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Biological Dynamics Builds Evidence for Electrochemical Platform in Exosome Isolation, Analysis

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NEW YORK (GenomeWeb) – New research has begun to demonstrate expanded use cases for Biological Dynamics' electrochemical chip platform in cancer biomarker detection and quantification — specifically that the technology can effectively isolate not just cell-free DNA molecules or proteins, but also extracellular vesicles, from unprocessed biological samples.

In a study published earlier this year in ACS Nano, a team from the same University of California, San Diego lab where the chip technology was initially developed provided new early evidence of how the technology could be applied to specific disease applications, in this case to the detection of pancreatic cancer biomarkers in isolated EVs.

The authors wrote that their results, while early, suggest that the platform could provide a simple and rapid tool for screening or early-stage diagnosis of pancreatic and potentially other cancers.

EVs, or exosomes, are the target of diagnostics development by numerous companies and academic groups using various technologies.

Legacy methods for unbiased exosome capture, which the Biological Dynamics chips provide, mostly rely on centrifugation, which can take a long time, and potentially shed some of the relevant exosomes in a sample.

More recently, companies have begun to employ new methods that incorporate microfluidics, nanostructures, and things like plasmonic resonance to separate exosomes from the other components of a blood sample. But the researchers working with the Biological Dynamics chip platform believe that it offers a significantly faster workflow than any other current methods, including plasmonic and nanoarray-based devices.

Another way to isolate exosomes is to pull them out of a sample based on a certain molecular or protein marker, and some groups have had luck demonstrating sensitive cancer detection with this type of approach.

Overall though, the ability to extract all the exosomes in a sample, regardless of what biomarker they express, offers greater diagnostic flexibility, and potentially greater sensitivity, said Jean Lewis, first author of the new study and a member of the UCSD lab that developed the AC current chip methodology now being commercialized by Biological Dynamics.

"One reason this is important is actually something we show in the paper," Lewis said. "The CD63 antibody for example is something a lot of [platforms] use as a general exosome marker … but in our paper, we could show that not all exosome populations have equal amounts of CD63 and that marker itself can change in different situations."

"This is one reason why there is a move to find more general ways of pulling out these vesicles," she added.

The UCSD team's new study in pancreatic cancer follows a previous publication, also in ACS Nano, in which the same group demonstrated the ability of the chips to isolate glioblastoma exosomes from undiluted human plasma samples in under 30 minutes.

The technology, which is being commercialized by UCSD-spinout Biological Dynamics, uses alternating current to create a non-uniform electric field. A whole-blood or plasma sample is run through the chip and over a microelectrode array, and when the current is applied, target particles within a specific size range are attracted to the array, while those that are smaller or larger are repelled and can then be washed away.

Depending on the goal, a user would then perform on-chip immunofluorescence analysis for identification and quantification of whatever target biomarkers they want.

In the new publication, the investigators used the biomarkers glypican-1 and CD63 to develop a bivariate model for detecting pancreatic ductal adenocarcinoma (PDAC), isolating exosomes using the previously defined chip process and then testing to see how accurately they could pick out pancreatic cancer samples from normal controls.

According to the authors, the two-biomarker method was able to distinguish twenty cancer samples from 11 healthy subjects with 99 percent sensitivity and 82 percent specificity.

Pancreatic cancer has also been the target of other research using exosomes. In fact, a previous study had already found that glypican-1-positive exosomes were present in higher numbers in pancreatic cancer patients compared to controls. But the technology used for that study was relatively complex and time-consuming, Lewis and her coauthors argue.

"Depending on the protocol, multi-step centrifugation can take at least overnight, and that really doesn't lend itself as well to clinical implementation," Lewis said.

The fact that the UCSD team was able to replicate an exosome biomarker association that has been seen in other studies using other technologies suggests that the same could be true with other markers in other types of cancer.

Lewis said that she and her colleagues are working with clinicians at the university to expand on their current results in pancreatic cancer by testing the chips in larger numbers of samples that include early-stage pancreatic cancer patients.

With other groups, the team is also investigating brain cancer and traumatic brain injury, she added.

The study's authors also highlighted that because there is some evidence that exosomes that circulate in cancer patients may be smaller than those of healthy individuals, there is a possibility that this could be exploited to increase the ability of the chip technology being explored.

According to Biological Dynamics, the pancreatic cancer study illustrates how its technology could help unlock the clinical translation of biomarkers that might otherwise have been confined to research because of the cumbersome nature of other exosome platforms. But the firm's CEO Raj Krishnan declined to comment on whether it would pursue development of a pancreatic cancer test specifically.

The company hasn't commercially released any test products so far, but has created a cell-free DNA quantification assay aimed at lung cancer treatment monitoring, which is being used internally and by research collaborators.

The same is true for the firm's base technology, which now comprises two different isolation platforms: the ExoVerita Flex system, which is a manual system designed to allow researchers to design their own workflow, and the NanoVerita system, which offers an automated workflow for direct isolation and quantification of a specific subset of biomarkers, such as cfDNA.

In addition to the group at UCSD, Biological Dynamics has also said it is providing platforms for research at Oregon Health & Science University.

When the company begins to supply platforms commercially, groups that bring the chips in house could ostensibly design and create any number of tests. Krishnan said that for its first generation of assays, such as the cfDNA-based testing for monitoring treatment response in lung cancer, Biological Dynamics has taken on the role of assay developer, but that the company is "open to various options" as it further develops its platform.

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