[Research on Ex Vivo Hematopoiesis Supported by Microcarriers]

To explore methods of maintaining the self-renewal capacity of hematopoietic stem cells, inhibiting their overdue differentiation and expanding hematopoietic cells massively, the murine bone marrow stromal cells were coated on microcarriers, then co-cultured with hematopoietic cells from murine bone marrow as group 2 (G2). The G2 contents were wrapped by sodium alginate, then cultivated as group 1 (G1). The only microcarriers coated with stromal cells as group 3 (G3) and the only bone marrow cells as group 4 (G4) were cultivated as control groups. Contrasting observation and microphotograph were performed; the number of total marrow cells, the colony efficiency of CFU-GM and the percentages of CD34(+) cells were determined. Three repeated experiments indicated that the colony efficiency of CFU-GM before culture (G0) were 118.8 +/- 38.1/10(5) marrow cells, and the total outputs of CFU-GM (G0) were 9 501.3 +/- 3 049.0. After culture for two weeks, hematopoietic cells were adhered to or embedded in stromal cells coating the microcarriers, and had formed hematopoietic focus. The colony efficiency of CFU-GM per 10(5) mononuclear cells in group G1, G2, G3 and G4 averaged 30.9 +/- 13.7, 147.3 +/- 66.0, 23.4 +/- 23.1 and 15.9 +/- 8.1, respectively; the total outputs of CFU-GM in group G1, G2, G3 and G4 averaged 273.8 +/- 75.3, 9 424.8 +/- 7 933.7, 419.1 +/- 305.6 and 140.7 +/- 20.7, respectively; the measured CFU-GM output in group G2 was significantly higher than that in group G4, and still significantly higher than the sum of groups G3 and G4 (t = 6.553, t = 5.494; P < 0.05). The percentage of CD34 cells before culture was 10.0 +/- 1.0; after cultuer for two weeks, the percentages of CD34(+) cells in G1, G2, G3 and G4 averaged 4.0 +/- 1.0, 11.0 +/- 1.0, 3.3 +/- 1.5 and 2.2 +/- 0.8, respectively. The percentage of CD34 positive control (3T3 cells) was 17.0 +/- 1.0. This result was consistent with the result of CFU-GM outputs measured. These data suggest that microcarriers coated with stromal cells can perfectly support the ex vivo hematopoiesis at least to four weeks, while hematopoietic cells fixed by alginate are not significantly different from control groups. The hematopoiesis-simulating model of microcarriers is successful, whereas the hematopoiesis-simulating model of alginate macrocarriers can not support the ex vivo hematopoiesis.