Physiological State And Genetic Stability Of Cord Blood Cells During Ex Vivo Expansion

It has been demonstrated that ex vivo expansion is a feasible strategy which could overcome the cell dose limitation in fresh cord blood (CB). However the quality and safety of expanded cells are critical for their clinical application. In this research, physiological parameters and genetic stability of CB CD34+ cells cultured with media at present of or absence of serum were examined extensively, producing following results:(1) Cell specific growth rate, S/G2/M phase cell proportion and telomerase activity had a similar variation tendency during culture with or without serum, suggesting the parameters were correlated each other to some extent. (2) The apoptosis of expanded CD34+ cells was much lower than cultured CD34- cells or freshly isolated CD34+ cells, sugggesting that cultured CD34+ cells are of anti-apoptosis. (3) The expression of Bmil, hTERT and Survivin genes related to cell genetic stability were upregulated differently in cultured CD34+ cells than those in freshly isolated CD34+ cells, although the expressions were not as efficient as those in K562 cells. Thus, the expresson pattern of these genes could not indicate neoplastic transformation occurs during the culturing. (4) Although high proportion of chromosomal alterations exsisted in cultured CD34+ cells cells in serum originated from 6 CB samples, the expanded cells with altered chromosomes could not proliferate neoplastically. Therefore, malignant transformation seems unlikely when expanded CD34+cells in serum were applied clinically, although potential risks were not excluded completely. These efforts were of importance for clinical transplantation efficiently and safely with expanded cells.