Figure 1.
Comparative growth of various leukemic cell lines at different starting cell densities. Growth of leukemic cell lines at HD of (A) 3 × 105 cells/ml (B) 2 × 105 cells/ml (C) 1 × 105 cells/ml and (D) 5 × 104 cells/ml. The DT for ALL3 cells are color coded and shown in figures. Comparison of the growth of leukemic cell lines (E) SKL7 (F) RWLeu4 (G) BM185 (H) K562 (I) ALL3 (J) R10+ and (K) R10- at low starting cell densities of 0.5 × 104, 1 × 104, 2 × 104 cells/ml. The doubling time (DTs) for each cell lines at different cell densities are shown in graph and color-coded. BM185 was fastest growing cell line with DTs of 13-14 hr. Other cell lines SKL7, RWLue4, K562 and R10+ were growing with DTs of ~20-26 hr. The R10- cell line at starting cell densities of 1 × 104-2 × 104 and 0.5 × 104 cells/ml was growing with DTs of ~48 hr and ~64 hr, respectively. ALL3 cells at starting cell densities of 2 × 104 cells/ml grew with DTs of ~38 hr, at 1 × 104 cells/ml they had slight growth with DTs of ~75 hr and they did not grow at all at 0.5 × 104 cells/ml. (L) RWLeu4 was growing with DTs of ~21-25 hr at very low cell densities (1-50 cells/ml in 5 ml in 6-well plates) with little cell death. (M) Growth of BM185 cells in liquid culture (RPMI-1640) at 6 low cell densities. The cells grow equally well at cell densities as low as 1 cell/ml (5 cells/well) and as high as 105 cells/ml with DT of 11-15 hr, but rapidly became overgrown at higher starting densities. (N) Growth of R10- and (O) R10+ cells in liquid culture at cell concentrations from 1.5 cell/ml to 1000 cells/ml. R10- cells grew with similar DTs at cell densities as low as 3 cells/ml (15 cells/tube) and R10+ as low as 12.5 cells/ml (62 cells/tube). (P and Q) Growth or failure to grow of ALL3 cells at the same total starting cell numbers but at different cell densities per ml and per cm2 of growing surface area. (P) 5,000 cells failed to grow at all except for initially doubling once and then promptly dying at the 3 highest cell densities (104-5 × 104 cells/ml) and most tightly packed surface growing areas (6667 -15625 cells/cm2) (left panel). 10,000 cells grow fairly slowly with a DT of ~28 hr at a starting cell density of 105 cells/ml and a growing area cell concentration of 31250 cells/cm2 and even more at 105 cells/ml with a DTs of ~52 hr with fewer cells per growing area (27778/cm2) (middle panel). There was no growth at LD or with lower number of cells/cm2. Starting with a total of 20,000 cells, the cells again grew best at the two highest cell densities per ml and per growing areas with DTs of ~29 hr and hardly at all at lower cell concentration (right panel). (Q) At starting cell densities of 5 × 104 and 105 cells/ml as shown in the left and middle panels the cells grow faster and to higher cell densities on the smallest surface area (1 cm2), whereas at very high starting cell densities (4 × 105 cells/ml), the growing surface area is less important (right panel). (R) Photos of ALL3 cells starting with a total of 5000 cells growing in 6 well and 96 well plates at 2 and 7 days. The cells only doubled transiently once in first 2 days in the small 96-wells and then died but much more slowly than the cells in the larger 6-well plates. They didn’t grow at all in the larger 6-well plates; most were still viable at 2 days since the LD ALL3 cells were prepared by dilution of HD cells, but all were dead by 7 days and only a few corpses remained. These photos are shown to illustrate the contrast between the wide dispersal of the cells in the larger wells compared to their tight packing together in the small 96-well plates.