9UNP0334SD_Gary_Lyons

- Cathy Vrentas: The lab, here at the UW biotechnology center. Tonight, we're welcoming Gary Lyons, who is a professor of anatomy in the UW School of Medicine. Specifically, he does research on mouse stem cells and also teaches first year medical students. He did his post-doctoral work at Stanford, as well as the Pasteur Institute in Paris. And he has a variety of roles relating to stem cells on the campus, including chair of the UW Stem Cell Research Oversight Committee. And he'll be telling us today about his work on cardiac stem cells. So please join me in welcoming him to Wednesday Nite at the Lab today. 
(applause)

- Gary Lyons: Can everybody hear me clearly? I'm delighted to be here to speak to you tonight. It's always my pleasure to talk about all our research and how it relates to everyone in Wisconsin. I'd like to help people understand what stem cell research is about, because it's a very complex issue. It has certainly been viewed in an unfavorable light by certain groups. And unfortunately, it has also become somewhat of a political issue. But we're gonna leave all of that aside tonight and talk about the science. And my hope is that by the end of the evening that you will be more fully aware of what stem cells are, that multiple different types of stem cells exist. Everything is not an embryonic stem cell. And at the moment, there are clinical trials being performed at different sites throughout the US including here on the Madison campus using stem cells and progenitor cells to treat cardiovascular disease. 

- What do you mean by "progenitor cells"? 

- Gary Lyons: Thank you, very good question. And thank you, please ask questions as you have them occur. What are progenitor cells? Progenitor cells are cells that come before mature cells, so what are mature cells? Mature cells are neurons, muscle cells, cartilage cells, bone cells. Whereas there are cells prior to that during the process of what we call differentiation and certainly during the process of developments, particularly in the embryo, but in us as we grow, particularly post-natal until we reach our mature age. The progenitor cells are in between the stem cells and the mature cells, so it's a matter of definition. Some people say "precursor cells," some people say "progenitor cells," everyone says "stem cells," but sometimes people call progenitor cells "stem cells," and that sometimes confuses the issue. So a stem cell is a cell that is able to replicate itself identically, and is also able to give rise to other cell types. 

Maybe only two cell types, maybe three cell types, but in the embryo, it gives rise to all cell types. Okay? So, I'm here to talk about heart disease. Heart disease is a major problem in our society. This is probably something you've heard before. What are the risks for, well, underlie heart disease? There are a good number of them. They include... high cholesterol in the diet. We as Americans are among the most guilty. 

Convenience foods that are high in fat, I'm not gonna name any restaurants, but I think you know who we're talking about. 
(laughter)

 Foods that are very high in fat are bad for you because they permit fat to build up in the blood and bind to those molecules that bind cholesterol called HDL and LDL. If there's too much fat in the diet, over time it leads to obesity. Obesity is a huge stress on the heart, because your heart has to work against all that extra weight. And if you are obese, you have a very, very high risk of developing type 2 diabetes and that has all kinds of problems associated with it, which I won't go into. We as Americans have jobs where we sit on our tush all day in front of a computer screen or answering the telephone, or I sit at my desk a lot writing lectures and grants and things like that, and we really don't get out and exercise as much as we should. High blood pressure is another very important risk factor. I have high blood pressure. Many people have high blood pressure. 

The problem is that you don't know when you have it, and you don't know until you go to see a doctor and your doctor says, "Hmm, your blood pressure's a little high, we should do something about that." Over time that creates incredible pressure, sorry, not pressure, but stress on your heart because your heart has to work against higher and higher pressures and over time, your heart starts to wear out a little bit. Stress. Many of us experience this, there are many, many causes of it and it also plays a role in the long term in the risk for developing heart disease. And then some of our favorite habits, like single malt scotch and fine cigars and other pleasurable things in life which we love to indulge in, but which really aren't very good for us. And of course, some of us are born with the predilection toward heart disease because of our parents, and with age there is increased risk, and if you're a man, you're at greater risk than if you're a woman. The good news is that heart disease deaths overall have dropped over the course of the past ten or more years. Why is that? It's because, and the correlation is strongest with, people stopping smoking. My dad smoked from when he was 16 all the way till the day he died when he was 76, and I tried to convince him that smoking was a bad thing and he cut back, but sometimes it's hard to get rid of habits that start so young. 

But this can be a major factor in cardiovascular disease. So from this, we can ask the question, how much would death rates drop if the people who are at risk started exercising more and ate a healthier diet? It could well be significant. So, what do we mean when we say "heart disease"? Most of us think right away about coronary heart disease because that's a very common problem. I don't know the statistics, I don't know if it is the most common form of heart disease. The term "atherosclerosis" is probably something you've also heard before. We'll talk a little bit more about this and I actually have a little video to present to you about atherosclerosis so that you can actually understand better how it works. But there are other types of heart disease and these are longer-term heart disease issues such as cardiomyopathy. Cardiomyopathy means a sick heart, heart that's not functioning properly. 

And sometimes that is, it causes dilation of the ventricles, and then it's called "dilated cardiomyopathy." Sometimes there is poor blood flow within the heart itself, and that's called "ischemic heart disease." And there is also something called "heart failure" which astounded me, that people can live with heart failure, I thought when the heart failed, that was it, but there are people walking around with heart failure, which is, they're severely compromised in their heart function, but because of medical assistance in terms of drugs and other things, they can actually continue to live a relatively normal life. So, this is an image to show you one type of heart disease and a comparison with a normal heart. Here we have the two atria and the two ventricles, right and left. And over time, because of high blood pressure or other issues, the heart enlarges, or dilates the volume inside the ventricles, and notice that the heart wall also thins. This is an adaptation to a stress that the heart is undergoing. The bottom line of what I would like you to take home is that all heart disease in any of its forms leads to the reduced ability to move blood out into the body. And in the short term, as it's in the early stages, it's not an issue. But you reach a threshold, and that's where problems start to occur. 

In heart disease, the heart must work harder to move blood, and because of the pressure, high blood pressure and other stresses, that smoking and other things, fatty diet, can cause, there are changes that take place in the heart wall and as those changes occur, the disease progresses. What most of us are familiar with is something called myocardial infarction. This is what we mean when a person has a heart attack. It usually starts as a very severe pain in the chest, which then radiates out into usually the left arm and persists. It makes you sweat, it makes you feel like an elephant is sitting on your chest, and it's something that needs immediate attention because it is something that can be fatal. And this is a problem that is highly prevalent. So each year, about more than a million people have a heart attack, okay? Yep? 

- Those are not the symptoms necessarily of heart attacks in women. 

- Gary Lyons: Thank you very much. 

Maybe I should ask you to get up and tell us about the symptoms of heart attack in women, but symptoms of heart attack in women are quite different. 

- My friends all tell me they're very diffuse and subtle and seem to not have anything to do with their left arms. 

- Gary Lyons: Yes, what I recommend that you do, if you are a woman, is to go to the American Heart Association Web site online, and they describe there very well what the symptoms of a heart attack are like in a woman. They are quite different, what I described is what is most commonly experienced by men having a heart attack. But you can, as a woman, you could just feel kind of bad, like you maybe just have the flu or the onset of the flu. There are a variety of symptoms that are much more difficult to recognize about having a heart attack if you're a woman, but please do go to that Web site where they give you the specific things to look for, and thank you so much for bringing that up. So this is a real problem, and 700,000 of those million or so heart attacks are brand new occurrences, 500,000 are repeat attacks, and 40% of all heart attacks are fatal. Accounting for 20% of all deaths in the US. This is the number one killer of people. So, we're gonna have a little film. 

- Atherosclerosis is contributing cause of coronary heart disease. It is characterized by fatty lesions which grow within the walls of medium-sized arteries, a class which includes the coronary arteries. These lesions, or plaques, form in a layer of the arterial wall called the intima. The intima consists of endothelium and a thin layer of connecting tissue, or collagen. The high turbulence of blood at the bifurcations of the coronary arteries begins the process of atherosclerosis, by entering the endothelial layer. Injured endothelium increases its permeability to monocytes, which migrate into the intima and change into macrophages. These macrophages express receptors for oxidized low density lipoproteins, or LDLs. Injured endothelium also increases its permeability to LDLs, which in the presence of free radicals are oxidized and bind to the macrophages. The macrophages continue to absorb oxidized LDLs, and enlarged, become foam cells. These macrophages also secrete substances which cause the migration of smooth muscle cells from the media and the proliferation of smooth muscle and collagen in the intima. 

The presence of foam cells and smooth muscle cells gives the appearance of the fatty streak. The further proliferation of smooth muscle cells and collagen and an increased absorption of lipid, leads to the formation of a fibrous plaque. As the fibrous collagen layer expands, necrosis occurs as the cells inside the lesions die from lack of oxygen. This lipid-rich plaque with a necrotic center is called an atheromata. Eventually, the necrotic region is walled off by calcification of the plaque base and a thickening of the fibrous cap, giving rise to the complicated lesion. A rupture of the lesion induces clotting, which begins with the aggregation of platelets, followed by the accumulation of fibrin, forming a thrombus. If this thrombus blocks the blood flow, a coronary infarct will occur. 

- Gary Lyons: Questions about that? 

- That sounds like a one-way process, in terms of what happens in the case of lesions. Is there any progress in reversing -- of that? 

- Gary Lyons: So the question is, is there progression or progress in treatment of atherosclerosis before it gets to the point where it will cause an obstruction in the artery? 

- After obstructions were cleared, is there still plenty of...? 

- Gary Lyons: Yes, so, actually this is what my next slide is about. If an occlusion is noticed by something called an angiogram, where a contrastize injected into the blood of the heart, or other methodology which allows physicians to notice that a particular artery is 70%, 80% occluded, they can do a couple of different things. They can do something called a coronary bypass, which is actually very common these days with very high success rates, in which blood vessels from your leg are taken and put into the heart to provide a path for blood around the developing blockage. Or they can put a little device into your coronary artery, which will open up that developing blockage and often they will leave something in place there that will prevent it from being re-occluded. And if they catch it earlier, you can use, or notice that it's developing earlier, you can use drugs called "statins," which help regulate how the metabolism of cholesterol in your body. And those are actually very common, I'm just interested by a show of hands. How many people here are taking statins? This is a very common drug nowadays. 

I'm on a statin, I have atherosclerotic plaques in my carotid arteries, and I'm only 52 years old. But the methodology for detecting these plaques as they develop is greatly increased, so all you have to do is go to your doctor and say, you know, I have a family history of cardiovascular disease, maybe we should look and see what's going on in my heart and my carotids. And they can detect things quite quickly and undoubtedly they are going to put you immediately on statins, they're gonna have you take aspirin, which helps prevent your blood from clotting, and they might put you on an anti-hypertensive, depending upon if you have high blood pressure or not. All of these things help reduce the chance. Blood thinners are often used to help prevent clotting. Maybe a drug like Warfarin or Coumadin. And then, depending upon the stage of development of disease, doctors will also give you drugs that will help regulate the contraction of the heart and will also help with chest pain. Now, if things develop to the point where the heart is no longer functional, sometimes the only option is a heart transplant, and I was just interested, on Monday I noticed on Channel 3000, where I keep track of my news, I hardly ever read a regular newspaper anymore. There was a very brief article that said 53% of Wisconsin drivers are designated as organ donors and that last year there were 228 organ donors in Wisconsin and 578 people in the state received an organ transplant, but this nowhere near meets the need, because there are thousands and thousands of people who require new organs as a result of disease. So I would strongly encourage you, if you have not already done so, to become, sign up to be an organ donor, because God forbid that you have an accident, your organs, more than one of your organs could go to benefit more than one, several different people and save the lives of several different people. 

Yeah, question? 

- When you're old, do they want your organs? 

- Gary Lyons: Well, I'm not an MD, so the question is, when you're old, do they want your organs? And since I'm not an MD I can't give you an absolute answer one way or the other, but I would ask your doctor, and your doctor will know the answer to that. And then you can make a decision as to what is best. Since there aren't enough hearts to go around, and since the current therapies do not restore cardiac tissue, so that little animation that I showed you showed an infarcted area. What happens in that infarcted area, an infarcted area is lost. The tissue dies. The muscle goes away. And it's replaced by fibrous tissue, and that fibrous tissue cannot contract. 

Okay? So what we need is a methodology, so this process is called "remodeling." And what I'm telling you is that the current treatments which we just looked at for heart disease do not lead to the regrowth or the regeneration of cardiac tissue, and this is a big problem. 

- It has also damaged the electrical system. I was gonna ask at some point if your research was addressing regenerating the nerves. 

- Gary Lyons: So the question is about the enervation of the heart and the damage that occurs in myocardial infarction? Or are you thinking about the heart's conduction system, the pacemaker cells and the Purkinje cells, the bundles of His, yeah. So, damage occurs to what we call the "conduction system." Those are not nerves, they are cardiac muscle, but they're specialized to carry the action potential from the pacemaker region of the heart all the way down to the tip or apex of the heart to initiate the contraction. So damage is done there, yes, and what we expect from what I'm about to tell you is that cells of the conduction system should be regenerated as what we call the "working" cells, or the working myocardium. 

The hope is that we can regenerate those cells rather than letting them be lost, because once they're lost it's very difficult to put them back. So the only hope we have at this point, not the only hope, I shouldn't say that, there's never only one hope, but one of the promising therapies is to use either the cells within the heart, or perhaps stem cell sources from other places in the body that will actually lead to the regeneration of the tissue that is lost. And if you look, you will see that many universities, including this university, now have a center for regenerative medicine. And this is not just about the heart, this is about the brain, this is about the pancreas, particularly the eyelet cells of the pancreas, which are lost in diabetes. This is about the liver, this is about skeletal muscle, other things like that. All of the options of stem cells within the body are being studied in the context of creating therapies that will regenerate tissue that is lost. And to do this, scientists are proposing to use stem cells. And as I mentioned, clinical trials are underway, and we'll talk a little bit more about that later. What is a stem cell? A stem cell is a cell that can make itself exactly, so it can replicate itself or renew itself, or instead, it can go and make one, two, or multiple different cell types, such as those that are shown here. 

Blood cells, neurons, muscle cells, fat cells, etc. So this is the definition of a stem cell, something that can make more than just what it is. Where do these stem cells live in our body? Well, most of us are aware that inside our bones is something called the marrow, and that marrow contains all kinds of stem cells. The marrow contains what we have recognized predominantly as cells that are the source of the blood in our bodies. So all of the cells that are in our blood come from bone marrow. And they come from stem cells that continue to divide and generate new blood cells over the course of time. But within this bone marrow there are also, people have now found, other types of stem cells. They can come out and make endothelial cells. And they can come out and make other types of stem cells that can actually play a role in the repair of the body. 

In addition to the bone marrow, there are stem cells that live within every single one of our organs. For a long time, we've known about the stem cell that lives in our skeletal muscle 'cause we can inure a muscle very badly and it will completely regenerate itself and look brand new with no connective tissue at all. But more recently we have found that within the heart itself, there's a population of stem cells, that over the course of our lives, as we're growing and developing and becoming mature individuals, slowly replace cardiac myocytes that wear out. So in your bodies right now, there are some cardiac myocytes that are no longer working that are being replaced by the stem cells within your heart. People have proposed using embryonic stem cells, but this is a very controversial issue, and it also has some fairly huge technical difficulties to get around. People have found that in cord blood, so, when you're born, or when you were born, when I was born, when your grandchildren are born, little bit of blood is saved from their umbilical cord for a certain amount of time in the hospital. Usually that gets thrown away. But people are saving that now because that blood is full of stem cells. And that blood can be stored and when a person is an adult, if they have a particular problem that requires stem cells, they can go back to that cord blood and it's a rich source of stem cells and there's no immune rejection because it's from the same individual. Yep. 

- Do stem cells wear out? 

- Gary Lyons: The question is, do stem cells wear out? And the answer is yes, everything wears out, unfortunately. Except cancer, that never stops. But that's a different story, that's not a real cell. So, that's why we have the placenta here and cord blood cells are considered a source that are known to be a source of stem cells, and then there are these things called mesenchymal stem cells, what's a mesenchymal stem cell? Mesenchymal stem cell is something that is not well-defined at this point. It comes out of the bone, primarily, bone marrow, and it can circulate and it can occur in places like fat. So we'll talk a little bit more about mesenchymal stem cells. 

- How do you spell that? 

- Gary Lyons: How do I spell it? M-E-S-E-N-C-H-Y-M-A-L. 

- Thank you. 

- Gary Lyons: You're welcome. And more recently scientists, including people on this campus, have found that they can reprogram cells in the adult to become just as if they were embryonic or very similar to embryonic. So you could give a biopsy of your skin, and that could be treated in a certain way that I won't go into the details. And those cells would become like embryonic stem cells and they would be like your embryonic stem cells, so we could take those cells and make anything that we want. Could make heart cells, could make brain cells, all kinds of things. 

- I believe this is true. Since, maybe you can comment on it, since President Obama has been president, he reversed the trend so that more money is generated into stem cell research, he reversed the trend from the previous president. 

Is this true? 

- Gary Lyons: So the question is, did our current president, Mr. Obama, reverse the trend in terms of stem cell research and funding? And the answer, what you're thinking of is that our previous president, Mr. Bush, limited research funding to human embryonic stem cells. That is particularly what has been reversed, there is no longer a limitation, or the limitations have been loosened significantly on human embryonic stem cells that can be used for federally funded research, that's the big change. That's a change that most scientists wanted to happen. 

- And that's for the good. 

- Gary Lyons: And that's for the good, I think, yes. 

- I agree. 

- So, what are the IPS cells, the induced pluripotent cells, are cells from an adult that have been reprogrammed to become pluripotent, which means they can become anything. And the beauty here is that this can be used, these cells can be used without the concern about immune rejection. And we'll talk a little bit more about that, 'cause they have a lot of other really interesting features as well. So if we wanted to take some of these stem cells, how would we introduce them into an area of myocardial infarction? Here in gray we have an area of myocardial infarction where the heart is having major problems, things are breaking down, cells are dying, macrophages are coming in and taking away dead cells and cells called fibroblasts are coming in and laying down connective tissue to replace the viable myocardium. Well, one way that has been proposed and one way that is currently being used in clinical trials is to use a very thin tube that can be injected into the coronary artery and you introduce cells in that fashion and those cells then go into the surrounding tissue and differentiate to form cardiac myocytes, endothelial cells, and smooth muscle, which is what the heart needs to regenerate itself to be restored to a better function. When these cells go in, what do they do? What are the benefits of stem cells that are introduced into an area such as one of myocardial infarction? Well, they have been shown in rodents to be able to form brand new cardiac muscle cells and to re-muscularize the heart. They have been shown to prevent --, that is, they blunt the formation of fibrous tissue and they promote the survival of the existing tissue. 

Very importantly, they promote the formation of new blood vessels. The heart is critically reliant upon its blood vessels. You take away any of those blood vessels and parts of the heart start to die, for every single cardiac myocyte there are four capillaries. That's how much the muscle relies on its blood supply. There are paracrine effects that encourage cell survival, that is, the cells that go in secrete things that keep the cells that are there happy, or make them happy, perhaps by preventing cell death. It's been proposed that sometimes these cells fuse with the existing cells, but it's now been shown that that happens only very rarely, less than 1% of the time. And perhaps one of the strongest influences might be that they could have a direct effect, a positive influence on the stem cells that live in the heart, causing them to become activated and starting the normal regenerative process. What is a cardiac stem cell? Well, it is defined as having the ability to form not only cardiac myocytes, but also blood vessel cells, the endothelial cells, and the smooth muscle that surrounds the arteries in the heart wall, so it's a multipotent, it can form at least three different cell types. It's self-renewing, and can generate... 

here we go, can generate a lifetime supply. And for research purposes and for clinical purposes, it can be isolated and grown in the tissue culture dish to expand the cell numbers, which is very important because when you have a myocardial infarction, you lose millions of cells. As much as a billion cells you can lose and still survive, but you're losing millions and millions of cells in these myocardial infarctions. And that's a lot of cells to replace. But most importantly, cardiac stem cells should have the ability to functionally repair the infarcted area and to regenerate cardiac tissue, that's the really critical thing. So we've talked about these endogenous cells that we used as stem cells or progenitor cells. Where are these cells and how do we study them in people? It's an important point. Human embryonic stem cells, although controversial, provide an invaluable method to study human disease because you can take these cells and put them in a tissue culture dish, you can treat them with drugs to see how they respond, you can do molecular analyses of these cells to better understand the mechanisms of disease, so these cells are incredibly valuable and have told us so many wonderful things, just in a tissue culture dish, not in people, just telling us what these cells can do, what they normally do. And occasionally, if you have a colleague who is a cardiac surgeon, you can get little bits of biopsies and pieces of tissue from cardiac patients or other patients that can be used for studies in the lab, and in that methodology, because of that reason, it's been discovered that many of the stem cells within the heart are sort of up near the atria and they trail down a little bit down toward the ventricle, at least this is one viewpoint. 

This is not something that is really well understood at this point, but these cells exist in the heart and they can form smooth muscle cells, cardiac cells, muscle cells, and they can form endothelial cells and maybe even they can form the thin layer that wraps the heart called the epicardium. And the molecules that exist in these cells that allow them to do the things that they do have been partially defined, but we still have a great deal of work to do to understand how they work and what they look like. This is a very, very high magnification picture of cardiac stem cells in a living heart. You do not see an entire cardiac myocyte here, which is in red, which is kind of washed out here, but don't worry about that. This is sort of a snapshot of what cardiac stem cells look like inside the heart. They're teeny little cells, very little cytoplasm, very large nucleus, and they sit there and they wait for signals to say, okay, divide and make miosis. And people have sort of had a schema for this, where the small cells live in their own little niche, which consists of multiple cell types, the stem cells along with cells called fibroblasts that are surrounded by myocytes, the functioning myocytes, and these cells have very complicated cell-cell junctions with each other. And these are the cells that are resting, that divide only occasionally as needed, and then the amplifying cells will go on and become cardiac myocytes or endothelial cells or smooth muscle cells. At least this is one way of thinking about it. So you asked me, why, if there are these stem cells in the heart, why don't they just proliferate and replace lost tissue? 

It's a logical question. Well, it gets back to the question of, do stem cells have a lifetime, and they do, and they also, when you deprive them of fresh oxygen and nutrients, they die just like the myocytes do. So the other problem is that we don't know what makes them start to proliferate. If we understood this, maybe we could simply treat people immediately after they had a heart attack, and that would stimulate their cardiac stem cells to start dividing and then the heart could actually have a fair chance of healing itself. But we have no ideas at this point, how that works. So what's another source of cardiac stem cells, let's talk about bone marrow. This diagram is simply one of how bone marrow is extracted from people. It's usually taken from the hip, and you get local anesthetic, and a big, sharp, very sharp needle is pushed into the bone and you suck out a whole bunch of cells, most of which make blood. And some of which make other things. So haematopoietic means blood, you also find the endothelial cells, which make blood vessels. 

And you also find these not well-characterized adult stem cells called mesenchymal stem cells. And another group in Minnesota has identified what they call "multipotent adult progenitor cells," which I think are a lot like mesenchymal stem cells, but no one has ever done a careful comparison. So you've got lots of stem cells in your bone marrow. And in bone marrow stem cells have been able to, shown to be able to make cardiac myocytes, smooth muscle and endothelium in rodent models. And the problem is that sometimes the cells that are capable of making the hardy cardiac tissue, regenerating cardiac muscle, don't have any identifiable marker. This is a problem in the study of these cells at the moment, we don't know what a cardiac stem cell looks like, what the proteins are on its surface. That's something many labs, including my own, are working on at the moment, to try to be able to identify, if you take out cells from your bone marrow, I would like to be able to identify what cells in that big mix are capable of making cardiac muscle cells. And just grow those, and then put those back into your heart. Others have proposed that growth factors can be used to mobilize the stem cells that are in the bone, in the bone marrow, and this has been successful using certain things, I won't go into the terminology because it doesn't really mean much, but basically the take home point is, there are molecules that will stimulate the exit of stem cells from the bone marrow so that they can get out into the blood and they actually home in on sites of disease. These mesenchymal stem cells, which we've talked a little bit about, come from the bone marrow, they float around in the blood, we all have them in our blood at the moment, they're also found in the umbilical cord at birth. 

They can be easily grown in the tissue culture dish, but they don't just spontaneously differentiate into the cell type you want, they need signals, they need instruction, they need sometimes cell-cell contact to induce them to form other cell types. So they need a little push. Very interesting other feature of mesenchymal stem cells is that they suppress the immune response. So there are clinical trials underway for people who are receiving organ transplants. And at the same time that the patient gets the transplant, they get their own mesenchymal stem cells that were taken out of their bone marrow and they're injected back in when they get transplant and lo and behold, they don't reject the transplant. It's really cool, it's not well understood. A little bit is understood, because it directly regulates the main effector cells, the T-cells and the B-cells of the immune system, to prevent them from attacking the new tissue. Fat, oh, I'm sorry, go ahead. 

- So that could possibly, if that worked, possibly people wouldn't have to take these anti-rejection drugs for the rest of their life? 

- Gary Lyons: Yes, so the question is, if the mesenchymal stem cells will suppress the immune system, will patients be able to go off all of those horrible immune suppressant medications that they have to take, and the answer is absolutely yes. 

When we get it all figured out, that will be the truth, and it will also be great for people with auto-immune diseases, like myself. So there's really interesting and wonderful possibilities here. Is that a question? 

- No, just sprawled out here. 

- Gary Lyons: Okay. Fat. We all have it, we all make more of it. Fortunately, it seems to be a good source of stem cells. This has been a relatively recent discovery. These cells are not well characterized but they seem to behave in a fashion similar to mesenchymal stem cells from the bone marrow. 

And who of us wouldn't mind giving up a little bit of fat so we could get some other cell types out? I think this has some wonderful potential, and in rodent models, stem cells from brown fat have the ability to form the cell types that are needed in the heart. And finally, these pluripotent cells. Embryonic stem cells and induced pluripotent stem cells. How do we do it? We take a little bit of your skin, particularly your dermis, not the epidermis, we can do it with the epidermis, but people often use the dermis. They grow the cells in culture, they put in three or four different, or induce the expression of three or four different genes, and what that does is to reprogram the adult cell to an embryonic-like cell. And the beauty is that it is these stem cells will be patient-specific. And there will be no immune response. The big problem is, how do we get these pluripotent cells to make at a very high percentage the cells that we want them to make? 

We haven't figured that out yet, but we're working on it. The other wonderful thing about these induced pluripotent stem cells is they can be made from patients of various diseases that are not well understood and that those cells in the tissue culture dish can permit analyses of disease that has not been possible previously. So I took this table from a paper, recent review paper, I believe from the lab of George Daley at Harvard, and they have now made IPS cells from patients with Gaucher's disease, -- muscular dystrophy, other forms of muscular dystrophy, Down's syndrome, Parkinson's, diabetes, etc. Having these cells will allow in-depth analysis of disease mechanisms that cannot otherwise be done. And some people are actually taking these IPS cells, correcting the defects, and putting the cells back into the patient. Isn't that interesting? There was a recent report about that, I forget the disease off the top of my head, what it was, but it did seem to work. What do you have to do to these pluripotent stem cells to get them to do the cell type that you want? Well, you have to differentiate them and the technology at the moment is a bit sloppy, 'cause they have to go through the germ layers and then you need to get the cells that you want to ultimately get the cell type that you want. So this is kind of a slow area where people are trying to make this work more efficiently so they can get certain types of blood cells in majority, or cardiac myocytes in majority, or neurons in majority. 

And that's an active area of study that, when we figure it out, is gonna facilitate this process greatly. What Tim Kamp and I did was to test whether embryonic stem cells could make cardiac myocytes in an area of myocardial infarction in a mouse. So a couple of surgeons who are very talented because a mouse heart beats at 600 times a minute, went in and ligated the coronary artery and created little myocardial infarctions in the heart. And then we injected ES cells, and those cells were marked by certain markers, and then we looked at cardiac function and looked at what cell types were formed, and this is just a brief overview showing an infarct area here, that you got cells that turned blue. So these were the injected cells that had gone on to differentiate into mature cardiac muscle cell types in the wall of the heart, and this just goes to show that they connected with the cells that were already there, so that they were functional. And the echocardiogram, which I'm not expert in, showed significant improvement in heart function and we compared the left end diastolic diameters and the fractional shortening, which are two physiological measurements of heart function, and it showed significant improvement. So the bottom line is, stem cells work. They have worked best studied in rodents, and that's why they have, in part, why they have, and are currently being used in human clinical trials to see if stem cells that are human stem cells, usually from the same patient, are of benefit to people who have had a heart attack, or have some form of cardiac disease. Challenges. Pluripotent cells can make tumors, so we have to be careful about that, how do we get around that? 

Well, we use, we allow those pluripotent cells to become multipotent cells and those multipotent cells are much less likely to form little tumors. 

- Have you actually looked through the entire organism to see whether there's any differentiation going on in other areas outside of the heart? 

- Gary Lyons: So the question is, if we inject stem cells, do they go to other places and differentiate and form other stuff which might not be what you want? That is a danger, I'm glad you brought that subject up, because that can happen. When we inject cells into the heart, they don't all stay in the heart. They go most commonly to the lungs and the liver, that's where lots of cells go, that's where the main circulation is. And they get stuck there, and sometimes they die, and sometimes they don't. So yes, that's quite an important issue. So what has been proposed is to use various methodologies to keep the cells in place where you inject them. And the biomedical engineers are being very helpful in that regard, because they're developing ways where you can inject the cells, or actually create a patch of cells and a surgeon will sew it into the area. 

- Put them in some sort of matrix? 

- Gary Lyons: Put them in some sort of matrix, exactly. Very good question, yeah? 

- This is rather simple, but if you inject what I would assume is very few cells, relative to the thing you're injecting them into, what do those cells do, do they take over the other ones? 

- Gary Lyons: So the question is, if you inject, say, 10,000 cells into an organ that is millions and millions of cells, what happens? What happens is that they have a number of beneficial effects. They colonize and they differentiate due to local environmental signals. They may simply die, but before they die they may secrete substances that promote the survival of tissue that's dying. And they can promote other things, they may promote angiogenesis, which is the formation of new blood vessels. And those stem cells may not actually survive, but because they have caused new blood vessels to form, that gives benefit to the heart, so there's a whole variety of things that they do which are positive. 

But often they don't stick around. 

- This little 10,000 of them has that much effect on such a large organism? 

- Gary Lyons: The question is, do that small number of cells have such a large effect, you have to understand that the area such as myocardial infarct, relatively is not the whole heart, because the individual would die. It's a part of the heart, and you inject the cells into that part of the heart, and some injections of bone marrow cells have gone into the millions in clinical trials. So it varies. It could be thousands, or it could be millions. And nobody really know what is the critical number of cells to inject. That's a very important question and nobody knows the answer. Yeah? 

- If you have an area of infarct, and those cells are dead there, and some of them have reformed, become cartilage or whatever, and you put stem cells in, what happens to that bad stuff that was there? 

- Gary Lyons: A very interesting question. The question is, if the heart has remodeled and fibrous tissue exists where cardiac muscle existed before, what do the stem cells do? Well, initially the primary benefit of the stem cells is gonna be to create blood vessels in a connective tissue space which is very oxygen and nutrient-poor. And the introduction of those blood vessels lays the foundation for other cells to come in. Because the blood vessels are critical to the survival of stem cells or any other cells that you introduce. So having new blood vessels there will permit stem cells, which are circulating in the blood now, they can come out of the blood, and start to populate at least in the region where the blood vessels are, and you can see how that might multiply over time to help alleviate the fibrosis and actually introduce some living tissue that might actually be of benefit to the heart. 

- So would those fibrotic patches just get absorbed or disappear? 

- Gary Lyons: The question is, does the fibrotic tissue disappear? We don't know. That is the hope. 

And there are cells that will do that in your own body, they're called macrophages. With the right signals, they will go in and do that. They just need the positive signals that say, "Okay, this stuff has to go because new cells are coming in." Yeah? 

- I never heard of heart cancer, cancer of the heart, is there such a thing? 

- Gary Lyons: The question is, is there cancer in the heart, and the answer is no. Cardiac muscle has some unique ability to resist cancer. There are things such as rhabdomyosarcoma which exist in skeletal muscle, but cardiac muscle rarely forms any cancerous tissue. Why, I wish I knew. 'Cause I would then use what the heart has for other tissue types in the liver and the lung, and maybe we could induce them to do what the heart does. 

But we don't know what it is. Okay. Cardiac stem cells originate from a number of sources in the body, heart itself, bone marrow, other sources such as fat. And could be made from either embryonic stem cells or induced pluripotent cells derived from the individual. If you're interested in what's going on, in terms of current trials, there's a wonderful web site called clinicaltrials.gov. It's incredibly informative, it lists all of the federally funded clinical trials in this country at this time. So what I did was I went to this web site, and I put in "heart disease" and "stem cell," I got 307 studies, some of these are recruiting, some of these are active, and some of these are completed. And what they're looking at is the ability of bone marrow stem cells to improve cardiac disease, the effect of cardiac stem cells, the effect of endothelial stem cells, and adult stem cells, which refers to mesenchymal stem cells and bone marrow stem cells and other things. Or, they are injecting growth factors that stimulate the bone marrow stem cells, or other growth factors, such as insulin and this molecule which stimulates angiogenesis and the formation of new blood vessels. They're also testing drugs, such as statins. 

And there are some that use a combination of both the stem cells and growth factors. So this is a really cool web site, I suggest you check it out. It has lots of interesting information, and it is, these are the cutting-edge studies that are ongoing at the moment about stem cells and disease. 

- They're not all of those on humans, though? 

- Gary Lyons: So, the question is, are these clinical trials on humans or on other organisms? They're all on people, yep, and they're a variety of different diseases, not just heart disease. Liver disease, lung disease, etc. Now I've mentioned that these stem cells can do what's called paracrine signaling, which is signaling to their next-door neighbors. And studies have shown that bone marrow stem cells don't really form cardiac muscle at that high a frequency, but they do prevent myocyte death, and they prevent this remodeling, which is such a problem for the heart. And they do that because they secrete things that are beneficial to the heart, and stabilize the area. 

And this is also a anoxia, or hypoxia is an interesting thing to think about, because an infarct is a hypoxic area, and that hypoxia may stimulate the signaling that activates stem cells. And in that way, we don't have to introduce stem cells at all. If we can figure out what they're making, all we would have to do is introduce those things into the heart, and get the same response, and not have any negative consequences when injecting cells. And finally, maybe we could just find small molecules that do the same thing. Because it's been found by a number of groups that small molecules can induce stem cell differentiation in the tissue culture dish, and in the organism. And maybe when a patient has a heart attack, all we have to do is to take a molecule and infuse it into them, just stick it into their vein in their arm, at a certain concentration, and that'll go directly to the heart, almost instantly, and it'll interact with the stem cells that are there, and say, "Proliferate and differentiate, and the heart's in trouble, make more." That's what we hope, at some point, will be able to occur, but that's a little bit, this is something that we know the least about, but also holds great promise. And I think that's the last one. 

- What kind of small molecules? 

- Gary Lyons: Ooh. 

An interesting question. So, what kind of small molecules? They don't know. They take these libraries of molecules, that are chemicals, related chemicals, and they put them into a tissue culture dish and they say, "What do the cells do?" And then they say they find things that make heart. Or cardiac muscle, and say, aha, here we can stimulate cardiac muscle. How do they do that? That is a whole other question, because many of these molecules are not things you normally find circulating in the body, they're mimicking something else. And that's why they're effective. Yeah? 

- Does aerobic exercise, like if I rode my bike for an hour, is that likely to stimulate stem cell growth, make your heart and other organs healthier by chance? 

- Gary Lyons: Does exercise stimulate stem cells? There is no proof at the moment, but my guess is yes. So, what does exercise do? It increases circulation in the body, it increases oxygenation of tissues, it increases nutrients to tissues, all of those are beneficial. So it must have, in addition to the mature or differentiated cells that are there, I have no doubt that it would have a positive effect on stem cells, whether it would activate them to divide right at that point, I might have some doubt about that, but the benefit of exercise has multiple, exercise has multiple benefits, most of which we really don't appreciate. And it's not that much, half an hour, five times a week. 

- So exercise, I would guess, might be better than a lot of medication, if you have a choice. 

- Gary Lyons: That's a wonderful statement. The statement was that exercise is better than a lot of medication, and amen to that. 

Yeah? 

- Most of what I've read about the clinical trials suggests, I think, people with fairly advanced degrees of function loss. If you have a heart attack when you're fairly young, and you don't lose a lot of function, where do you stand on the ladder of clinical assessment? 

- Gary Lyons: The question really is, what does it take to qualify for a clinical trial? 

- No, how important is it to start addressing these things earlier rather than later in the progress of the disease? If you have a heart attack at 51, would it be better if you try to address it right away? 

- Gary Lyons: The question is...? 

-(inaudible) 

- Gary Lyons: The question is, if you have disease that starts early on, should it be addressed early on? Absolutely. So the first thing to do is always to see your doctor, but your doctor's not gonna be a stem cell expert, and your doctor's not gonna be reading clinical trials on the web site about what's available. So people like yourself need to be proactive, and need to, I have actually informed my doctor about things, based on what I have learned from a variety of sources. 

- I knew your clinical trials here were started, but I didn't think that I was gonna be precluded from it. 

- Gary Lyons: So, part of the problem with clinical trials is that you have to fit into a very well-defined group. So, people who have heart disease but also have some other disorder, say, inflammatory bowel disease, or arthritis, or something else, will not qualify, because there are always people that get excluded because they don't fit into the well-defined group that they need. 

-(inaudible)
 
- Gary Lyons: Well, you never know till you inquire. And it doesn't cost anything to inquire. But you shouldn't take it personally if they say no. 

- Once this process has been started and it's moving along on its differentiation from a stem cell, is there anything that they know of that will stop it? Can you halt it in some way? 

- Gary Lyons: Can you halt stem cell differentiation? 

- Yes. 

- Gary Lyons: That's a very interesting question. So, what am I dealing with in the lab even as we speak? I'm trying to find a mesodermal cell that is something, so the mesoderm makes muscle, it makes the blood vessels, it makes blood cells, etc. 

So a mesodermal cell is what we want to find because a mesodermal cell will give rise to cardiac muscle in addition to other things. So here we have these pluripotent cells and we know how to keep them un-differentiated, and we know a lot about them, but we don't know anything at all about these mesodermal stem cells, or these ectodermal stem cells that will form neurons, or these endodermal stem cells that will form pancreas. And yes, we would like to be able to stop their differentiation at a stage where we can get them to multiply into the millions because we need millions of these cells for successful cell therapy. But do we know how to do that? No. But we're trying, we're trying lots of different things. But at the moment, we don't know how to do that. Yeah? 

- How many subjects are in your cardiac clinical trials, and what are their qualifications to qualify? 

- Gary Lyons: So the question was, how many people are usually in these clinical trials and what are the qualifications that are being requested? 

I recommend that you go to the web site, and for any clinical trial that is listed there, you can, by clicking on certain links, obtain who they are looking for. So go and look for those trials where they are recruiting people and they will tell you in very great detail the type of person that they are looking for, and if you fit in, contact them right away, because they spend a great deal of time trying to find people who will qualify for these clinical trials. 

- What about at UW? There are current clinical trials at UW, is that true? 

- Gary Lyons: The question is, are there current clinical trials at the UW? Absolutely, the only one I know about, because it's in my field, is Dr. Rovall, who is heading a study to isolate endothelial stem cells from the blood, and inject these stem cells that make blood vessels into the hearts of people with chronic heart disease to see if it will alleviate the disease symptoms. But I'm sure there are many other clinical trials going on here at the moment, I just don't know what they are. 

- Do you know how many people are participating in that one? 

- Gary Lyons: Do I know how many people are participating, no I do not. 

Since I'm not an MD, I haven't been actively involved in any of these trials, but the amount of information that's available on the web site is quite detailed and should be able to answer all your questions. Thank you very much. speak to you tonight.