OBJECTIVETo explore the ex vivo expansion characteristics of selected CD(34)(+) cells and mononuclear cells (MNC).

METHODSCD(34)(+) cells were isolated from umbilical cord blood MNC by MiniMACS system, expanded under the same conditions as that for MNC. The effects of re-isolation and the MNC supernatant (MNC-SN) on the selected CD(34)(+) cells were investigated. And the CD(34)(-) cells of MNC were cultured ex vivo.

RESULTSIn the culture of selected CD(34)(+) cells, both the colony density and the proportion of the CD(34)(+) cells declined continuously with the culturing, although they presented a high proliferation potential. However, in the culture of the MNC, from day 0 to day 7, the colony density and the proportion of CD(34)(+) cells were increased from 412 +/- 167/10(5) cells and (1.12 +/- 0.42)% to 1 162 +/- 566/10(5) cells and (4.17 +/- 1.44)%, respectively. It was found that both the total cells and the CD(34)(+) cells restored expansion potential by re-isolating. CD(34)(-) cells of MNC had the ability to form colony and could transform to CD(34)(+) cells. MNC-SN can promote colony forming ability and lead to CD(34)(+) cells differentiation at the same time.

CONCLUSIONSIn ex vivo culture, selected CD(34)(+) cells presented a high proliferation and differentiation potentials, and the CD(34)(-) cells produced during the cultivation had inhibition effect on CD(34)(+) cells expansion. CD(34)(-) cell population from cord blood MNC contained hematopoietic stem/progenitor cells and the cytokines secreted by CD(34)(-) cells could induce CD(34)(+) cells to more mature colony-forming cells.