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At least 19 recordsLinked to original sources
PubMed1992

[The role of the hemopoiesis-inducing microenvironment in the mechanisms of the regeneration of hemopoiesis after cytostatic exposure].

On the model of adriamycine-induced hemopoiesis hypoplasia it has been shown that the accelerated differentiation of hemopoietic precursors regeneration is of great importance in regeneration of hemopoiesis. This differentiation is provided by preceded recovery of bone marrow structural-functional organization. The important role in regeneration of hemopoiesis belongs to hemopoietic microenvironmental elements which express its induced influence by the increase of colony-stimulating and erythropoietic activities, interleukin-1 and interleukin-3 production.

Animals↗
PubMed1988

Splenic hemopoiesis of the platypus (Ornithorhynchus anatinus): evidence of primary hemopoiesis in the spleen of a primitive mammal.

The generation of blood cells has been observed in the spleen and in the bone marrow of the platypus. Hemopoiesis was found to be far more active in the spleen than in the bone marrow judging by the number of proliferating hemopoietic elements within a unit area of tissue from each organ. Granulocytes, erythroblasts, and megakaryocytes, with the related immature forms for each cell line, were noted in the spleen. In contrast, there were very few examples of immature forms of these cell lines and a complete absence of mature megakaryocytes in the bone marrow. These findings suggest that the spleen is the primary hemopoietic organ in the platypus. Since the platypus is one of two species representing the most primitive existing mammals, it seems likely that the spleen may be the primary hemopoietic organ in mammalian evolution.

Animals↗
PubMedDate not supplied

[The role of the hemopoiesis-inducing microenvironment in the postradiation regeneration of hemopoiesis].

The dynamic of granulocytic macrophages and erythroid precursors content in bone marrow of CBA mice, irradiated by 2.0 Gy and the level of colony-stimulating and erythropoietic activities in supernatant of bone marrow myelocariocytes and blood serum were studied. The process of haemopoiesis regeneration was accompanied by increasing of the values of these indexes in bone marrow and peripheral blood. The treatment of bone marrow cells by monoclonal antibodies to Thy 1.2 antigens resulted in decreasing of myeloid precursors and diminishing of colony-stimulating activity of bone marrow cells supernatant.

Acute Disease↗
PubMed1991

Embryonic and fetal hemopoiesis: an overview.

Our current knowledge of embryonic and fetal hemopoiesis is critically reviewed in this article. In both murine and human systems, embryonic and fetal development is associated with multiple switching in the sites of hemopoiesis. The phenomenon is first extraembryonic, occurring in blood islands of the yolk sac. Hemopoietic stem cells (HSC) appear to derive from hemangioblasts that are of mesodermal origin. Yolk sac milieu is permissive only for erythropoiesis which proceeds synchronously and may be erythropoietin-insensitive. Yolk sac milieu is not permissive for the development of other cell lines. The final product is nucleated red cells. Yolk sac hemopoiesis is an example par excellence of primitive (as compared to definitive) form of hemopoiesis. HSC then seem to migrate via the bloodstream to the liver and spleen to seed these tissues, which then carry the burden of hemopoiesis until birth and for some time thereafter. Here also erythropoiesis predominates, but some granulopoiesis also occurs. Thus, the milieu is not totally impermissive. Hemopoiesis is in definitive form, lacking synchronicity of cell growth with the end product being anucleated cells and synthesized hemoglobin not limited to embryonic type. The site of hemopoiesis is finally transferred to the bone marrow, which is predominantly granulopoietic. Certain cellular and embryological features of these types of hemopoiesis in the context of more recent molecular understanding of stem cell homing are discussed.

Animals↗
PubMed1976

Cellular subclasses in human leukemic hemopoiesis.

Cellular organization and communication in leukemic hemopoiesis may be compared with its counterpart in normal hemopoiesis. Results obtained using cell culture methods have provided some support for the view that leukemic hemopoiesis, like normla hemopoiesis, may involve 3 levels of differentiation: leukemic stem cells, committed leukemic progenitors, and more mature cells. Evidence is also beginning to emerge that leukemic populations may be regulated by messages from the environment in a manner analogous to normal hemopoiesis. The apparent similarities between leukemic and normal hemopoiesis raise, the possibility that the target cell for leukemic transformation is the normal pluripotent stem cell. The development of culture methods for the production of leukovirus-like particles from human leukemic cells provides a possible first step toward the direct identification of leukemic target cells.

Anemia, Sideroblastic↗
PubMed2001

Clonal hemopoiesis and risk of thrombosis in young female patients with essential thrombocythemia.

OBJECTIVE: Several studies demonstrated a high prevalence of nonrandom X-chromosome inactivation pattern (X-CIP) in essential thrombocythemia (ET). This study explored the incidence of clonal hemopoiesis in myeloid precursors and endogenous erythroid colonies (EECs) in ET patients and its correlation with thrombotic manifestations. MATERIALS AND METHODS: Clonal analysis of hemopoiesis using X-CIP was performed in 40 female patients with ET. Median age was 40.5 years (range 20-64), and median platelet count at testing time was 700 x 10(9)/L (range 220-1300 x 10(9)/L). Patients older than 65 years were excluded to reduce age-related skewing. Clonality was assessed on neutrophils, platelets, EECs, and bone marrow CD34(+) cells. RESULTS: Eight (20%) of 40 patients developed thrombosis mainly at diagnosis. Clonal hemopoiesis was found in 17 (42.5%) patients, 15 (37.5%) had polyclonal hemopoiesis, and 8 (20%) were considered uninterpretable due to constitutive skewing. Clonality was confirmed on purified CD34(+) subpopulations from bone marrow, documenting that clonality does not appear lineage-restricted. There were no statistical differences in age at diagnosis, median platelet count at testing time, and length of follow-up. Thrombotic episodes were significantly more frequent in the monoclonal group (p = 0.04, Fisher exact test). CONCLUSIONS: Young female patients with ET exhibiting a clonal pattern of hemopoiesis by X-CIP analysis are at higher risk for thrombosis. X-CIP analysis may contribute to defining the individual risk leading to appropriate treatment. X-CIP will allow a correct diagnosis in patients with latent myeloproliferative disorders and thrombosis in unusual sites. Clonal hemopoiesis is easily recognized by X-CIP, but its applicability is limited to the female sex and is hampered by the presence of age-related or constitutive skewing.

Adult↗
PubMed1977

Embryonic and fetal hemopoiesis in the Mongolian gerbil (Meriones unguiculatus).

A study of the development of hemopoiesis in the Mongolian gerbil (Meriones unguiculatus) was conducted in order to determine the temporal sequence, the organs involved and the cytology of blood cell formation in this species. Hemopoiesis in the intrauterine life of the gerbil can be divided into four phases based on the site of blood cell formation: (1) the vitelline phase, (2) the hepatic phase, including thymic histogenesis, (3) the splenic phase and (4) the medullary phase, with the development of secondary lymphoid tissues. At the onset of each of these phases a blast-like cell was identifiable in each hemopoietic organ which, because of its morphology and its presumed multipotentiality was classified as a "lymphoid cell". In the yolk sac phase (gestational day 12) two generations of erythrocytes, a primitive and a definitive, are formed. The liver is by day 15 erythropoietic and megakaryopoietic, but later, a few granulocytes are also found in its extravascular compartment. The thymus is exclusively lymphopoietic from the appearance of its earliest cells on day 15. Splenic hemopoiesis is initiated with the presence of lymphoid cells (day 20) followed later by the appearance of morphologically identifiable blood cell lines. Early normoblastic and granulocytic activity begins in the marrow cavities on day 23, though the marrow is not considered to be a source of circulating blood cells during fetal life. Lymph node histogenesis occurs during the last four days of gestation, first in the cervical region and then in other parts of the body. The finding of undifferentiated lymphoid cells in all organs at the initiation of hemopoiesis and in the peripheral blood throughout gestation is discussed in light of the migratory theory of hemopoiesis.

Animals↗
PubMed1988

Studies on hepatic hemopoiesis induced by immunization with syngeneic liver extracts in mice.

After a 9-week immunization period, all the livers in inbred C57BL 6 mice immunized with syngeneic crude liver protein (LSN) in Freund's complete adjuvant showed histological changes mainly in the portal areas. Morphological features and the subsequent in vitro and in vivo data suggested that the principal histological changes were due to extramedullary hemopoiesis and not to autoimmune hepatitis. This is the first description of extramedullary hemopoiesis in studies concerning experimental autoimmune hepatitis. The significance of our findings is, first, that the occurrence of hepatic hemopoiesis induced by the usual immunization method necessitates morphologically distinct evidence of inflammation to be a prerequisite in studies of experimental autoimmune hepatitis. Without this proof, subsequent investigations would be confusing. Second, immunization can be added to a variety of conditions to induce hepatic hemopoiesis. This would provide a convenient and interesting tool for application to further studies of hemopoiesis.

Alanine Transaminase↗
PubMed1984

Light and electron microscopy of bone marrow hemopoiesis in late embryonal and early postnatal mice: a qualitative and quantitative study.

Using serial sections of the entire body of late embryonal and early postnatal mice, a morphologic analysis of the bone marrow in the whole skeleton was made qualitatively and quantitatively. Hemopoietic cells in the developing marrow were also examined at the light and electron microscopic levels. Before birth, the bone marrow is quite small in volume. During the first five postnatal days, the marrow shows an approximately 65-fold increase in total volume. At 0-3 days of age, hemopoiesis begins in the marrow throughout the body. Marrow hemopoiesis starts earlier in the rib, scapula, humerus and femur. The development of hemopoiesis proceeds through the following three stages: formation of the marrow cavity, accumulation of neutrophils in the cavity, and appearance of hemopoietic cells. In the bone marrow prior to active hemopoiesis, a majority of cells first appearing are mature neutrophils, among which immature erythroblasts and dark small lymphocytes, although very small in number, are seen. The functional significance of the cells appearing early is discussed in relation to the subsequent events involved in marrow hemopoiesis. In addition the marrow, development of the other blood forming tissues and lymphatic organs is also examined quantitative-morphologically.

Animals↗
PubMed2006

[Effect of parathyroid hormone (PTH 1-34) on hemopoiesis in long-term cultures of human bone marrow].

AIM: To study effects of parathyroid hormone (PTH) used in therapy of osteoporosis on hemopoiesis in long-term culture of human bone marrow (LCBM) in terms of its potential influence on stem hemopoietic and stromal cells. MATERIAL AND METHODS: For a long time LCBM was treated with PTH (1-34) and compared for cell production, concentration of late and early hemopoietic precursors. Maintenance of hemopoiesis and adhesion at early hemopoiesis precursors on the stromal sublayers treated with PTH (1-34) was used as a functional test. A relative level of expression of genes participating in regulating proliferation and self-support of stem hemopoietic cells was studied. RESULTS: PTH (1-34) in the above concentrations did not affect hemopoiesis in LCBM. Stromal sublayer treated with PTH (1-34) for a long time supports cell precursors better, their adhesion to such sublayers enhances. CONCLUSION: PTH (1-34) in pharmacological but small concentrations had no irreversible effects on hemopoiesis, i.e. contraindications for its use in the treatment of osteoporosis were not revealed.

Adult↗