Problem: To fully understand cellular processes such as pathway activation and phenotypic change, scientists need tools to monitor the expression of multiple proteins per cell simultaneously. The technique of flow cytometry, in which cells are optically counted and examined while suspended in a stream of fluid, has emerged as a powerful cell analysis tool that can satisfy requirements for speed and reliability while also providing multiparametric information on individual cells.

Despite the power of flow cytometry, the size, complexity and cost of conventional instruments have historically confined this technology to the core lab and limited its use to experts.

Solution: Benchtop, micro-capillary flow cytometers, paired with readyto- use cell analysis kits, enable any researcher to leverage the power of flow cytometry, regardless of expertise or access to a core facility. These systems accommodate smaller sample volumes, generate less waste, have lower operating costs, and are easier to set up and run than traditional flow cytometers.

Guava Technologies, part of Millipore, developed the first commercially available micro-capillary flow cytometer and helped to launch benchtop flow cytometry. Today, Guava® flow cytometers span a broadening range of sophistication, from simple, two-color detection of single samples, to four-color detection of multiple tubes or 96-well plates. In fact, these are the only benchtop flow cytometers capable of 96-well format data acquisition and analysis.

Guava flow cytometry instruments incorporate innovative microcapillary flow cell technology that eliminates the need for “sheath fluid”—the liquid used to carry the cells through the laser beam. This innovation allows researchers to use smaller samples and results in a minimal amount of liquid waste (from liters per day to less than 50 mL per day). The technology results in an instrument much smaller than conventional flow cytometry systems, which means the Guava instrument can easily fit on a benchtop.

Along with changes in instrumentation, the commercialization of turnkey assay kits and specialized software has made flow cytometry analysis easy for scientists with no prior experience with the technique. Millipore has developed a portfolio of reagent kits validated specifically for use on Guava flow cytometers. More than 20 FlowCellect™ assay kits are available for measuring chemokine receptor levels, stem cell phenotypes, cell viability, apoptosis, cell cycle progression, proliferation and toxicity. Because all necessary reagents are included in the kits, no assay development is required. Assay-specific software modules enable researchers to get meaningful data even more quickly.

Sophisticated cell analysis enabled by flow cytometry is now a powerful “on demand” tool for researchers looking for answers to increasingly complex questions about protein activity, function and interaction.

When characterizing mixed cell populations, it may be insufficient to determine gross protein levels across an entire cell population. Biological processes can manifest themselves as shifts in relative expression or signaling events between subpopulations of cells. The ability to quantitatively distinguish subpopulations of cells according to their protein expression profiles and elucidate complex cell signaling pathways using bench-top flow cytometry opens up new opportunities for researchers seeking to understand biological processes and diseases at their most fundamental levels.

The availability of benchtop, microcapillary flow cytometry has allowed this powerful cell and protein analysis tool to be accessible to researchers of any skill level, right at the lab bench. The traditional barriers of cost, extensive assay development and challenging software have been eliminated, allowing flow cytometry to be integrated directly into the research setting and into protein expression workflows.

For further information, please visit www.millipore.com/flowcytometry.