ORLANDO, Fla. — At last week’s Society for Biomolecular Screening conference here, Alpha Innotech and Applied Precision were among several companies showing off new instrumentation for cell-based or high-content screening.
The companies’ exhibit booths were across the aisle from one another — but that wasn’t the only way they were connected. Both companies are arguably best known for their microarray scanners, and both were introducing cellular imaging systems based on the same technology found in those scanners. And finally, both join a growing number of companies marketing imaging systems with non-laser-based illumination and CCD cameras in an attempt to drive down cost and increase throughput.
Another thing is for certain — both are entering a rapidly expanding market. Many companies in the cell-based assay and high-content screening arena market products that have been dedicated to those applications from the very start. But like some newer entries into the market space, Alpha Innotech and Applied Precision have decided to modify or build upon technology that they had already developed for other applications — specifically, reading microarrays.
The technology behind most microarray scanners — CCD cameras — may prove to be well suited for cell-based assays. As the resolution of CCD-based scanners has increased along with increasingly dense arrays, it has approached a level — 10 microns or less — that, at the very least, can image individual cells, if not begin to distinguish sub-cellular features.
For true sub-cellular imaging, laser-based confocal microscopy or variations thereof still can’t be beaten. But as engineers struggle to increase the throughput of such systems, CCD camera-based instruments that take snapshots of entire microtiter plates or slides can gather data — albeit fewer points of it — much faster. Furthermore, lasers are expensive and high-maintenance. This isn’t as much of an issue for large pharmaceutical companies, but smaller drug discovery firms, biotech companies, and academic institutions often desire something cheaper.
Alpha Innotech wasn’t introducing a new instrument at SBS; rather, it was demonstrating how its existing detection platform, NovaRay, might be used for cell-based screening in gene expression studies and drug discovery.
Alpha Innotech was founded in 1992 with the intent of “providing tools for molecular biology,” David Heffelfinger, vice president of R&D for the company, told Inside Bioassays last week. At the time, he said, this primarily meant instrumentation to read and quantify proteins in gels. Soon thereafter, the company started selling consumables, and in 2002, the company completed an $8 million first round of financing, the purpose of which was to move the company into the gene expression market, Heffelfinger said.
“The company quickly realized that the microarray market was in transition,” Heffelfinger said, “from the paradigm of ‘many genes, few samples,’ to ‘few genes, many samples’ as it moved into the drug discovery market.”
The natural progression from this point, Heffelfinger said, was to design instruments to study protein expression using protein arrays, and then gene expression in cells.
“One of the advantages our system has is its versatility and simplicity, and I think that carries over from the original product line, which was based on CCD technology,” he added.
Alpha still sells dedicated instruments for reading gels and microarrays, but at SBS it was plugging NovaRay as an all-in-one solution that could take on cell-based assays, as well. NovaRay uses a halogen light source and eight interchangeable filters for multiplexed fluorescence imaging. The instrument accommodates microtiter plates or microscope slides, and has an in-house developed software package.
Heffelfinger said the NovaRay would officially be available in late December or early January, at which time the company will include a software package for high-content cellular analysis. Meanwhile, the company has secured beta-testers, two of which — biotech firm Integral Molecular and a University of Pennsylvania researcher — were at the conference touting the instrument’s benefits.
Tiffani Greene, a researcher with Philadelphia-based Integral Molecular, is using the NovaRay in combination with cellular arrays to analyze membrane protein structure and function. “We were working on cell arrays in a slide format,” Greene said. “So we had live, wet cells on a slide, and anybody with a chip scanner won’t let you put cells into the scanner, because they’re too messy.” Greene also said that the instrument allowed a wider variety of fluorescence imaging than other options.
Heffelfinger conceded that living cell arrays spotted on microscope slides is a “very interesting” application that the company wants to heavily pursue.
Dhaval Gosalia, a graduate student at Penn’s Institute for Medicine and Engineering, is using the NovaRay to study protease substrate specificity with homemade nanowell protein microarrays, in which each of thousands of spots on a slide contains an individual chemical reaction.
“The problem with new technology like this is that you have to fit it with whatever instrumentation is currently on the market,” Gosalia said. “A laser scanner was our first choice, but they are limited in the number of colors available, and prohibitively expensive.” Gosalia added that he used to piece images together, and an entire slide would take him one day. On the NovaRay, however, he said that he now scans 12 slides simultaneously and averages 300,000 reactions per day.
Depending on the application, Alpha Innotech said that the scanner offers a resolution of between four and 15 microns. To increase the resolution for higher-content cellular analysis, Heffelfinger said the company has exclusively licensed a digital micromirror device from Digital Optical Imaging of Vancouver, British Columbia, Canada, which it hopes to install in a newer model.
Across the aisle, Applied Precision was previewing its CCD-based cellular imaging system, CellWorks, which it plans to officially launch early next year.
Applied Precision’s instruments truly span several scientific fields, including metrology, photonics, micropositioning, and life sciences. The life sciences division’s two major existing products are the DeltaVision microscope for low-throughput, sub-cellular imaging, and the ArrayWorks microarray scanner.
The company has also built its new instrument based on white-light, CCD technology from its microarray scanner, but unlike Alpha Innotech, has designed a dedicated box for cell-based assays and high-content screening. Joseph Victor, senior vice president of life sciences at Applied Precision, corroborated the general trend of moving toward non-laser based imaging systems.
“For high-content imaging … the sensitivity is about three to four times that of a laser photomultiplier tube, from a detector standpoint,” Victor told Inside Bioassays. “When you’re doing high-throughput, lower resolution imaging, maybe this is less of an issue. But as soon as you move into high-content or cell-based screening, then this a big deal.”
Victor also cited wavelength flexibility, saying “by merely switching filters, you can cover the range from UV to near-IR. With a laser, you have to add different [photomultiplier tubes], and once you have more than two, it gets not only complicated, but expensive.”
The CellWorks is capable of simultaneously acquiring four wavelengths, and offers resolutions between 0.5 microns and 1 micron, making it a true “high-content system,” Victor said. He added that this resolution is achieved using a proprietary optical train that has been “optimized and carefully matched with the CCD.” The instrument is compatible with microtiter plates, although Victor said that the company is planning to implement a microscope slide holder in the future.
Victor shunned comparisons with Alpha Innotech and other upstart cell-based imagers, saying that in high-content screening, Applied Precision compares itself to Cellomics, GE Healthcare, and Molecular Devices because of its high resolution.
Victor said that the CellWorks will not be packaged with any high-content analysis software, but that Applied Precision plans to do so at or near the official launch date. Whether that software will come from an outside vendor or internal engineering remains to be seen. However, Inside Bioassays saw company reps having a long conversation with Whitehead Institute researcher Anne Carpenter, who was awarded a grant from SBS for her continuing work on developing software for living cell arrays (see story in this issue, SBS Conference Takes an Indirect Hit from Hurricane Ivan, But Forges Ahead Regardless).
“We are very interested in the project Anne Carpenter is doing,” Victor said.
For the time being, he added, the instrument is compatible with several image analysis software packages, such as Molecular Devices’ (formerly Universal Imaging) MetaMorph. Right now, the company has a few beta-testers around the world, primarily academic. “The only one we can talk about is Tim Mitchison’s group at Harvard,” Victor added. In a May interview with Inside Bioassays, Mitchison, co-director of Harvard’s Institute of Chemistry and Cell Biology, said he thought the CellWorks “was going to beat the pants off the rest of [the imaging systems].” (See Inside Bioassays, 5/25/2004)
On the Cheap
It remains to be seen whether Alpha Innotech or Applied Precision can make a dent in the high-content screening market, but the companies certainly seem ready to deliver on their promise of reduced cost.
Heffelfinger told Inside Bioassays that the NovaRay system will cost somewhere between $89,000 and $100,000, “depending on options such as lamps, filters, and other accessories.”
Meanwhile, Victor said that the company was telling visitors to the company’s booth that the ballpark price of the CellWorks would be around $119,000.
Both of these prices are very competitive — will the instruments be?