PhD student Arianna Arbona discusses her exciting work isolating brain-derived microvesicles from saliva and blood to identify early biomarkers of Alzheimer’s disease. She shares her techniques, the promise of digital PCR, and how curiosity fuels her scientific journey.
Can you detect Alzheimer’s with a spit sample? That’s the question driving Arianna Arbona’s exciting research at Universidad Pablo de Olavide in Sevilla, Spain. In this episode of Absolute Gene-ius, she shares how she’s isolating microvesicles from saliva and blood to identify early biomarkers for neurodegenerative diseases like Alzheimer’s—an effort that could one day lead to minimally invasive diagnostic tools.
Arianna describes the scientific and technical hurdles she’s overcoming, from low vesicle concentrations to validating the brain-specific origin of those vesicles. She also reflects on her previous lupus research, where digital PCR enabled detection of faint mRNA signatures that qPCR missed—making it an essential tool for rare target quantification. Her future plans include integrating immuno-PCR and multiplex assays for more sensitive and multi-marker detection in Alzheimer’s and beyond.
In the career corner, Arianna recounts her journey from the Canary Islands to Helsinki to Sevilla, balancing passion, mentorship, and a healthy sense of humor. She talks about working through uncertainty after her master’s degree, the mentors who kept her smiling, and how an early accidents taught her resilience. Her message to aspiring scientists: follow your curiosity and don’t be afraid to change direction.
Visit the Absolute Gene-ius pageto learn more about the guests, the hosts, and the Applied Biosystems QuantStudio Absolute Q Digital PCR System.
Jordan Ruggieri00:00
Welcome to Absolute Gene-ius, a podcast series from Thermo Fisher Scientific. I'm Jordan Ruggieri, and alongside Christina Bouwens, I'm excited to introduce today's Gene-ius Arianna Arbona. Arianna is a PhD student in biochemistry and neuroscience at Universidad Pablo de Olavide in Sevilla, Spain. Her research centers around early detection of Alzheimer's disease, and we loved learning about how she uses digital PCR and other great tools to advance her work. Thanks for joining us for this fascinating conversation. We began by asking Arianna to describe the different markers that she looks for in blood and saliva and how she goes about locating them.
Arianna Arbona00:54
So right now, we're trying to find microvesicles in those fluids. So that's really difficult, because we know there are microvesicles in all those fluids, but it's really difficult to isolate those. So we don't have any protocols or any idea how to do it. There are some studies doing that, but it's really difficult, once you have them, to make sure that you're isolating the right microvesicles. So the idea would be like in the brain, the cells are producing these microvesicles, and they might be going around in like around the body, in those microvesicles. So these the cells produce those and then they secrete the microvesicles to the blood or to the saliva. And we're trying to find those microvesicles because they could have important or some information regarding what is happening in the brain. So we're trying to find some, maybe proteins or nucleic acids that could give us any ideas what is happening.
Jordan Ruggieri02:01
What about those microvesicles are difficult to detect? Is it simply that they are there in very small amounts, or is it actually something in the structure of them that makes it difficult to isolate or to discover?
Arianna Arbona02:17
The main problem would be the concentration, yeah, it's really low. We don't have a specific like number, but it would be around 1% of the things we have in saliva, let's say, because the saliva, it's 99% water. In that 1% you need to find maybe a 1% that would be microvesicles. And then in blood, it's something kind of the same. But the thing is that we could have microvesicles coming from all the tissues and all the cells. So the difficult thing would be to find some markers to tell you that those microvesicles are actually coming from the brain and not from another tissue or organs.
Jordan Ruggieri03:03
Can imagine too, you have the blood brain barrier for a reason, right? Is there, is there some of that as a factor as well? As you know, we know that there's a barrier from what can get in from the blood into the brain, but does, does it work the opposite way, where it's actually even more limited of what's getting from the brain into the blood?
Arianna Arbona03:21
Yeah, yeah, that's all the thing. The good thing about the microvesicles is they're, they’re really small. So as they're that small, they can cross the barrier, and then we can find them in the saliva or in the blood. It's not completely sure that those vesicles coming from the brain are in the saliva. We have that hypothesis because we know that the saliva, it's right next to all the blood system, is like passing and in contact with the saliva. So as we know that we think that some of those microvesicles could come to the saliva. And we thought about the saliva because it's a much easier thing to have from a person, so some of them didn't like to have blood taken or would be maybe your fastest way. So that's why we thought about saliva first of all. And then we're trials with blood, because we know there's always more things in blood.
Christina Bouwens 04:22
Is it very important to get whole micro vesicles intact to do your analysis? Or are you just looking for, you know, those signatures to be present, even if they've kind of degraded? I imagine, you know, it reminds me a lot of what we talk about for oncology and circulating tumor DNA, and those pieces are just bits and pieces. So is it similar or different?
Arianna Arbona04:42
It's really difficult to know if you have the whole microvesicle, or if you're not. There's actually not a way to know that, because we know that those vesicles have some proteins in their membrane. So if they have those proteins in their membrane, we're trying to capture those proteins, and when we have a positive in those proteins, we say, “Okay, then we have those microvesicles.” But you never know if you're actually capturing the whole microvesicle or they're just free proteins you have from in your blood or in your saliva.
Jordan Ruggieri05:15
So it sounds like on one end, you're looking at proteins in the membrane to make sure that you were actually getting the right microvesicle. But what exactly are you trying to measure in terms of an identifier that the subject might have Alzheimer's or have a, you know, a pre-existing, or the start, right, the onset of something like Alzheimer's?
Arianna Arbona05:39
Once we have the saliva or the blood, we start extracting the microvesicles from there. And once we have those, what we're doing right now is trying to immunocapture those microvesicles. So we know certain proteins are in the membrane, and we tried with magnetic beads to capture those microvesicles. And then we can see in a western blot if we're actually capturing those micro vesicles or not.
Jordan Ruggieri06:13
Yeah, no, it makes sense. And then once you once you know that you've captured them, what exactly are you looking for to see if they may have Alzheimer's, you know? Or even a, they're moving towards that right, a predisposed right to kind of move that direction? Is there, are you looking at a DNA signature or proteins within the microvesicle to help kind of see those different levels?
Arianna Arbona06:41
So the thing is that as we have the two groups, the groups that we already know that they have Alzheimer's, in the group that would be not having Alzheimer's yet, we can compare once we have, let's see, let's say we can cut, like extra, extra and isolate all the microvesicles from both groups. Then once you're completely sure that you have all the microvesicles then you can compare the information they have inside, either proteins or nucleic acids or whatever. So if you can compare both groups, you can see if there's enrichment in one of them in something, and then we can start studying that protein and what it does and whatever. And then we're also having a look other protein and all the markers that we already know that are using in other studies.
Christina Bouwens 07:33
Maybe one more question about like this, this like kind of signature you're looking for. Um, like once you've identified, you know, I have the right microvesicles, how many types of markers, both protein and nucleic acid, do you look for in that signature?
Arianna Arbona07:46
We're trying to find in literature, too, and like published papers, all the proteins that they have described, and all the markers that have described. And we're trying to find those in the microvesicles, and then we're just doing proteomics and see whatever is inside them.
Christina Bouwens 08:06
So maybe, if I just, if I'm understanding right, like, right now, we're kind of in the process of identifying that signature more than we actually know what it is, or more than one person has a signature that we're looking for? Maybe a good transition. So you know, at Absolute Gene-ius, we love to talk about digital PCR, how do you use digital PCR as part of this process? I know we talked a lot about, like, how we get to the cells that we're really interested in looking for, but could you give us a background on how you find dPCR useful?
Arianna Arbona08:34
So we're not doing, using digital PCR yet. We're trying to do immunocapture with PCR, so immuno PCR. But we're still like, we're exactly in the beginning of it, so we're still having a lot of problems. And as this is a new technique, and no one is working with microvesicles, there's no protocol or no whatever to use. So every time we buy something, we try to do a PCR, we try to do whatever, we never find something because there's nothing published yet about this. Every time we buy something, we say, “How can we use this with microvesicles?” And no one knows. So then we need to, like, run hundreds of experiments until we find the right conditions to do everything. So we do have the idea to use immuno PCR, but we're still working on it.
Christina Bouwens 09:27
That's fantastic. Yeah, you're truly trailblazing.
Jordan Ruggieri09:31
Another question, you know, we've talked about this in the context of Alzheimer's. Are you doing something similar for biomarker discovery or research for other conditions?
Arianna Arbona09:44
We do know that, like neurodegenerative diseases, they all share some kind of background, or they all have some things in common, so we always try to have a big view of what it could be we could have. So we do not just focus on the things of one disease. We usually have Parkinson's, was the one we're having, like most more things in common, but we always try to find things regarding the brain. So if it's a disease that affects the brain, we can always have a look and try to find similarities with those.
Christina Bouwens 10:27
So another aspect that we always like to talk about here is the idea that, you know, and it was a theme of our of our previous season, I'm sure it'll come out in this season, is the types of tools that you're using to accomplish a research. It's never a one-fit solution. So we talked a little bit about western blot. What are some of those other like tools and techniques that you're using to identify signatures?
Arianna Arbona10:48
So first, to isolate the microvesicles, we're using size exclusion chromatography. So we tried several types of extraction techniques, and we saw that the best one, and the one we were having the best results with was with the chromatography. So right now we're using that one, and then we saw that the best way to immunocapture those microvesicles was with Dynabeads. So when we're using this magnetic capture to have those. And we always use western blot to check what we're having if we're having positive, immunocapture microvesciles. I think that's most of it what we're using right now.
Jordan Ruggieri11:39
I know at one point we discussed your work on systemic autoimmune diseases. Can you elaborate a little bit about what you're doing on the research you're doing on those as well?
Arianna Arbona11:51
So I already finished that one and we were studying lupus. So the thing would be that we were trying to see in a multiplexed digital PCR. So we designed with Thermo Fisher, the TaqMan probes, and we had four different genes that we were trying to see in those samples we have from lupus. So we designed the probes in a way we could measure four genes at the same time in one sample. So the idea would be to have a faster and easier way to see if you already know, like you already have a sample, and you want to test the levels of three, four different genes regarding and that we already know they're affected in those, in that disease. So then you can, just with the digital PCR, have the levels of the four of them at the same time.
Christina Bouwens 12:54
So then maybe to also ask a parallel to your Alzheimer's research, are you looking when you talk about nucleic acid signatures, are you talking about gene expression, so, like, the actual functional side? Or are you looking for those markers, and I know we hear a lot about like specific, like germline mutations that can make you predisposed?
Arianna Arbona13:14
We were more interested in the gene expression. So we were wanting to know the expression of those four genes that we already know that had something to do with the, with lupus.
Christina Bouwens 13:27
So maybe to kind of parallel, um, you know, looking back at what you were using for lupus, can you describe why dPCR was helpful for multiplexing in that context, and then your future plans on how you might integrate it into the Alzheimer's research, and if there are any parallels?
Arianna Arbona13:42
So the good thing about the digital PCR, we were first trying to do it with qPCR, but the amount of DNA in those samples was so, so small, we cannot see it with qPCR. So that's why we moved to digital PCR because there you can see, when you have four copies, you can already see the signal, and you can already have a signal with the TaqMan probes. So that's why we moved to digital PCR, because we had a really low amount and with that technique, it could give us a really good view of what was happening, even if we didn't have enough.
Christina Bouwens 14:24
Yeah, and you said something earlier that piqued my interest in your Alzheimer's, when we were talking about immuno-dPCR. So are you thinking about integrating like, like, protein detection into dPCR? Like, is that where it'd be useful, or it would it be the same like, just to get better resolution for gene expression signatures.
Arianna Arbona14:41
Yeah, I think it would be useful to have better like, if it's still the same, we're still working with a sample that has really low amounts of what you want to find. So I think digital PCR would be useful in that way, because you always can see with digital PCR things that you cannot see with other techniques. We were still in the beginning, so we still have a lot of things to do.
Jordan Ruggieri15:04
It seems exciting to be at the beginning sometimes in in research. It's a lot of exploration and unknowns, right? And just trying things to see, to see if you can find some, some different either parallels or something that stands out, that's worth investigating deeper. I actually want to go back a little bit and talk a little bit about some of your autoimmune disease research. Can you talk a little bit about some of the targets and expressors that you were looking at?
Arianna Arbona15:38
Well with all the immune diseases, there's always like interferon signature. So we do know that the interferon signature, we cannot measure the interferon in in blood. That's the thing. There are very few techniques to measure the interferon in plasma. So the idea was to use those genes to have an idea of what was happening with interferon. So we do know when the interferon increases. All these genes increase too. So we wanted to see with these genes, like an indirect, for like indirect way to measure if the interferon what's increasing, because they're still trying to find a way to measure that in the in blood. But there are not really good techniques to do that.
Jordan Ruggieri16:30
Instead of trying to measure an interferon protein in the blood, you're looking at different gene targets as a way of approximating if there would be more or less in the blood. So would you be looking maybe more at mRNA and like as it's on its way to maybe, you know, be translated into those proteins, right? You're looking more at maybe those mRNA expressors to see if they're elevated or decreased?
Arianna Arbona17:04
Yeah, we were trying to measure mRNAs. The thing is that they were really, really low copies, right. Really low number. So that was really difficult, because you could maybe have two or three copies. So then it was really difficult to measure those. That's why I was doing these with the RNAs, because in that way, we had not many, but a bit more copies. So then the PCR was a bit easier.
Christina Bouwens 17:33
Yeah. I was going to ask, actually, if there's any kind of special sample prep, like to bring me back on when we were looking at cell free DNA, you know, running the tubes from the hospital to make sure that you separate everything before everything starts degrading. The half-life of RNA has to be, has to be much shorter. So how does that impact you, yeah, is there anything that you're doing up front to make sure that your time point is as accurate as possible?
Arianna Arbona18:00
So we were working with hospitals, and we were having the samples, the same day they were extracting the samples, we had them. So as we were working, like, that's that connected with the hospitals, it was a bit easier, because if you do, like, if you get the RNAs after a bit, like, a long time, then you won't get anything. So that was the good thing, because we have connections with the hospitals, we can keep a follow up of those, and then we have the samples the same day.
Christina Bouwens 18:31
That totally brings me back. So you're also running to and from running your ice buckets!
Jordan Ruggieri18:36
I am. I've worked with RNA a little bit in my past as well, and I have to say, my experience was, if you look at it incorrectly, it starts degrading. So I can only imagine some of the complexity of making sure you get something that is as close to what's actually happening in the subject as possible. Can you talk a little bit, again just because I think it's it's interesting, and I think it would be useful for our listeners as well. What, what are interferons and how? What role do they play in in in a body?
Arianna Arbona19:12
So they're proteins there you can find in blood, and they increase or decrease depending on what is happening in the body. So when, for example, you have an infection, you have a virus or whatever, you can see the levels of those proteins that increase in your in your blood. And then with some others let's see, immuno diseases and so on, you can also see the how the levels of interferon change in the in the blood.
Jordan Ruggieri19:45
They're kind of a signaling protein, right? So they are produced when you have some sort of virus or infection to alert the body and alert neighboring cells that there is some sort of infection happening. Is that a correct assumption?
Arianna Arbona20:03
Yeah, yeah, yeah. So the cells produce that every time they let's say they have an infection, or they have some kind of disease that is kind of, yeah. For example, with the autoimmune diseases, you can see how the cells are producing those proteins, because they do have something that is not working in the right way, let's say.
Jordan Ruggieri20:28
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Christina Bouwens 20:41
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Jordan Ruggieri20:56
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Christina Bouwens 21:20
Let's go back to our guest.
Jordan Ruggieri21:27
Arianna, well, it's time for our career corner portion of the podcast where we talk a little bit about how you got to where you are today. Can you give a little bit of background on your educational journey and your career journey?
Arianna Arbona21:44
Yes. So when I was in high school, I was, like, really interested in all the biological parts. And every time they explain something to me, it sounds like I don't know, fascinating, fascinating, because it seems like everything is connected. So I was thinking like, how is it possible that everything is connected in such a perfect way? So every time you touch something or you see something happening in one cell, you can see how in another cell, in a completely like separated part of the body, is also showing that something is happening. So I was fascinated by that. So I decided to study biochemistry. I did that in Madrid, and for my last year, I decided to, to do an Erasmus and go to Helsinki. So, there I, like, did a lot of labs and so on, and I really liked the genetic part. So I was fascinated by the genetic part, and again, how you can have just in four letters, all that information and all the things happening just from four letters, if we say it in a like, simple way. So then I did my masters in genetics, and I finished my master's last year, and I was kind of not lost, but I didn't know if to continue in that part, because I knew that there were some other fields that I'd like to. So I, in the end, I end up here in, I'm in Sevilla, and I'm doing this, this my PhD in neuroscience. So I also like this part, and I also see how you can apply the genetics and so on in everything you work with. So it's not that I studied genetics, and now I don't apply it anymore, and I'm studying neuroscience. You can always mix them and try to find similar things in both of them. So that's what I'm doing right now.
Jordan Ruggieri24:00
That's amazing. You know, you talked about, you know, leaving Spain and, and studying in Helsinki, what was it like studying in a different country where there, was there some really good value there that that you brought back as part of your PhD? And what advice would you give for anyone that might want to study science in it in a different country?
Arianna Arbona24:21
So I really loved that experience. I knew, and I heard that the one of the best educations we have in the world is in Finland. So when I had the opportunity to go there, I didn't hesitate. It was like, “Yeah, I'm going. I don't care.” So I'm, I have to say I'm from Canary Islands, where it's usually like 20 degrees all the year, and then I moved to a country when it was minus 20. So everyone was like, “What are you doing here?Like, seriously, what are you doing here?” But I really loved that, and I learned a lot, and it was a bit different of what we're used to in Spain. So the education is, I would say it's better. Sorry to say that, but I would say it's better, because they really know how to plan everything, and they really know how to make you learn. I would say in the best way you can learn. So I really love that, and I really love, loved how easy it was to, in the scientific part, how easy it was to go to a lab and start practicing and so on. Maybe sometimes here it's more like you need to have all the papers and all the things, like all the permissions to go to a lab and so on. And there it was just, I talked with a teacher and said, “Listen, I would really like to learn more about it.” And he said, “Yeah, come tomorrow to my lab and we can see what you can do.” So I really enjoy it there. And there were also, like so many opportunities, and all the labs were super connected. And I think it was pretty easy to work there, but as the scientific part, always super connected. It's true that it's international, so you can always understand and do the things they're doing there, because that's the good part about science, that it's international and the things you're doing here, people from China would understand it too.
Jordan Ruggieri26:18
Did you have any mentors along the way? It's a theme we we've heard from a lot of our guests that mentors have played a really critical role in in getting to where they are in their career. Um, did you, similarly, did you have any mentors that that played a critical role?
Arianna Arbona26:37
Yeah, see, I think when I did my bachelor thesis, my teacher was, he was amazing, and he was always so happy. And even you made 100 mistakes, he was always so positive about it that he also made me stay, made me want to stay in the lab. Because sometimes it really depends who you're working with, how it, how you feel about it, and so on. So I think when you have someone that is really positive next to you, things go much better.
Jordan Ruggieri27:11
That's a great, that's great to, great to hear. And I think a good piece of advice too. You know, you mentioned for you as well, it was difficult to make a decision after your master’s on which direction to go in next. How did you approach that problem? How did you end up coming to a decision?
Arianna Arbona27:33
So the thing is that after I finished my masters, there's kind of the question if I'm going to do my PhD, or if I'm not. So you always have the pros and the cons. And I knew I really liked the lab, and I knew I wanted to maybe do a PhD, because I still wanted to learn more. So that I said, “Whatever I hear, and I feel like I'm doing it, I'm just going to go with the flow and do it.” So I heard about this project, and they talked to me and explained everything, and I was amazed about it. So they were talking to me, and it was like, “I want to hear more. I want to learn more.” So that was it, I said, “Okay, this is the one.”
Jordan Ruggieri28:17
What advice would you give for anybody that is looking to maybe follow a similar pathway to you and get into the sciences?
Arianna Arbona28:26
I would say, just to enjoy it, to stop maybe thinking about what if, what if the, what if this doesn't work? What if I start something and then I don't like it? I think you don't need to think about it. You just need to do what you feel. And then there's always time to change things, to move to another thing. So I think it doesn't matter, even if you start something and then you see that is not the way you want to do it, you can always change it. And of course, you'll learn something for from it.
Jordan Ruggieri28:59
That's awesome advice. I've, again, I echo that as well. It's rarely a case where a decision you make is 100% permanent, right. You can always change your mind and go back and try something else. It's the backbone of even running experiments in science, right, is you pick something, and if it's the wrong thing to pick, you go back and you try again a different way. So it's good advice. I have one more question. It's a two-parter here; we ask this of everybody. What was your proudest moment so far in the lab or in your career? And on the other side of the coin, what was maybe your most embarrassing lab moment?
Arianna Arbona29:46
I would say that we the best one that would be with my bachelor thesis, because it was the first time I was kind of actually working in a lab. So when I saw that I was getting results there, I was so happy about it. And I have to say, I don't know if it was lucky or it was just that I worked really hard, but I got the results they were trying to get after so many years. And I started there, and I was working with cells, and we were trying to differentiate those cells, and we were doing that protocol, and it took, like, eight weeks, and we were doing eight weeks, nothing, eight weeks, nothing. And at some point it worked, and I was so happy about it. And I really loved those cells. I was like, in love with them. I was like, “Oh, they're so cute. They're working, so cute.”
Jordan Ruggieri30:36
That's awesome. What about what about your most embarrassing moment?
Arianna Arbona30:41
Yeah, I think it's so easy to make a mistake in a lab. Like, I think I make mistakes every day. Every day. So I remember once I like, I made a fire. So I was trying, I saw that something was burning, and then I was trying to stop it, and then I put it in the wrong place, and then everything started on fire, and I was alone in the lab, and it was like the first week I was in that lab and I was so embarrassed. In the end, I fixed it, and someone came and said, “It smells a bit weird, doesn't it?” And I was like, “What’s that? I don't smell anything.” I don't smell anything because I was so embarrassed.
Jordan Ruggieri31:24
Oh, that's really funny. Arianna, thank you so much for being a part of our Absolute Gene-ius episode today. We loved having you. It was a very, very interesting conversation, and thank you so much for your time.
Arianna Arbona31:37
Thank you. Thank you for having me.
Jordan Ruggieri31:42
That was Arianna Arbona, PhD student at Universidad Pablo de Olavide in Sevilla, Spain. This episode of Absolute Gene-ius was produced by Sarah Briganti, Matt Ferris and Matthew Stock. With more great conversations around the corner in future episodes, stay curious and we'll see you next time.