Cell magnetophoresis is a cell motion induced by the magnetic field in electrolyte solutions. During the current funding period (ending 01/31/08) we have used Cell Tracking Velocimetry (CTV) to compare effects of binding of various commercial immunomagnetic reagents on cell magnetophoretic mobility (MM) and demonstrated that MM is an accurate predictor of the magnetophoretic cell sorting performance in applications to hematopoietic progenitor cell enrichment, T cell depletion, and rare cancer cell detection. We also measured intrinsic cell MM without binding of the immunomagnetic tagging reagents on red blood cells infected with malaria parasites, and spores of Bacillus globigii (a prokaryote). Here we propose to extend the investigations to cancer cell lines and primary cancer cells. The working hypothesis is that differences between normal and transformed cancer cells, including their metabolic activity and physical properties, lead to differences in cell MM.
Aim 1. To screen the available cancer cell lines for differences in cell MM against baseline normal peripheral leukocyte MM. The screening will be performed using currently available CTV and magnetic flow cell sorting equipment. The measurements will be performed in typical cell culture media and modified media with the increased level of iron (and potentially other paramagnetic elements, such as manganese). The cell lines will be purchased from American Tissue Culture Collection, and will be initially selected for high probability in elevated iron content (such as leukemic leukocyte lines).
Aim 2. To re-design CTV for the maximum magnetic energy gradient configuration using available permanent magnet materials. The high magnetic energy gradient is necessary to induce motion of weakly magnetic cells and to resolve differences between sample means of cancer cells and baseline control (peripheral leukocytes). The existing expertise, analytical and machining capabilities will provide the necessary resources to accomplish this aim. Preliminary discussions regarding use of superconducting magnets led to the conclusion that the technical complexities exceed the capacity of this funding mechanism. On the other hand, the commercial availability of high magnetic energy permanent materials and innovative designs demonstrated feasibility of achieving fields of 3 tesla (T) and gradients of 1,000 T/m on a small laboratory scale, sufficient for work with cells.
Aim 3. To demonstrate feasibility of cancer cell isolation by intrinsic cell magnetophoretic mobility. Based on the findings in Aim1 and the improved analytical and separation capabilities achieved as a result of Aim2, selected primary cancer samples will be prepared as single cell suspensions and analyzed for their MM against the background control. In the final analysis, we will determine recovery and purity of the cancer cells isolated magnetophoretically from clinical biopsy samples using immunocytochemistry and other molecular markers of cancer. Detection of tumor cells in the peripheral blood and tissues of cancer patients exhibiting no evidence of metastatic disease is of critical clinical importance as it will lead to early intervention therapy and modification of treatment in an attempt to halt or retard disease progression. The past NIH support resulted in the development of magnetic cell sorting and cell analysis instrumentation, and their application to rare cancer cell detection and stem cell separation using immunospecific magnetic particle labeling (now commercialized by our institutions, Cleveland Clinic and The Ohio State University). Based on our preliminary studies with red blood cells, we propose to extend this research to the detection and analysis of cancer cells without the requirement of a cumbersome magnetic particle tagging step, but only based on naturally occurring, weak cell magnetization.
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