Application of immunomagnetic cell separation in cancer cell detection: Development and optimization

Detection of rare, circulating tumor cells (CTCs) in peripheral blood is a potential prognostic/diagnostic tool in oncology. The use of immunomagnetic cell separation has been shown to improve the target cell purity and thus detection sensitivity. In this dissertation, a repeatable enrichment process including a flow through immunomagnetic cell separation system, the quadrupole magnetic cell sorter (QMS), was continuously developed and optimized. Molecular analysis technologies such as immunocytochemical assay and the Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) were combined with the enrichment process to reliably and accurately detect the presence of CTCs in peripheral blood. The novel technique was applied involving samples from head and neck patients undergoing surgery. Immunochemical staining and RT-PCR analysis of the same, enriched sample result in congruent outcome in all but one cases. Furthermore, the data with respect to the quantitative detection of CTCs is generally consistent with the pathological report on these patients. Data suggested that if a sample had 10 or more CTCs per ml of blood, a metastatic disease was present in the corresponding patient.; In order to further improve the final purity of cancer cells, to be eligible for studies including cDNA microarray, continuous development and optimization of the novel system was desired. A kinetics model was used to describe the process of ligand binding to cell surface receptors, which demonstrated that the ratio between the initial free antibody concentration and its dissociation constant (L0/KD) is the limiting factor for a given magnetic labeling system. Based on the theory, an optimal labeling scheme is identified, including the use of a tetrameric antibody complex, resulting in significantly better separation performance with order of magnitude higher log depletion.; In the second part of the study, a reaction-diffusion model was constructed to describe the in vitro tissue dissociation process. It is not only useful in recognizing the rate-limiting factor in the tissue dissociation process, but also provides quantitative guidelines to establish an optimal tissue dissociation technology. A rapid tissue dissociation process is established and characterization followed by a positive selection of EGFR targeted cancer cells. Evidence presented in this dissertation proofed the concept that it is feasible to isolate pure cancer cells from solid tumor biopsies within 2 hrs by applying the newly established rapid tissue dissociation method followed by a positive selection of cancer cells by immunomagnetic labeling.