Hemopoietic stem cell mobilization in mice

In mice hemopoietic stem cells and progenitor cells are almost totally confined to the bone marrow and spleen. Only small numbers can be detected in the peripheral blood. Relatively little is known about the mechanism(s) modulating the circulation and mobilization of stem cells. At present their function and ultimate fate are unknown. Mobilization of hemopoietic stem cells in mice has been achieved by injection of a variety of substances, the most well known being LPS. For some substances, including endotoxin, the transient increase in blood CFU-s immediately following injection (early mobilization) is followed by a second one some days later (delayed mobilization). The purpose of the investigations presented in this thesis was to get insight into the mechanism(s) underlying both early and delayed mobilization of hemopoietic stem cells by LPS and other agents. Additionally, the changes in splenic hemopoiesis seen after administration of LPS have been subject of investigatio

Complement Split Product C5a Mediates the Lipopolysaccharide‐Induced Mobilization of Cfu‐S and Haemopoietic Progenitor Cells, But Not the Mobilization Induced By Proteolytic Enzymes

Abstract. Intravenous (i.v.) injection of mice with lipopolysaccharide (LPS), and the proteolytic enzymes trypsin and proteinase, mobilizes pluripotent haemopoietic stem cells (CFU‐s) as well as granulocyte‐macrophage progenitor cells (GM‐CFU) and the early progenitors of the erythroid lineage (E‐BFU) from the haemopoietic tissues into the peripheral blood. We investigated the involvement of the complement (C) system in this process. It appeared that the early mobilization induced by LPS and other activators of the alternative complement pathway, such as Listeria monocytogenes (Lm) and zymosan, but not that induced by the proteolytic enzymes, was absent in C5‐deficient mice. the mobilization by C activators in these mice could be restored by injection of C5‐sufficient serum, suggesting a critical role for C5. The manner in which C5 was involved in the C activation‐mediated stem cell mobilization was studied using a serum transfer system. C5‐sufficient serum, activated in vitro by incubation with Lm and subsequently liberated from the bacteria, caused mobilization in both C5‐sufficient and C5‐deficient mice. C5‐deficient serum was not able to do so. the resistance of the mobilizing principle to heat treatment (56°C, 30 min) strongly suggests that it is identical with the C5 split product C5a, or an in vivo derivative of C5a. This conclusion was reinforced by the observation that a single injection of purified rat C5a into C5‐deficient mice also induced mobilization of CFU‐s. Copyrigh

Fatal ischemic stroke in a patient receiving lenalidomide for multiple myeloma

Paroxysmal Cerebral Disorder