Migration potential of CD38^lo/CD34⁺⁺ cells and myeloid progenitors pretreated with TGF-β1 and SDF-1. (A) Ex vivo–expanded CD34⁺ cells cultured in cytokine cocktail alone (medium) or containing TGF-β1 (0.5 ng/mL), SDF-1 (200 ng/mL), or SDF-1 (200 ng/mL) along with TGF-β1 (0.5 ng/mL) for 24 hours were assayed for their chemotactic activity toward SDF-1 (200 ng/mL). The proportion of CD38^lo/CD34⁺⁺ cells that migrated was determined by staining aliquots of input and migrated cells with CD34-FITC and CD38-APC and isotype-matched control antibodies. Data are presented as mean ± SD of 3 independent experiments. (B) Freshly isolated CD34⁺ cells cultured in medium alone or containing TGF-β1 (0.5 ng/mL), SDF-1 (200 ng/mL), or SDF-1 (200 ng/mL) along with TGF-β1 (0.5 ng/mL) for 20 hours were assayed for their chemotactic activity toward SDF-1 (200 ng/mL). The proportion of CD38^lo/CD34⁺⁺ cells that migrated was determined by staining aliquots of input and migrated cells with CD34-FITC and CD38-APC and isotype-matched control antibodies. Data are presented as mean ± SEM of 3 independent experiments. (C) Cytokine-expanded and (D) nonexpanded, myeloid in input (upper chamber), and migrated cells (lower chamber) were assayed by methylcellulose colony assay. The fold increase in progenitor cell migration for SDF-1 and SDF-1 + TGF-β1 pretreatment was normalized with respect to the efficiency of progenitor migration in untreated CD34⁺ cells. (C) Data are represented as mean ± SD of 3 independent experiments, and (D) data are represented as mean ± SEM of 3 independent experiments. *P < .05 compared with cells cultured in medium and **P < .05 compared with cells pretreated with SDF-1.