How 3D Bioprinting Replaces Animal Testing in Drug Discovery
For biotech and life sciences founders, drug discovery researchers, and academics commercializing their own work.
About Stephanie Willerth
Stephanie Willerth is the co-founder and CEO of Axolotl Biosciences, which sells bioinks for printing human tissue models, and a full professor and Canada Research Chair in Biomedical Engineering at the University of Victoria, where she holds appointments in both mechanical engineering and medical sciences and runs a lab engineering neural tissue from pluripotent stem cells. She is a member of the Royal Society of Canada's College of New Scholars, was named a Woman of Innovation in 2017 and a Young Innovator in Cellular and Biological Engineering in 2015, and was recognized as a star in Global Health by Grand Challenges Canada. She served as acting director of the University of Victoria's Centre for Biomedical Research.
Dr. Stephanie Willerth is co-founder and CEO of Axolotl Biosciences and a professor at the University of Victoria, where the company spun out of her lab in 2020 with an all-women founding team. Axolotl makes bioink, the filament a 3D bioprinter uses to print living human tissue. The argument underneath the whole field is one she states plainly: drugs get tested in mice and rats, which do not naturally develop Alzheimer’s or Parkinson’s, so the test is inaccurate and the diseases stay untreated, while tissue printed from human stem cells is a far better model of a real body. The founder story is a single clean commercial insight made from inside the science. While a partner company was selling bioprinters, and sold about seven before pivoting, she worked out that the business was selling the ink to everyone who bought a printer from anyone. She also makes a point most researchers have backwards, that commercialising the work made the science better, because a product people buy has to be reproducible. That is the throughline 79 Development keeps coming back to. Knowing exactly what you are and are not is what makes a company legible, and an honest, legible account of that work is what makes a brand understood, trusted, and findable by the systems people now ask for answers.
KEY TAKEAWAYS
- "They were like, oh, we’ll sell printers. I’m like, yeah, we’ll sell ink to the people who buy their printers." The company exists because of that sentence. Her lab had been collaborating with a Vancouver bioprinter company that needed materials and cell expertise, and she watched them sell, by her count, about seven printers before pivoting entirely to clinical work. Then she spoke to the president of a printer company that had sold thousands worldwide, who asked her why they were not selling her product. "I was like, well, if we sold our product for your printer, that would be a market. That would be a company." That is when they incorporated. It is a picks-and-shovels decision made from inside the science rather than from a strategy deck.
- Mice do not get Alzheimer’s, and that is why the drugs do not work. This is the argument underneath everything. Drug candidates are tested in rats and mice, which because of their lifespan and biology do not naturally develop Alzheimer’s or Parkinson’s, so the test is not very accurate and the diseases stay untreated. Print the tissue from human stem cells instead and you get a far better replica of what is actually happening in a body, plus the ability to ask biological questions animals cannot answer. She notes there is now a global movement away from animal models across the US, Canada and Europe, which makes the timing hers.
- The hard part was keeping delicate cells alive. Before their ink, printing something as finicky as a neural stem cell left roughly half of them surviving, which is not a viable basis for anything. Their ink kept them alive and, more importantly, functional. The useful accident: a material good enough for the pickiest cells turns out to work well for cells that are not picky at all, so the same base ink now prints skin and cancer models. On top of that base sit patented drug-releasing particles, the "flavors," which signal a cell to become brain tissue or heart tissue.
- Personalised medicine, with an honest timeline. You can draw a patient’s blood, reprogram the cells into stem cells, print brain tissue from them, and watch the Alzheimer’s symptoms appear. Screen drugs against that tissue and anything that works could be prescribed back to the person whose cells made it. She is careful about the clock: mature diseased brain tissue takes 30 to 60 days, while bioprinted tumour models show up in about a week, which is why the cancer applications are moving faster. Hospitals are already biopsying tumours, growing the cells, and testing drugs outside the body before choosing a treatment.
- Machine learning aimed at the cost of being wrong. They trained their own models, because the datasets have to be that specific, on how an ink behaves at day one and day two, and use it to predict what the tissue will look like at day 30. The paper is in Biofabrication and open access. The point is money: they print at physiological density, millions of cells per millilitre, and cells are expensive, so predicting a failed print beats running it. She tells newcomers to get their printer working on the cheap ink first.
- The most surprising project has nothing to do with brains. Working with the Vancouver Prostate Centre on male infertility, they printed testicular tubules, the structures sperm mature by travelling through, for a patient who lacked them internally, and started getting sperm to mature. Because IVF does not require clinical-grade manufactured cells the way an implanted tissue does, only a functional one, this is a genuinely short path to patients. "It’s very much a structure function relationship there."
- A field that talks to each other. Asked whether competitors know her team, she says yes and describes the community as collaborative because the products are differentiated enough that sharing costs nobody anything. She lists the landscape unprompted and generously, which is its own signal about the state of the field.
- Wearing both hats made the science better. She expected commercialisation to be a distraction and found the opposite. Selling a product forces reproducibility, and people buy the ink and print things she never would, which feeds back into the research. Keeping the academic hat is what lets her run the patient-derived collaborations that are not especially commercial but are closest to actually reaching a clinic.
FULL TRANSCRIPT
What We Need to Grow, Episode 034: We’ll Sell the Ink. A Founder Talk conversation with Stephanie Willerth, Co-Founder and CEO of Axolotl Biosciences. Cleaned for readability; the words are the speakers' own.
Caleb Pedosiuk: All right, Stephanie, really excited for this conversation. What you have built with your company is mind blowing to me, and the fact that you named your company after an animal that is famous for regrowing its own spinal cord. Maybe if we could start there. Can you share a little about your company, what it does, and how you got into it?
Stephanie Willerth: Yeah, and thanks for having us, Caleb. My company, Axolotl Biosciences, makes bioink for 3D printing human tissues. If you want to make a human tissue using a 3D printer, you need filament, similar to how you have filament in a 3D printer that would extrude something like one of my other axolotls I have on my desk.
The way we came up with this is, I am a professor at the University of Victoria, and our lab had spent a lot of time trying to make, as you were talking about, spinal cord tissue from stem cells. My graduate PhD and first years in the lab were a lot of pipetting, manual production of these tissues. So when we saw, about a decade ago, people were making 3D printers that you could use to make tissues, we were very excited about finding a way to automate that process, to make a lot of neural tissues, mainly for applications in drug screening.
Caleb: Maybe help the average person who does not understand it. I do not know if you will be at a grade six level or something, but what is the importance of the ability to create these tissues?
Stephanie: Yeah, well, it is actually a really hot topic now around the globe. The way people normally test drugs, if you think of things like the neural tissue we work on, things like Alzheimer's and Parkinson's, these diseases do not really have good treatments. And that is because when researchers are trying to develop these treatments, they are studying them in animal models, like rats and mice.
One of the issues, especially in our field, is that mice and rats do not traditionally get Alzheimer's or Parkinson's, just based on their short lifespan and biology and things like that. So when you are testing your drugs on animals, it is not very accurate. And that is one of the reasons why a lot of these diseases do not have treatment.
But if you use bioprinting, and we do this, you can use human stem cells. The neural tissues we make actually are human tissues. So it is a better way to replicate what is going on in your body, to actually look at drugs, and even just for some of these diseases like Alzheimer's and Parkinson's, to ask questions about the biology that you cannot do just using animals.
Caleb: So in this sense, at the academic level, the laboratory level, or at the pharma level, are those the three categories you primarily serve?
Stephanie: For neural, definitely. I think there are other areas. For example, there was a company out of New York which actually 3D printed ears for people with microtia. I would say skin is something people are very interested in 3D printing and actually putting into people. There is a group out of Stanford, Mark Skylar-Scott's group, that is leading a large ARPA-H project where they want to bioprint a whole human heart, which if you could figure out all the biology, kind of makes sense. You could scan your heart and then print a heart that would have the right dimensions for transplantation.
For neural, that is not usually the case, given that most of the disorders are not, you know, you do not do brain transplants. So for us it is more the drug screening applications that are the big ones, with pharma and for research.
Caleb: Just on that topic, it is interesting to me because one of the very controversial subjects surrounding scenarios where somebody needs a transplant of a major organ is human trafficking. In different parts of the world, some of the actual available donors, where the organs come from, it is really tragic what is happening. We have worked with an anti-human trafficking organization and got to learn and understand some of the statistics of that. I remember thinking, what is the solution for this? Because in some instances people were looking for a viable option and they really do not even know where some of it has come from. And I thought, with some of the emerging science, and I am certainly not familiar with it, I have no idea how much is still theoretical or practical, but the ability to actually manufacture some of those solutions in a reliable way seems like it would be really helpful.
Stephanie: Oh, yeah, for sure. And even if you look at, obviously being in the medical field, some of the issues with donor organs is that they are being donated from someone who has been living life. So there is a lot of, how do you rejuvenate an organ even before you transplant it? If you have a damaged organ, can you repair it before transplantation? So the idea that you could actually make them from fresh cells, with the right dimensions, that are younger, that is a really good alternative.
The devil is in the details in this case, which is how do you get enough cells and put them in the right order for something like the heart. Obviously that is very complicated. Skin is a bit less complicated, and also from a testing standpoint, the same with the ears, which is why they were one of the first 3D printed tissues to transplant. If you transplant an ear and something goes wrong, you can go in and take it back out. The same with skin. Obviously if you are putting in a heart, you had better make sure it is working really properly.
Interestingly, Aspect Biosystems and a couple of other groups are working on a replacement pancreas for diabetes with bioprinting, because there it is less about, if you think about the heart, it obviously has a mechanical function that drives blood through all of our body. But with pancreas it is more, are you getting your insulin secreted? So you can put those types of tissues in more locations. There are a lot of different things to think about when we are using it, and I think that is why it is such an exciting field.
Caleb: What was that journey like, to go from being in a strictly scientific background and path, to recognizing the benefit these new printers could bring to your work, and to make that shift from functioning purely in a scientific capacity to founding your own company?
Stephanie: Yeah, it was a really interesting journey. Here in Canada there is a lot of support to commercialize your work. We had gotten a lot of support at the time, working with Aspect Biosystems, who were based out of Vancouver, who had made a bioprinter and needed someone with materials expertise and cell expertise.
To be honest, we were getting all this money to commercialize, but Aspect, and do not worry, they have raised plenty of money and have completely pivoted, they were like, oh, we will sell printers. I am like, yeah, we will sell ink to the people who buy their printers. And I think they sold seven printers ever, including one to us. They have pivoted now to be all clinical.
So I was kind of like, we are getting this grant funding, we have a really good product. People really appreciated it. Prior to our work, if you wanted to print delicate cells like stem cells, people would print them and about half would survive. So it was not really super viable. And then we made an ink that was really good at keeping them alive, and you actually started to get function.
And then I was talking to the president of CELLINK at the time, and they have actually sold thousands of bioprinters worldwide. They were like, why are we not selling your product? And I was like, well, if we sold our product for your printer, that would be a market. That would be a company. And then that is when we decided to incorporate.
Caleb: So in a really simple way to look at it, what does the path look like over the next five or ten years, in terms of both your company doing what it does well, and the benefit of actually helping people? I think of it a little bit like stepping stones. What problem is it that you solve, who is it actually helping, and what does it matter? If this problem is not solved, what problems still persist or get worse?
Stephanie: Yeah, well, what is really interesting about 3D printing, and being able to not just make tissues on demand but lots of things on demand, is this. We have published papers on this. You can do a blood draw in a patient with Alzheimer's and reprogram the blood cells to become stem cells. We can print those stem cells and turn them into brain tissue, and you see the Alzheimer's symptoms. So now the idea would be to screen drugs to see if we could reverse those symptoms, and if it worked, you could prescribe that back to the patient whose cells you made the tissues from.
Just practically speaking, and my lab reminds me of this all the time, if you want to make mature brain tissue, and mature brain tissue that is diseased with Alzheimer's, it does take between 30 and 60 days. But some of the cancer models, we have done bioprinting of cancer, and you will see tumors form in our little bioprinted mini brains in about a week. So the drug screening applications, whether for Alzheimer's or cancer, are very big.
I know several hospitals have been starting to do this, where they will biopsy a patient's tumor, grow a bunch of those cells up, and then hit the tumors with different drugs and personalize what drugs they use based on how they respond, outside the body, before the patient actually gets it. I think that is where some of the big benefits are, using a patient's own cells to say, this is the treatment you should be getting, especially for things like cancer and Alzheimer's where there is a lot of variability.
And there is the whole other branch, which we are not currently involved in. Our ink would be compatible with being made to good manufacturing practice, which for the layperson means the ink we make now you would not want to put in a person, but given its components you can make a medical grade version that would be suitable for going into people. It is just a lot more expensive. And obviously if you are taking something into humans with clinical trials, that is a lot more expensive than being a reagents company that sells bioinks. But given some of the recent movement in the field, I think there is a lot to be excited about. And there is this global movement in the US, Canada and Europe away from animal models, for the reasons I was detailing. So I think it is a good time to be in the field.
Caleb: How many different inks would you say you have? I feel like you are using a word that works in the printer analogy, and it works, but in a way, at least for me, thinking about printing, it feels like we are talking in metaphor when actually we are talking very accurately about reality. Is this sort of like a red, blue and yellow scenario, where you have primary colors or primary inks that you are creating, or is it much more of a spectrum?
Stephanie: So I would say our base ink, which we developed to print neural stem cells. As I said, they are very delicate and very finicky. So it turns out if you make a material that is very good at printing something that is picky, it is also very good at printing cells that are not very picky. So we have also printed skin, cancer and some other models with it.
And then we have patented technology where you add these ingredients, and those little drug releasing particles tell the cell specifically, you should become brain tissue, or you should become heart tissue. So the spectrum is kind of like a base, very general ink, and then your flavors would be what works best for each tissue.
Caleb: If there is a bell curve in looking at how AI and these large language models and the tools that are available are increasingly capable and accessible, how much of a bell curve have you seen in your work, in terms of being able to process large sets of data?
Stephanie: Yeah, we actually have a paper come out in Biofabrication, which I think is open access, so anyone watching this should be able to Google and read it. We have made some of our own machine learning models, just because you need very specific data sets. The interesting thing is we have trained our models using early stage properties of our ink, how the material behaves at day one and day two, and that actually enables us to predict what the neural tissues will look like 30 days down the line. Which is very important, because all the stuff we use to make our bioinks and keep cells alive is very expensive, so being able to cut down on that matters.
We also did some other interesting modeling a few years back. Unlike traditional 3D printing, where you melt plastic and the plastic always behaves the same way within a temperature range, with biological materials the properties vary much more. So even figuring out, can we print this structure, can we print a half dome, can we print an ear, is often done by trial and error. We have been using our machine learning to predict whether or not things will print the first time.
And again, cells cost a lot of money. We print our tissues at physiological density, so we are printing millions of cells per mil, which is expensive as well. So what we always tell people who start off in this field is, go read our cheap bioink recipe. We have a cheap bioink you can make for very low cost. Once you get your printer working with that and it is printing the shapes you want, you save money.
So that is really where the machine learning has come in to help, on optimizing materials and being able to do it more cheaply than a traditional degrees of freedom experiment, which for people who do not normally do science means you scan a large parameter space, which usually means doing tons and tons of expensive experiments. We have also used some of it to analyze the functionality once we have our tissues printed, seeing how the different cells in our tissues talk to each other and replicate the activity you find in the brain.
Caleb: I am curious to know how many companies similar to you exist. Let's say first in Canada, and then I do not know if the set is large enough to ask that same question for the US or globally.
Stephanie: Yeah. In Canada there are a few prominent ones. Aspect Biosystems is very much making their own multiple bioprinters, and they have got, I think, one or two hundred people now, really working towards putting tissues into humans. There is kind of a curve in this field of, okay, you can make a bioink, and then if you have a company, can you scale the production, and then if you are going into people, can you scale and produce something that is going to treat humans.
Here on the island we also have another company called Voxel, and they do vasculature. They bioprint models of blood vessels to see where drugs go in the body. And there are a few more back east that also do bioinks, and 3D BioFibR, that does some collagen type work. And then there are a few more in the US, although it has been up and down the last few years with how the biotech industry has gone. CELLINK is definitely still around. And there are definitely a lot in Europe too, as well as Korea.
There is also a difference, because we are very much on the we-sell-bioinks side. We are not a bioprinter company. So there is REGEMAT 3D out of Spain, and they are all very focused on making the printers, not necessarily the inks.
Caleb: And do you feel like they are all aware of your team and what you are doing?
Stephanie: Yeah, no, it is a really good community. I find that because it is so interdisciplinary. Oh, I forgot to mention FluidForm out of the US. And also, there was a recently funded round of ARPA-H grants in the health space, and all the ARPA-H projects will be spinning off companies as well, and most of those are focused on 3D printing liver.
It is a pretty good community. We all talk. Because a lot of the products are really different, and there is no one optimal bioprinter or one optimal bioink, you usually have an eye on what other people are doing. And also, we need a lot of cells, so we are always talking to the new startups about how they are making all the cells to go with their bioink. There is a lot of really interesting work being done around, if you do want to bioprint a heart, you need to constantly be monitoring whether your cells are alive in the printing process, monitoring the different steps. And they are still standardizing what the standards would be for producing a human heart, which is a bit more difficult than what the standards are when you produce a part for an airplane. So there is a lot of work being done. But in general it is very collaborative. I was just over in Europe for the big biofabrication winter school in January. So it is definitely a good community and seems to work together worldwide.
Caleb: Do you have some picture or vision that you see, where all of this problem or disease is dealt with in the future, that you are working towards? Or is this more that you are focused in front of you with the microscope, and looking down the road a little bit, as opposed to some larger sense?
Stephanie: Yeah, well, some of our most exciting work has been in collaboration with UBC, using patient derived cell lines, which is less company and more research. Because if we found something that worked on a patient's own cells, there are certain types of drugs that doctors can just prescribe off label. So I think that is probably our best chance at getting something into the clinic and to patients in a reasonable time scale, as opposed to the teams out there building pancreatic tissue to be implanted into humans. So that is usually what I think about, or even the cancer work. Those are the things that are really closely linking, directly, the patients to the work that is actually in the lab. And I think that is the most exciting.
Another project, which is not necessarily Axolotl focused but is in the field, is we work with the Vancouver Prostate Centre. Our collaborator, Ryan Flannigan, runs a male infertility clinic. So we have been working with some of his patients' sperm stem cells, because they cannot produce sperm, but they have cells that could produce sperm. And if you actually can 3D print the structures to make mature sperm, interestingly enough, you can just use those for IVF.
The reproductive biology field and 3D printing is very interesting, because unlike if you are putting a tissue into a human, because of how babies are made, you actually do not need to have a GMP made sperm or a GMP made egg. You just need to have a functional one to do IVF. So that is another field where it is a project I am really interested in, and we have done some really interesting work with Ryan's team. It is one of those things where you are really close to the patients, and this could be something that patients could be getting in the next few years. So I think that is another really exciting field and application, a bit different from what I consider our traditional research wheelhouse of Alzheimer's and Parkinson's and the other neural tissues.
Caleb: In that case, would it be a sampling of the DNA of the person who has a lower count, if I am understanding this properly?
Stephanie: Yeah, well, in that case, the way sperm are made is that they mature by traveling through testicular tubules. So it is a combination of the travel and the flow that makes them mature enough to fertilize an egg. In the one case, the patient just lacked those structures internally. So we had the starting material, the cells, which is what was biopsied. And then, interestingly enough, with 3D printing the advantage is you can print different shapes and different sizes. We printed long testicular tubules and actually started to get some of the sperm to mature. And because it is not genetically modified at all, if you actually made a functional sperm cell, it could work for IVF.
Caleb: So the sperm are actually moving through a physical structure that you have created that exists outside of the body, those tubules that it goes through, and then once they have come through that, it is ready for IVF. Is that correct?
Stephanie: Well, eventually, if we could get it there. We have made immature sperm, but that is the idea. We have the one paper that was the patient's own cells, and we did another one from stem cells, where we actually made all the structural cells, the support cells you find in vivo, on the outside, and then in the core you would have the sperm stem cells. It was really interesting, because if you go to the paper, with the printing you can essentially match the dimensions of these tubules you would find in vivo, you are matching the cell composition, and you would see similar behavior.
And again, talking to a person who is not normally in the field, I always like that one, because people are always like, well, why do you need the 3D printing? And there I am like, well, the 3D printing is what is actually making the tube shape, which is what you need. So it is very much a structure function relationship there.
Caleb: So how do you find going back and forth? You have got to wear a CEO founder hat as well as being deep in the science, so you have both of these pieces happening. How do you find switching back and forth?
Stephanie: I think it is good, probably, in the long run. We will need to find a better structure to be sustainable as Axolotl grows. But it is really interesting, just because with the company and selling our product, people will buy it and print things that I would not. So it is really interesting to see the science people do.
And still having the researcher hat is nice, because it allows us to do some of these collaborations where we are just looking at patient specific Alzheimer's tissues, which are not necessarily the most commercial but might be getting us closer to getting drugs into the clinic.
I have actually enjoyed the commercialization process a lot more than I thought I would, because as a researcher it really forces you to make your work so much more reproducible. It is one of those things where I was like, oh, it made our science better, and other people's science better, that I had not really thought of when I was a younger PhD student, or even a postdoc.
Caleb: I love that way of understanding business, where it is, what is the problem that a business or a project can solve, and if it can, then do so in a manner that can scale in a way that is essentially self-sufficient, even if you are factoring in some form of investment structure or financing, to help as many people solve that problem as needed. Of course there are countless variables in that mix, but the fundamental of it is to be able to help more people solve that problem. That is really cool.
Well Stephanie, thank you so much for sharing about this. I think it is really exciting to see innovation in such a groundbreaking frontier. If anybody wants to follow along more with what you are doing, where would you recommend they do so?
Stephanie: Yeah, you can check, we have a website for Axolotl Biosciences. Also, I think we are on Instagram, Twitter and LinkedIn. I am also on LinkedIn, probably the easiest way to reach out if you are interested in learning more. Or also find me on Google Scholar. And as I said, a lot of our papers are open access, so lots of reading to do there.
Caleb: Well Stephanie, thank you so very much.
What We Need to Grow is a conversation series by 79 Development, hosted by Caleb Pedosiuk. New episodes on YouTube and Spotify.