Releasing the Handbrake on Exosome Applications
Blog Apr 02, 2019
Exosome are tiny vesicles that are derived from multivesicular endosomes. They are released from cells and have been shown to persist in the circulation for hours. As exosomes contain a variety of components (including proteins, lipids, mRNA and DNA) and are taken up by target cells, they are thought to represent a novel form of cellular communication.
Given their resilience in extracellular fluid and unique source of origin, it is hoped that knowledge of exosomes could be leveraged for a whole host of diagnostic and therapeutic applications.
Learn more about exosomes here.
Despite the great excitement about exosomes, the technology which is needed to advance this area is lacking.
To find out more about the current unmet need, we spoke to Jim West, CEO of Clara Biotech, who tells us how his team is working to fill that gap.
Michele Wilson (MW): Could you tell us about Clara Biotech and how it came about?
Jim West (JW): The foundation of our platform came about in 2014, when Dr. He, our inventor, was working at the University of Kansas Medical Center and they started working on some exosome diagnostics, specifically around cancer. Seeing what they were doing, she was a little bit appalled at the state of the technology and the amount of effort that goes into isolating these exosomes. In addition, the technique lacked repeatability. They were very expertise-oriented. So even running the same person on the same sample over different time periods could result in different outcomes.
So, she started looking around at the options and had a background in microfluidics and biochemistry, and was able to combine those together into where we are today.
In 2018, we were awarded two grants from the NIH - one was a NIH/NCI SBIR phase one. The other one was an I-CorpsTM grant. The I-CorpsTM is a customer validation experience that happened over the summer where we interviewed 100+ customers over an eight-week period.
I joined the company in July, shortly after they started the I-CorpsTM program. They had a team member drop out of the program, and they needed someone to replace them. And I had been talking to Mei for a few months previously, providing some business guidance. My background is business entrepreneurship and medical device product development. I joined the team as CEO in July, and we got through the program. Since then we've been working on funding and our platform technology.
MW: What was the aim of the I-CorpsTM program?
JW: The NIH has this program called the I-CorpsTM and they offer it to phase one grantees. The goal is to perform a customer market validation of your technology before you apply for a phase two grant. By talking to customers, you're able to understand the market, the need, and sort of validate that, yes, there is a problem, and there's a need for our product.
Out of that program, we launched into a two-part strategy:
- We launched an exosome isolation service based on our platform technology (Jan 2019)
- We're working towards a lab tool that can be put into any facility for people to do their own isolation in the future
In about a year we're going to be launching an early access program with early-adopter customers, for people who want to get first access to the technology. And then about a year after that, we'll do a product launch.
MW: Where do you hope your screening tool will be used? In research, the clinic, or both?
JW: Clara’s overall vision is to enable tomorrow's medical breakthroughs today. So we believe that the major bottleneck in the industry is the isolation of these exosomes in a pure, discrete way that's repeatable, automated and fast.
By solving that problem, we want to bring that solution to anybody who wants to use it. Our company is focused on enabling any company or research group to do the work that they need to do.
As an entity, we are not actively pursuing our own diagnostic assay or screening tool. We're not pursuing our own therapeutic application. But we're building a platform that enables anybody else to do that.
MW: How does this approach compare with other techniques used to separate exosomes from other vesicles?
JW: The gold standard right now is, unfortunately, a process called ultracentrifugation. So ultracentrifugation is the very fast spinning of very small samples, maybe six samples in a device. They're very expensive, and they're very time-consuming. These things spin in an order of magnitude faster than a normal centrifuge, and they need to run from 6-12 hours…and 8-10 is not uncommon. And they'll spin these for a period of time and they'll get about 5-25% of the exosomes extracted from the fluid at that point, and there's a fairly large loss rate. And because of the forces involved, that crushes them and deforms the exosomes. You get a sort of heterogeneous mixture that has to be sorted through, it's more than exosomes.
There are other technologies like precipitation methods, which can change the pH of the solution - and the exosomes and vesicles can rise to the surface. It's quite a bit faster, it's a little bit better on the extraction rate, but you still sort of get this heterogeneous mixture out of it.
What I think is becoming a little more common is size-exclusion chromatography. So in that case, they have tubes, and they're able to diffuse the sample through the column, and filter by size. And then they can do extractions at various levels to get size ranges of exosomes. But there are a variety of reasons as to why that’s not the perfect solution either, although it can be fairly fast, less than an hour.
The fourth method is immunomagnetic beads. In this case, you mix in a tube, and you would mix your sample with beads that have antibodies fixed to the beads, and the antibodies attached to the surface markers of the exosomes and are able to pull out specific affinities of exosomes, which is pretty good. But the problem is it takes a long time. The extraction rate is not ideal, and you can't detach the exosomes from the beads.
So, Clara's solution that we're developing is we have a bead, a reagent that is an order of magnitude better performing. We have a very high affinity - we tracked about 90-95% of the exosomes from the sample.
And we have the ability to detach these exosomes from the beads so we can actually produce whole exosomes for therapeutic application over a single course.
So the benefits of our platform is the exact isolation of the exosomes, with the microfluidics at a high throughput rate and an automated platform, which is really the only one that doesn't require specialized expertise.
MW: Which biofluids are you working with?
JW: Other than the requirement that the fluid can go through our microfluidic channel so it has to be filtered at some level, there's no limitation to the fluids that we can use. We've done validation in blood, plasma, saliva, urine, milk, ascites, cerebrospinal fluid, and cell cultured media. So those are the ones we validated but really as long as we can get exosomes into a fluid media, there's no limitation to what we can process.
MW: Why are exosomes seen to be such a precious diagnostic tool?
JW: It's a great question. And I think that we've got some answers. But there's still a lot to figure out, I think one of the major benefits of exosomes, versus cell-to-cell analysis, is that we can work with much smaller samples.
There's between a 100:1 and a 1000:1 ratio of exosomes to cells in our blood, for example. So through significantly smaller samples we are able to do much more specific diagnostics. If you have a free-floating tumor in the body, you might need a large sample of fluid to actually detect that cell itself.
In addition, for the liquid biopsy, it’s a huge opportunity because there are so many areas where you can't actually go in and do a biopsy without causing major disruption. And so, a passive liquid biopsy, where you don't actually have to have the cells themselves is, I think, quite valuable.
On the cancer state itself, being able to diagnose brain cancer, or pancreatic cancer, just through a blood draw… part of our phase one work is looking at bladder cancer, through urine, so we're actually able to detect cancer mutations in urine from the DNA in the exosomes from that with our platform.
It is the non-invasive, the low volume (aspect), especially with some of these patients that you can't get much volume of sample from them. So, being able to have a very information-rich source to look at is helpful.
MW: What did you learn from the market validation activity?
JW: We did a couple of different activities. One of them was customer interviews, about half of which were in the academic research space, and the rest were in various aspects of industry - from pharma research and development groups doing drug validation/ drug discovery, up through core labs and hospitals doing their own independent work. We talked to a couple of lab-developed test groups, and then also therapeutic diagnostic companies.
It's interesting because when you talk to people in the industry, everybody hates the isolation part. There were a lot of conversations where people were like “we're really interested in exosomes, we think there's a lot of potential there, but man, it's just so hard to get into. We don't have the expertise and it's just too much.”
We actually met a lot of people who wanted to work with exosomes but were intimidated by the options (available) right now, and didn't have the expertise or didn’t want to commit the expertise.
We found a couple of groups that were doing research, who were outsourcing their isolation of exosomes to another entity that had more experience.
And again, it's mostly because of the time-consuming aspect, a lot of it's done at the academic research states because companies can't mess with it.
The lack of repeatability, the time-consuming aspect of it is all really daunting for industry.
So, the high-throughput automated option, where you could go and put one in a core lab in a hospital and they could have it as part of an assay or a process, got extremely good feedback.
In addition to the interviews we did, the NIH also provides what they call a “niche analysis.”
And in the niche analysis, they hire a consulting group to basically go and validate the market for us, again, with some high-level industry contacts. So they ended up interviewing six or seven folks, John Hopkins Medical Center, and a couple of other companies. Most of them were pretty well-respected individuals and interviewees.
One of the questions asked is, is this technology compelling? Would you be interested in being a beta user of the device? And everybody said that if the if the technology met up to the description that they were given, everybody was interested in beta testing our device.
Just to add on a little bit more, one of the things we learned was that initially, our focus is on the research industry, but based on the program and the interviews, we came to the conclusion that as a growth factor, the academic research labs were not going to be sufficient to support the long-term growth of the company.
So, we're starting in research support right now to get people using us, to get the word out, to get some validation performed and to get groups comfortable with our platform.
But really, for us, the market is the application. We want to support the clinical work and the diagnostic therapeutic work that that people want to do downstream. And I think that's where the real need is and where the real value can come in to enable tomorrow’s medical breakthroughs today.
Jim West was speaking to Michele Wilson, Science Writer for Technology Networks
Edit: Since the interview, Mei He had a paper accepted in Nature Biomedical Engineering, detailing this work:
Ultrasensitive detection of circulating exosomes with a 3D-nanopatterned microfluidic chip