[The effects of the short-term ex vivo expansion on the adhesion characteristics and chemotactic function of expanded ex vivo CD34(+) cells].

OBJECTIVE: To study the effect of ex vivo expansion on the adhesion activities and chemotactic function of umbilical cord blood (UCB) hematopoietic stem and progenitor cells (HSPCs). METHODS: CD34(+) cells isolated from fresh UCB samples were cultured in serum-free and stroma-free culture system. After 7, 10 and 14 days' culture, CD34(+) cells were re-selected from the expanded products. Stromal cell- derived factor-1 (SDF-1) 100 ng/ml was added into the experimental CD34(+) cells and the absorbance at 570 nm of all groups was examined. 20 micro g/ml fibronectin (Fn) was added and the spontaneous adhesion between CD34(+) and FN was detected by MTT method. The homing-related functions including expression of homing-related adhesion molecules (CAM), adhesion activity and chemotactic function of the re-selected CD34(+) cells were evaluated and compared with those of the initial fresh CD34(+) cells. RESULTS: (1) The expression of CD49d, CD44, CD11a and CD49e on expanded CD34(+) cells increased or sustained the same levels as those of the fresh isolated UCB CD34(+) cells, while the expression of CD62L, CD54 and CD31 on expanded CD34(+) cells declined during the culture. (2) The spontaneous adhesion between CD34(+) and FN and SDF-1-induced adhesion continuously increased in the course of the first 10-day culture. The spontaneous adhesion rate and SDF-1-induced adhesion rate on day 0, day 7 and day 10 were 28% and 63%, 60% and 70%, 63% and 90% respectively. (3) The migration efficiency of re-selected CD34(+) cells on day 7 was almost the same compared to that of fresh CD34(+) cells. CONCLUSION: The expanded HSPCs sustain most of the homing-related characteristics and activities during one-week culture while extended culture may partly impair their intrinsic homing potential.

[Studies on the homing-related adhesion activities of UCB HSPC in short-term ex vivo expansion].

OBJECTIVE: To study the effect of ex vivo expansion on the adhesion activities of umbilical cord blood hematopoietic stem and progenitor cells (HSPC). METHODS: Fresh 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. CONCLUSIONS: The 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.

[The effects of cytokines mediated ex vivo expansion on the cell adhesion molecule expression of cord blood hematopoietic stem and progenitor cells].

OBJECTIVE: To 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. METHODS: AC133+ 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. CONCLUSIONS: Our 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.