Tumor Cells Profiled by Microscopic Imaging

Improved capture of circulating tumor cells and hyperspectral microscopic imaging facilitate identification and quantification of many molecular markers in cells at different times, recognition of coexpression of markers, and, thereby, allow noninvasive diagnosis and improved targeted therapy.

Scientists at the University of Texas Southwestern Medical Center (Dallas, TX, USA) analyzed normal and tumor cells using an HMI platform. They balanced the intensity of 10 fluorochromes bound to 10 different antibodies, each specific to a particular tumor marker, so that the intensity of each fluorochrome can be discerned from overlapping emissions.

By using two touch preparations from each primary breast cancer, the average molecular marker intensities of 25 tumor cells gave a representative molecular signature for the tumor despite some cellular heterogeneity. The HMI system is composed of an Olympus IX-70 inverted microscope (Olympus; Center Valley, PA, USA), SP-500i imaging spectrograph (Acton Research Corporation; Acton, MA, USA), Quantix KAF1600 charge-coupled device (CCD) camera (Photometrics, Tucson, AZ, USA), and X-Y motorized stage (Ludl Electronic Products Ltd.; Hawthorne, NY, USA).

The team quantified 10 molecular markers in 25 cells from five different cancer cell lines and two normal breast epithelial cell lines, providing 1,700 measurements of tumor marker intensity. The intensities determined by the HMI correlate well with the conventional analysis by experts in cellular pathology. Because additional multiplexes can be developed using the same fluorochromes but different antibodies, this analysis allows quantification of many molecular markers on a population of tumor cells. HMI can be automated completely, and eventually, it could allow the standardization of protein biomarkers and improve reproducibility among clinical pathology laboratories.

The authors concluded that conventional pathologic examination together with current fluorescence microscopy is insufficient to obtain the level of molecular profiling necessary to optimize new treatment regimens. However, HMI analysis of touch preparations of tumor tissue and circulating tumor cells represents a major step forward because a large number of molecular markers can be detected and their expression precisely quantified in individual tumor cells. The study was published in the May 2012 issue of Translational Research.

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University of Texas Southwestern Medical Center
Olympus
Acton Research Corporation