Browsing by Subject "Megakaryocytes"

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    Dynamics of bone marrow changes in patients with chronic idiopathic myelofibrosis following allogeneic stem cell transplantation
    (Murcia : F. Hernández, 2005) Thiele, J.; Kvasnicka, H.M.; Dietrich, H.; Stein, G.; Hann, M.; Kaminski, A.; Rathjen, N.; Metz, K.A.; Beelen, D.W.; Ditschkowski, M.; Zander, A.; Kroeger, N.
    Scant knowledge exists about the dynamics of fibro-osteosclerotic bone marrow (BM) lesions and regeneration of hematopoiesis following allogeneic peripheral stem cell transplantation (SCT) in chronic idiopathic myelofibrosis. Therefore, an immunohistochemical and morphometric study was performed on BM biopsies in 20 patients before and at standardized intervals (days 30 through 384) following SCT. In responding patients, a total regression of the pretransplant increased fibrosis was completed in the posttransplant period after about six months, while the extent of osteosclerosis did not change significantly during observation time. The quantity of CD61+ megakaryocytes including precursors was strikingly variable after SCT and, by using planimetric methods, atypical microforms exhibiting a dysplastic aspect could be demonstrated. These anomalies may be responsible for posttransplant thrombocytopenia. CD34+ progenitor cells were increased before transplantation, however, their number declined rapidly to normal values in responding patients. Nucleated erythroid precursors revealed a decreased amount before and after SCT accounting for anemia. Large clusters of this cell lineage indicated an initial hematopoietic reconstitution comparable with the expansion of the neutrophil granulopoiesis. Proliferative activity and apoptosis showed an increase until one year after SCT that implied a still regenerating hematopoiesis in keeping with an enhanced cell turnover.
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    Spleen and bone marrow megakaryocytes as targets for inhaled vanadium
    (Murcia : F. Hernández, 2008) Fortoul, Teresa I.; Piñón-Zarate, Gabriela; Diaz-Bech, María Eugenia; González-Villalva, Adriana; Mussali-Galante, Patricia; Rodriguez-Lara,Vilaney; Colin-Barenque, Laura; Martinez Pedraza, Michelle; Montaño, Luis F.
    An increased incidence in ischemic and thromboembolic events in the population of cities with rising air suspended particle pollution has suggested the interaction of some of the components of these particles in the coagulation system. A previous report from our laboratory identified thrombocytosis as a consequence of the subacute and chronic inhalation of vanadium. With this preceding information we decided to evaluate the effects of this element in the spleen and bone marrow in a mouse experimental model. CD-1 male mice inhaled V2O5 0.02 M for one hour twice a week for twelve weeks. The spleen and bone marrow were processed for light microscopy. The increase in quantity and size of megakaryocytes (MKs) in the exposed group in both organs was striking. Also, modifications in the cytoplasm, granule content and nuclear ultrastructure were evident. Our results indicate the influence of vanadium on megakaryopoyesis, an effect which could be the onset of the thrombocytosis previously reported by our group. The modifications in MKs described here suggest that inhaled vanadium could induce megakaryocytic proliferation, which may result in increased production of platelets and increased risk for thromboembolic events.
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    The effects of cyclophosphamide on pulmonary thrombopoiesis in rats
    (Murcia : F. Hernández, 1998) Sulkowski, S.; Sulkowska, M.; Musiatowicz, B.
    Cyclophosphamide (CP), an antineoplastic and immunosuppresive agent, even when administered in large doses, slightly affects the quantity of blood platelets. The aim of the present study was to analyse the effect of single intraperitoneal administration of CP (150mg/kg b.w.) on the quantitative changes in platelets obtained from the left and right ventricle of the heart, as well as to evaluate the occurrence of megakaryocytes in lung tissue depending on the period of time that passed from CP administration. In control subgroups, fewer platelets were found in the blood collected from the RV compared with the left ventricle at all time intervals. After 1 and 3 days following i.p, administration of CP, a decrease was observed in the number of platelets both in the blood from the right ventricle and left ventricle when compared with control. However, after 14 days, the number of platelets in the blood from the left ventricle was higher, compared with the left ventricle and right ventricle of control animals, and significantly higher (p<0.001747), compared with their number obtained from the right ventricle of CP-receiving animals. Simultaneous ultrastructural examinations with transmission electron microscopy revealed the increased number of platelets in the lung vascular bed of CPreceiving rats at all time intervals. However, megakaryocytes were found 7 and 14 days after administration of CP. The findings clearly indicate that the lungs could be a major place of thrombopoiesis following therapy with a single large dose of CP.