ACCELERATED ESTABLISHMENT OF MURINE LONG-TERM BONE-MARROW CULTURES BYADDITION OF STEM-CELL FACTOR

The effect of stem cell factor (SCF) on the establishment of hematopoi etic activity in murine long-term bone marrow cultures (LTBMC) was inv estigated by addition of SCF to (a) normal LTBMC from the onset of cul ture and (b) pre-established irradiated bone marrow stroma inoculated with Lineage negative (Lin(-)) primitive hematopoietic progenitor cell s enriched on the basis of low rhodamine-123 uptake (Rh-dull). Hematop oietic activity was established more rapidly in LTBMC grown in the pre sence of SCF (70 ng/mL), and the typical decline in cellularity and pr ogenitor cell content during the first weeks of culture was not observ ed. SCF also promoted the rapid expansion of progenitor cells derived from Lin(-), Rh-dull primitive hematopoietic cells inoculated onto irr adiated preestablished bone marrow stroma. The data demonstrate that e xogenous SCF augments hematopoietic activity in LTBMC, and that the le vels of endogenous SCF elaborated in LTBMC may be suboptimal for expan sion of hematopoietic cells.