Donor stromal cells support hematopoiesis in CFU-S colonies

To examine the effect of hematopoietic stromal cells on bone marrow transplantation (BMT), CF-1 cells, which were previously established from splenic stroma of a mouse that was administered recombinant human granulocyte colony-stimulating factor (rhG-CSF), were transplanted with bone marrow cells. The stromal cells were transfected with the plasmid DNA of beta-galactosidase (beta G-CF-1) cells for studying immunohistochemistry. Using immunohistochemistry, the spleen and bone marrow of the recipient mice were examined for beta-galactosidase on the 8th and 12th day after BMT. In the spleen, beta G-CF-1 cells were observed within and in the regions immediately surrounding the colony-forming unit-spleen (CFU-S) on the 8th and 12th day after BMT. In certain regions, beta G-CF-1 cells existed in or surrounded the CFU-S colonies that consisted of the undifferentiated hematopoietic cells, while in other regions the granulopoiesis increased, especially in correspondence with the existence of beta G-CF-1 cells. In the bone marrow cavity, beta G-CF-1 cells were also recognized, though hematopoiesis was lower than the normal bone marrow. These data demonstrate that CF-1 cells, that is, donor stromal cells, can be transplanted to the hematopoietic organs and can then support hematopoiesis.