Hannah Rosen: 00:00:07 Hello everyone. Welcome to New Matter. I'm your host Hannah Rosen, and joining me today is our scientific director, Lesley Matthews. And Lesley is here to help me break down some of those terms that you may often come across in your reading or in your podcast listening, but may just not quite know exactly what they mean and you're always a little bit afraid to ask. And so, we're here to break those down for you. And today, Lesley is gonna help me to better understand what a spheroid is, what an organoid is, and what's the difference between the two. So, thank you Lesley for coming to explain this to me.
Lesley Mathews: 00:01:01 Hi Hannah. Thank you. Other than the fact that they both end in, um, ds, they do have some differences, um, in their instruction and makeup. And so, I hope today to be able to demystify a little bit about what spheroid is versus what an organoid is. So, when you think of a sphere, right, you think of this circular structure, 3D structure that has, um, almost looks like a perpetual, um, uh, circle, right? So, you think of something round, right? I'm trying to think of the adjectives to use to describe it.
Hannah Rosen: 00:01:16 Like a ball, like an inflatable ball.
Lesley Mathews: 00:01:22 Exactly like a ball. Um, perfect example of a spheroid structure. And when we think of these in science, most commonly spheroids are groups of cells that make up a 3D ball of cells. So, if you remember back from developmental biology, the evolution of the gametes, when the sex cells come together, the sperm and the egg, essentially you get the, you know, the addition and it becomes a cell and that cell divides and that divides into four cells. And then, you know, on and on and on exponentially it divides well that blastocyst, or that group of cells, kind of looks like a 3D ball, if you remember from your BIO101 classes.
Lesley Mathews: 00:02:12 So what people have discovered is just like that, that sphere, that ball of cells in the body, is that we can actually do that same thing in a cell culture dish with cells instead of, um, having to just stick to the bottom of a dish like they would in what's called two dimensional cell culture. Now there's a way to do three dimensional cell culture where you have many cells in this sphere where it's a spheroid of cells. So that's basically where the terminology spheroid came from. It's used a lot in cancer biology. 'cause if you think of the context of a tumor, even though it's not, you know, a perfect circle, it's a steroid in its structure. It's 3D in nature and its structure. So that's really where spheroid comes from. And a lot of times it's like, one cell type. It's very simple, very simple cell culture biology that goes on ovarian cancer cells that are grown in 3D and that makes a spheroid.
Lesley Mathews: 00:03:12 Now organoid is a little different because if you understand the tissue architecture, that is a lot of our glandular tissue in our body, it's lined by, so say like a, a breast duct gland, it's lined by a layer of epithelial cells and then there's a duct at which something can pass through. Well, that's very much 3D in nature, right? But there's not just one cell type there. There's epithelial cells there, they're the foundation cells. There's endothelial cells, which are the blood cells. There's immune cells, there's cells that support the growth of the matrix such as cells that make fibronectin and collagen. So, an organoid is much more reminiscent of the organ or the actual tissue where it comes from. So, a breast cancer organoid or an ovarian cancer organoid would have these other tissue layers that make it more like an organ than just a ball of one type of cells. So, that's kind of the basic breakdown is one cell type versus multiple cell types that look more like the cells is an organoid.
Hannah Rosen: 00:04:08 So when you're describing these balls of cells, are they solid balls of cells or are they hollow?
Lesley Mathews: 00:04:17 That’s a great point. Um, some structures that form actually need the organoid component to make the inside hollow. So, not just like the one cell type, the spheroid one cell type very rarely has hollow inside 'cause it's literally just a bunch of that one cell type lump together. Whereas the organoids do have the ability to form structural like dimensionality and have what's called the lumen. The lumen is the inside or open part of the glandular tissue. So, you really do get more bang for your buck with an organoid, but it's a lot more complex to make. If you think about in a dish adding, you know, four different cell types plus matrix like collagen or fibronectin drug discovery, biologists can't really put that into 1536 well plate as easily as they can just one cell type that makes a spheroid.
Lesley Mathews: 00:05:22 So, there's trade-offs to what your endpoint of the biology is, if you're finding a drug or screening versus if you're doing like, a real functional study in a lab.
Hannah Rosen: 00:05:34 Interesting. Yeah. 'cause I was gonna ask, you know, it sounds like the organoids are so much more accurately representing what's actually going on in the body. Why would you ever use a spheroid, something that's less accurate? But it sounds like it's just if you're doing maybe like, a high throughput screening, spheroids would be better just because they're easier to make.
Lesley Mathews: 00:05:54 Yeah. But there are, um, scientists like Dr. Tim Spicer in our field, um, from the University of Florida Scripps, um, who's actually gonna be part of our BB3D meeting coming up in April, where he's actually figuring out ways to use pancreatic cancer and other tissues in a more organoid fashion to do hide throughput complex screening.
Lesley Mathews: 00:06:17 So, emerging from 2D to 3D and then into the next generation 3D and organoids, I think is the way the direction of the research community is going because clinicians inform us that the more relevant context the tissue is in the dish, the better outcome that the productivity will have in informing if the medicines will work or not.
Hannah Rosen: 00:06:39 Now, when you, when we're talking about organoids, I feel like the first thing that I think of is like a teeny tiny little liver on a plate or a teeny tiny little heart on a plate. But I'm guessing that these organoids probably don't resemble the same form as the actual organ that they're representing. So how much, you know, you've got all the different cell types, but how much physiological and anatomical similarity could there be between an organoid and the actual organ it's representing?
Lesley Mathews: 00:07:14 Yeah, that's a great point. Especially as like, a systems biologist, right? You, you want the integration with the other bodily functions too, right? So, I would say that that's where kind of the field has taken its next step into these chip based and microfluidic systems that have the ability to have perfusion and flow and directionality of that flow similar to the way the kidneys and the heart work. So, when, when I think of like something more like what you're thinking of, I think of, uh, a liver on a chip it's called, or devices like from companies like Memetis, who make perfusion and flow-based plates so that you actually have flow in your 3 84 well plate. So, it's, it's getting there. It's just definitely not as easy with that much tissue to do. You know, 20, 30 drugs at a time would be fine, but like you said before, if you're trying to do like a thousand drug screen, we're getting there. We are with this technology, but an organoid is definitely a more simplified version of that, even, that liver.
Hannah Rosen: 00:08:14 I'm wondering how much, so with spheroids, you know, you're, you've got the same cell type, but it's just kind of, you know, a mass of all of these cells that are of the same cell type. How much more information are you really getting from having a ball of cells versus having a 2D plate of cells?
Lesley Mathews: 00:08:41 Sometimes it's, it's not about the quantity of the information but the quality. And so, like, when, for example, I worked on a inhibitor at Novartis that affects the RAS-RAF-MEK-ERK pathway, and what we found was that when we screened for the drug in two dimensions, our drug target was actually not as widely available in the cell as it was in 3D. So, something about culturing that ball of cells off the plastic shot up the expression of the actual drug target that then allowed us to give it the medicine to reverse the effect.
Lesley Mathews: 00:09:23 We would've never seen that if we stuck on the 2D dishes. And what we found is that RAS biology like, the oncogene that drives cancer in a lot of different cancer types, that RAS biology was really more relevant physiologically at the levels in the patient cells than they were on the 2D culture. So, it can have translatable effects and not just spatial architectural effects.
Hannah Rosen: 00:09:35 Yeah, that's so interesting. And it's that we don't know, it's like what's so different about a cell being off of the plate versus being on the plate, but apparently the cells care.
Lesley Mathews 00:09:59 And the cool thing is, is that there now are manufacturers out there that are making these plate types that are amenable to culturing cells in three dimensions in scale. So there's a number of different vendors that make 384 well plates that have round bottoms or have micro nano well plate, you know, capacities where you can hold multiple individual spheroids in one, well, there's 1536 well plates, things are really emerging that the screening field is trying to come up with these more physiologically relevant ideas and models in our dishes and, and translate it back into the human, which I think is why we're getting better at getting the predictive medicine right. We're getting closer to the patient and not as far away from, you know, the lining of the 2D epithelium. It's more relevant in this case.
Hannah Rosen: 00:10:40 Yeah. But it's, it's very interesting to me that you always still have this trade off of throughput versus complexity of the model. And I'm sure, you know, based off the trajectory that we will get to that point, it sounds like where organoids can be used for higher throughput research, we're just maybe not quite there yet, or we're at the very beginnings of it.
Lesley Mathews: 00:11:11 Yeah, definitely. I think as more and more instruments and research goes into the technology development of how to do this, I think it'll catch up. But I think about, you know, where I started studying things 20 years ago, you know, a 96 well plate was high throughput for me and now we're in 3456 <laugh>. So, I guess, um, it's all about patience. Innovation takes time.
Hannah Rosen: 00:11:35 Yeah. And it can be hard sometimes to have that patience, but Mm-hmm. Yeah, that's a little bit about steroids versus organoids. Thanks Lesley. Yeah, I really learned a lot about the differences between spheroids and organoids and why you use different types for different types of research. And I hope that some of you out there listening have come away with better understanding of spirits and organoids as well.