By Nicholas Borgert

In the months since receiving clearance to launch its BD FACSCanto™ flow cytometer to the United States’ in vitro diagnostics market, Becton, Dickinson and Company (BD) has made a significant impact. After building a record in the life sciences and research arenas, the FACSCanto analyzer is expected to become one more successful addition to BD’s line of flow-cytometry products. That analyzer line has expanded to include a worldwide customer base, with well beyond 10,000 installed systems.

BD FACSCanto™ flow cytometer.

FACSCanto comes from the term “bel canto”—an operatic style focusing on ease and purity of tone and employing agile and precise vocal techniques. BD officials say the FACSCanto cytometer offers a novel, yet simple, optical design in combination with robust electronics. The result is a flow-cytometry system that keeps signals precisely separated—even at the highest acquisition rates.

The FACSCanto system reflects BD’s more than 3 decades of design experience with flow-cytometry technology and applications. The latest model borrows heavily from technology first available from the BD™ LSR II expandable cell analyzer and the company’s BD FACSAria™ cell sorter. It offers a flow cytometer with high-sensitivity optics, extremely low sample-to-sample carryover, and rapid processing rates—up to 10,000 events per second. Among its performance highlights, the flow cytometer delivers high-fluorescence sensitivity to resolve dim events, clean data resulting from minimal sample contamination, and high processing speed. The FACSCanto™ system overcomes obstacles known in rare event analysis and in functional studies for low detection ranges.

Fiber Optics Routing
The FACSCanto employs blue and red excitation sources. The system’s laser beams are routed by fiber optics to beam-shaping prisms, where two lasers project onto separate spots in the flow cell. Once the particles intercept with the laser-excitation beams, the resulting optical signals are collected with a gel-coupled collection lens at the rear of the flow cell. The gel enhances the light collection; scattered light and fluorescent signals are then focused on the emission fiber pinholes. BD’s design incorporating the flow cell into the optical plate creates an integral excitation and collection system. Because the optical alignment is fixed, users avoid time-consuming manual laser-alignment tasks.

In addition, the system includes fluorochromes that have already been validated by BD Biosciences for users. The FACSCanto’s integrated fluidics cart holds all fluids necessary to operate and maintain the flow-cytometry system. The cart is equipped with fluid tanks to provide fully automated cleaning, startup, and shutdown routines. The system’s integrated fluidics cart provides everything necessary to run the cytometer and significantly reduces required fluid handling by an operator. That includes the collection of waste fluids. With a single click, the system software controls startup, shutdown, and monthly cleaning cycles automatically. Ease of maintenance is especially attractive where many operators routinely use a single analyzer.

When configured with the BD FACS™ automated loader option, the system offers lab users walkaway sample acquisition. This task reduction frees staff to concentrate on what’s most important: the science of technology-assisted diagnostic testing, instead of routine instrument operation and maintenance.

Innovations Drive Applications
An increasingly essential tool in hematology, flow cytometry involves the liquid suspension of cells obtained from blood, bone marrow, body fluids, or tissues that have been incubated with fluorescently tagged antibodies. The antibodies are used to target specific proteins on cell surfaces or inside the cell.

The system allows for minimal sample-to-sample carryover during sample injection.

Besides their use in oncology, immunology, hematology, and pathology, flow-cytometry systems are expanding into a wealth of microbiological applications. These include prokaryotic DNA and drug-resistance determination, and broad ecological applications: aquatic environment, plankton, algae, determination biology, and more.

Depending on the clinical task, flow cytometers accommodate a wide range of antibody panel types. BD’s current flow cytometers are capable of examining up to 16 different antigens simultaneously, although only two to four antigens are currently examined simultaneously in routine diagnostic use.

Customers rank enhanced optics, ease of maintenance, low sample-to-sample carryover, and high speed as the most popular features of the FACSCanto flow cytometer, according to Kerstin Willmann, BD Biosciences’ product manager for the new analyzer. “We have found that our customers especially benefit from the FACSCanto system’s unique six-color capability in combination with sophisticated optics that deliver high sensitivity,” Willmann says. The added color capability can harvest more information per cell while using smaller sample volumes.

Automated sample acquisition with the BD FACS™ Loader option. Each carousel accommodates 40 tubes.

With its newly developed sample-injection tube, the FACSCanto flow cytometer boasts sample carryover levels of less than 0.1%. The automated sample loader is a popular option that reduces operator involvement. Operators can switch quickly and easily between the standard manual sample loading and the automated approach.

“It is important to know that BD Biosciences offers system solutions—an issue of vital interest during the product-development process, so that hardware, software, application protocols, and reagents are all fully synergized, “ Willmann says. Complementing the product is BD’s established reputation for service excellence and commitment to customers, she says.

More Color, More Economies
Changes in medical reimbursement at the start of 2005 have resulted in customers seeking clinical systems with six-color capability. It’s a productivity issue: Added coloration helps run tests more economically than systems with limited color, she says.

Patented optics assembly for segmentation of laser emission signals.

The FACSCanto premiered worldwide for research use in February 2004. Two months after the worldwide launch, it was released to the European market following CE-IVD clearance. The system earned Food and Drug Administration clearance in the United States in September 2004. That clearance included the hardware, the FACSCanto clinical software for lymphocyte subsetting and enumeration (used in diagnosis and treatment monitoring of HIV infection), and BD FACS 7-color setup beads—a sophisticated one-tube system for handling application-specific instrument setup and instrument quality control.

In addition, BD FACSDiva software has been cleared for use on the FACSCanto. Highly modular acquisition and analysis software, FACSDiva enables users to run self-validated applications such as leukemia and lymphoma on the FACSCanto.

The FACSCanto flow cytometer provides high sensitivity for signal detection. The more fluorescent parameters are measured in parallel by a flow cytometer, the greater the need for a highly sophisticated optical design, Willmann says.

The integrated fluidics cart provides all fluids necessary to run the flow cytometer.

Key benefits users enjoy from the FACSCanto system include high-end optics with patented serial reflector arrays that allow for minimal light loss (optimal signal retention on the detector level). Unlike conventional flow cytometers, the FACSCanto analyzer routes the laser light using fiber optic cables.

Excellent sample carryover is another advantage offered by the FACSCanto system. Willmann says the analyzer provides a 10-fold better spec for sample-to-sample carryover than other flow cytometers in its class. The extremely low carryover results from the system’s unique sample-injection design. The injection tube is rinsed with sheath solution inside out between sample runs. The aspirator arm below the sample tube has a vacuum applied before a new tube is put on. The result: The sheath running top to bottom achieves a superior level of cleaning from one sample to the next.

Configured as a complete system, FACSCanto includes the benchtop flow cytometer, an integrated fluidics cart, a computer workstation, and an LCD monitor. “Customers love the automated sampling feature using our 40-tube carousel loader,” says Willmann. “Efficiency is extremely important in clinical labs, especially for large reference labs.”

High-end optics with patented serial reflector arrays that allow for minimal light-loss (optimal signal retention on the detector level) is one of the key differentiating benefits users enjoy from the FACSCanto system.

Because flow cytometry has evolved over 3 decades, a cell population that is frequently expressed or signals that are strongly expressed have been well documented.

Flow cytometry today helps identify rare populations in the immune system that play an important role, such as dendritic cells. More parameters make the identification process more effective. High sensitivity for signal detection is crucial because during the study of cell functions, responses often are subtle and not pronounced.

Another technical concern in rare event analysis is that to obtain statistically relevant information, a lab tech needs to acquire a fairly large sample volume—and that can be time-consuming. The FACSCanto cytometer can monitor as many as 10,000 events per second—faster than any other clinical instrument in its class.

Enhancements on the Horizon
At this point, functional studies of cells have hardly penetrated the diagnostic market. Such studies are by and large research-based, yet they are likely to become significantly more important for the clinical market in the near future. Challenges remain. Whether a cell is present or not is one type of diagnosis; whether the cell is functional or not is a completely different matter.

As mentioned earlier, much of today’s flow-cytometry testing occurs in oncology, immunology, hematology, and pathology, as well as in leukemia and lymphoma laboratories with customer-validated testing for diagnostic use. In most of these medical domains, rare event analysis has become a leading trend, in addition to the need to harvest an increasing amount of information from smaller sample volumes. Willmann says BD plans to continue expanding clinical applications that make use of the FACSCanto analyzer and its multi-color capabilities and unique performance characteristics.

Nicholas Borgert is a contributing writer for Clinical Lab Products.