SDF-1 increases CFU-G, CFU-M, and immature BFU-E colony formation by PB Inc⁺ CD34⁺ progenitor cells.

PB CD34⁺ progenitor cells were purified after incubation on a plastic support (Inc⁺) and plated in duplicate, at a density of 500 cells/mL, on semisolid Stem α ID medium containing IL-3, IL-6, IL-11, SCF, Epo, G-CSF, GM-CSF, and various concentrations of SDF-1. Colonies were scored on day 14. (A) Results for total BFU-E, CFU-G, CFU-M, CFU-GM, and CFU-Mix are expressed as a percentage of SDF-1 untreated control (CT) cells (mean ± SD). Control colony numbers were 91.7 ± 5.9 (BFU-E); 16 ± 3.1 (CFU-G); 2.8 ± 1.3 (CFU-M); 0.4 ± 0.2 (CFU-GM); and 1.75 ± 1.3 (CFU-Mix). The control plating efficiency (calculated on the total number of colonies) was 23.1% ± 2.1% (n = 5 independent experiments). (B) Results concerning mature and immature BFU-E are expressed as a percentage of untreated control (CT) cells (mean ± SD). BFU-E maturity was determined on the basis of clone size: large bursts containing 16 or more clusters with low levels of hemoglobin were classed as immature BFU-E, whereas small bursts with a higher hemoglobin content, containing fewer than 16 clusters, were defined as mature BFU-E. Control colony numbers for mature BFU-E and immature BFU-E were 77.7 ± 9.2 and 14 ± 3.5, respectively. An asterisk indicates significant difference from control values: * .001 < P < 0.05; ** .0001 < P < .001; *** P < .0001.