OBJECTIVETo study the effect of ex vivo expansion on the adhesion activities of umbilical cord blood hematopoietic stem and progenitor cells (HSPC).

METHODSFresh UCB CD(34)(+) cells were cultured in a serum and stroma-free culture system. At day 7, day 10 and day 14, CD(34)(+) cells were re-selected from the expanded products. The expression of adhesion molecules (CAMs) such as VLA-4, VLA-5, LFA-1, ICAM-1, HCAM, L-selectin and PECAM-1, and the adhesion activity of the expanded CD(34)(+) cells were evaluated and compared with those of precultured fresh CD(34)(+) cells.

RESULTS(1) The CD(34)(+) cells expressing homing-related CAMs were increased (from 15-fold increase for CD(34)(+) CD(54)(+) subset to 72-fold increase for CD(34)(+) CD(49e)(+) subset at day 14). (2) The expressions of CD(49d), CD(44), CD(11a) and CD(49e) on the expanded CD(34)(+) cells were increased or sustained the same levels as those on fresh UCB CD(34)(+) cells, while the expression of CD(62L), CD(54) and CD(31) on expanded CD(34)(+) cells declined with the cultivating. (3) Spontaneous adhesion and SDF-1-induced adhesion tended to be increased in the course of the first 10 day's culture.

CONCLUSIONSThe culture system used in this study could substantially support the expansion of HSPCs expressing the above CAMs, and the expanded HSPCs would sustain their intrinsic adhesion potentials.

Antigens, CD ; analysis ; Antigens, CD34 ; analysis ; Cell Adhesion ; Cell Adhesion Molecules ; biosynthesis ; Cell Division ; Fetal Blood ; cytology ; immunology ; metabolism ; Flow Cytometry ; Hematopoietic Stem Cells ; cytology ; immunology ; metabolism ; Humans ; Receptors, Lymphocyte Homing ; biosynthesis

OBJECTIVETo compare the expression of cell adhesion molecules (CAMs) among VLA-4 (CD49 d), VLA-5 (CD49e), LFA-1 (CD11a), L-selectin (CD62L), and PECAM-1 (CD31) which are more related to the homing of hematopoietic stem and progenitor cells (HSPC) on the ex vivo expanded CD34+ subset with that of fresh isolated AC133+ cells.

METHODSAC133+ cells selected from fresh cord blood (CB) samples were cultured in QBSF-60 serum-free media in the presence of Flt-3 ligand + SCF + TPO (FST), with initial addition of IL-3 for up to 2 week. Expansion potential and the expression of above CAMs were evaluated at day 0, day 7, day 10 and day 14.

RESULTS(1) Simultaneously numerical expansion of various HSPC was constantly observed during the culture, and the fold expansion of AC133+ cells and CD34+ cells on day 14 were 33.50 and 64.56 respectively; (2) The number of CD34+ subsets expressing the above adhesions were all increased at different degrees (from 20 fold to 160 fold). (3) The expressions of CD11a, CD49d, and CD49e on ex vivo expanded CD34+ cells were increased as compared to their baseline levels, but the percentage of CD62L+ and CD31+ subpopulations in CD34+ cells were decreased.

CONCLUSIONSOur short-term culture system can not merely support the simultaneous expansion of CB derived AC133+ cells, but the expanded hematopoietic progenitors may well sustained the expression of homing-related adhesion molecules.

AC133 Antigen ; Antigens, CD ; Antigens, CD34 ; metabolism ; Cell Adhesion Molecules ; biosynthesis ; genetics ; Cell Division ; drug effects ; Cells, Cultured ; Culture Media, Serum-Free ; Cytokines ; physiology ; Female ; Fetal Blood ; cytology ; metabolism ; Glycoproteins ; metabolism ; Hematopoietic Stem Cells ; cytology ; metabolism ; Humans ; Interleukin-3 ; pharmacology ; Lymphocyte Subsets ; Peptides ; metabolism ; Pregnancy ; Receptors, Lymphocyte Homing ; metabolism

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 1x10(5)/mL in media supplemented with a combination of SCF (20 ng/mL)+TPO (50 ng/mL)+FL (50 ng/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+/-7.8~26.3+/-4.9, CFU-GM 4.7+/-5.1~11.7+/-2.6, CD34+CD38- cell 214.0+/-251.9~464.1+/-566.1, CD34+CXCR4+ cell 4384.5+/-1664.7~7087.2+/-4669.3, CD34+VLA4+ cell 1444.3+/-1264.0~2074.9+/-1537.0, CD34+VLA5+ cell 86.2+/-50.9~ 113.2+/-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.
ADP-ribosyl Cyclase/metabolism ; Antigens, CD/metabolism ; Antigens, CD34/metabolism ; Cryopreservation ; Fetal Blood/*cytology ; Humans ; Integrin alpha4beta1/metabolism ; Integrin alpha5beta1/metabolism ; Membrane Proteins ; Receptors, CXCR4/metabolism ; Receptors, Lymphocyte Homing/*metabolism ; Research Support, Non-U.S. Gov't ; Stem Cell Factor ; Stem Cells/*cytology/*metabolism ; Thrombopoietin