Effects of rhIL-11 on MK progenitor formation from murine bone marrow primitive progenitor-enriched subpopulations.
Sorted subpopulations were isolated from the bone marrow of 5–fluorouracil-treated (A,C) and normal (B) mice as described in “Materials and Methods.” Two thousand Lin−Sca-1+c-kit+ (A,C) and Lin−Sca-1+c-kit+CD34−(B) cells/mL were plated in liquid cultures with 50 ng/mL SF and 50 ng/mL rhIL-11. Cells were removed from the cultures on specified days and were replated as follows: 400 cells/mL on days 0 and 2; 2000 cells/mL on day 4; and 40 000 cells/mL on day 6 in semisolid agar medium with either designated cytokine combinations (50 ng/mL SF, 20 ng/mL IL-3, 10-50 ng/mL rhIL-11, 50-100 ng/mL Tpo) (C) or 50 ng/mL SF plus 50 to 100 ng/mL Tpo (A,B). After 7 days of incubation at 37°C, 5% CO2, plates were dried, fixed, and stained for the detection of acetylcholinesterase activity (MK cells). Clusters of 3 or more stained cells were scored as MK colonies. Absolute numbers of MK progenitors (C) are based on culturing 500 sorted cells. Results are representative of 3 to 5 separate experiments.
