The cells of hematopoietic and vascular endothelial cell lineages are believed to share a common precursor, termed hemangioblast. However, the existence of a growth factor acting relatively specifically on hemangioblasts remains unclear. Here we report the identification of hemangiopoietin (HAPO), a novel growth factor acting on both hematopoietic and endothelial cell lineages. In vitro in the ...

The hematopoietic system of the young child acquires, through time, the ability to cope with exposure to a number of environmental toxins and infectious agents. Occasionally, severe aplastic anemia occurs secondary to exposure to some of these toxins or infectious agents. The occurrence of severe aplastic anemia provides an opportunity to study the maturation of the hematopoietic system because...

The WT1 tumor-suppressor gene is expressed by many forms of acute myeloid leukemia. Inhibition of this expression can lead to the differentiation and reduced growth of leukemia cells and cell lines, suggesting that WT1 participates in regulating the proliferation of leukemic cells. However, the role of WT1 in normal hematopoiesis is not well understood. To investigate this question, we have use...

Although information about the development of primitive and definitive hematopoiesis has been elucidated in murine embryos and embryonic stem (ES) cells, there have been few in vitro studies of these processes in primates. In this study, we investigated hematopoietic differentiation from cynomolgus monkey ES cells grown on OP9, a stromal cell line deficient in macrophage colony-stimulating fact...

Changes in structure, cellularity, hematopoietic progenitor cell and macrophage content, and osteoclast activity were investigated in the hematopoietic organs of the colony-stimulating factor l(CSF-1)-less osteopetrotic (op/op) mouse. The data indicated that op/op mice undergo an agerelated hematopoietic recovery and resolution of osteopetrosis, suggesting that the hematopoietic system has the ...

The development and emergence of the hematopoietic stem cell involves a series of tightly regulated molecular events that are not well characterized. The hematopoietically expressed homeobox (Hhex) gene, a member of the homeobox gene family, is an essential regulator of embryogenesis and hematopoietic progenitor development. To investigate the role of Hhex in hematopoiesis we adapted a murine e...

The Steel Factor (SF) and its receptor c-Kit play a critical role for various cell types at different levels in the hematopoietic hierarchy. Whether similar or distinct signaling pathways are employed upon c-Kit activation in different cell types within the hematopoietic hierarchy is not known. To study c-Kit signaling pathways in the hematopoietic system we have compared c-Kit downstream signa...

The ob gene product, leptin, has been shown in several studies to be involved in weight control and recombinant leptin recently has entered clinical trials to treat obesity. The leptin receptor (OB-R/B219) is expressed in a variety of protein isoforms not only in the central nervous system, but also in reproductive, and hematopoietic tissues. We reported recently that the OB-R/B219 was associat...

Hematopoiesis is the process by which a limited number of hematopoietic stem cells (HSCs) maintain a functioning blood and immune system. In adults, hematopoiesis occurs in bone marrow and is supported by the microenvironment. The tachykinin family of peptides regulates hematopoiesis. Tachykinins can be released in bone marrow as neurotransmitters from innervating fibers, and from resident bone...

The sequestration of rat leukocytes and bone marrow cells by the lung vasculature was studied using an isolated perfused rat lung preparation. The passage of latex particles of 7.6 µm in diameter and non-hematopoietic cells through the lung blood vessels was also studied. Leukocytes and bone marrow cells were reversibly sequestered from circulation, whereas, latex particles and non-hematop...