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Digital PCR Startup Espira Seeks Funding to Advance Prototype 'Spinning Disc' Platform

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With the market for digital PCR poised for growth over the next several years, led by established life science tool vendors such as Fluidigm, Life Technologies, RainDance Technologies, and Bio-Rad, one small startup is looking to put a new spin on the technique — literally — while making the technology more affordable and accessible.

Espira, a spinout of the University of Utah, has developed a prototype digital PCR platform that uses an inexpensive, disposable spinning plastic disc to quickly partition samples into the thousands of nanoliter-scale reaction volumes necessary to perform digital PCR.

The system may have advantages over existing digital PCR systems in the areas of cost, speed, and footprint that would make it more amenable to everyday laboratory use and certain specialized applications, Scott Sundberg, a former University of Utah graduate student, co-founder of Espira, and primary inventor of the spinning disc technology, told PCR Insider in a recent interview.

"It seems like … people are finally becoming aware of [digital PCR], and now that we've got a few large companies that have launched a product in the area … the whole hope we had was to bring an instrument in that's lower cost just due to the simplicity of the technology, so it could potentially start to enter into some other markets," Sundberg said. "Right now it's a really big research tool, and not much else is being done with it. The hope is to get this into more of a mainstream style use."

However, the company is sorely in need of additional funding to move the prototype platform forward to a more integrated, commercial-ready system, Sundberg said.

"We raised some local funding to develop prototypes for proof of concept … but we've gone through all of that funding," he said. "We've been submitting lots of grants and pursuing partnerships with other companies, but to date, none of those has come through for us. We've kind of been struggling to get that next step of funding to move it into the commercialization process."

Sundberg developed the spinning disc digital PCR technology while a graduate student working in the laboratories of Carl Wittwer, a professor of pathology at the University of Utah School of Medicine and co-founder and CSO of Idaho Technology; and Bruce Gale, an associate professor of mechanical engineering at the university, and co-founder and CSO of Wasatch Microfluidics.

With the help of the University of Utah's Technology Commercialization Office and the Utah Science Technology and Research Initiative, or USTAR, Sundberg and colleagues formed Espira in 2010 as a means to commercialize the technology.

First described in a paper published in January 2010 in Analytical Chemistry, Espira's technology combines the disposable plastic disc, about the size of a compact disc, which can passively compartmentalize a sample into 1,000 nanoliter-sized wells by centrifugation; a rapid air thermocycler; and specialized CCD camera-based optics to read the "on/off" signal of each well that indicates whether the target nucleic acid was present and amplified.

"[We looked at] all the different implementations of digital PCR, the Fluidigm style of a large grid system; the droplet-based systems; SlipChip (PCR Insider, 10/20/2011); Life Technologies' [OpenArray]," Sundberg said. "Our implementation was to come up with a way to quickly partition samples … using centrifugal force … into thousands of wells in the nanoliter-volume range, and having a less-expensive disposable than some methodologies. The droplet systems are getting down in cost, but still, the Fluidigm style is up there in price for a disposable product."

Further, Sundberg added, many systems require separate sample preparation and thermal cycling steps; or comprise multiple instruments that take up valuable lab bench space.

"The piece that we're trying to plug is that the instrumentation could be all-inclusive for loading, thermal cycling, and reading … within a relatively small footprint," he said. "It’s kind of like a large CD player, basically."

Sundberg said that the prototype system is currently in the "breadboard" stage, but that he expects it could be easily integrated into a compact system. And, although he noted it was too early in the platform's development to provide a potential price range for the instrument or disposable disc, the latter would consist of injection-molded plastic and could be manufactured at a relatively low cost.

One potential drawback of the technology is that it will have a physical space limitation on the individual number of reaction volumes, as opposed to droplet-based systems — a limitation that manufacturers of droplet-based systems have previously claimed about Fluidigm's chip-based consumable.

"The prototypes all use 1,000 wells, but we're confident we can get that up into the 5,000- to 10,000-well range," Sundberg said. "We won't be able to quite get to the droplet range, so we'll be a little bit limited in that way."

Another option, he said, is to employ what Espira is calling "quasi" digital PCR, where "you're not necessarily just getting one copy of something in there, but actually loading up with lots of wild type and specifically amplifying just the mutation copy so we can get around this limitation of well numbers, but still be able to enrich and amplify just the mutation copy," Sundberg said. "You still have lots of DNA in there, but you're able to amplify just that specific mutation to potentially get that rare event."

Using this technique, Sundberg and colleagues in preliminary studies have been able to achieve rare mutation detection rates of one in 10,000 or 100,000, which does begin to approach some of the droplet systems. Sundberg said that he is currently working on a manuscript describing this research and will submit it soon for peer-reviewed publication.

Sundberg also declined to name specific applications that might be ideal for Espira's platform, noting that "there is potential for lots of different markets. For some things, where qPCR is accurate enough, it might not make sense. But for other applications it might be useful. You just have to pick carefully which markets to go after.

"We would really be trying to target certain niches of the digital PCR world … that desire to have quicker thermocycling throughput, so it's probably ideal for some applications but not for others," he added.

While Espira seeks additional funding, either through grants or investment, one member of the team, Himanshu Sant, a research assistant professor of mechanical engineering at the University of Utah, has taken the Espira name to India and is attempting to leverage company expertise to develop non-digital-PCR-based research tools in that country.

"We are still pursuing some things. Himanshu is … not terribly involved with digital PCR, but is working on some collaborations in India for point-of-care diagnostics," Sundberg said. "They have been working on some field-based instrumentation to prepare raw samples for testing, for things like serotyping and agricultural [applications] instead of human health."

The University of Utah and Espira submitted a PCT patent application in March 2009 covering the technology, but have not yet received patent protection.

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