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At least 19 recordsLinked to original sources
PubMed1979

Humoral control of thrombopoiesis.

There is increasing evidence that an important mechanism by which platelet production is regulated depends upon a humoral substance (thrombopoietin) that affects the production of platelets by megakaryocytes. Plasma from thrombocytopenic donors increases the rate of appearance or concentrations of subsequently administered Na235SO4 or selenomethionine-75Se in platelets. Both isotopes are initially incorporated into the cytoplasm of megakaryocytes, and labeled platelets appear in the circulation after their production and release from megakaryocytes. Thrombopoiesis-stimulating activity also can be detected in the plasma of normal donors when endogenous thrombopoiesis has been suppressed in recipient assay animals by the hypertransfusion of platelets. Recent studies have indicated that certain fractions of plasma from throbocytopenic donors are also capable of stimulating thrombopoiesis in recipient animals. The nature of thrombopoietin(s) and its mechanism of action remain unknown. However, currently available data indicate that thrombopoiesis-stimulating factors may act both on diploid precursors and immature megakaryocytes and upon maturing megakaryocytes. The site of production of thrombopoietin also is unknown. Although the sensor that regulates thrombopoietin or other humoral mediators of thrombopoiesis has not been identified, it appears that platelet numbers, per se, are not the sole variable to which megakaryocytopoiesis eventually responds.

Ammonium Sulfate↗
PubMed1979

A mathematical model of thrombopoiesis in rats.

A mathematical model of thrombopoiesis in rats is presented. This has four compartments; stem cells, megakaryocytes, thrombocytes and thrombopoietin. A high thrombopoietin concentration influences bone marrow proliferation in three ways. Firstly the stem cells are stimulated and a slow increase in megakaryocyte number follows. Secondly there are additional endomitoses in the (early) megakaryocytes resulting in an increase in megakaryocyte volume. Thirdly the megakaryocyte maturation time is shortened. The parameters of the model are determined from experimental values for the normal, maximum and minimum proliferation rates, maturation times and destruction rates. The model is tested by comparing simulated results for acute and chronic thrombocytopenia and thrombocytosis with experimental curves from the literature. The model and data agree within the limits of experimental error. Not all of the thrombopoietic regulatory system is known yet, so some important alternative hypotheses are investigated and compared with the model. Several hypotheses have been excluded in this way.

Animals↗
PubMed1976

Relationships between thrombopoiesis and erythropoiesis: with studies of the effects of preparations of thrombopoietin and erythropoietin.

The effects of administration of partially purified human urinary erythropoietin and rabbit thrombopoietin, and of endogenously produced erythropoietin and thrombopoietin on both red cell and platelet production were examined in mice. Partially purified thrombopoietin was prepared from rabbit plasma by sequential fractionation with ammonium sulfate precipitation, and DEAE and Sephadex G-100 chromatography. Preparations of thrombopoietin and partially purified human urinary erythropoietin (NIH No. H-11-TaLSL) were administered subcutaneously to normal mice, and the rate of incorporation of selenomethionine-75 Se into platelets was measured as an index of thrombopoietic activity of the infused material. Erythropoietin and thrombopoietin were assayed for erythropoietic activity by measuring the rate of appearance of 59Fe in the red cells of posthypoxic polycythemic mice. Preparations containing thrombopoietin had barely measurable erythropoietic activity, and 7 units of partially purified erythropoietin had little thrombopoietic activity. When endogenous levels of erythropoietin were increased by hypoxia, platelet production was not enhanced. Similarly, increased levels of thrombopoietin, induced in response to thrombocytopenia produced by platelet antiserum, did not alter red cell production. These data suggest that physiologically increased levels of thrombopoietin do not stimulate erythropoiesis, and that physiologically increased levels of erythropoietn do not stimulate thrombopoiesis. However, currently available, partially purified preparations of erythropoietin and thrombopoietin may be capable of stimulating both platelet and red cell production if used in sufficient quantities.

Animals↗
PubMed1978

Humoral regulation of thrombopoiesis in man.

Plasma was obtained before and after plateletpheresis-induced thrombocytopenia from two healthy male subjects during periods of ethanol ingestion and abstinence. Autologous reinfusion of these plasmas was performed at a later date when both subjects were hematologically normal. Eight thrombopoietically active plasmas produced an increased percent of immature megakaryocytes 24 hr after reinfusion and a peak rise in platelet count (averaging 148% of baseline values) at 5.8 days. Similar changes were not found with inactive plasmas, plasma collected at the end of a "sham" plateletpheresis, or plasma collected after 8 hr of ingestion of 296 gm of ethanol. A transient increase in TSA was found in plasmas collected at the end of plateletpheresis during abstinence, but this activity was not detected 12 hr later. The rapid disappearance of TSA, despite persistent thrombocytopenia, coincided with the appearance of an increased percent of immature magakaryocytes in the bone marrow. Elevated TSA was also noted at the end of plateletpheresis during ethanol ingestion but, in contrast to events during abstinence, remained elevated as long as ethanol ingestion continued.

Blood Cell Count↗
PubMed1979

Partial purification of thrombopoietin from the plasma of thrombocytopenic rabbits.

Partially purified thrombopoiesis-stimulating activity was prepared from the plasma of thrombocytopenic rabbits using ammonium sulfate precipitation and DEAE cellulose, Sephadex, and carboxymethyl cellulose chromatography. The protein fraction precipitated by an ammonium sulfate saturation of 60%-80%, previously shown to contain thrombopoiesis-stimulating activity, was used as starting material. Column chromatography was carried out at room temperature at pH 5.6. Under these conditions, thrombopoiesis-stimulating activity (thrombopoietin) was retained by DEAE cellulose (0/03 M citrate-phosphate buffer) and carboxymethyl cellulose (0/003 M citrate-phosphate buffer), and eluted with 0.4 M NaCl. Thrombopoietin was retarded by Sephadex G-100; the ratio of the elution volume to the void volume was 1.32:1. Immunoelectrophoretic analysis of partially purified thrombopoietin indicated that following removal of most of the albumin by DEAE chromatography, only proteins with the mobilities of beta-globulins and albumin and traces of other anodally migrating proteins were detectable in the fractions that contained thrombopoiesis-stimulating activity. Thrombopoietin was not dialyzable and was stable from at least pH 5.6 to 7.5. It was approximately 1000-fold purified following sequential chromatography with DEAE and carboxymethyl cellulose. Although the three fractions described reproducibly stimulated thrombopoiesis, as measured by increased levels of selenomethionine-75Se (75SeM) in the circulating platelets, platelet counts did not increase.

Animals↗
PubMed1977

[Changes on platelet adhesion, aggregation and production in course of mumps and mumps meningitis (author's transl)].

In 20 children with mumps and mumps meningitis thrombocyte functions, the thrombopoiesis and the platelet count were examinated over a four week period. The spontaneous, standardized platelet adhesion and aggregation on silikonized glass surface showed a statistically significant increase from the 5th to the 15th day of the illness. Within the first four days a decrease of the megathrombocyte portion respectively of the youngest platelet forms was noted as revealed by the platelet spreading preparations. Then the thrombopoiesis index as well as the platelet count arised from the 5th day of the illness parallel to the other platelet functions. The enhanced thrombopoiesis diminished at the end of the 3rd week of the illness but the platelet adhesion and aggregation continued to be further increased. A distinct correlation could be established between the development of the specific antibodies and increased platelet adhesion, aggregation and thrombopoiesis in epidemic parotitis. The influence of the immune complexes and of the virus itself, furthermore the occurrence of the regenerating phase as well as the effects of the possible thromboplastic activity following a tissue damage or an inflammatory reaction were discussed.

Antibodies, Viral↗
PubMed2025

Studying the Role of HOX Genes in Thrombocyte Development.

In our laboratory, we study thrombopoiesis and hemostasis using zebrafish as a model organism to unravel the mechanisms of differentiation and development of thrombocytes. We have shown in our earlier work that thrombocytes are functional equivalents of platelets and have transcriptional machinery similar to megakaryocytes. We recently found evidence that hox genes play a role in their development. We used piggyback gene knockdown and thrombocyte quantification assays to understand the influence of these ancient developmental regulators on thrombopoiesis. In this chapter, we describe methods used to discover these hox genes.

Animals↗
PubMed1977

Thrombocyte functions, thrombelastograms and fibrinogen of healthy children in different age groups.

Platelet counts, adhesiveness, aggregation and spreading capacity, as well as the thrombopoiesis index, thrombelastogram and fibrinogen were examined in 74 healthy children aged from 2 to 14 years. Sex-linked differences were only found in the thrombopoiesis index. Age-linked differences showed in practically all the parameters, especially in the platelet counts, fibrinogen and thrombelastograms.

Adolescent↗
PubMed1976

A comparison of platelet size, latelet count, and platelet 35S incorporation as assays for thrombopoietin.

Average platelet size, platelet count, and 35S-incorporation into platelets were compared as methods for the measurement of thrombopoietin-stimulated thrombopoiesis. In mice injected with rabbit anti-mouse platelet serum (RAMPS) average platelet size was shown to be increased as mice were recovering from thrombocytopenia. Also, 35S-measurements on platelets of these mice showed significant increases in cpm/average platelet 2-4 days after RAMPS treatment. Significant increases in 35S-incorporation into the total circulating mass of platelets were found on days 3-4. In normal mice or mice in rebound-thrombocytosis injected with thrombopoietin, platelet size remained unchanged, whereas the platelet cound and 35S-incorporation into platelets were shown to be significantly increased. Moreover, a dose-response experiment in mice pretreated with RAMPS showed a slight increase in platelet count as the dose of TSF was increased, but platelet sizes were unaltered. The % 35S-incorporation into platelets showed a significant linear dose-response, i.e. as the dose of thrombopoietin was increased, as increase in % 35S-incorporation into platelets was observed. These data indicated that of the three indirect measurements of thrombopoietin, the % 35S-incorporation into mouse platelets was the most sensitive, followed by platelet counting; the least sensitive measurement of thrombopoiesis was change in platelet size.

Animals↗
PubMed1977

Biphasic thrombopoietic response to severe hypobaric hypoxia.

Thrombopoiesis has been studied during and after an 11 d exposure to discontinuous hypobaric hypoxia. Exposure of rats to 0.4 atmospheres for 16--17 h daily initially caused an increase in platelet count which reached a peak of 1.5 times baseline on days 4 and 5. This thrombocytosis was followed by a decrease in platelets to a nadir of 50--60% of baseline on days 12 and 13. That thrombocytosis results from increased platelet production is supported by increased [35S]sulphate incorporation into platelets and increased megakaryocyte size and turnover. The thrombocytopenia with continued hypoxia seems to result from decreased platelet production since 51Cr-platelet survival was normal while megakaryocyte concentration was decreased to one-half that of untreated controls. These observations suggest that differentiation of precursors into megakaryocytes was decreased during the thrombocytopenic period, although the fewer remaining megakaryocytes appeared stimulated because of their larger size and increased [3H]thymidine labelling. Thus, hypobaric hypoxia had a biphasic effect on thrombopoiesis with increased platelet production in the first few days of exposure followed by subnormal production.

Animals↗
PubMed2026

The alarmin interleukin-33 modulates platelet proteome, function, and biogenesis.

Platelets, traditionally recognized for their involvement in hemostasis and wound healing, also play a central role in immune regulation and inflammation. Their function and production adapt in response to inflammatory cues such as cytokines and danger-associated molecular patterns. Interleukin-33 (IL-33), an alarmin released during tissue damage, particularly in lung inflammation, has been implicated in influencing platelet biology, though its exact effects remain poorly understood. To clarify IL-33's role, we examined its impact on platelet production, proteome, adhesion, secretion, and aggregation using platelets from IL-33-deficient (IL-33 knockout [IL-33KO]) mice and IL-33 stimulation in vivo. Our results reveal that although platelets themselves do not express IL-33, platelets isolated from IL-33KO mice display altered proteomic signatures and reduced adhesion to fibrinogen, podoplanin, and laminin, alongside impaired thrombus formation under shear stress. IL-33 administration in vivo led to proteomic remodeling characterized by increased expression of inflammatory proteins, as well as changes in platelet morphology, including increased size, typically associated with de novo production. Using lung intravital microscopy, we visualized platelet fragmentation within the lung vasculature in real time, and observed enhanced fragmentation following IL-33 stimulation. Interestingly, ST2, the receptor for IL-33, is expressed in subsets of mouse and human megakaryocytes and hematopoietic progenitors, particularly those involved in a noncanonical pathway of thrombopoiesis that enables the rapid replenishment of platelets during inflammation, infection, and aging. Together, these findings identify IL-33 as a pivotal regulator of platelet function and production, linking inflammatory signaling to the dynamic regulation of thrombopoiesis.

Interleukin-33↗
PubMed1977

Extreme thrombocytosis associated with malignancy.

A case is described in which a platelet count of 6,000,000/mm3 occurred in association with adenocarcinoma of the lung and remitted following definitive radiotherapy of the primary lesion. Despite the magnitude of the platelet elevation, thrombohemorrhagic phenomena were not observed. Extreme thrombocytosis of this magnitude is rare in either primary or secondary disorders of thrombopoiesis. The occurrence of unexplained thrombocytosis demands the exclusion of malignancy.

Adenocarcinoma↗
PubMed1976

Pathomorphologic findings in severe combined immunodeficiency and reticular dysgenesia.

Pathomorphologic findings in an 11 month old boy with severe combined immunodeficiency (case 1) and in a 4-month old boy with reticular dysgenesia (case 2) are reported. Case 1: The bone marrow exhibited regular granulo-, erythro- and thrombopoiesis. The hypoplastic thymus consisted exclusively of epithelial reticulum cells. The spleen and lymph nodes showed considerable depletion of lymphocytes in both the T- and B-cell areas. There was a complete lack of all lymphatic structures in the gastrointestinal tract and aplasia of the tonsils. Death resulted from Candida sepsis in conjunction with giant cell pneumonia closely resembling Hecht's pneumonia in measles. Case 2: The bone marrow showed a total lack of granulopoiesis. The storngly dysplastic thymus weighed only 1 g. The spleen, the lymph nodes and the gastrointestinal tract exhibited a very strange histologic structure resulting from a complete absence of lymphocytes and plasma cells. The tonsils were aplastic, the para-thyroid glands as well as the other endocrine glands were normally developed. The cause of death was Klebsiella sepsis and Pneumocystis pneumonia, the latter without the characteristic interstitial plasma cell infiltration. The importance of the immune system for activation of the nonspecific mechanisma of defense is discussed with respect to the two types of immunodeficiency states described here.

Agranulocytosis↗
PubMed1976

[Relationships between hemopoiesis and peripheral blood counts in untreated and 32P-treated patients with polycythaemia vera (author's transl)].

The composition of the hemopoiesis was determined in iliac crest biopsies of 51 patients with polycythaemia vera. There was a good correlation between thrombopoiesis and thrombocytes and, to a minor degree also between erythropoiesis and erythrocytes in untreated patients as well as between granulopoiesis and granulocytes in 32P-treated patients. In patients with normal blood counts there existed no correlation between the bone marrow and the blood counts within smaller limits of the cell count. Histomorphometric analysis shows no difference either between untreated and 32P-treated patients or between patients with and without splenomegaly. This is an argument against a significant intrasplenic hemopoiesis or an intrasplenic cell pooling, or destruction (hypersplenism), respectively. The blood sinusoids are hyperplastic and distended. With increasing hyperplasia of the hemopoiesis the sinusoids become relatively smaller. So changes in vascularisation may be of importance in the infrequent transitions into myelofibrosis and/or leukemia.

Biopsy↗
PubMed1978

[Alcohol-related disturbances in haematopoiesis (author's transl)].

Alcohol-related disturbances are seen against the three blood cell systems. They appear after important alcohol consumption within few days and are independent from the existence of liver cirrhosis with splenomegaly. They are promptly and completely reversible after interruption of alcohol supply. Disturbances in erythropoiesis are manifested in bone marrow with megaloblasts, ring sideroblasts, and vacuoles in cytoplasma and nucleus of nucleated red cells. They are caused by folate deficiency and by perturbations of iron utilization, which is perhaps connected with impaired heme synthesis following pyridoxal phosphate deficiency. Serum iron generally increases during alcohol consumption and decreases in the following alcohol-free period. The anemia may be macrocytic and normochromic or dimorphic with hypochromic microcytes. Anemias of hard alcohol drinkers are observed also as consequence of bleeding or hemolysis of different causes. The lability against infections of drinkers is associated with changes in granulopoiesis. The most important findings are granulocytopenia, vacuoles in the immature marrow cells, perturbations in granulopoietic maturation, and decrease of marrow response. Frequently, alcohol drinkers demonstrate thrombocytopenia which is caused by ineffective thrombopoiesis and by shortened life span of platelets as direct effect of ethanol. Functional impairments of thrombocytes have been published, too.

Alcoholism↗
PubMed2026

Integrative computational analysis combining network pharmacology, regulatory network modeling, and molecular dynamics reveals the mechanisms of Quanshen compound in ITP.

UNLABELLED: Immune thrombocytopenia (ITP) is a hemorrhagic disorder caused by immune dysfunction. Quanshen Compound (QSC) is an in-house preparation developed by the Uyghur Hospital in Hotan Prefecture. This study primarily investigates and validates the potential pharmacological basis and mechanism of action of QSC in modulating immune thrombopoiesis. Based on the multi-database screening of the QSC and the related targets of ITP, the intersection was obtained to construct a protein-protein interaction (PPI) network and screen the core targets; the intersection targets were analyzed for gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis using R packages; a component-target-pathway network was constructed to screen the key active components and their mechanisms of action. At the same time, the TF-mRNA-miRNA regulatory network of the core targets was constructed, and chromosome localization and subcellular localization analysis were performed; further, the binding stability of key components and core targets was verified through molecular docking and molecular dynamics simulation. A total of 227 potential target sites were screened out, among which TNF, IL6, AKT1, TP53 and IL1B were the core targets. The enrichment results indicated that these intersecting target sites mainly participated in inflammatory responses, immune regulation and hemostasis-related biological processes, and were significantly enriched in the PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, Th17 cell differentiation and PD-1/PD-L1 signaling pathway. The core target TF-mRNA-miRNA regulatory network contained 184 nodes and 200 edges, suggesting that the core targets were subject to multi-level regulation. Molecular docking results showed that the main active components had good binding activity with the core targets, and molecular dynamics simulation further verified the stability of the complex. QSC may improve ITP through a multi-component, multi-target, and multi-pathway synergistic mechanism involving key targets such as TNF, IL6, AKT1, TP53, and IL1B, as well as the PI3K-Akt signaling pathway. These findings provide new insights into the potential therapeutic mechanisms of QSC against ITP and warrant further experimental validation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at https://doi.org/10.1007/s40203-026-00718-0.

Immune thrombocytopenia↗