Expansion characteristics of CD34+ cells derived from umbilical cord blood HS/PCs in single-parameter culture under serum-free static suspension condition.

Currently, the ex vivo expansion of hematopoietic stem/progenitor cells (HS/PCs) is one of the effective ways to address the shortage of HS/PCs for clinical transplantation. Therefore, the optimal in vitro expansion strategy for HS/PCs is a critical issue to be addressed in current researches. In this study, we separated UCB Mononuclear cells (MNCs) and CD34+ cells, and cultured them for 14 days under serum-free conditions (only growth factors added). Then, the effects of the growth factors on HS/PCs expansion were analyzed and compared. The results showed that under short-term culture (< 7 days) the number of nucleated cells expanded significantly more in CD34+ cells than in MNCs, and the content of CD34+ cells was also significantly greater than that of CD45+CD34+ and CD34+CD38- cell subpopulations in MNCs. It is confirmed that static suspension culture without serum was unable to promote the expansion of HS/PCs for a long term (14 days) and maintain their primitive stem cell activities. Under identical culture conditions, cell products harvested by expansion with CD34+ cells as the starting cell source outperformed MNCs in terms of hematopoietic stem/progenitor cell yields and hematopoietic reconstitution capacity.