Scientist Stories: Mathew Blurton-Jones, Using Stem Cells to Understand and Treat Disease

I'd like to introduce the next speaker. Dr. Matthew Mark Burton-Jones received his PhD in Neurosciences from the University of California, San Diego in 2002. His research is currently focused on the application of stem cells to the underlying molecular mechanisms that mediate neurodegenerative disease and to identify novel therapeutic approaches to to treat these diseases. It's not simple for me, but I'm sure it is for him. Dr. Burton Jones currently conducts research at the Institute of Memory Impairments and Neurological Disorders, the MIND Institute, at the University of California, Irvine. I'd like to welcome Dr. Matthew Burton—

Mark Burton Jones. Thank you very much. I know my name's a real handful. So it's a real pleasure to be here today. Let me just get my slides going here. So I'm excited to be here today to tell you a little bit about some of the basic science research that we're doing, mainly here at UC Irvine, that I'm going to talk about today. My focus has predominantly been in regards to Alzheimer's disease, but I've also more recently been collaborating with other researchers here like Leslie Thompson on Huntington's disease. So I'm going to also towards the end talk a little bit about some of the data we've generated in that area. So just a brief introduction, you've heard quite a lot about Alzheimer's disease. It's an age-related progressive disorder and it gradually destroys a person's memory and ability to learn and reason and make judgments. By the time a patient passes away from Alzheimer's, there's actually, you can see on the right-hand side here, a huge amount of loss of brain tissue. We heard just a minute ago about a number of these staggering statistics about the impact of Alzheimer's disease worldwide. Right now there's over 35 million people suffering from dementia, and sadly that number is going to increase to about 115 million by 2050. Even just in California, we have 10% of our nation's Alzheimer's patients. And even just in Orange County, there's 60,000 patients with Alzheimer's right now. And that, again, that number is going to increase and double by 2030. We've known for quite a long time about the underlying pathology that occurs in Alzheimer's patients' brains, for over 100 years actually. This pathology has been described. Called amyloid plaques, which is shown here in this, in this figure. These are aggregates of a small protein we call beta amyloid or A-beta that accumulate in the brain and build up over many, many years. And they seem to be toxic, killing a lot of the brain cells and causing all sorts of other downstream damage. In addition to this pathology, another what's considered a hallmark pathology of Alzheimer's are called neurofibrillary tangles. And they occur within the neurons themselves and are an accumulation of a protein called tau that becomes very aggregated and insoluble and essentially just stops the neurons from functioning normally, eventually killing them. The last pathology I want to just briefly mention here is that in Alzheimer's disease there's also a very significant decrease in the connectivity between the neurons. In the brain. So our neurons, our brain cells, are what allows us to think, and they have thousands upon thousands of connections with each other. Example here is these are just, in green, two neurons in a little dish, and each of those red dots represents one of these synapses. So just these two neurons have hundreds of synapses, and in the brain it's estimated we have billions upon billions of synapses. What's important is that in Alzheimer's, the very best correlate to how demented a patient becomes is this loss of these connections. And I'm going to come back to that point in a few minutes. So how do we scientists study Alzheimer's disease? Well, I've worked for some time with a researcher here called Frank LaFerla who generated a mouse model. What he did was took a rather aggressive approach, taking 3 different human genes with mutations, putting them all together into one mouse, The end result, though, is that he made a model that really for the first time recapitulated these two hallmark pathologies. So on the left-hand side here, there's in green these amyloid plaques and in red the neurofibrillary tangles. What's also important is that these mice go on to develop a lot of the cognitive deficits one sees in Alzheimer's disease, and it occurs in an age-related way. So Frank and I were interested a couple years ago on wondering whether stem cells, and in particular neural stem cells, might be able to have some benefit in this animal model of Alzheimer's disease, either by perhaps modifying the pathology or the cognitive phenotype that we see. Neural stem cells, you've heard some introduction from Peter earlier on about stem cells in general. Neural stem cells are a type of stem cell that can be derived from a number of sources. They can come from embryonic stem cells, or they could also potentially be derived from tissue donors., and they can be expanded in culture. And what's special about neural stem cells is they can become the 3 principal cell types that occur in the brain: the neurons, and then these other 2 very important cell types called astrocytes and oligodendrocytes that help to support the neurons, also speed up the conductivity, the communication between neurons. So what Frank and I decided to do was to ask whether Neural stem cells might have some effect on these animal models, and we were very interested in testing this in old animals. So we worked with 18-month-old animals, and the main reason for this was that when a patient is first diagnosed with Alzheimer's, we know they already have a lot of pathology. They have a lot of these plaques and tangles. In fact, it looks like, based on some imaging studies recently, that these have been accumulating for some 20 years before the first symptoms show up. So it's really important for us to try and test therapies under this setting with established pathology. We injected these mice specifically in an area called the hippocampus, which is severely affected in Alzheimer's disease, and it's also considered one of the central areas involved in learning and memory, which of course suffers in Alzheimer's disease. And we decided to use cells that were labeled so that we could very easily track these cells and see what they were doing and what they were becoming. We used actually a jellyfish protein that labels the cells so that we can see them in green fluorescence. So I mentioned earlier that this model suffers from some deficits in memory that increase with age. And this is sort of the gold standard test that many scientists use to look at memory in a mouse model. It's called the Morris water maze. You take a mouse and train it to find a submerged hidden platform in a pool of water. They want to kind of get out of this water, it's a little bit cold. They use cues within the room to help navigate and find where that location is so that on subsequent days of testing they get better and better at finding that platform and can escape quicker. Now in the case of Alzheimer's mice, they show deficits in this. They take longer to find that platform and escape because they have problems finding their way around, their spatial memory is not working effectively. So this is the kind of data one gets when you do this experimentally. These are what we call wild-type mice, so these are normal unaffected mice. And you can see with successive days of training, the mice take less and less time to reach this area of this platform, which we call latency. So the time it takes for them to escape is decreased. In contrast, when we look at the transgenic models, they start to learn this task, but they have problems with it. They take significantly longer to find that platform. Illustrating their deficits in memory. When we looked at the animals that received neural stem cells though, we were really pretty impressed to find that these animals were able to find this platform as fast as the control wild-type animals. So somehow these stem cells were rescuing their ability to navigate in this maze and restoring their memory function. We did a number of other measures. It's always good to do 2, 3 different types of behavioral assays, and And just for the sake of time, I'll just briefly tell you that, that in each case, the stem cells always improved the mice almost to the levels of the wild-type animals. So we were seeing some really strong evidence that somehow by putting stem cells in their hippocampus, we were rescuing this behavioral impairment in this model. As scientists, we of course want to try and find out what's going on. I mean, it's— this is great and everything, but if we can pinpoint the mechanism behind this, it might help give rise to other approaches or other drugs. So we did a number of experiments to try and understand this. I mentioned that the cells were labeled with this jellyfish protein, so it made it real easy to look at them and see where they were. They seemed to migrate to certain regions in the brain. But we could also look at what the cells were becoming. Right away we noticed that the majority of these cells were starting to express markers of these glial cell types. So they were becoming astrocytes or oligodendrocytes. When we looked for the cells becoming neurons, we only saw about 5 or 6% of them showing markers of neurons. So based on that data, we thought, well, it's unlikely our cells are making a whole bunch of new neurons and reconnecting appropriately and rescuing the behavior that way. It must have something more to do with these glial cells. So we had to dig a little deeper. Now, we were very interested in determining whether cells might have any effect on the underlying pathology that we know drives this disease. Disease. And we looked by a number of measures and a lot of data in the next two slides. The bottom line is if you look at these bottom two panels in red, we saw no differences in these amyloid plaques in any measure that we looked at. Likewise, we saw no differences in this tau pathology. So this was actually really exciting for us because this was the first time we had seen an ability to improve the behavior in this mouse without affecting these two pathologies. But what's important to us, because I said earlier on, when a patient's first diagnosed, they have a lot of this pathology already. So it's going to be hard to prevent that. But we still didn't have an answer. We just know, okay, it's not amyloid and tau. Now I mentioned earlier on that the synapse loss, that this is a really important component in Alzheimer's disease and the best correlate to dementia. And I showed you this picture of the two cells in the dish. This is a picture from a brain section. And each of those little red dots there represents a synapse. In fact, it's 1 quadrillion, which until I looked this up I didn't know that number. There's 1 quadrillion little red dots in our brains, and that's the loss of these synapses really correlate to dementia. So we wondered if the cells might in any way be affecting these synapses. We did a number of different measures, I'll just show you one here, but we found that the neural stem cells did indeed increase the number of these connections between the neurons in the brain. So we were increasing the communication of those normal neurons in the brain. Gave us our first hint of a possible way the cells might be working. Now it's been known for quite a while that there's a group of proteins called neurotrophins that can enhance this synaptic growth and this connectivity. And so we wondered, well, are the stem cells in some way affecting neurotrophins or increasing neurotrophin levels? And we looked at a number of these classical neurotrophins We were really excited to find out that the stem cells in particular that we'd been working with expressed very high levels of a neurotrophin that's called BDNF, or brain-derived neurotrophic factor. And part of the reason we were excited is this is known to be expressed very highly in the hippocampus, this area that's important for memory. It's also known to be involved in the formation of synapses, and it turns out in Alzheimer's there's a dramatic decrease in BDNF in the brains of patients. So now we have a little more clue as to what might be going on. But we did a number of other experiments. We found that the cells after transplantation were making this protein and that transplanted animals had high levels of the protein. And for the sake of time, I won't go into it, but we also did a lot of experiments where we removed that protein from the cells and found that we lost the effect. So it really helped us to identify this BDNF as being a really critical factor in how the stem cells were improving. So I'm gonna switch gears just a little bit here and talk about whether we think neural stem cells can also improve function in some other neurodegenerative disease models. And fortunate for us, our lab is located right adjacent to Leslie Thompson's lab, who many of you know is an amazing woman, an amazing researcher in Huntington's disease. And we talked about the data a little bit. She said, you know, BDNF is reduced in Huntington's patients. Really dramatically. I wonder if neural stem cells might have benefit in there. So we got together and she's been leading these studies and I've just been helping a little bit along the way. But she asked if I could present some of that, this data to you guys too, to mention some of these pretty interesting results in the Huntington's mice. So there's Leslie, for those of you who don't know her. I mentioned that she told me about BDNF in Huntington's being reduced. I think you're going to be hearing quite a lot more about Huntington's a little later, so I'll just very briefly introduce it. It's characterized by neuronal degeneration, especially within the striatum, but then that progresses to lead to a pretty massive loss you see on the right side of this figure, even in the cortex. And we know quite a lot about Huntington's. It's caused by a genetic mutation in which a single amino acid gets expanded, so you get multiple copies of this amino acid within a protein, and that defective protein causes the disease. But much like in Alzheimer's, one can model this disease using mouse models by adding in mutant forms of the human protein. And Leslie took one of these models and asked, what happens if we put neural stem cells into these mice? Now in this case, the area that's affected is an area called the striatum. So we delivered the cells to the striatum rather than the hippocampus as we'd done before. You can again see our green cells engrafting in there. And one uses different behavioral tasks for Huntington's because they suffer from different symptoms, a lot of motor impairments and things like that. And this is one very simple task which was the first measurement they looked at, which is called clasping. And a normal mouse, when you hold it by its tail, will splay out its legs getting ready to be dropped and be able to land properly. But a mouse with Huntington's disease does this clasping reflex shown on the left here where it clasps in. It's unable to open up its paws normally. Now it turns out this mouse on the right is actually a Huntington's mouse but it was treated with neural stem cells. And when the researchers quantified this they saw a very large recovery in this function that we were alleviating this deficit in these mice. They looked again at a number of other measures one can For instance, watch— look at the time it takes for a mouse to cross along a small beam, and then also look at the errors they make, how many times their foot might pull off. And up on the top here, you can see that the stem cells reduce the time it takes for these mice to cross this beam. And on the bottom, it also reduces the amount of errors they make, the amount of time their feet fall off this beam. This beam. So really, really interesting data in a number of different measures, and they actually did several other experiments I can't show you. But essentially the neural stem cells were improving the motor performance in these mice. And an important point here is the mouse model she used is considered the most aggressive Huntington's model. There's very, very few studies where anyone's been able to show any benefit of anything in this model. And so that's really promising, and Leslie's leading a number of CIRM-sponsored experiments to try and follow up on that, test it in other models with a number of collaborators. They've started looking into the mechanism behind this, and I'll just briefly mention that it looks like there's some similarities to some of our data. They see increases in these neurotrophins, they see increases in activation of these protective pathways, BDNF is one of the culprits. In the case of Huntington's, GDNF is another neurotrophin that's important, and they see that's being elevated too. So, just in the last couple minutes, I want to briefly touch on another use of stem cells. Peter mentioned early on this ability to use stem cells to understand the disease. Can we model the disease in a dish or get a better understanding of what's going wrong? And I'm going to just briefly show you a couple slides in regards to that. So Leslie's group is part of a huge Huntington's disease consortium that are making these IPS cells you heard briefly referred to. These are cells where you can take a skin biopsy and by adding in a few genes, reset them to embryonic stem cell-like cells to then generate neurons and start to understand what's going on in this disease. And you can see here their goal here is to generate this panel of well-characterized Huntington's these lines to use them to elucidate the pathogenesis and potentially test new drugs. We're starting to do some similar experiments with Alzheimer's disease, but I just want to show you one or two slides of another set of experiments we've done to simply ask what is the function and what does a gene that's implicated in Alzheimer's do when you put them into embryonic stem cells. I mentioned this amyloid, this beta amyloid that drives Alzheimer's right at the beginning of the talk. That's actually derived from a much bigger protein called APP, or amyloid precursor protein. So we asked, if we increase expression of amyloid precursor protein in human embryonic stem cell lines, what happens? This data just shows that we made these lines, that they make higher levels of this protein. But when we looked at the cells, we noticed some really strange things going on. In fact, the postdoc who was working on this was really frustrated, wanted to throw the cells out because she thought something was going terribly wrong. If you look on the left side, that's a normal embryonic stem cell colony. But on the right side was one of our colonies that was overexpressing this gene. And you can see some very weird structures that are showing up. It piqued our interest, so we decided to look a little deeper and try and understand what was going on. And we were really amazed to find that what was actually happening in these colonies was they were differentiating. They were turning into neurons. And they were doing it incredibly fast. This was within just 5 days. They were making huge numbers of neural precursors or even significant numbers of neurons. And just to, just to give you a little background, the standard protocols for making neurons from embryonic stem cells take about 3 weeks, and we were seeing this within 5 days. So this was a real shocker to us, but we followed up on it, try and understand what's going on. This is this protein that gives rise to the beta amyloid that drives the disease, and we had put the whole protein in. Bottom line is we did a number of experiments to try and understand what was going on and identified these other cleaved products as being responsible for this effect. And some of the best evidence we have for that is we could just take protein, just that part of the protein, throw it on normal embryonic stem cells, and see the same thing. So the green on the left is a marker of neural stem cells, and just by adding in a dose-dependent fashion, adding this compound, we could make neurons. So this is just an example of how you might set out to, say, model the disease in a dish, but along the way you might surprise yourself and find some very interesting results that tell us a lot about perhaps the normal function of that protein. And it may even give us a new way to make neurons very quickly from, from stem cells. So it's one of those sort of fortuitous discoveries that, that are really exciting in science. So just to summarize what I've briefly talked to you about today, we showed that neural stem cells could improve learning and memory in these aged transgenic models of Alzheimer's, and it seemed to involve this BDNF and effects on the connectivity between neurons. We also— Leslie's group showed that neural stem cells can improve motor function in a very aggressive model of Huntington's disease, and it seemed to occur by some similar mechanisms.. And then lastly, I've just introduced this idea that you can use these IPS or transgenic approaches to model aspects of the disease and really get a better understanding for what's going wrong in the disease and even what the normal function of those proteins are. One last thing, of course, how could I forget? Frank LaFerla, who generated the mouse, who I've worked with for several years. Leslie Thompson, of course, instrumental in these studies. Peter's been very helpful over the last several years too. A number of people in Scripps in San Diego. And this is the most important point, is none of this could even come close to being done without the support of CIRM. Frank's been able to get early translational grant as well as seed grant, and that's what's driven this research, and it wouldn't have been possible without CIRM. So with that, I'd like to answer any questions someone might have. Thank you. Hope there's not a test after this. I know it was a lot. A lot of information. I like squeezing it in. In the mice themselves, is there any recurrence in the— After the transplant, that's it. Could you repeat the question for the video? Yes, so the question was, after the transplantation of the neural stem cells, does this disease come back? And that's an excellent question. I don't know the answer yet. We're doing those studies. What concerns us is that while we can improve the behavior, we're not affecting the pathology. So if you go longer and longer, as that pathology accumulates, do you start to have, lose your effect? And I'll tell you, we're taking two approaches. One is to do those exact experiments to try and determine if that's the case. But just in case it is the case, we're seeing if we can use these stem cells to also modify the pathology. And I swear I didn't plant that question, but I've got a slide that shows it. I had it just in case. On the left-hand side here, so in red is this beta amyloid. And this is in a mouse after 3 months after where one side received some modified stem cells which are expressing now an enzyme that we can know degrades this beta amyloid. And on the right are some control modified cells. And you can see there's a dramatic reduction in the red in this beta amyloid in these mice. So we're now also doing studies with those kind of cells to see do they provide more long-term benefit. But brilliant question. So would this be a gene therapy stem cell combination? Exactly, exactly. Which of course comes with more regulatory hurdles, but I think things are moving that way.

I have a question, Matthew.

Yeah.

I think you know what it is. So you deliberately used older mice to mimic the human condition. Yeah. But as we heard from Surgeon Susan, Susan noticed the signs of memory loss, have you now gone back into a younger animal and asked, can you prevent the disease from developing altogether?

Absolutely. Very good question, and I'm glad you asked it, Peter. Peter asked me that I think probably about 2 years ago, and so I did those experiments, so now I can answer them. So the bottom line is yes, we see improvement, and we see pretty pretty prolonged improvement. We've looked about 6 months out. So we started in animals that were what we call pre-pathologic. They didn't have much of this amyloid accumulation and they were just starting to develop some symptoms, very early stages. We transplant the cells then, and then we tested the behavior at a couple different time points. Bottom line is both at 1 month and 3 months, and then at 6 months, we see improvement in behavior in those animals as well. So we're trying to get that together to publish it, but Yes, it seems to have some benefit in terms of prevention as well. Yeah? What is the source of these neuro stem cells? Good question. That's one of the things that CIRM's really helping us with. Sorry, the question was what is the source of these cells, where are they coming from? We started off doing what seemed like the logical experiment which was to put mouse cells into a mouse. So a lot of the data I've showed you in the earlier part was with mouse cells. We've now, with the help of CIRM, been exploring and trying to identify the ideal human stem cells to see if we can see similar benefits. Now that gets more complicated because that's called what we call xenotransplantation. So you're taking a human cell and putting it into a mouse. And the mouse doesn't like the human cells. So you have to do a lot of things to try and damper down the immune system to try and get those cells to even survive. Whereas here we match those cells perfectly to the mouse that went in. But the hope is, and we're doing those experiments right now, that we'll be able to get human cells to engraft and see similar benefits. Because those then would be the cells one could start to think about moving forward towards eventual clinical trials.

Matthew, quickly, because we need to move ahead. Could you briefly say what impact CIRM has had on your career? People might not know this, but you're the newest member of the UCL Mind faculty.

Yeah. As of last week. And the bottom line is I wouldn't be here. I'd probably be in Australia right now, actually, if it wasn't for CIRM. I have been studying Alzheimer's for quite a while. I'd done a postdoc here, joined Frank's lab, and became very interested in stem cells around the same time that Prop 71 was being approved. Went to Frank with this idea of starting to look at stem cells and Alzheimer's disease. Was able to be funded on a training grant through CIRM. So getting further postdoctoral training, paying for my training for a couple years. I showed you some of the support that Frank and I have been able to get to do these experiments. If I hadn't done these experiments, if they hadn't come with these exciting results, I don't think I would have had the opportunity to apply for these jobs. And be lucky enough to get one. So as far as my career goes, CIRM's made my career in the last few years.

Could you maybe, for people in the audience who don't understand the terminology, explain what an early translation award means and why that's so important?

Sure, sure. So an early translation award I think is a very important type of grant that CIRM has. It takes some of the earlier data, like some of this stuff we have with mouse stem cells and promising data, and brings it that first step to start to think about potential clinical applications. So can we develop human cells that have similar benefits? Can we start to work out some of the details so that at the end of that grant the idea is you can start to think about talking with the FDA, starting to plan preclinical trials that will get FDA approval. So it's this critical stepping stone kind of grant. That really takes this early research a big step towards the clinic. And really, NIH doesn't have the equivalent. There's not that kind of funding to take these steps. And so it's very critical type of grant, I think. Real quickly, there's never been any clinical trials from human stem cells to humans, right? So the first ones are the ones that Lisa mentioned the Geron trials with spinal cord injury, and they've transplanted one patient so far, I believe, and so far so good. I think that's the very first trial with human ES-derived cells. There's been some neuro stem cell trials in Europe and other places, but nothing for Alzheimer's at this point.

Francis, last question. Yeah, just a real quick question. If 1 in 10 people are gonna get Alzheimer's, and a lot of us here Here are baby boomers. I would think that at least 10 or 15 of us are going to get it. Is there anything we can do right now? I mean, those of us that are not symptomatic or anything, but anything we can do to try to—

Sure, there's quite a lot of data out there about things that might reduce your chance of developing Alzheimer's disease, and it's the things we always keep hearing about: exercise more, eat a little more healthy. All the things we know we need to be doing. But there's strong evidence that both of those can decrease your chance of getting Alzheimer's. The other one that I think is very interesting is there's, you're less likely to develop Alzheimer's if you read more, do crosswords, use your brain. It's kind of a use it or lose it phenomenon. There's really strong data on that. So you guys being here listening to this jargon, yeah, you know, you're using your brain. That's good, you're preventing Alzheimer's, so keep doing that kind of thing. Is that a bad sign if we don't understand it? No, no, no, no, no. That's my fault. How long do we have to wait for trials? Oh yeah, that's always— So the question was how long do we have to wait for trials, and I wish I had a crystal ball to give you a good answer. I know you've probably heard this before, but we're moving as fast as we can. CIRM's facilitating this greatly. 'cause you can't do this research without the funding. These mice are ridiculously expensive to maintain. Our hope is that, you know, if all goes well, by the end of another couple years, at the end of our early translational grant, we'll be at the point where we can now start to do those tests still in animals, but do those tests that the FDA will look at and decide whether or not to approve. So if I had to realistically guess, If everything went perfect, I think we might get to early Phase 1 trials in 5, 6 years, 7 years. I know, I know, I wish I could say it was sooner, but you know, as Peter alluded to, we've got to be careful and we've got to make sure that we don't do any harm.

Matthew, you've made a big step forward with a corporate tie.

You've got a corporate interest already. We've got a couple actually, so that helps, yeah. So we've started doing some tests both with Jaron and StemCells Inc. now. So that helps a lot because they have the cells that are already approved, that have been tested in other situations. So Don's absolutely right. That could speed things up a lot. I didn't take that into account. So maybe it's a little shorter horizon if all goes well.

I'd like to thank all this morning's speakers. They did a great job. And we're going to take a short break now because although you've been using your brains, you might need to use a different organ right now. We're going to have what we call a physiology break for 5 minutes if people want to take a break and use the bathroom.