Dissociation of Intact Cells from Tumors and Normal Tissues

Cell dissociation remains a major obstacle to the technical evolution of solid tumor flow cytometry. Unfortunately, intertumoral heterogeneity represents the most significant, and most difficult to control, variable in these procedures. Typically, colorectal carcinomas have fewer cytokeratin-positive events than breast carcinomas, indicative of their generally greater proliferative capacity. These considerations imply there is probably no single dispersion protocol that optimizes yield and efficiency for every human carcinoma, even from a given primary site. Criteria for quality of cell dispersion are poorly defined in the cytometry literature. Moreover, controlled studies comparing dissociation techniques, especially for whole-cell methods, are difficult to find. In this chapter, disaggregation success is assessed by the following parameters: (1) overall yield (i.e., cells per gram of tissue), (2) proportion of detectable neoplastic events in DNA histogram, (3) histogram quality (coefficient of variation and baseline profile), and (4) morphologic appearance of disaggregated cells in cytologic preparations. Concepts of two-color, whole-cell analysis are also introduced in the chapter to illustrate the effect of certain dissociation artifacts on DNA histograms.