Enhancing ex vivo expansion of cord blood-derived unrestricted somatic stem cells for clinical applications.

OBJECTIVES

To study effects of serum-containing medium (SCM) versus serum-free medium (SFM) and influence of seeding density, on rate of expansion of cord blood (CB) unrestricted somatic stem cells (USSCs), as a prerequisite for evaluating their therapeutic potential in ongoing clinical trials.

MATERIAL AND METHODS

Isolation, propagation and characterization of USSCs from CB samples were performed and followed by their passage 3 culture in SCM and SFM, at cell densities of 5, 50, 500 and 5000 cells/cm(2) .

RESULTS

The cells were CD44(+) , CD90(+) , CD73(+) , CD105(+) , CD34(-) , CD45(-) , and HLA-DR, with Oct4 & Sox2 gene expression; they were differentiated into osteoblasts and adipocytes. USSCs cultured in SCM had significantly higher population doubling levels (P < 0.01) than those cultured in SFM. Those cultured in SCM at 5 cells/cm(2) and those cultured in SFM at 50 cells/cm(2) had significantly higher population doubling (P < 0.01) levels than those cultured at higher cell densities.

CONCLUSIONS

For scaling up of USSCs from 106 (?) to 1012 (?) in 6 weeks, culturing of CB-derived cells of early passage (≤P3) in SCM at low cell seeding density (5 cells/cm(2) ) is suggested for increasing cell count with lower passaging frequency, followed by culture of expanded USSCs at 50 cells/cm(2) in SFM, to avoid undesirable effects of bovine serum in clinical applications.