Cord blood progenitor cells have greater transendothelial migratory activity and increased responses to SDF-1 and MIP-3 beta compared with mobilized adult progenitor cells

When cord blood is used as a source of haemopoietic stem cells for transpla ntation, fewer cells are required per kg of recipient. This greater engraft ment efficiency of cord brood cells may relate to an increased ability to t raverse sinusoidal endothelium, a crucial step in the homing of stem cells. We report that freshly isolated cord blood progenitors migrated more effic iently than mobilized adult cells. Cord blood progenitors responded rapidly to growth factor stimulation with an increase in migratory ability within 24 h whereas mobilized adult cells responded only after 72 h (P < 0.01). Co rd blood cells also exited G(0)/G(1) rapidly; after 24 h of growth factor e xposure, 20.2 +/- 1.2% of cord blood CD34(+) cells were in S + G(2)/M compa red to 6.9 +/- 1.2% of adult CD34(+) cells (P < 0.01). Proliferating CFC mi grated more efficiently (13.3 +/- 3.4% for GM-CFC) than non-proliferating C FC (1.4 +/- 0.5%, P < 0.01) as determined using a H-3-thymidine suicide ass ay. Cord blood progenitor cells also demonstrated a greater transmigratory response to chemokine stimulation compared with adult cells; this was manif ested as a differential response of freshly isolated cells to SDP-1, and of growth factor activated cells to MIP-3 beta. Finally, cord blood CD34(+) c ells express higher levels of the chemokine receptor for SDF-1, CXCR4, when compared with mobilized adult CD34(+) cells (P < 0.05).