Arteriovenous Malformation can cause stroke & disfigurement and is difficult to manage surgically. Dr. Wang’s research studies the molecular control of angiogenesis, currently focused on the functions of Notch pathways in arterial venous specification, leading to malformation.
You're at the cutting edge of cardiovascular sciences. And I'm your host, John Cook. I'm professor and chair here of the Department of Cardiovascular Sciences at Houston Methodist Hospital. And joining me in the studio today is uh doctor Lee Lai, who is an assistant professor in the Department of Cardiovascular Sciences. And uh doctor Lee La is going to be introducing our guest today. Um Good evening everyone. So today it's my great pleasure to introduce doctor Rong Wang, who is our speaker today. So Dr Rong Wang is a professor and Mel V Strauss chair and director laboratory for accelerated vascular research in Department of Surgery at the University of California San Francisco. Doctor Wang got her phd at the University of North Carolina Chapel Hill where she pioneered a study of angiogenesis using cystic inro bodies. Actually, our lab is uh used to use this method to differentiate human IP sc to and the C cells. It's good to know who is like um developing this uh develop this method. And Dr Wang did her post fellowship in the laboratory of uh Lauren James Michael Bishop at U CS F where she joined the faculty there and focused on the molecular programming in arteria Venus specification, concentrating on the knowledge and the would be two pathway underlying those processes. Her lab also explored implication of these molecular pathways in vascular diseases such as stroke using sophisticated mouse genetics with cutting age two photon live imaging capabilities. Welcome to the show, Dr Wang. Thank you. I really appreciate this kind of invitation from Doctor Cook and you and I'm really happy to participate in this uh um uh web webcast. Well, we're really interested to hear what you have to say, Dr Wong, you've been doing some amazing work in our two malformation, understanding the genetics of it, understanding how this uh abnormal uh vascular aberration occurs. And it's really a significant clinical problem which can cause stroke, it can cause disfigurement if it's affecting the face. So it's really a difficult problem to deal with also surgically. So maybe we can talk about your work in that context during the discussion. But I think first you're going to be telling us a little bit about the science behind avms. Correct. Absolutely. Yeah. Um We entered this field uh serendipitously and we were just studying programming and our mut developed the A BM and that's uh to my knowledge, one of the most robust, 100% A BM with all hallmarks of A BM that's opened this area of investigation for us. And we published the first page for 2005 at that time. Not much, uh um certainly not much is known as now for A BM. And not as many people in the broader angiogenesis field were paying attention on A BM. And now we see the whole transformation of the field. It's really gratifying. You said that uh it was serendipitous that you got into this field, tell us how that happened. So that was back in 2005, you said that you started getting into arteriovenous malformation. The science of that, my journey started much earlier. So when I started my lab, uh we were fascinated by the developmental biology field um and showing that there is a distinctive actual and Mo a Venus molecular programming which I'll touch upon later. Um At that time, I before that I was already interested in uh four because um it's our uncle gene when it's discovered it's uncle gene. But when it's cloned, the homolog of that uncle gene is not four. Well, uncle gene is called three integration three. And uh because I was in Doctor Jay Michael Bishop's lab and uh he won Nobel Prize because of the discovery of Uncle. And so uh in three is Uncle, the log is not full, which expressed in the vasculature very specifically, that's how I got interested in. And uh Furthermore, uh joining the Departmental or Developmental Biology study and understanding the art Venus molecular programming and large signing also play a major role. And in that context, we made the express a large, which I'll talk a little bit more later and turns out that those mice develop A BM. At that time, I must be, I must say we didn't predict they will get a BM. We did not know. Uh And then with all the um meticulous characterization, those mice indeed um uh exhibit the A BM pheno type 100%. And this has been followed up. This type of research has been followed up by many uh investigator, many labs since you're in a department of vascular Surgery at UCSF. Tell us how you work with the vascular surgeons, how you work with the clinicians, what you've learned from the clinicians that maybe he's informed your work. Tell us a little bit about that kind of interaction between the clinicians and the scientists. Um That's a great question. Uh It started with even um when I was looking for faculty position from a poster and I, that's before the time we, we we before translational research become more uh uh known. At that time, I just have a single goal that with all my um basic science education and training and the skill and expertise. And I wanted to contribute to something in my future career or in my um faculty position, contribute to something, understanding disease and finding treatment for disease. I felt that um human health and the diseases are the biggest challenge of our time. And DNA double headaches was discovered 1953. And at the time I was uh looking for faculty position. 50 years later, we still know many genes, but we still have so few um cure and so so few drug. So even today, I feel that is the great, greatest opportunity of our time. And uh I often tell my students um we now have great car, great uh computer and great phone. Um but we still don't know um as we would like to, to know about the disease and particularly how we treat them. So, um so basically I choose to join clinical department and in that context, I have been um continuing learning and as if I'm going, going to our mini me medical school and interacting with the clinicians, um vascular surgeons on our um routine basis. Um Both me and my lab and my lab has been in that environment um ever since. Um So, um I hope I answer your question um that we certainly, uh when we have questions about our research related to clinical aspects, uh not only the vascular surgery division, our department and the UCF uh as a whole, um my lab is very well connected to the um to the um um research uh and related to disease at the US. F and I liked what you said about science and the service of humanity that's uh struck a chord. Uh We have uh folks listening in and I'm going to give them an opportunity to ask questions during your talk. Um So if you don't mind, I'm just going to let them know how we do that. Um So for those of you who are listening, um, online, you can text the bay to 37607. So once again, you dial 37607 and text to Bay and then you can just text in your question to Dr Wong. Uh if you're, uh, if you're on online on your computer, you can go to pole ev dot com, enter and then respond to that. Uh So um I'm gonna do you have any questions for Dr Wong before we start? I think it's, I, I would like to hear her talk first. Yeah. Why don't we go to your talk, Dr Wong and then we'll have a little discussion after that. Sure. So um the title is Molecular, my talk title um as I posted is Molecular Regulation in Artus Programming and the Artus malformation or A BM. And today I'm going to, the molecular regulation is going to be centered on not signaling in this process. So, mm how can I not advance? Oh, here we go. Um So is a very interesting and uh I wanted to bring this up how basic science shape our understanding of very important medical uh uh related uh conditions. So, Natch was uh um identified uh this mutant Jola Mu with a NA wind blade, was identified in the thirties in Morgan, famous morgan Drosophila um uh mutant screen. And through many efforts, uh oxygen is known in Drosophila to decide the cell fate of two progenitor cell or in our in our population of progenity cell, they have two potential fates and not determining one fate. In fact, without not also determining the other fate. So notch is known to be universal, universal arbiter of self fate decision. So not determining by potential self fate. That is the classical function. The reason uh the mutant get not blade is there's a loss of epidermal cells and the reason not mutant exhibit this is not, there is a um a population of cell can give rise to epidermal cell or neuronal cell. And those express notch um become epidermal cell and those without notch become neuronal cell. If you have a notch mutation, you have a lot of epidermal cells, therefore not wind blades. It's a beautiful study. And and later the notch gene is cloned. Um what's really lacking and interesting is uh in the um uh in the co the vascular system, you can see this uh um um expression pattern and showing that one of but not receptor and other. And uh um mediators are um ex exhibiting or not downstream um target are exhibiting similar pattern that is expressed in artery, not in the vein. And in fact, many studies um have um through zebrafish uh mouse um have shown that not determining arterial and the venous fate super interesting and this decision may occur before the first embryonic heartbeat which challenged or um or advanced the understanding of what determine artery and vein. In textbook right now, perhaps it's still written that the differences between artery vein are determined by the hemodynamics largely. And uh here there is this uh uh genetic programming, determining artery nerve are certainly um provocative and um and and open up a new study um ever since. So, it's a very exciting area of study. I must also say that those genetic programming may actually mediate hemodynamic signaling. Even we think it's uh um we think it's making sense that many of the differences of artery in the vein are because the hemodynamic difference is exposed to the, the different vessel segment. However, we don't know um uh well how those hemodynamic differences are converted into biochemical cues that mediate the biological and the pathological differences between artery and vein. So I just wanna connect the genetic programming with the known uh hemodynamic signaling at the molecular juncture. Um So let's take a look. Um it differ in jos um in um zebrafish or um other organ model organism and diff in in Maman system. And this is a showing not synchrony in maia system mouse and human. There are four notch receptors in mammal and one through four, they are type one transmembrane proteins and um one and four are expressed in cell. Not three. For example, is a uniquely expressed in smooth muscle cell. Not two are expressed more, um not as uniquely and not four is expressed primarily in cell while actually expressed in other, many other cell types. And that's why my lab has been focused on not four uh for a long time. And the notch receptor is activate the when it's bind to the lion, which is also type one trans protein sitting on the adjacent cells. So it does mediate cell cell uh communication cell cell signaling. And the lion type one uh transmembrane protein. There are five of them in mammal, 12, delta 13 and four. And the one expressed in the cell cell are highlighted in here and many of them expressing uh smooth muscle cell as well. And my lab is more focused on endothelial cell. I my talk is a little bit in the cell centric. So um those express in the cell are highlighted. So the activation of notch receptor through like and binding and this uh cell cell contact um um influence um not receptor get activated. So what what it is this activation following? This activation is cleavage of not intracellular domain by gamma secrets. And this intracellular domain so called notch I CD then get translocated into nucleus and there it kick out transcription repressors and then contact the transcription factor and needs to not downstream target transcription. That is how not from cell cell communication to the downstream transcription mediating the self decision. I'm coming back to not four. And here we, I call it not four star, but this is the um the mutant originally named as the integration three. And this three is cloned in lab or identified in Hero lab. And by the way, Doctor Cowan Nobel Prize with Dr Jay Michael Bishop, the two labs were um were were together running together. And at those exciting time. And um so I did my post uh in Doctor Bishop's lab and also very, very interactive with uh the work and the colleagues from uh Harold lab and they um the all the, their lab and the co the subsequent colleagues. Uh And the in three here is also called four for simplicity is a mutant that without the extra domain and this mutant is constitutive Cleve so constitutive active. Um And um you know, uh the I CD large four I CD will be trans translated, translocated into nu- nucleus and immediate in large signaling. And I will be talking more about this mutant and, and in the subsequent talk. OK. Any questions so far? Keep uh no, not at the moment, please continue. OK. And then through this uh paradigm, um it's really interesting um And many people's work at least in here and some may have not been included. Um And, but there is a whole field of uh awesome developmental biology and uh really um reveal that there is uh at this thing in the cell are um signaling pathway determining arter molecular pate versus Venus, molecular pate. So, for example, um not vegan delta delta like four cannot activate the notch receptor and the leading to downstream target FMB two expression and repressing EPHB four B four, excuse me, Venus marker expression, even a molecular artur programming in the vein, then co TF two set upstream of notch repress a notch, also repress an FB two expression And uh actually um allow EPHB four Venus marker expression and the um providing a molecular Venus molecular programming. But what's the, this is uh quite well known. But what we don't know is exactly the physiological function and the pathological ramification of this important genetic signaling or the in the in development. And we wanted to know more about the uh post natal um um function of this pathway. And that's where leading me um to the um A BM. Uh I should have gave her a little bit better introduction. But basically, my lab made uh or me um um at the juncture of um towards the end of my post doctoral fellowship, I um made a mice mouse model where, where uh notch is expressed in um endothelial cell uh through our tetracycline inducible system. Basically, we express notch in endothelial cell, we can turn it on and off and it's only in endothelial cell very specific. And that mouse um it's published them uh since 2005, develop A BM And so let me give a little bit of introduction of the A BM. This is a disease. Uh Doctor Cook was talking about disfiguring in many cases, um very dangerous when it happened in vital organs such as the brain and uh lung and uh um uh many other um and tissue. So, um as you can tell this is a very difficult disease to treat uh no um molecular or no drug. And um there are interventions such as the surgery to remove it, but it's very, very dangerous. And there um there was a, a Aruba trial um basically is um um and asking whether the natural cause versus surgical intervention, uh which one is more safe uh or, or whether surgical intervention is beneficial uh in treating the uh the disease. It's a very controversial trial and it's very, um we, we want, I wanted to say it's complicated but the trial was ended because that uh the uh surgery um as the collected, the data collected were more um it, it were not beneficial for patients. So, um as you can, I just, I don't want to get into detail of that trial trial. It's very controversial, but I we we through this study, we understand how difficult to treat this disease and there's no uh um safe um and drug. So, a BM from its ology and this is a cardiovascular um audience. So I, I don't have to uh introduce in great detail. But we all know that artery, the fundamental microcirculation is artery and deliver blood to arterial and then um peruse the capillary and nutrient and waste exchange and the waste blood return from venue to vein. That's a normal uh microcirculation. However, in a VM, it's a clear artery directly shun blood to the vein, um displacement capi. So there's no nutrient and oxygen exchange. So you suffer ischemia at the same time, this high flow every is also prone to hemorrhage. So, and therefore, patient also suffer from a hemorrhagic insult. So, this is a disease um deadly or detrimental for two major problem. And that's basically um uh the core pathology, how it occur is completely unknown. Um We basically proposed a hypothesis that aberrant venous programming uh may be a molecular mechanism of the A BM formation. We are still continue pursuing this and many other level are uh are um sharing their results in this uh uh line of uh uh uh study. So this is the evidence leading us to uh for that uh um hypothesis in the proposal. So this is uh uh another molecular marker, arturo marker FMB two showing in blue and not expressed in the vein. It's only expressed artery, not in the vein in arterial, yes, but not in the vein. However, in the uh not mut we developed in here, we call four star mice. Again, those mice express not four in all in the cell. And uh in an inducible manner. And uh those mice develop a BM evident by those uh um torturous vessel connecting artery to vein directly. You don't see capi in this uh um image uh in the mutant. And uh what's interesting is the which is uh uh I hope you can see my cursor, right? You can see um can you. So basically, vein is the uh unlike the control vein, express FMB two as well as the A V connection or the A VM segment, they also express FMB two. So we show in this mice that we reprogrammed molecularly, at least the vein and the A V connection. So, unlike in the control, there is a specific demarcation of artery in the vein uh molecularly. And by this molecular um uh identification, the vein also express arterial marker as well as the A V connection and the Venus marker. Similarly in the control, this is the EPH GB four Venus marker and it's uh expressed in the vein not in the artery um but in the notch mutton, if you look at the middle panel, the Venus marker are uh miss consistent with the notch, arterialized the vein and, and uh repress the Venus molecular programming. And what's interesting is, as I mentioned, this gene, we can turn it on and off even in the affected the A VM mice in A BM, we turn it off. We can actually lead to the reversion of art programming as well as a VM, as well as uh um um clinical uh recovery of the mice. I'll show you the data in a little bit, but this data basically suggests that not fully capable and indeed artur the vein in this mice and in a reversible manner. So this is a summary of the data I just showed you, we propose in the control that there is the arterial molecular identity as well as the Venus molecular identity in the notch mutant. When notch is on the Venus uh molecular identity were repressed and uh the not reprogrammed the vein. Um and uh li leaving um arturo molecular programming in the mutant vein. However, this is reversible. We can um turn off notch and restore the Venus programming. Um And uh using this mouse model. Um At the same time, we also develop our uh uh collaborating with the bioengineer laser physicist. Uh We built a two photon microscope that's not commercially available specifically um benefit in um a vascular imaging. It's a so called the five D imaging. Uh We build a cran window, a mouse skull and the mice will be fixed and stear text. And uh it can go into imaging the precise spot over days. So we can for the first time uncover the disease initiation progression and regression and in a 3D at the single cell resolution over time, four D and with measuring the um um uh velocity of the of the blood So this five D imaging is an amazing um approach. And for us to, to learn many things, number one, we were for the first time to find that the A VM, the large vessel originated from capillary. So this is random imaging. And then we, then we go back once we find the A VM trace back and they all come from microvessel. And as shown here, um we also um actually let me advance. Uh we also were able to show that the A VM can also reverse back into micro vessel and in under this uh five D imaging. So, for example, in this case, we found a VM uh with uh abnormal vessel topology as well as the hemodynamics. So you can see they have a high flow and uh very um turbulence and as we turn off notch to and this turn not fall off and the abnormal vessel and the hemodynamics quickly reverse to normal, they did not disappear. It's a safe return. And this paper published in science translation medicine um featured on the cover and er um uh our um perspectives um basically um um really highlighting the importance and clinically, we only can use surgery and intervention to remove a BM. This is the first time we can safely turning off just one gene need, need, needing to save regression of the A VM returning our dangerous A VM with high flow to our flow microvessel. Um amazing. And then I also wanted to mention that not only a BM um pathology can, can uh be normalized mice suffer. Those mice are 100% suffer from hemorrhagic stroke or they display neural um uh dysfunction and just like uh many human uh suffer from um neuron, neuronal deficit. And the mice once we turn off for not for the same mouse quickly recover uh ever since. So I'm going to go back um to talk about uh that this quick um formation over days and the safe regression and leading us to think what did not do to the mice to the vessel leading to A BM. There are obviously meaning hypotheses and one of the one we pursued for a few years and uh hopefully we will publish soon is a paper impress right now. Uh Oh No paper in minor revision, not impressed yet. I hope it's impressed. Um And then we are pursuing this hypothesis that not actually affect the vascular tone in those mice. And that leads to the A BM initiation. Uh We have a many, many evidence in this uh um manuscript, but this is one of the vivid in um data that I can I wanted to share. So this is can the vessel isolated from cannulated artery from the um from the um mouse brain. And uh with the increase of pressure, it's known that the vessel will constrict compared to the maximal dilated stage, which is that of the line uh on the left and uh with increasing of the um pressure, the will constrict. And you can see the solid um black line. However, in the Mutter mice increase, the pressure is unable to um constrict, the vessel, the vessel fail to constrict and remain maximally dilate. So, this data, we have a many other data in vivo um vascular to analysis showing that those mice for sure um have um uh defects in vascular to um they are unable to constrict, they are dilated. Um And that is uh what we think um that A BM is forming. And uh we also provided the evidence. I'm not showing here due to the interest of the time that in us is the media uh involved in this process. So basically, what we are proposing is not for at least three in part in us and not, not signaling and affect the um or compromising the um tone of the vessel and beca because the uh lack of the constriction and the flow um perpetuate a inflammation that I ask you a question about that. Um The there, there could be what you're talking about is the loss of cerebral auto regulation, which is really an important um physiological response to changes in pressure in the cerebral vasculature. It's a way to control the to reduce the uh pressure that's transmitted to the to the brain to the microvascular. And if you, if that's lost in the cerebral arterials that that can cause a lot of problems downstream. Um Do you know, I, I, is this purely a functional abnormality or is it also a structural abnormality? For example, it's a vascular smooth muscle of the arterials intact in these vessels, not for mutant vessels that have lost the ability to auto regulate. Yeah. Yeah. It's under investigation. Very good question. And uh uh I don't have the data to show yet and we have uh work, we have a work in progress. All right. Yeah, thank you. Uh But in this study, we did show that uh uh hydrogen peroxide, we use very sophisticated uh uh mass spec analysis uh collaborating with the um uh redox biochemists. Um And we show that the um mass sensitive um hydrogen peroxide production is red or is increased that could beyond other factors. And uh that could also compromise the vascular tone. So there might be multi um avenue, multiple avenue leading to say, reduce the vascular tone. And this is one of the uh the one we nailed down and with um very clear um biochemical evidence. Um I didn't show those data. Uh Hopefully the paper will be coming out soon. I'm happy to share that. Uh So, so basically what I wanted to end is uh um also very exciting. Not only those uh A BM can uh safely regress and completely regress the A VM uh when turned on later. And at least one month later, we analyzed the very little relapse. So there is also hope, what we think is uh even if A BM were formed, they are able to completely regress and at least they using this uh this model and uh they completely regress the uh organ and e even later, maybe due to age and when not flow is turned on, it will have much delayed uh if not, um um you know, uh even more prevention of future A V information. What I'm trying to say is uh the regression followed by even if the uh same insult um uh is imposed, they um the body possibly due to age. I believe it's due to age after treatment. A BM often occur in young people after treatment in adults and there might be um hope um for um for minimize and relapse. So, and this is the paper we published in journal of experimental re uh medicine um a few months ago. Uh in with that, I'd like to thank the um lab member, past and present for this work uh Lawrence as well as uh well, their name were not here. Um Patrick Murphy and uh um Tyson Kim uh as well as the Tim Carson who um initiated this work. And I also wanted to thank many of the current lab members um um as well as the hazel um um for the current contribution. Uh I do want to mention the um the um um vascular tone data. I want to particularly mention for carrying that work uh uh to um this stage. Um I wanted to thank the collaborator Chris Schaffer from Cornell, the um bioengineer laser physicist uh whose lab we have a collaborator for almost 15 years on this remarkable journey. And um Manuel Navis lab from UC Davis particularly met then in his lab um and current Met is also an independent investigator in Louisville, Kentucky. Um Their work uh what I showed in the isolated can the vessel. And Jessica from Medical College of Wisconsin is the redox biochemist, awesome biochemists and that I mentioned um in our work and as well as other um who contribute to, to this work. Um Thanks for the funding and I dod H A uh TRDRP which is uh California uh tobacco related uh uh research program. Um Finally, I just wanna um give our, our um um posting that we are recruiting if you are interested in this type of work. Um Please contact me. This is my email. Thank you. Thank you, Dr Wang. And it certainly does look like a very nice place to do your post doc somewhere there in San Francisco. Um Well, that was fascinating and I, I think I'm going to start with a question, but before I do, I just want to let our audience remind our audience that they can join us with questions uh text to, to 37607. So call 37607. Text to or you can go to pole V dot com and enter. Um So thank you for that Dr Wong. I have a question for you. Um I've had several patients with our two venous malformations and particularly when it affects the brain, it's a terrible disease. And as you mentioned, the, the surgical treatment is not very successful. And the another approach has been to use em embolic approaches to feed a catheter into the A VM and use Embolic approaches. And that can be very useful if someone is bleeding and is having worse symptoms because of bleeding. But long term, it doesn't seem to cause the A VM to wither. In fact, it seems I've had many, seen many cases that where you, you, you try to treat it surgically or with embolization and it gets worse. And so I'd like your thoughts about that. What is causing it to become worse when you intervene upon it surgically or with the catheter. The other thing I want you to remind us about is embolize our surgery is not going to be the answer because you still are left with an area around that. A VM that's perfused by that. A VM that is not perfused. Well, it's ischemic, correct. So tell us, tell us about, you know, what, what, what, why are these things so aggressive? Why is the A VM so aggressive and resistant to surgical or catheter based treatment? Mhm. Um, I, I, I'm happy to share my thoughts. And I'm I'm not a clinician treating the patient and uh um many colleague um may have a better idea. Uh But my thought is that um the, the reason A BM is so aggressive is uh my thought is because the the vessel may have compromised the um constriction. So if you imagine your vessel with a high flow without the capability or with compromise the capability for constriction and you will get a um higher flow, keep getting higher flow and the vessel getting bigger and the bigger flow. So that's our, our bigger flow, wider diameter, wider diameter, bigger flow. So it's a perpetuating process until disruption, until rupture or until something terrible happened. Basically rupture. So, rupture is the biggest problem. So that is how the destination of the disease by, by its virtual um it's difficult to treat and the surgically removed, you will have to remove uh completely. And also it does not, in my view, um treat the uh roots, which is if it's a vessel, um constriction problem, surgery is not going to um to complete and minimize that. And furthermore, it's known I didn't talk about that. Our work and others also proposed that uh vessel during um repairing um active angiogenesis um are more prone to a BM formation. So that's why sometimes after surgical recession and there might be recurrence. And in terms of uh Doctor Cook, you asked that uh sometimes the afterwards is getting even worse, correct. And for that one, my thought is embolization is not complete you ay the major conduit or a and in fact, that may lead to higher flow in the adjacent um um a vessel and therefore may push those vessel and even worse and more of them. So that would be just one thought that makes sense. He has a positive modelling. Yeah, Doctor Lela has a question. So uh Doctor Wong, thank you for your uh talk is very interesting. So I guess I'm more interested in the molecular mechanism of this disease. So I uh in your talk, you show very nicely with all the mice work. You show that notch plays an important role in the A VM formation. But uh uh do you see the notch up regulation in a VM patient? Absolutely. We, I didn't show for the interest that I thought I can only allow 15 slides. So I cut many of them. But um it's a great question and it gave me opportunity to explain that. So, um and uh um uh and not um um downstream target, uh quite a few of them are, are up regulated in a BM compared to biopsy or autopsy controls. We did that work, we published that work um and then followed, subsequent to the other lab or about the same time, other lab also um report to the labs and including not four is upper. So, um so far there are quite um um some publication uh showing Not signy is uh up in um human A. Thank you. And uh I I may have another question regarding the core pathology of A BM. Because when you show the illustration of the pathology of A VM, you showed, oh, there is uh re vain uh contribution to the A BM. But there is also capillary contribution to this A BM because in the A VN, there's the cap, it seems like the capillaries are gone. So where do you, where do you think those capi go? And uh what do you think happens to capillary? Yeah, very good question. And uh uh um uh II I need to explain this better when I say core pathology that's primarily from clinical um um perspective. So those drawing are from uh clinical um largely from clinical understanding. Ie that's uh when it's well formed um diagnosed the A BM or that pathology ie the artery shank to blood directed to the vein. There is less capi around. Um so and so forth. So I talked about that at the same time, I also talk about in the mouse model that we find that cap selected the cap in March to form a VM. And so certainly cap is involved in that. And I didn't say is that as a BM in our moss mouse model continue, they will develop similar pathology like human. And so if you imagine when there's a high flow, it be shunt, their adjacent capi resistance is too big and the flow would not go to those capi they will just shunt from the high flow. So those cap will have less and less flow without flow or less of flow will leading to their regression and the disappearance. And that continue to feed the A BM form information. And I hope this uh connect uh um this con I connected the dots on this point. And I answer your question, me, that made sense. The one question that I have is why is this process or how is it that this process is so localized? Because if it is a notch mutation that's responsible for the A VM, there's something else that must be going on that explains the localization of the A V to a certain part of the brain or a certain part of the tissue that's affected like the face. Great question, Doctor Cook. Um You are certainly uh a vascular biologist. So you can ask this question um uh in inside for vascular biologist. What, what it is is the, is the um in my view, our view is the when the vessel lose constriction. And so yes, the large expression is pervasive. And we also see that the popular enlargement also um widespread and the focal development of this is uh um is due to the fact that the vessel don't constrict and then the flow basically take over the, the flow uh will drive with the um will drive the vessel um um continuously grow um with the most energy efficient. So um the proximal and uh vessel with the topology that can easily uh adopt this A B flow will gradually take over the um other adjacent vessel. In fact, some A BM will regress when we watch it. During the two photon imaging, it's not initially vocal but eventually become vocal. I think this become even more apparent in in human case that it may grow even longer time. That's one reason. The second reason is uh uh I didn't touch upon is that we become more and more uh realize that uh in, in this paper, we also include, we only detect the 60% of the endothelial cell express large form, 40% didn't. So, um however, the phenotype uh is uh strong uh throughout. Um So we think that the even the um chimeric expression or um uh subset of cell express uh natural style or abnormal can cause a VM. This is related to um in human. Um somatic mutation is found in um brain A VM. Uh somatic mutation by definition um may be sporadic. And so that is another um possibility of focal A BM. I hope I answered this doctor. Yeah, that, that actually makes a lot of sense to me that a sporadic mutation, a somatic mutation could be responsible for the localization that that does make sense. And that actually could explain also why sometimes you'll see an A BM in the brain. Sometimes it's in the spinal cord, sometimes it's in the face, like the picture you showed us, sometimes it's in the hands. And so when, when those different tissues are looked at is, is the, is the mutation still the same? Is it not for mutation? Or are there are tissue specific mutations that are responsible for a? Uh let me just mention, yes, semetic mutation is uh our um is a um a great explanation for focal A BM. But even in our mouse model is uh uh is the um why do they express in um vessel segments or vascular beds? And we still do, we still see focal A BM. So certainly hemodynamics, what I'm talking about the flow driven. Uh A BM is also another potential mechanism for for focal A BM as far as uh the uh mutation. Uh In fact, the semantic mutation first identified in brain A BM are um KR mutation uh uh not, not. And in other um A BM, um there are hereditary A BM such as the um he CD uh hemorrhagic teens, uh hemorrhagic hereditary hemorrhagic generic. He are a certainly a known gene. Um But in other sporadic A BM, what are the other um mutation are remain to be um to be identified? I think we have time for one last question. I'm gonna let Dr Lai give it. Yeah, I, so I think my last question is more related to what uh I'm I'm interested the most because uh my studies uh talk about the cell transition from fibro cells to end the cells under the condition of hypoxia, which is um also happening in the A VM. So I'm wondering whether in the A VM you have observed like other kind of uh self a transition or what's your opinion of, of uh the contribution of uh maybe fibroblast in this uh in the this disease? Hm. Uh We certainly have not looked at the um um fibroblast. Our gene is uniquely expressed in doce. So we focus on the endothelium programming and reprogramming. Um However, um we think endo send signal, not in endo signal, affect uh the M cell nearby. So this is our follow up study to look at the adjacent cells even including immune cells. So, uh it will be um it will be interesting to learn more about that. Thank you. We uh actually, you know, we just got a bunch of questions from our audience. They just came in and uh maybe we can, you can just address a couple of them. Um One is uh can uh a VM occur? Can it spread to other parts of the body if you have an A VM localized in the brain, do you, do you see it affecting, you know, popping up somewhere else in the patient? Certainly A BM can be a multifocal versus uh, you know, um, focal, uh, especially hereditary A VM. So, whether it's spread, I can contagious from one to the other. Iii I don't have the evidence to think that. So if the vascular is abnormal, it can be multifocal. Ok. And then it's a related question. There was a question about which are the most commonly seen A V MS if they occur throughout the body, which are those that are more commonly seen? Um Wow, what's the common thing? Um uh, well, brain A BM is the most dreadful. Uh So I think that, that, uh you know, uh draw a lot of medical attention and dermal A BM. I know many A BM researcher in the A BM program are through dermatologist. So, um especially like body cover uh widely um throughout the body. So, uh certainly there's no A BM, liver, A BM, um spinal cord A BM, I guess, I guess one last question. And that is, uh, since we talked about the, the, the poor outcome with, um in many cases with surgery or, or with embolization, particularly in the brain, um Are there, is there something from your work that is coming down the pike that could be useful of molecular therapy based on your work with not four. We'd love to um we are pursuing those. Great, great. Well, that was wonderful and hope for the future understanding the cause of A V MS. Thank thanks to you, Dr Rong Wong. Thank you for visiting us tonight and joining us at the cutting edge of cardiovascular sciences. Thank you, Doctor Cook and doctor um and for this opportunity and thanks for the audience. Wonderful. Thank you. Bye.
