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UC Berkeley Spinout Zephyrus Launches into Single-cell Proteomics Space with $1.9M in Funding

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NEW YORK (GenomeWeb News) – University of California, Berkeley spinout Zephyrus Biosciences this week announced its launch behind $1.86 million in funding.

The company aims to commercialize the single cell Western blotting technology (scWestern) developed in the lab of UC Berkeley researcher and Zephyrus co-founder Amy Herr. Detailed in a paper published in Nature Methods in June, the scWestern approach could prove useful in a variety of research areas, including drug development work and cancer heterogeneity and stem cell differentiation studies, Kelly Gardner, Zephyrus co-founder and CEO, told ProteoMonitor.

The funding consists of a $1.5 million seed funding round, a $350,000 Phase I SBIR grant from the National Institutes of Health, and $10,000 from the UC Bakar Fellows Program. The seed round was led by angel investor group Life Science Angels with Mission Bay Capital, The Angel Forum, the Stanford-StartX Fund, and a number of individual investors also participating.

Zephyrus' launch comes amidst a recent surge in interest in single-cell proteomics techniques among researchers and tool vendors.

Fluidigm, for instance, this year purchased mass cytometry firm DVS Sciences, giving it a foothold in both the high-end flow cytometry and single-cell proteomics markets. This followed a co-marketing deal the company signed in July 2013 with Olink Biosciences that combined the two firms' tools to create a high-throughput proteomics platform.

Fluidigm also announced last month plans to launch in 2015 a CyTOF imaging system for single-cell proteomics based on work done by University of Zurich researcher Bernd Bodenmiller and Swiss Federal Institute of Technology Zurich researcher Detlef Günther.

The lab of Stanford University researcher Garry Nolan, who was one of the earliest adopters of mass cytometry, has also developed a technique using mass spectrometry and metal-conjugated antibodies for highly multiplexed protein analyses at the subcellular level.

Also this year, NanoString obtained an exclusive option to license intellectual property to a proteomic assay developed by researchers at Massachusetts General Hospital that uses DNA-barcoded antibodies to simultaneously measure in the range of 100 proteins at single-cell sensitivity.

And, last year, GE Healthcare launched its MultiOmyx protein detection system through its Clarient Diagnostic Services.

Zephyrus expects its technology will stand out in this increasingly busy field due to its relative simplicity and low price and the familiarity of biology researchers with conventional Western blotting technology, Gardner said.

"Western blotting is very widely used and people are very comfortable with it," she said. "So to be able to do the Western approach on single cells is something that we are excited about. There has been a lot of work in single cell genomics and transcriptomics, but a lot of researchers are very interested in directly measuring protein expression, and I think the Western-based approach that we are developing really opens up the proteomics side of the market."

One key aspect of both the scWestern and Western blotting in general is the specificity provided by combining electrophoresis-based separation with antibody detection, Gardner noted.

Another factor differentiating the platform from tools like Fluidigm's CyTOF, she said, "is that we are really envisioning this as an individual lab-level tool."

"Our approach is to enable it to be [owned] by an individual lab, and it's pretty flexible in the types of targets it can analyze," she said. "It can be used with any Western-validated antibody that is commercially available."

As presented in the Nature Methods paper, the scWestern approach uses microscope slides coated with a thin layer of photoactive polyacrylamide gel divided into 6,720 microwells. These wells are then seeded with the cells of interest, with each well collecting up to four cells.

The researchers then lyse the cells and perform electrophoresis. In the Nature Methods paper, Herr and her team achieved separation of molecular mass differences of 51 percent in separation lengths of 500 μm and a separation time of 30 seconds, making the approach significantly faster and more compact than existing microwestern arrays. Following separation, the gels are exposed to UV light to immobilize the proteins and allow for probing with antibodies.

As Herr explained in an interview with ProteoMonitor upon release of the study, the photoactive hydrogels used in the separation step can be turned, essentially, into blotting membranes using UV light stimulation, allowing researchers to move between steps without any sample handling.

Gardner declined to provide pricing information or a timeline for a commercial launch of the system, but said that the company "is actively working on product development."

In addition to developing the platform itself, company researchers are also working on application development, with the goal being to have several research kits available when the product launches. Most likely these applications will focus on stem cell and cancer research, Gardner said.

In the Nature Methods study, Herr and her colleagues applied the system to an analysis of stem cell signaling, looking at the heterogeneity of signaling in rat neural stem cells in response to stimulation with fibroblast growth factor 2. Measuring total and phosophorylated levels of the kinases ERK1/2 and MEK1/2, the researchers tracked variations in stem cells' responses to the stimulus.

They also used the technique to track stem cell differentiation to both astrocytes and neurons, measuring levels of the proteins NESTα, NESTβ, SOX2, βIIITUB, and GFAP, which are used as markers of differentiation.

Gardner didn't give an employee headcount for Zephyrus, saying that it is "early stage and still growing." In addition to Herr and Gardner, Josh Mohlo, formerly a senior program manager at PerkinElmer specializing in microfluidics, is Zephyrus' third co-founder as well as the firm's chief technology officer.

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