Stem cells expressing homing receptors could be expanded from cryopreserved and unselected cord blood.

We assessed the cytokine combinations that are best for ex vivo expansion of cord blood (CB) and the increment for cell numbers of nucleated cells, as well as stem cells expressing homing receptors, by an ex vivo expansion of cryopreserved and unselected CB. Frozen leukocyte concentrates (LC) from CB were thawed and cultured at a concentration of 1 x 10(5)/mL in media supplemented with a combination of SCF (20 ng/mL)+TPO (50 ng/mL)+FL (50ng/mL)+/-IL-6 (20 ng/mL)+/-G-CSF (20 ng/mL). After culturing for 14 days, the expansion folds of cell numbers were as follows: TNC 22.3 +/- 7.8similar to26.3 +/- 4.9, CFU-GM 4.7 +/- 5.1similar to11.7 +/- 2.6, CD34+CD38- cell 214.0 +/- 251.9-464.1 +/- 566.1, CD34+CXCR4+ cell 4384.5 +/- 1664.7similar to7087.2 +/- 4669.3, CD34+VLA4+ cell 1444.3 +/- 1264.0similar to2074.9 +/- 1537.0, CD34+VLA5+ cell 86.2 +/- 50.9similar to113.2 +/- 57.1. These results revealed that the number of stem cells expressing homing receptors could be increased by an ex vivo expansion of cryopreserved and unselected CB using 3 cytokines (SCF, TPO, FL) only. Further in vivo studies regarding the engraftment after expansion of the nucleated cells, as well as the stem cells expressing homing receptors will be required.