OBJECTIVETo explore the rapid neutrophil engraftment and long-term hematopoietic reconstitution.

METHODSMononuclear cells (MNCs) were isolated from 5-Fu treated male BDF1 mouse bone marrow and CD(34)(+)/c-kit(+) cells were selected from the MNCs by using MoFlo Cell Sorter. MNCs and CD(34)(+)/c-kit(+) cells were co-cultured with mouse bone marrow-derived mesenchymal stem cells (MSCs) in a two-step expansion. The expanded cells were then transplanted into sublethally irradiated female BDF1 mice.

RESULTSCo-culture with MSCs resulted in 10.8-, 4.8-, 65.9- and 38.8-fold increases yields of median total nucleated cells, CD(34)(+) cells, GM-CFC and HPP-CFC, respectively, as for the MNCs culture, and 76.1-, 2.9-, 71.7- and 51.8-fold increase respectively for the CD(34)(+)/c-kit(+) cell culture. The expanded cells could rapidly engraft in the sublethally, irradiated mice, reconstitute their hematopoiesis, and be detected in the recipients bone marrow 2 months after transplantation.

CONCLUSIONSHematopoietic stem/progenitor cells co-cultures with MSCs in two-step expansion could increase expansion yields of total nucleated cells, GM-CFC and HPP-CFC. The availability of increased numbers of expanded cells may result in more rapid engraftment of neutrophils following infusion to transplant recipients.

Animals ; Antigens, CD34 ; analysis ; Hematopoiesis ; Hematopoietic Stem Cell Transplantation ; Hematopoietic Stem Cells ; physiology ; Male ; Mice

OBJECTIVETo explore the biological characteristics of mesenchymal stem cells (MSC) derived from umbilical cord blood (UCB) and their supporting capacities in ex vivo expansion of hematopoietic stem/progenitor cells (HSPCs).

METHODSLow-density mononuclear cells (MNCs) from UCB were cultured in IMDM containing 20% FBS to form confluent adherent cells through 15 passages. Some cytokines in the conditioned medium were determined with ELISA. UCB-derived adherent cells were displayed with antibodies and analyzed with flow cytometry. The supporting capacity of UCB-derived adherent cells for ex vivo expansion of CD34(+) cells was assayed by co-culture in a two step culture. UCB-derived adherent cells were induced for chondrogenic differentiation with chondrogenic medium, and the induced cells were analyzed for the type II pro-collagen gene expression with RT-PCR.

RESULTSThe mean number of adherent fibroblast like colonies derived from UCB was (3.5 +/- 0.7)/10(6) MNCs. UCB-derived MSCs could survive for at least 15 passages of expansion. In their undifferentiated status, UCB-derived MSCs were CD13(+), CD29(+), CD90(+), CD105(+), CD166(+), SH2(+), SH3(+), SH4(+), CD45(-), CD34(-), and CD14(-). Stem cell factor (SCF), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) could be detected in the supernatant of the cultures. The MSCs cultured in chondrogenic media could differentiate into chondrogenic cells and express type II pro-collagen mRNA. UCB-derived MSCs could support the proliferation and differentiation of UCB CD34(+) cells in vitro.

CONCLUSIONUCB-derived MSCs are similar to those derived from adult bone marrow and can support the proliferation of hematopoietic stem/progenitor cells.

Antigens, CD34 ; metabolism ; Cell Adhesion ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Coculture Techniques ; Collagen Type II ; genetics ; Cytokines ; metabolism ; Enzyme-Linked Immunosorbent Assay ; Fetal Blood ; cytology ; Gene Expression ; Hematopoietic Stem Cells ; cytology ; metabolism ; Humans ; Mesenchymal Stromal Cells ; cytology ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction