Cell kinetic analysis of human tumor stem cells.

The application of the tumor stem cell assay to the study of human tumor cell kinetics has the potential for major advances in our knowledge of proliferative characteristics of clonogenic human tumor cells. From simultaneous evaluation of in vitro drug sensitivity, in vitro doubling time, and the thymidine suicide index, plus flow cytometry, cytogenetic analysis, and assessment of differentiation markers, substantial insights into the basic biology of tumor cell growth may be attained. As discussed in other chapters, using modifications of the two-layer system, one can assess both local cell-mediated and humoral factors that might influence in vitro kinetics and drug sensitivity. The next few years should see the acquisition and integration of valuable new information that should allow more rational approaches to the treatment of tumors by taking full advantage of information on both kinetics and drug sensitivity of clonogenic human tumor cells.