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.