The purification of cellular populations and individual cells is pivotal for the reliable characterization of gene expression, many aspects of life science research, and the development of cellular therapies. Cell sorting routinely involves fluorescence-based separation through flow cytometry, which has proven superior to crude techniques such as differential sedimentation. Through this process, large numbers of cells are rapidly analyzed for specific fluorescence signatures. Traditionally, cell samples are parsed in charged aerosol droplets, which are electrostatically sorted, enabling purification at thousands of cells per second at purities often greater than 90%.
This technology enables exceptional specificity using multiple fluorescent signatures (e.g., cell surface labels, cell size, and granularity).
However, the contributions of current flow-sorting platforms are balanced against significant limitations, including: high processing pressures that can result in loss of function and/or cell death; sample processing speeds/volumes that make processing clinical-scale samples (>500 million cells) unfeasible; a high degree of technical expertise needed to manage device complexity; increased risk of sample contamination through the use of open systems; and user safety concerns when processing aerosolized patient samples.
These limitations, plus the high unit and sample processing costs, must be overcome to enable further clinical application and commercialization.
To address these issues, Owl biomedical developed a fully closed cell-sorting system. This microchip-based technology employs closed fluid path cartridges with aseptic ports that permit the straightforward administration and collection of cell samples. At the heart of the cartridge is a patented microchip capable of very high-frequency fluidic valving (Figure 1).
Propelled by modest positive pressure, typically less than 0.2 atmospheres, cells pass through microchannels where laser-directed fluorescent signals are detected with photo-multiplier tubes. Upon identification of a positive target cell, the microchip valve opens, redirecting the cell to a collection chamber. Both positive and negative selected cells can then be retrieved from the cartridge and used for any number of downstream applications.