Myeloid cell kinetics in mice treated with pure hematopoietic growth factors have been investigated using tritiated thymidine labeling and autoradiography. Mice were injected subcutaneously with 125 micrograms/kg granulocyte colony-stimulating factor (G-CSF) (in some cases 5 micrograms/kg), or 10 micrograms/kg of granulocyte-macrophage CSF (GM-CSF), or interleukin-3 (IL-3) every 12 hours for 84 hours. 3HTdR labeling was performed in vivo after 3 days of treatment. G-CSF increased the peripheral neutrophil count 14-fold and increased the proportion and proliferation rate of neutrophilic cells in the marrow, suppressing erythropoiesis at the same time. Newly produced mature cells were released into the circulation within 24 hours of labeling, compared with a normal appearance time of about 96 hours. By contrast, GM-CSF and IL-3 had little effect on either marrow cell kinetics or on the rate of release of mature cells, although GM-CSF did stimulate a 50% increase in peripheral neutrophils. Monocyte production was also increased about eightfold by G-CSF and 1.5-fold by GM-CSF, but their peak release was only slightly accelerated. While the peripheral half- lives of the neutrophilic granulocytes were normal, those of the monocytes were dramatically reduced, perhaps due to sequestration in the tissues for functional purposes. The stimulated monocyte production in the case of G-CSF required an additional five cell cycles, a level that might have repercussions on the progenitor compartments.

Our study does not produce any data suggesting increased cancer risk following breast reconstruction after a mastectomy or a lumpectomy combined with local radiotherapy. It may be concluded that an autologous transplantation of fat augmented with ASC is a safe and efficient procedure. Longer observation time and the observation of larger numbers of patients would be useful for strengthening the conclusion.

The major effect of granulocyte colony-stimulating factor (G-CSF) is to induce neutrophilia in previously untreated animals or after chemotherapy or marrow transplantation in humans, primates and rodents. In addition, it has been reported that migration of committed progenitor cells to the blood occurs during G-CSF therapy. In this article, by using sex mismatched transplants and a molecular probe for Y-chromosome specific DNA sequences, we show that among the peripheral blood cells during G-CSF therapy are substantial numbers of primitive stem cells capable of (1) reconstituting the hematopoietic system in the long term, and (2) making a contribution to the lymphoid populations of the thymus, in radiation ablated recipients. These data suggest that blood from patients treated with G-CSF may provide a convenient source of the most primitive stem cells for autologous or allogeneic bone marrow transplantation.

IntroductionAn effective immune response to severe bacterial infections requires a robust production of the innate immunity cells from hematopoietic stem and progenitor cells (HSPCs) in a process called emergency myelopoiesis. In sepsis, an altered immune response that leads to a failure of bacterial clearance is often observed. In this study, we aimed to evaluate the impact of sepsis on human HSPCs in the bone marrow (BM) microenvironment of humanized mice subjected to acute endotoxemia and polymicrobial sepsis.MethodsHumanized mice (hu-NSG) were generated by transplanting NOD.Cg-Prkdc/scidIL2rγ (NSG) mice with the human cord blood CD34+ cells. Eight weeks after the transplantation, hu-NSG mice were subjected to sepsis induced by endotoxemia—Escherichia coli lipopolysaccharide (LPS)—or by cecal ligation and puncture (CLP). Twenty-four hours later, HSPCs from BM were analyzed by flow cytometry and colony-forming unit (CFU) assay. CLP after inhibition of Notch signaling was also performed. The effects of LPS on the in vitro proliferation of CD34+ cells from human BM were tested by CellTrace Violet dye staining.ResultsThe expression of Toll-like receptor 4 receptor was present among engrafted human HSPCs. Both CLP and endotoxemia decreased (by 43 % and 37 %) cellularity of the BM. In addition, in both models, accumulation of early CD34+ CD38− HSCs was observed, but the number of CD34+ CD38+ progenitors decreased. After CLP, there was a 1.5-fold increase of proliferating CD34+ CD38−Ki-67+ cells. Moreover, CFU assay revealed a depressed (by 75 % after LPS and by 50 % after CLP) production of human hematopoietic colonies from the BM of septic mice. In contrast, in vitro LPS stimulated differentiation of CD34+ CD38− HSCs but did not induce proliferation of these cells in contrast to the CD34+ CD38+ progenitors. CLP sepsis modulated the BM microenvironment by upregulation of Jagged-1 expression on non-hematopoietic cells, and the proliferation of HSCs was Notch-dependent.ConclusionsCLP sepsis and endotoxemia induced a similar expansion and proliferation of early HSCs in the BM, while committed progenitors decreased. It is suggestive that the Notch pathway contributed to this effect. Targeting early hematopoiesis may be considered as a viable alternative in the existing arsenal of supportive therapies in sepsis.

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) induces leukocytosis in vivo in both intact and splenectomized mice. Full dose response data showed a plateau in this effect at doses over 500 micrograms rhG-CSF/kg body weight/d in intact mice. The effect is magnified in splenectomized mice, where leukocyte numbers reach 100 x 10(6) mL after 4 days' treatment at 250 micrograms/kg/d. Further hematopoietic precursor populations are also affected in both marrow and the spleen; in general, marrow parameters were depressed, while splenic populations were enlarged. In splenectomized mice, both blood- borne stem cells were enhanced, and foci of extramedullary hematopoiesis were enlarged in addition to the effects seen in intact mice. In the marrow of splenectomized and intact mice treated with a high dose of G-CSF, erythroid suppression in the marrow was confirmed with radioactive iron. Our studies confirm and extend previous work on the mode of action of G-CSF, and indicate that side effects of high dose G-CSF therapy might include erythroid suppression in the bone marrow.