IMMUNOBEAD FILTRATION - A NOVEL-APPROACH FOR THE ISOLATION AND PROPAGATION OF TUMOR-CELLS

We have developed a method to facilitate the isolation and expansion o f tumor cells from body fluids and tissue biopsies, Antibody-conjugate d magnetic beads (immunobends) were used to isolate tumor cells from b lood, bone marrow, ascitic/pleural fluids, and enzyme-digested tissue biopsies, Filtration of the resulting cell suspension through a 20-mu m nylon monofilament filter secured to the base of polystyrene 36-well strips purged the bend-resetting cell function of contaminating norma l cells and unbound beads. Tumor cells that bound the magnetic beans w ere retained on the membrane due to their increased size and concentra ted into a small area (0.332 cm(2)), thus maintaining a high cell dens ity. The filters provided a stable and uniform three-dimensional matri x for cell growth, with a total surface area of 1.42 cm(2) available f or cell attachment. The filters could be easily removed from the base of the 36-well strips to facilitate handling and transfer between cult ure vessels, Tumor cells grown on the filters could subsequently be ha rvested using trypsin/EDTA or left in situ for immunostaining with con ventional immunohistochemical procedures. Filter-grown cells have show n extended passage in conventional cell culture in six cases. In two o f five cases, the orthotopic implantation of confluent filters that co ntained approximately 10(4) cells/8 x 8 mm filter successfully produce d tumors in nude mice after only 4 weeks. Our new approach may be of v alue in improving the success rate of generating long-term cultures fr om previously unproductive sources of tumor cells and thus may yield a greater variety of cell lines/strains for the study of malignant dise ase.