Objective: To reveal the crucial toxic components of ambient fine particles (PM_2.5) that affect the maturation and differentiation of megakaryocytes. Methods: Human megakaryocytes were exposed to the organic fractions, metallic fractions and water-soluble fractions of PM_2.5 at two exposure doses (i.e. actual air proportion concentration or the same concentration), respectively. The cell viability was performed to screen the non-cytotoxic levels of toxic components of PM_2.5 using the CCK-8 assay. CellTiter-Blue assay, morphological observation, flow cytometry analysis and WGA staining assay were used to evaluate the cell morphological changes, occurrence of DNA ploidy, alteration in the expressions of biomarkers and platelet formation, which were key indicators of the maturation and differentiation of megakaryocytes. Results: Compared to the control group, both metallic and organic components of PM_2.5 resulted in a lag in megakaryocytes with an increase in cell volume and the onset of DNA ploidy. Flow cytometry analysis showed that CD33 (the marker of myeloid-specific) decreased and CD41a (a megakaryocyte maturation-associated antigen) increased in metallic and organic components of PM_2.5 treatment groups. Moreover, compared to the control group, budding protrusions increased in metallic and organic components of PM_2.5 treatment groups. The water-soluble components had no effect on the maturation and differentiation of macrophages. Conclusion: Metallic and organic components of PM_2.5 are the crucial toxic components that promote the maturation and differentiation of megakaryocytes.
Biomarkers ; DNA/pharmacology* ; Humans ; Megakaryocytes/chemistry* ; Particulate Matter/toxicity* ; Sincalide/pharmacology* ; Water/pharmacology*

Objective: To establish an intramedullary transplantation model of primary megakaryocytes to evaluate the platelet-producing capacity of megakaryocytes and explore the underlying regulatory mechanisms. Methods: Donor megakaryocytes from GFP-transgenic mice bone marrow were enriched by magnetic beads. The platelet-producing model was established by intramedullary injection to recipient mice that underwent half-lethal dose irradiation 1 week in advance. Donor-derived megakaryocytes and platelets were detected by immunofluorescence staining and flow cytometry. Results: The proportion of megakaryocytes in the enriched sample for transplantation was 40 to 50 times higher than that in conventional bone marrow. After intramedullary transplantation, donor-derived megakaryocytes successfully implanted in the medullary cavity of the recipient and produce platelets, which showed similar expression of surface markers and morphology to recipient-derived platelets. Conclusion: We successfully established an in vivo platelet-producing model of primary megakaryocytes using magnetic-bead enrichment and intramedullary injection, which objectively reflects the platelet-producing capacity of megakaryocytes in the bone marrow.
Animals ; Blood Platelets ; Bone Marrow ; Bone Marrow Cells ; Bone Marrow Transplantation ; Humans ; Megakaryocytes/metabolism* ; Mice

Abivertinib, a third-generation tyrosine kinase inhibitor, is originally designed to target epidermal growth factor receptor (EGFR)-activating mutations. Previous studies have shown that abivertinib has promising antitumor activity and a well-tolerated safety profile in patients with non-small-cell lung cancer. However, abivertinib also exhibited high inhibitory activity against Bruton's tyrosine kinase and Janus kinase 3. Given that these kinases play some roles in the progression of megakaryopoiesis, we speculate that abivertinib can affect megakaryocyte (MK) differentiation and platelet biogenesis. We treated cord blood CD34⁺ hematopoietic stem cells, Meg-01 cells, and C57BL/6 mice with abivertinib and observed megakaryopoiesis to determine the biological effect of abivertinib on MK differentiation and platelet biogenesis. Our in vitro results showed that abivertinib impaired the CFU-MK formation, proliferation of CD34⁺ HSC-derived MK progenitor cells, and differentiation and functions of MKs and inhibited Meg-01-derived MK differentiation. These results suggested that megakaryopoiesis was inhibited by abivertinib. We also demonstrated in vivo that abivertinib decreased the number of MKs in bone marrow and platelet counts in mice, which suggested that thrombopoiesis was also inhibited. Thus, these preclinical data collectively suggested that abivertinib could inhibit MK differentiation and platelet biogenesis and might be an agent for thrombocythemia.
Acrylamides/pharmacology* ; Animals ; Blood Platelets/drug effects* ; Cell Differentiation ; Megakaryocytes/drug effects* ; Mice ; Mice, Inbred C57BL ; Piperazines/pharmacology* ; Pyrimidines/pharmacology*

OBJECTIVE: To investigate the effect of Rheb1 in the development of mouse megakaryocyte-erythroid progenitor cells and its related mechanism. METHODS: Rheb1 was specifically knocked-out in the hematopoietic system of Vav1-Cre;Rheb1^fl/fl mice(Rheb1^Δ/Δ mice). Flow cytometry was used to detect the percentage of red blood cells in peripheral blood and erythroid cells in bone marrow in Vav1-Cre;Rheb1^fl/fl mice and control mice. The CFC assay was used to detect the differentiation ability of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Real-time fluorescence quantification PCR was used to detect the relative expression of PU.1,GATA-1,GATA-2,CEBPα and CEBPβ of Rheb1 KO megakaryocyte-erythroid progenitor cells and control cells. Rapamycin was added to the culture medium, and it was used to detect the changes in cloning ability of megakaryocyte-erythroid progenitor cells from wild-type mice in vitro. RESULTS: After Rheb1 was knocked out, the development and stress response ability of megakaryocyte-erythroid progenitor cells in mice were weaken and the differentiation ability of megakaryocyte-erythroid progenitor cells in vitro was weaken. Moreover, the expression of GATA-1 of megakaryocyte-erythroid progenitor cells was decreased. Further, rapamycin could inhibit the differentiative capacity of megakaryocyte-erythroid progenitor cells in vitro. CONCLUSION Rheb1 can regulate the development of megakaryocyte-erythroid progenitor cells probably through the mTOR signaling pathway in mice.
Animals ; Cell Differentiation ; Erythrocytes ; Flow Cytometry ; Megakaryocyte-Erythroid Progenitor Cells ; Megakaryocytes ; Mice ; Signal Transduction

Tubulin affects platelets count through the control of mitosis and the formation of pro-platelets during the maturation of megakaryoblast to platelets. Tubulin is involved in maintaining the integrity of platelet skeleton, and also participates in the change of platelet morphology during platelet activation. Some new anti-tumor drugs targeting cell mitosis are trying to reduce the effect on tubulin in order to reduce the side effect of drugs on platelet formation. In some patients with thrombocytopenia, the variation and polymorphism of the tubulin gene affect the structure of microtubule multimers, which leads to the decrease of platelet formation. This review summarized the latest progresses of tubulin in the regulation of megakaryopoiesis and thrombopoiesis.
Blood Platelets ; Humans ; Megakaryocytes ; Platelet Count ; Thrombopoiesis ; Tubulin

Actinin/genetics* ; Anemia ; Blood Platelets/pathology* ; Female ; Humans ; Male ; Megakaryocytes ; Mutation, Missense ; Pedigree ; Thrombocytopenia/genetics*

OBJECTIVE: To investigate the effect of enhanced autophagy in megakaryocyte to proplatelet formation in children with immune thrombocytopenia(ITP). METHODS: Giemsa staining and immunofluorescence staining were used to observe megakaryocyte morphology and proplatelet formation, Western blot was used to determine the expression of cytoskeleton protein and autophagy related protein. Autophagr regulation drugs Rap or 3-MA was used to regulate autophagy of megakaryocytes. RESULTS: Some vacuole-like structures was found in ITP megakaryocytes of the children, the expression of LC3II/I (ITP 1.32±0.18； Ctrl 0.49±0.16，P<0.05) and Atg5-Atg12 (ITP 0.69±0.17； Ctrl 0.12±0.08，P<0.05) was significantly higher in ITP children as compared with those in control group. The immu- nofluorescence staining showed that the cytoskeleton arrangement in megakaryocytes of ITP children was abnormal, and the phosphorylation of myosin light chain was also increased(ITP 0.74±0.09, Ctrl 0.05±0.02，P<0.05). In vitro, inducer or inhibitor of autophagy could regulate the production of proplatelet and the expression of cell cycle related protein, including CyclinD1（Veh 1.08±0.12; Rap 0.46±0.04; Rap+3-MA 0.70±0.03）, CyclinD2（Veh 0.47±0.04; Rap 0.27±0.04; Rap+3-MA 0.41±0.03）, P21（Veh 0.15±0.01; Rap 0.04±0.01; Rap+3-MA 0.05±0.01）. CONCLUSION Enhanced autophagy is the key factor of poor proplatelet formation in megakaryocytes of ITP children.
Autophagy ; Blood Platelets ; Humans ; Megakaryocytes ; Purpura, Thrombocytopenic, Idiopathic ; Thrombocytopenia

OBJECTIVE: To explore the phenotypic and genetic characteristics of acute megakaryoblastic leukemia (AMKL) in young children accompany by WT1, MLL-PTD and EVI1, in order to improve the diagnosis level of AMKL. METHODS: EDTA-K RESULTS: White blood cell count was 12.3× 10 CONCLUSION Acute megakaryocytic leukemia has unique and complex phenotypic and genetics characteristics.
Bone Marrow ; Child ; Child, Preschool ; Chromosome Aberrations ; Humans ; Karyotyping ; Leukemia, Megakaryoblastic, Acute/genetics* ; MDS1 and EVI1 Complex Locus Protein ; Megakaryocytes ; Oncogene Proteins, Fusion ; WT1 Proteins

OBJECTIVE: To explore whether thrombopoietin (TPO) can rescue megakaryopoiesis by protecting bone marrowderived endothelial progenitor cells (BM-EPCs) in patients receiving chemotherapy for hematological malignancies. METHODS: Bone marrow samples were collected from 23 patients with hematological malignancies 30 days after chemotherapy and from 10 healthy volunteers. BM-EPCs isolated from the samples were identified by staining for CD34, CD309 and CD133, and their proliferation in response to treatment with TPO was assessed using CCK8 assay. DiL-Ac-LDL uptake and FITC-UEA-I binding assay were performed to evaluate the amount of BM-EPCs from the subjects. Tube-formation and migration experiments were used for functional assessment of the BM-EPCs. The BM-EPCs with or without TPO treatment were co-cultured with human megakaryocytes, and the proliferation of the megakaryocytes was detected with flow cytometry. RESULTS: Flow cytometry indicated that the TPO-treated cells had high expressions of CD34, CD133, and CD309. CCK8 assay demonstrated that TPO treatment enhanced the proliferation of the BM-EPCs, and the optimal concentration of TPO was 100 μg/L. Double immunofluorescence assay indicated that the number of BM-EPC was significantly higher in TPO-treated group than in the control group. The TPO-treated BM-EPCs exhibited stronger tube-formation and migration abilities ( < 0.05) and more significantly enhanced the proliferation of co-cultured human megakaryocytes than the control cells ( < 0.05). CONCLUSIONS TPO can directly stimulate megakaryopoiesis and reduce hemorrhage via protecting the function of BM-EPCs in patients following chemotherapy for hematological malignancies.
Bone Marrow ; Bone Marrow Cells ; Cells, Cultured ; Hematologic Neoplasms ; Humans ; Megakaryocytes ; Thrombopoietin

OBJECTIVE: To explore the method for inducing the differentiation of bone marrow cells into megakaryocytes in vitro so as to use for evaluating the activity of traditional Chinese medicines. METHODS: The bone marrow cells were separated from femurs and tibias of mice. The experiments were divided into 4 groups: control (no adding cytokines), TPO (adding 50 ng/ml TPO), TPO+SCF (50 ng/ml+50 ng/ml) and TPO+SCF+IL-6+IL-9 (50 ng/ml+50 ng/ml+20 ng/ml+20 ng/ml). The bone marrow cells in 4 groups were cultured in vitro for 6 d. Then the cell growth status was observed by the inverted microscopy, and the cell count was detected by using the automatic cell counter. The ratio and absolute count of megakaryocytes were detected by flow cytometry. RESULTS: Compared with control, three induction methods could stimulate the differentiation of bone marrow cells into megakaryocytes in vitro. TPO could slightly enhance the differentiation of bone marrow cells into megakaryocytes. Both the combination of TPO and SCF, and the combination of TPO, SCF, IL-6 and IL-9 could intensively stimulate proliferation of bone morrow cells and promote the differentiation of bone marrow cells into megakaryocytes. The addition of IL-6 and IL-9 could decrease the proliferation of non-megakaryocytes, but promote the differentiation of bone marrow cells into megakaryocytes. CONCLUSION The optimized differentiation of bone marrow cells into megakaryocytes has been completed by co-induction regimen of TPO, SCF, IL-6 and IL-9, which can be used to screen and evaluate traditional Chinese medicines promoting formation of platelets.
Animals ; Bone Marrow Cells ; Cell Count ; Cell Differentiation ; Cell Division ; Cells, Cultured ; Interleukin-3 ; Megakaryocytes ; Mice ; Stem Cell Factor ; Thrombopoietin