach. We put these cells specifically in these regions here, which is an area called the hippocampus. Some of you may have heard the word hippocampus before, and it's because it's an area that's very affected in Alzheimer's disease, undergoes a lot of degeneration. And is known to be very important for learning and memory, one of the key symptoms that's affected in Alzheimer's disease. So, we thought, well, let's put the cells where we think we most need them. We waited about a month and then tested these mice in various cognitive tasks. So, how do we test cognition? Well, there's lots of different ways to test a mouse in terms of aspects of cognition. This is probably what is often referred to as the gold standard. It's called a Morris-Morton maze, named after a guy who invented it. So if you do something really clever, they'll name it after you. The idea is that you put a mouse in this pool of water, and under that water is a submerged platform, but that platform's hidden. The mouse swims around kind of aimlessly. It can swim pretty good, but it doesn't really want to be in there. It wants to go back home. So it swims around until it bumps into this platform, or maybe after about 60 seconds we show it where the platform is. And then after it gets on the platform, we take it off, dry it off all nice, and put it back in its cage with its friends. What happens is if you take a mouse and do this repeatedly day after day, they start to learn where that platform is, so that after about 5 days, they'll swim straight to the platform. We can measure the time it takes for them to reach that platform along with various other aspects, and it's a measurement of their memory for where that platform was., and they're using spatial cues in the room to navigate and find it. So it's really a measure of spatial memory. So this is one of the tasks that we can use to assess memory. And we knew that in this model, this triple transgenic model, they have some impairments in this task as they age. So the kind of data you get looks like this. In this case, these are not our Alzheimer's mice. These are what we would call control mice or wild-type mice. So here's a normal mouse, essentially. That on successive days is learning this task and spending less and less time to get to that platform. If we look at our Alzheimer's mice that receive a control injection, you can see they start to learn the task, but they kind of plateau out a little earlier. They're having difficulty on those last few days really achieving the task at the same level as the controls. But if we look at the same kind of mice, these Alzheimer's mice that have received the neural stem cells, we see a pretty amazing effect. Here in the green line, these are Alzheimer's mice that have now been transplanted with stem cells. And you can see that they are finding that platform at least as well as the normal mice. So somehow we've improved their ability to perform this task. We can do a second part to this task, which is a little bit mean. We take the platform away, put the mice back in there, and we ask a couple questions. First, we ask, how long does it take for the mouse to get where that platform used to be?. And that's measured here. And again, you can see that the control takes longer than the animals that receive the stem cells. The ones that receive the stem cells do at least as good as the control, the wild-type animals. We also asked this question: How many times did that mouse cross over where that platform was? Like, they really remember, hey, the platform's supposed to be here, where's it gone? And you can see that that's a measure of their memory for that location. And so what you would expect is a mouse that has good memory is going to cross that platform more often.. And that's what we see with the stem cells. The mice cross more often. We did a couple other tasks. I don't want to go through it now in the interest of time, because there's a lot of things I want to tell you about. But the important point is that all of these tasks showed essentially the same phenomena, that the stem cells were improving cognition in these transgenic models of Alzheimer's disease. Okay, so then comes the big question for us, which is, how do stem cells improve cognition? If we can understand the basis of this, Maybe we can find an even better approach that doesn't involve putting a needle in your head. So, remember we had our green mice, so that made it really easy for us to track these cells that the neural stem cells are becoming. And what we found right off the bat is that these stem cells will migrate in the brain. Here you can see there's kind of a pattern here. This is a part of the hippocampus called the dentate gyrus. And what's interesting is, remember how I said we have neural stem cells in our brain? Well, there's only two areas in our brain where they reside, and this is one of them. So there's something about that area these cells really love, and they actually migrated to them. Our injection site would be somewhere on the wall here, and they went and traveled right to where they most want to be. So that's an important finding. We also were interested, would they interact with the amyloid plaques? They didn't really like them. They didn't really hate them. They just preferred this area. So what else can we tell by looking at these brains? Well, we can see what are the cells becoming. Remember, they can become those 3 different cell types. What I'm showing you here are different markers for some of those cell types in red. So we can look at our green cells and see how many of them have these other red markers. An example here is a cell that has become what we call an astrocyte, one of these really critical support cells. Down here we have some cells that have become oligodendrocytes, those cells that wrap around and insulate the neurons. If we look for neurons, we also see them with various markers. But what really surprised us was only about 6% of the cells were becoming neurons. So, somehow we were having an improvement in cognition with very few of these cells becoming neurons. And that really supported the idea that these cells were having some sort of more indirect effect on memory. Okay, so we don't think the cells were improving behavior by making new neurons. What else might they be doing? In these mice models, we know that the cognitive impairments correlate with the pathology to some degree. And so we, of course, needed to see whether the stem cells might affect the pathology. We can look at that by a variety of measures, including sort of complex biochemistry. These are some antibodies from Charlie Glaab, our next speaker. You'll probably hear more about some of these kind of things. Here's some images of these plaques. Bottom line is, however we looked, we couldn't find a difference in the amyloid pathology. And that really was interesting for us, because it was the very first time in probably about 6 years of working with these mice that we saw that we could improve cognition without affecting this pathology. And I think the other thing that's interesting about it is that means this could be a therapy that could be useful in the presence of a lot of this pathology and may not rely on preventing the accumulation of this pathology. Pathology as many of the current therapies that are being tested do. So it's sort of a different approach that these cells might be having. We also looked at the other pathology, the tangle pathology, and again found that there were no differences in the levels of tangle pathology. So there's no effect on the key pathologies. Well, how are these cells helping then? They're not affecting pathology, they're not becoming neurons. Okay, I'm running out of ideas. Well, turn back to this one, which I introduced at the beginning, that synapse loss is the very best correlate to dementia and Alzheimer's disease. And I showed you this picture of these two cells. If you look at a brain section, hopefully you can make out that this image is made up of a lot of little red dots. And in fact, in the human brain, we have 1 quadrillion little red dots, 10 to the 15th. So we have huge numbers of these synapses. And there's various ways we can label them and quantify these, including this kind of approach.. So we next asked whether the stem cells might be affecting these synapses. As we know, this can correlate to cognition. And that's where we finally saw an interesting effect. So you can see here, this is an animal that received neural stem cells. This is an animal that received a control injection. And there's a very significant increase in the number of these little red dots, i.e., the number of these synapses. And we can measure that with a variety of other approaches, biochemical approaches that also confirm that Somehow the stem cells are increasing these synapses. Okay, well, that's good. That gives us some idea. Next question is, well, how are the stem cells increasing the synapses? And there we can turn back to some interesting discoveries that were made about 20 years or so ago regarding a group of proteins called neurotrophins. Sorry, it's not 20, it's more like 30 or 40 now. A group of proteins called neurotrophins.. And these proteins have been shown to enhance the outgrowth of neurons. So here, for example, are some neurons just treated with a control. And here's the same kind of neurons treated with this one neurotrophin called nerve growth factor. And you can see they're growing out, and they love it. So neurotrophins have been studied on Alzheimer's disease. And in fact, levels of neurotrophins decrease as Alzheimer's disease proceeds.. And there's a couple key neurotrophins that have been studied in Alzheimer's. One is this NGF, but another one is a protein called brain-derived neurotrophic factor. And that's because this protein, BDNF, is really important in learning and memory, which of course is affected in Alzheimer's. So we asked whether our cells might in some way be affecting these neurotrophins, because that could explain our effects on the growth and the synaptic plasticity. What we found was that our cells did indeed make very high levels of this BDNF protein. You can see here. We could find the green cells making this BDNF protein. And if we quantified this biochemically, we could see that the animals that received the stem cells had much higher levels of this BDNF protein. So now we were starting to build up a potential explanation that perhaps our stem cells we transplant in, they seem to increase BDNF. That leads to an increase in synapses, and that leads to improvement in cognition. So it all looked pretty promising, but I would say, if I'm going to criticize my own work, which we try to do, probably not as well as we should, but we try to, is all of this data I've shown you right now is correlation. We show that all of these things are occurring, but these arrows, we haven't proven any of that. We just know all of these are occurring at the same time. So how do we go about trying to prove that connection? Well, one way is to try and take the BDNF out of the equation. So we asked this question: Is neural stem cell-derived BDNF necessary for improved memory? And the way we can do that is we can take our cells and genetically modify them so that they make barely any BDNF. And then we can take a new set of animals and repeat the study. So that's what we did. And what you can hopefully see here— this is, again, this water maze data. The green here represents animals that received the normal neural stem cells that do express BDNF. The black line is our— sorry, the blue line is our control group that's got just a control injection of saline. And the black line now are animals that received these stem cells in which BDNF has been depleted. So you can see they're no longer performing as well. They're doing about the same as the control. So we've lost the benefit of the stem cells by taking away the BDNF that they make. We can also see— here's some more data from the other part of the— behavioral task. We can also see that when we look at the synapses, the animals that receive these BDNF-depleted cells have less synapses as well. So it all kind of fits in. So now we can kind of say, well, if we block this step here, we block these other steps. And I think what's important to take home from this is that by understanding and exploring the mechanisms behind what we saw, we may have perhaps identified a new— therapy. So maybe we can find ways to elevate BDNF in the brain that could be useful in Alzheimer's and perhaps develop ways that are less invasive than stem cells. So I think that's an important point that we as researchers try to do is understand what's going on so that we can think about all the options we have. So this came out recently as a review, and it always makes you feel good when you find that after your work other people are finding very similar results now. In several different Alzheimer's models, essentially finding the same kind of thing, that the stem cells seem to improve cognition, they don't seem to affect the pathology, and a couple of these other studies have shown similar effects on neurotrophins and synaptic density. Okay, so going forward, what are our key challenges? We're excited about this data. As the title said, we think it could be a new hope, but there's a lot of steps we have to it take to move this forward to testing in the clinic? So I'll just talk about a couple of what we think are the key ones. The first of which, of course, human neural stem cells. All the data I just showed you were with mouse neural stem cells. Now we don't want to put mouse neural stem cells in people because who knows, they might suddenly become— have a high affinity of cheese or start squeaking or something, but I just wouldn't want to go there. So we really need to find some human neural stem cells that are going to be able to show similar benefits. And yet we can't just go straight from human cells and put them in patients. We have to prove that they're going to work. We also need to do longer-term studies, and that's a key thing. Alzheimer's is a very protracted disease, and we need to see how long is this benefit going to last. I think that's important too. So how are we doing this? How are we moving this forward? Well, to work with the human cells is another hurdle, which means, which is sort of something the FDA says, which you have to have very very special cells. They have to be prepared by people running around in these little spacesuits with all sorts of special conditions, and everything that ever saw those cells has to be incredibly sterile and clean and tested for everything you can think of. That's what we refer to as GMP-grade. So we need to have a very specialized type of stem cell to even begin to think about putting them in people. But we're going to need to test them in our animal models, and that's what we call xenotransplantation. So we're taking a human cell and putting it into a mouse. And what probably many of you realize is that we have an immune system, as do mice. And one of the roles of the immune system is to get rid of foreign cells, like a human cell being put in a mouse. So that's an extra challenge. We, we actually got lucky in terms of the cells because we found a company that was starting to develop therapies using these kind of cells that the FDA was happy with. This company had actually already even done some early-stage trials for some rare childhood disorders and shown that these cells were safe when you inject them into the brain. So that was a real bonus and a way to sort of accelerate moving forward with this. So we contacted the company and teamed up with them to start working with their cells. So the next part was figuring out this: how do we get human cells into a mouse, which is very challenging to do. What you may remember is that there's a lot of things that are used to allow transplantation therapy. So if someone gets an organ donation, they have to be put on immune suppressants, which are a type of drug that suppresses the immune system and allows that transplant to survive. And so we can use some of those approaches to treat our mice and allow these cells to survive when we transplant them. So this is work that Rassane Ager, who's in the audience here, has really led the approach on of asking whether these human stem cells can improve memory when we immune suppress these animals. So the paradigm is exactly the same as I showed you before, except now we're giving these animals an immune suppressant to allow us to put the human cells in. To make a long story short, we see that, yes, the cells can improve performance in the same water maze. So here's our cells. They're taking less time to reach that platform and they're crossing it more often. So that looks really promising. Couple other tasks, I won't go into the details of these, but the basic gist is the higher the value, the better. And again, our green cells are helping, or in this case, these aren't green cells, human cells are helping improve performance in that task too. We can see that the cells are surviving nicely, so the immune suppression is working. So it looks very promising. We now need to go forwards with much longer-term studies. Now, what I didn't tell you is achieving this transplantation is still very difficult in humans— in mice. This is after about 1 month, but if you start to go 2, 3, 4 months, the mouse's immune system overcomes that suppression and still starts to kill off these cells. So it's very difficult, and it's because human cells into a mouse is a much different mismatch from a human cell into a human. Or a mouse cell into a mouse. So, how do we go about dealing with this? Well, we're developing an approach to try and tackle this, which is to take a specialized type of mouse that has an impaired immune system. So they lack some of the key immune cells that mediate that rejection. An important point is these immune cells are what are called adaptive immune cells. They're not very well implicated in Alzheimer's disease. You heard from Andrew Tanna that the immune system is certainly implicated in Alzheimer's disease. But it's a different part, a different arm of the immune system that's implicated. And I think that's an important point. But we can take these animals and cross them with an Alzheimer's model and, first off, confirm that, yes, we've lost these important cell types that normally mediate rejection when you transplant human cells. But more importantly for us, we've confirmed they still have lots of this pathology. They still have activation of this, what we call the innate immune system. The microglia, for instance, that Dr. Tennant talked about, and astrocytes, they're still very much responding to pathology. Pathology. So that important part is still modeled. And the hope is that with these cells now, we can transplant human cells and look much longer term. And I'll just show you one piece of preliminary data, which is we put some cells in these mice, waited 6 months, and the green here represents these cells, the red represents amyloid plaques. And these cells survive beautifully and migrate throughout the brain. There's a very interesting feature of these stem cells that they can migrate to areas of injury, so that's an added bonus of them. But we now have a model where we can look very long-term, up to a year, at the effects on cognition. So those studies we're pursuing right now. Okay, so to switch gears and come back to my Star Wars theme, so is there a dark side to stem cell therapies? I've told you all this great news that's really exciting, that puts a smile on my face. Is there a dark side? Well, sadly there is, and sadly it doesn't have such a funny-looking face. Often it has a very beautiful face associated with it. As is always the case, snake oil-like salesmen have cropped up using some of this early data, even showing some of our data, saying that, hey, this is proof that stem cells are going to be able to treat all these diseases, including Alzheimer's. I would be the first to say, no, we have no proof of that whatsoever yet. We are hopeful and we're working towards it, but Improving a mouse and improving a person are two very different things. But capitalism is capitalism, and these kind of things have cropped up all over the world. A lot of them fortunately aren't in the US because there's a lot of regulation, but just go down to Mexico, even up to Canada, Russia, Germany even. There are these kind of clinics, as they call themselves, that have cropped up promising a lot of things. So just to give you an example of the problems with this, this is an example of a boy who had a different disease, a rare neurodegenerative disease, and was offered stem cell therapy. They saw some of this website and they were convinced this might help them. He got tumors. Remember how I said these stem cells can divide? Well, if you don't control them the right way, they can keep dividing and keep dividing and keep dividing i.e., form a tumor. And that's exactly what happened to this poor boy. He got brain tumors from the treatment. The way they know that this is from the treatment is a pretty clever trick. They looked for the Y chromosome. The Y chromosome is only in— is going to only be in male cells. He's a male. And they found cells that didn't have Y chromosome, just had X chromosomes. And so they knew— within the tumor. So they knew that tumor was coming from those transplanted cells. But this is sort of a worst-case scenario if one gets these unregulated treatments. And it's really become such a problem, even clinicians here at UCI have emailed me or talked to me and said, "I just had a patient saying they want to go to China for this therapy. What do I tell them?" I often refer them to this website, which was started by the International Society, which really talks about what is possible, what has been proven, and what isn't, and how to avoid these kind of things. So just a word of caution there. I think there's a lot of hope with stem cell therapies, but we need to be cautious. All right. In the very last minute or so, I want to just mention one other way that I think stem cells might be very useful to treat Alzheimer's disease. And that's with the use of what are called induced pluripotent stem cells. So this is a method that was developed by this guy, Shinya Yamanaka. This paper just came out in 2007. And then just last year, he got the Nobel Prize, which is a very rapid move from the the paper to the Nobel Prize, and it really shows the excitement behind this technology. So what does it entail? Well, it entails taking a person's fibroblast or skin sample, and he figured out that if you add just 4 key genes into those skin samples, you can get a cell that, in essence, looks just like an embryonic stem cell. So it's pluripotent. It can give rise to any cell type in the body. So now you have an ability to take a patient cell and make a neural stem cell, make a neuron, make a heart cell, you name it. There's a couple big advantages to this. One is you could have personalized medicine where you're getting transplants of your own cells. The other is that we can take cells from patients and try and understand what's driving the disease. And that's one of the areas that we're researching at UCI. So the idea is we can take a fibroblast from an Alzheimer's patient, reprogram them into these iPS cells and then interrogate these cells about Alzheimer's disease. And an important point here is that Alzheimer's is very genetic. Even what we refer to as sporadic or late onset forms of Alzheimer's disease are about 80% genetic. The thing is, there are small little changes in genes working in concert to cause the disease. So the thought is that this genetic basis will lead to certain, what scientists call phenotypes, certain changes in the activity of of brain cells that might explain the onset of the disease. So we can understand a lot about Alzheimer's disease, not just relying on our mouse models, but now working with human patient cells to try and understand the disease, and perhaps even test drugs. One can envision screening drugs with these cells. It's kind of a cheap way to go as a first-line approach to see what drugs can affect these things. All right, I'm getting away. The very last slide here is just to show you that we're making some good progress with this. We are actually the one of about 30 Alzheimer's disease research centers, and we're the only one that has started producing these induced pluripotent stem cells from our patient samples with the idea of providing these to the larger research community. So, I think you guys all know the summary. Stem cells look good. There's some promise. A lot of work needs to be done. We need to be a little bit cautious in places, and this new approach really may offer a whole other paradigm shift. Good question. So let me, let me just show the last slide here, which is to acknowledge all the people who did all the hard work here. So a lot of this is in collaboration with Frank LaFerla. I mentioned Rasaan, who's done a lot of the human work, and Sam, who's worked with this new model, many other people, and of course all the financial support, including the Alzheimer's Association, that helped to fund this. So the first question was, how long will it take? And oh, I wish I had a crystal ball to tell you. We've been fortunate enough to get a grant. The goal of the grant, and we recently started this, it's a 4-year grant. The goal is to file what's called an IND, which is an investigational new drug. If one's able to get an IND, you can start a Phase 1 clinical trial. So if everything goes perfectly, in 5 years maybe we could start a trial, the first trial, and that's a very small-scale trial just looking for safety. But, you know, there's a real push because of, as we've heard, we desperately need new approaches and new therapies. There's a real push to try and move this forward. We've taken a couple leaps forwards by finding the right cells, getting some data, but we still have to be cautious and take our time. Fascinating. One of the mechanisms that has been proposed for the action of antidepressants, particularly SSRIs, is sort of a delayed increase in BDNF. Yes. Have you folks fooled around with that all in your mouse model? Yeah, good question. So we haven't personally, but there are some Several studies showing exactly that, that some of the antidepressants can elevate BDNF and improve cognitive function in Alzheimer's models. And likewise, exercise that you guys have probably heard many times, that's one of the best ways to increase BDNF in a very natural way. So, and there are trials, ongoing trials that Karl Kauffman's leading at UCLA Irvine to actually test exercise in patients and see if it can delay things. So that's a very good, very good point. Yes, other approaches that can enhance BDNF are certainly on the table and worth pursuing. Ah, good question. Can you repeat the question? Well, the best studies are in mice where they have a running wheel, but they're not forced to run. They can do it as much as they want. Turns out they do run quite a lot. In humans, we're just starting to. Yeah, exactly. In humans, we're just starting to ask those questions. So I'm not, I'm not sure if the trial is going to have sort of different levels, but I think obviously in a population of 70 or 80-year-olds, you don't want them, you know, bench pressing 300 pounds, but I'm sure some is better than none. Any others, or are we moving on? I think we're moving. Oh, one last one? Okay. Thank you. You're addressing memory in the hippocampus, and I'm curious if you look at other cognitive functions in other parts of the brain, because Alzheimer's disease is not limited to memory. Absolutely. That's an excellent question and really where we're going with some of our research. As I showed right at the beginning, Alzheimer's affects all these different regions, and it's not just memory that's affected. And there are tasks to test these other aspects. Some of our trials that we're doing right now in the mouse models, we're starting to affect what we call cortical-dependent tasks, so things affected by the cortex. At this point, we don't know. We do— we're encouraged by the fact that these cells migrate. So we start with them in the hippocampus, but they will spread out into these other regions. Given enough time. It may be that to have a really effective therapy, you might want to inject a few different places, but that's one of, one of the many questions we have to figure out. It's a good question. Thank you. Thank you. We'll likely take more questions at the panel a little bit later. Thank you.