Splendid Isolation for Cells Screened via High-Throughput Microfluidics

A scientist in biologics discovery or cell line development, working at peak efficiency, typically can screen between 5000 and 10,000 antibody-secreting cells per day. What if we could increase daily output to 40 million? Imagine what could happen.

Frank F. Craig, PhD, needn’t imagine it. He knows. As CEO of Sphere Fluidics, he has been instrumental in the development and commercialization of the Cyto-Mine^® Single Cell Analysis System.

“We are the first company in the world to commercialize picodroplet microfluidics for biopharmaceutical discovery and cell line development,” Craig says. “With the Cyto-Mine, we can rapidly screen the entire repertoire of cells obtained from an immunized mouse—up to 40 million cells—for production of a specific therapeutic antibody, and subsequently select, dispense, and image ‘hits’ with guaranteed monoclonality.”

As testament to the disruptive nature of the company, Sphere Fluidics caught the eye of 24Haymarket and other early-stage investors, attracting some $22 million in funding. Its technology also has collected awards for disruptive innovation, such as being named number one in The Scientist magazine’s “Top 10 Innovations of 2018.”

High-throughput, single-cell screening

Cyto-Mine uses picoliter volume droplets to make such high-screening throughput possible. “Picoliter droplets encapsulate and protect single cells and trap their released proteins. This eliminates the problems of rapid diffusion and cell pretreatment when cell sorters are used to measure secreted molecules” he explains. “We automate this process on a microfluidic Cyto-Cartridge^®, and our Cyto-Mine runs the workflow automatically, using imaging to ensure single-cell monoclonality of the hits.”

When multiple tasks are performed, contamination risks and turnaround times are reduced, bench space is optimized, and scientists can focus on assay design and data interpretation.

“Even after assaying 40 million cells,” Craig notes, “a scientist still ends up with a small, manageable number of high-quality hits, but the speed of discovery and development is greatly increased and the management pressures for improved efficiency are reduced. By processing the entire genetic repertoire of available cells rather than only a subpopulation, the very best antibody achievable will be discovered.”

A Cambridge spinout

The company spun out of the University of Cambridge in 2010 to produce novel biochip systems and provide R&D services. “The chips used picodroplet methodology, which enabled novel workflows with single cells and molecules—such as encapsulation, fusion, splitting, and sorting—that couldn’t be accomplished with conventional fluidics,” Craig asserts.

“I was asked by Cambridge select University) Enterprise to help assess the commercial potential of the founders’ nascent technology. After positive feedback from other industry experts and meeting select and being impressed with) the other two co-founders, I became excited about the company’s potential and its team. We became committed to forming a company,” Craig recalls.

“The first challenge was agreeing on the market focus,” he continues. There were three major potential markets: biopharmaceuticals, chemicals, and biofuels.

“For biopharma, we could use picodroplets to trap and measure valuable, novel molecules, such as secreted antibodies and other medically relevant proteins, from single cells. In the chemical industry, the picodroplets could be used to identify rare enzyme variants produced by in vitro transcription and translation or after secretion from engineered microbes. For biofuels, picodroplets could be used to identify engineered microbes or algae that secrete valuable biofuel precursors.”

“The biopharmaceuticals market seemed the better business choice,” Craig says, citing its focus on innovation and its large potential market. The next step was “convincing investors of the potential of the company—challenging, especially when you have no real products or resources.”

Growing a scalable business

Since its inception, Sphere Fluidics has had to work smart. Company leaders augmented the talents of a small internal team with complementary outside expertise in product design, development, and manufacturing. Funding came from R&D grants and angel investors and was stretched as far as possible through a lean management philosophy.

The original plan of developing chips and providing R&D services was a solid foundation, but not the scalable, sustainable business the founders visualized. “The former wasn’t a high value opportunity,” Craig admits.

Market research concurred. Sphere Fluidics’ big pharma customers preferred a plug-and-play device for in-house use rather than a service-based model and standalone chips. “We wrote a business plan around an integrated device concept, raised investment, and then developed the product and named it Cyto-Mine,” Craig says. “Fantastically, performance of the final product surpassed our original technical concept.

“Originally, Cyto-Mine was developed to isolate rare antibody-secreting variants from naturally occurring cell populations select for example B cells union ” he points out. “We now have extended this to measure cytokine secretion and also antibodies produced from engineered cells such as hybridomas and CHO cells.”

Now, Sphere Fluidics is developing complementary assay systems and continuing software upgrades to enable new workflows. Systems in development “enable single-cell engineering and isolation of useful phenotypes from single, engineered cells. This is done by fusing individual picodroplets containing single cells with an individual member of a different set of picodroplets that contain cell engineering reagents,” Craig says. The first application, just completed, enables individual T-cell therapy engineering with just a single virus.

Sphere Fluidics is also working with Oxford Genetics, Twist Biosciences, and the University of Edinburgh to develop a desktop system to miniaturize and automate precision genome editing of single cells. That project has achieved proof of concept, and an automated rig is being developed.

Attentive to customers

Some part of Sphere Fluidics’ focus on technology innovation can be attributed to its attention to customers’ evolving needs. “We’re open to customer-driven suggestions, such as new software features or improvements that can enable different assays,” Craig declares. “Feel free to ask us. If you have an idea for a new application you would like to try on Cyto-Mine, contact us. We can help you design and even implement your concept.”

For Sphere Fluidics, the ongoing challenge is to maintain focus. With 85 patents, there are many potential opportunities and applications. Therefore, he says, “we have had to learn to get—and stay—focused on key priorities, and to use our resources wisely.”

Currently, that focus includes increasing Cyto-Mine availability. With sales offices in the U.K. and U.S. East Coast, “We are expanding to the U.S. West Coast and accessing further international markets via our 11 distributorships,” Craig insists. The company plans to grow its staff 50% by year’s end.

With such rapid growth, leadership’s continued tight focus must broaden from developing the science to also managing an evolving company. “With various novel products in our pipeline, we will have to balance our focus on supporting and selling Cyto-Mine along with bringing in new investment to migrate our R&D team to support new, innovative product streams,” Craig says. That’s a type of balance many young companies struggle to achieve. He isn’t worried.