384-channel parallel microfluidic cytometer for rare-cell screening

• Published in: Lab on a chip 2009-01, Vol.9 (2), p.305-310
• Main Authors: Mckenna, Brian K, Selim, A A, Richard Bringhurst, F, Ehrlich, Daniel J
• Format: Article
• Language: English
• Subjects: Animals; Cell Line; Cell Separation; Flow Cytometry - methods; Microfluidic Analytical Techniques - instrumentation; Osteocytes - cytology; Receptor, Parathyroid Hormone, Type 1 - genetics; Receptor, Parathyroid Hormone, Type 1 - metabolism
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/b811889b

We have constructed a 384-channel parallel microfluidic cytometer (PMC). The multichannel architecture allows 384 unique samples for a cell-based screen to be read out in approximately 6-10 min, about 30-times the speed of a conventional fluorescence-activated cytometer system (FACS). This architecture also allows the signal integration time to be varied over a larger range than is practical in single-channel FACS and is suitable for detection of rare-cells in a high background of negatives. The signal-to-noise advantages have been confirmed by using the system to count rare clonal osteocytes in the most difficult early stages of an expression-cloning screen for the carboxy-terminal parathyroid hormone receptor (CPTHR). This problem requires finding several dozen positive cells in a background of one million negatives. The system is automated around a scanning laser confocal detector and a 96-tip robotic pipettor and can maintain in vitro cultures on-system in 384-well plates. It is therefore directly practical for biology applications using existing high-throughput culture facilities. The PMC system lends itself to high-sample-number cytometry with an unusual capability for time synchronization and rare-cell sensitivity. A limited ability to handle large sample numbers has restricted applications of single-channel FACS in combinatorial cell assays; therefore the PMC could have a significant application in high-throughput screening.