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

Summary. When cord blood is used as a source of haemo-poietic stem cells for transplantation, fewer cells are requiredper kg of recipient. This greater engraftment efficiency ofcord blood cells may relate to an increased ability to traversesinusoidal endothelium, a crucial step in the homing of stemcells. We report that freshly isolated cord blood progenitorsmigrated more efficiently than mobilized adult cells. Cordblood progenitors responded rapidly to growth factor stimu-lation with an increase in migratory ability within 24hwhereas mobilized adult cells responded only after 72 h(P <0·01). Cord blood cells also exited G 0 /G 1 rapidly; after24 h of growth factor exposure, 20·2 61·2% of cord bloodCD34 ⁄ cells were in S ⁄G 2 /M compared to 6·9 61·2% ofadult CD34 ⁄ cells (P <0·01). Proliferating CFC migratedmore efficiently (13·3 63·4% for GM-CFC) than non-proliferating CFC (1·4 60·5%, P <0·01) as determinedusing a 3 H-thymidine suicide assay. Cord blood progenitorcells also demonstrated a greater transmigratory response tochemokine stimulation compared with adult cells; this wasmanifested as a differential response of freshly isolated cellsto SDF-1, and of growth factor activated cells to MIP-3b.Finally, cord blood CD34