Effect of erythrocyte degradation products on the migration of hematopoietic stem cells in lethally irradiated mice

In experiments on CBA mice it was shown that erythrocytes administered at the stage of prehemolysis or the stromal fraction of erythrolysate caused an additional increase in the haemopoietic stem cell migration which had been intensified by hemorrhage or hypoxic hypoxia.     

Appearance of foci of hematopoiesis and hematopoietic stem cells in the liver of mice following a single administration of cyclophosphane]

The nidi of hemopoiesis appeared in the liver and the lymph nodes of DBA/2, C57BL/6j and F1 (C57BL/6j X CBA) strains of mice of the 6th day after a single intraperitoneal injection of cyclophosphamide in a dose of 200 mg/kg. This process was accompanied by the appearance of stem hemopoietic cells in the liver. Their maximum number was observed on the 6th and the 9th days. On the 12th day their level decreased, but it still exceeded the one in the animals which received a suspension of normal liver cells. In myelosan exhaustion the pool of the bone marrow and splenic stem cells, the subsequent cyclophosphamide injection failed to induce the appearance of the nidi of hemopoiesis and stem cells in the liver.     

Leukotriene-induced radioprotection of hematopoietic stem cells in mice

Leukotrienes (LTs), known primarily for their pathological roles, may also be capable of exerting "cytoprotection" against toxic agents in a manner similar to that of prostaglandins. In this report, it is shown that treatment of mice with leukotrienes C4, D4, E4, or B4 prior to sublethal irradiation increased the number of endogenous hematopoietic stem cells (E-CFU), with LTC4 producing the greatest response (LTC4 much greater than B4 greater than E4 greater than D4). LTC4-induced hematopoietic radioprotection was examined in greater detail using the exogenous spleen colony (CFU-S) and granulocyte/macrophage progenitor cell (GM-CFC) assays. The dose reduction factors for these cells in LTC4-treated mice at radiation doses resulting in 37% cell survival were 1.65 and 2.01, respectively.     

Proliferation and splenic migration of mouse hematopoietic stem cells following a single injection of Mycoplasma arthritidis

The effect of a single injection of live M. arthritidis microorganisms on the bone marrow and spleen CFU-S populations was assessed. One of the principal findings is that marrow CFU-S are recruited into cell cycle (as determined by hydroxyurea kill) early after M. arthritidis administration and stay in the cycle for at least 2 weeks thereafter. The peak level of cycling value (47%) was observed on day 4. The duration of increased CFU-S cycling activity was shown to coincide with a time period during which a significant rise in the number of endogenous CFU-S was maintained. The other important finding is that splenic seeding efficiency ("f-factor") declines by 56% one day following M. arthritidis administration. The latter effect could be attributed to the binding of mycoplasmas to the surface of CFU-S as specific rabbit antiserum against M. arthritidis incubated in vitro with the bone marrow cells of infected donor mice caused an up to 48% reduction in the in vivo colony-forming ability of CFU-S.     

Molecular mechanisms underlying adhesion and migration of hematopoietic stem cells

Hematopoietic stem cell transplantation is the most powerful treatment modality for a large number of hematopoietic malignancies, including leukemia. Successful hematopoietic recovery after transplantation depends on homing of hematopoietic stem cells to the bone marrow and subsequent lodging of those cells in specific niches in the bone marrow. Migration of hematopoietic stem cells to the bone marrow is a highly regulated process that requires correct regulation of the expression and activity of various molecules including chemoattractants, selectins and integrins. This review will discuss recent studies that have extended our understanding of the molecular mechanisms underlying adhesion, migration and bone marrow homing of hematopoietic stem cells.     

Molecular mechanisms underlying adhesion and migration of hematopoietic stem cells

Hematopoietic stem cell transplantation is the most powerful treatment modality for a large number of hematopoietic malignancies, including leukemia. Successful hematopoietic recovery after transplantation depends on homing of hematopoietic stem cells to the bone marrow and subsequent lodging of those cells in specific niches in the bone marrow. Migration of hematopoietic stem cells to the bone marrow is a highly regulated process that requires correct regulation of the expression and activity of various molecules including chemoattractants, selectins and integrins. This review will discuss recent studies that have extended our understanding of the molecular mechanisms underlying adhesion, migration and bone marrow homing of hematopoietic stem cells.     

Cloning stem cells in the bone marrow of irradiated mice]

Different amount of intact or irradiated bone marrow from syngenous donors was administered to mice irradiated with a lethal dose. There was revealed a linear dependence of the number of the 8-9-day colonies grown in the bone marrow of the femur on the amount of the administered cells, and an exponential dependence on the irradiation dose. Regularity of the stem cell cloning in the bone marrow was analogous to such in the spleen. Radiosensitivity of the colony-forming units (CFU) differed depending on the site (the spleen, the bone marrow) of their colony formation. The CFU settling in the marrow proved to be more radioresistant (D(0) equalled 160-200 P) in comparison with the CFU settling in the spleen (D(0) constituted 80-100 P). It is supposed that a different radiosensitivity of the CFU was caused by the presence of heterogenic population of the stem cells and also by specific peculiarities of the organ (the spleen, the bone marrow) in which the colonies formed.     

Factors controlling the recirculation of hematopoietic stem cells. IV. The effect of thymosin on the migration and differentiation of hematopoietic stem cells

Thymosine, a thymus hormone, restores the thymectomy induced deterioration of the routine pathways of migration and differentiation ofhemopoietic stem cells in mice. Administration of thymosine together with bone marrow cells from thymectomized mice to irradiated recipients also restores the level of migration and differentiation of hemopoietic stem cells. The inducing effect of thymosine on the maturation of T-lymphocyte precursors, which in their turn restore the usual rate of migration and differentiation of hemopoietic stem cells, has been suggested.     

Murine hematopoietic stem cells after acute and chronic administration of vincristine

The effects of vincristine on bone marrow hemopoietic stem cells were studied in mice. After the administration of a single dose of the drug there is a sharp decline in the content of CFUs. When the drug is given in small, weekly doses for 16 weeks, after an initial drop, the stem cell content rises at a normal level where it remains, although with wide oscillations. On the whole the effects of vincristine on b.m. CFUs are comparable with that observed after vinblastine administration.     

BIGH3 modulates adhesion and migration of hematopoietic stem and progenitor cells

Cell adhesion and migration are important determinants of homing and development of hematopoietic stem and progenitor cells (HSPCs) in bone marrow (BM) niches. The extracellular matrix protein transforming growth factor-β (TGF-β) inducible gene H3 (BIGH3) is involved in adhesion and migration, although the effect of BIGH3 is highly cell type-dependent. BIGH3 is abundantly expressed by mesenchymal stromal cells, while its expression in HSPCs is relatively low unless induced by certain BM stressors. Here, we set out to determine how BIGH3 modulates HSPC adhesion and migration. We show that primary HSPCs adhere to BIGH3-coated substrates, which is, in part, integrin-dependent. Overexpression of BIGH3 in HSPCs and HL60 cells reduced the adhesion to the substrate fibronectin in adhesion assays, which was even more profound in electrical cell-substrate impedance sensing (ECIS) assays. Accordingly, the CXCL12 induced migration over fibronectin-coated surface was reduced in BIGH3-expressing HSPCs. The integrin expression profile of HSPCs was not altered upon BIGH3 expression. Although expression of BIGH3 did not alter actin polymerization in response to CXCL12, it inhibited the PMA-induced activation of the small GTPase RAC1 as well as the phosphorylation and activation of extracellular-regulated kinases (ERKs). Reduced activation of ERK and RAC1 may be responsible for the inhibition of cell adhesion and migration by BIGH3 in HSPCs. Induced BIGH3 expression upon BM stress may contribute to the regulation of BM homeostasis.     

Pre-CFU-f: young-type stromal stem cells in murine bone marrow following administration of DNA inhibitors

Occurrence of young-type stromal stem cells (defined here as "pre-CFU-f") in murine bone marrow is reported in this study. Two consecutive intraperitoneal (i.p.) cytosine arabinoside (ara-C) injections were administered to C57B1 mice (2 X 200 mg/kg at 6-h intervals). Two days later the bone marrow was collected and assayed for colony-forming units-fibroblastoid (defined here as "CFU-f"). In additional experiments, ara-C-treated marrow was exposed in vitro to hydroxyurea (HU; "hydroxyurea killing test"), prior to plating, to establish the cycling state of stromal stem cells. In separate cultures of ara-C-treated marrow, replating of adherent cells was carried out up to quaternary sub-cultures. The results indicate ara-C-treated marrow produces approximately 20% "huge" fibroblastoid colonies (approximately 5 mm diameter versus 0.5-2 mm normal size); most stromal stem cells producing huge colonies are cycling cells; and adherent cells from primary ara-C-treated marrow cultures replated to secondary cultures produce adherent layers with double the number of cells than in the control secondary cultures. We conclude that the ara-C-treated murine bone marrow contains certain young-type cycling stromal stem cells which we refer to as pre-CFU-f. These stem cells produce huge fibroblastoid colonies in culture, indicating that they probably go through more cell cycles than CFU-f during the culture period. Alternatively, pre-CFU-f may have a higher self-replicative capacity than CFU-f.     

Kinetics of hematopoietic stem cells in the bone marrow of hepatectomized mice

Two-thirds of the liver was removed from (CBA X C57BL/6j) F1 female mice. A significant increase of the number of endogenous colonies count in the spleen of partially hepatectomized mice was observed on the 5-th day after the operation. This increase was not associated with the changes in the number of stem cells in the bone marrow as partial hepatectomy at different times after the operation exerted no effect on the number of colony-forming units (CF1) in the bone marrow.     

Endogenous DNA damage clusters in human hematopoietic stem and progenitor cells

Clustered DNA damages-multiple oxidized bases, abasic sites, or strand breaks within a few helical turns-are potentially mutagenic and lethal alterations induced by ionizing radiation. Endogenous clusters are found at low frequencies in unirradiated normal human cells and tissues. Radiation-sensitive hematopoietic cells with low glycosylase levels (TK6 and WI-L2-NS) accumulate oxidized base clusters but not abasic clusters, indicating that cellular repair genotype affects endogenous cluster levels. We asked whether other factors, i.e., in the cellular microenvironment, affect endogenous cluster levels and composition in hematopoietic cells. TK6 and WI-L2-NS cells were grown in standard medium (RPMI 1640) alone or supplemented with folate and/or selenium; oxidized base cluster levels were highest in RPMI 1640 and reduced in selenium-supplemented medium. Abasic clusters were low under all conditions. In primary hematopoietic stem and progenitor cells from four non-tobacco-using donors, cluster levels were low. However, in cells from tobacco users, we observed high oxidized base clusters and also abasic clusters, previously observed only in irradiated cells. Protein levels and activity of the abasic endonuclease Ape1 were similar in the tobacco users and nonusers. These data suggest that in highly damaging environments, even normal DNA repair capacity can be overwhelmed, leaving highly repair-resistant clustered damages.     

Altered colony-forming activities of bone marrow hematopoietic stem cells in mice following short-term in vivo exposure to parathion

This paper describes a study of hematopoiesis in parathion-treated mice. Adult mice (48 C57B1/6) were given a daily dose of parathion (4 mg/kg p.o.) or corn oil vehicle (5 ml/kg p.o.) for 14 days. During the pesticide and the examination period, treated animals showed no signs of poisoning and had normal body weights. On days 2, 5, 7, 9, 12 and 14 following parathion or corn oil, femoral marrow cells were assayed in vitro for granulocyte/monocyte (CFU-gm), erythroid (CFU-e and BFU-e), megakaryocyte (CFU-meg), stromal (CFU-str) and multipotential (CFU-mix) hematopoietic stem cells. Leukocyte counts were elevated on days 2 and 5, while platelet counts were not increased until day 12. No change was observed in either hematocrits or numbers of marrow cells. BFU-e were reduced (23% of control) by day 7, then increased to 137% of control by day 14. CFU-e were reduced (41% of control) on day 9, then increased to 71% of control by day 14. CFU-mix were 130% of control (day 2), then declined to control values by day 5. On days 12 and 14, CFU-mix colonies decreased to 40% of control. CFU-str were reduced at all time points examined. CFU-gm were 123%, 136% and 130% of control on days 7, 12 and 14, respectively, while CFU-meg were increased (145% of control) on day 7. The data suggest that parathion alters the cloning potential of bone marrow precursor stem cells.