Use of the Matrigel-based assay to measure the invasiveness of leukemic cells.

The reconstituted basement membrane (Matrigel)-based assay was used to quantify the invasive potential of hematopoietic cells including cultured human leukemic cells (KG-1, K-562, HEL, HL-60, and U-937), normal bone marrow (BM) cells, and normal polymorphonuclear leukocytes (PMNL). We found that (i) in contrast to 6- to 72-hour incubation periods typically used in assays with solid tumor cells, most of the invasive cell populations tested here required only 2 to 4 hours to cross the Matrigel layer; (ii) unlike that of PMNL, whose invasiveness was stimulated by the addition of FMLP, the invasive rate of cultured leukemic cells was not affected by this chemoattractant; (iii) the rate of invasion was inversely proportional to the Matrigel concentration per filter but varied with the Matrigel batch used; (iv) the most consistent results were obtained when 2.5 to 4 x 10(5) cells were added to the top portion of the blind well; and (v) of all leukemic cells tested, the least differentiated myeloblastic KG-1 cells exhibited the highest invasive potential, which was comparable to that of normal PMNL. We conclude that the Matrigel-based assay can be used as a model system in studies of mechanisms regulating movement of hematopoietic cells across basement membrane barriers.