In patients with carcinomas
tumor cells are shed into the blood, enumeration and characterization of these cells offers the opportunity to obtain a “real time”
biopsy of the tumor and may improve the management of the
disease. The frequency of circulating
tumor cells is rare (<1
cell / ml) and technology is needed that has sufficient sensitivity and specificity to enumerate and characterize these cells. The present
system was developed to provide an immunophenotype,
fluorescence wave forms as well as images of immunomagnetically enriched cells. Blood volumes
ranging from 7.5-30 ml are immunomagnetically enriched for epithelial cells. The
sample volume is reduced to 320 μl and inserted into an analysis chamber. Upon introduction of the chamber in a
magnetic field, the immunomagnetically tagged cells rise out of the sample and align between
nickel lines (period 30 μm, space 15 μm) that are present on the viewing surface of the chamber. A multi
laser system is used to detect the
fluorescence emitted by
DAPI,
Phycoerythrin and Allophycocyan labeled and magnetically aligned cells. Compact disk
optics are used to maintain alignment and focus of the
laser beams onto
nickel lines while moving the chamber. The chamber is scanned with a speed of 10 mm / sec and the entire chamber is analyzed in approximately 5 minutes. The fluorescent signals obtained from the events provide an immunophenotype similar to that of a flow cytometer. The
fluorescence waveforms improve the characterization of the events and add to the classification as background,
cellular debris and cells. Since the
cell locations are preserved, objects that immunophenotypically classify as epithelial cells can be revisited for further analysis. Bright field and fluorescent images of the selected objects are captured to confirm that the identified objects are
tumor cells.