OBJECTIVETo Explore a two-step culture system to generate a large number of dendritic cells (DC) differentiated from cord blood (CB) CD(34)(+) cells.

METHODSEnriched CB CD(34)(+) cells with immunoadsorption were primarily cultured in the presence of stem cell factor (SCF), Flt-3 ligand (FL), thrombopoietin (Tpo) and interleukin-3 (IL-3) for 7 (group I), 10 (group II) or 14 days (group III) respectively, and then further cultured with GM-CSF, IL-4 and TNF-alpha for 5 - 8 days to induce DC. The expansion and cell function were evaluated by flow cytometry (FCM) and mix-lymphocyte reaction (MLR), and detection of IL-12 in the supernatant by using ELISA.

RESULTSThe total nucleated cells with 53.39 +/- 20.59-, 307.17 +/- 119.59- and 1117.25 +/- 335.49-folds expansion could be respectively obtained after 7 - 14 days of expansion culture. After DC induction, CD(1a)(+) cells were 21.40 +/- 16.70-, 143.2 +/- 60.35- and 150.8 +/- 42.16-fold increase as compared to the initial nucleated cells. Comparing with that in group I, the CD(1a)(+) cells were much more in groups II and III; but there was no difference between the latter two groups (P > 0.05). The cultured cells in the three groups showed almost the same allo-stimulatory capability and IL-12 excretion when the second culture duration maintained 8 days, while the capability and excretion were greatly decreased when the duration shortened to 5 days (P < 0.05).

CONCLUSIONA plenty of functionally mature DC could be obtained from the CD(34)(+) cells in the two-step culture system of 7 - 10 days HSC expansion followed by 8 days DC induction.