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

The main physiological function of megakaryocytes is the production of platelets, whose development, maturation and platelet production are a complex regulatory process, and are involved in many factors. In recent years it was found that the lung is also the main site of megakaryocyte-producing platelets in addition to bone marrow. Based on the findings of recent years, this review summarizes the process of megakaryocyte development, maturation and platelet production, with emphasis on the analyzing the regulatory effects of apoptotic factors, miRNA, thrombopoietin and its receptors, interleukins, transcription factors and their corresponding signal pathways on platelet production. To understand the regulatory mechanism of platelet production can help to understand the pathological mechanism of platelet-related diseases and provide new ideas for the diagnosis and treatment of platelet-related diseases.
Blood Platelets ; Bone Marrow Cells ; Megakaryocytes ; Thrombopoiesis ; Thrombopoietin

OBJECTIVETo study the role of PDGF/PDGFR in essential thrombocythemia (ET) by investigating the expression of PDGF-BB in bone marrow and the expression of PDGFR-β in bone marrow cells of patients with ET and explore the new target for treating ET patients through inhibiting the PDGFR of megakaryocytes.

METHODSThe expression level of PDGF-BB in bone marrow of ET patients and normal controls were assayed by using ELISA, the expression level of PDGFR-β (CD140) in bone marrow of ET patients and normal controls were detected by using flow cytometry, the effect of PDGF-BB in JAK2/STAT3 and PI3K/AKT pathway was detected by using flow cytometry or Werstern blot, and the effect of imatinib on the megakaryopoiesis of PDGF was observed.

RESULTSThe expression level of PDGF-BB in bone marrow of ET patients was significantly higher than that in normal controls; the expression level of PDGFR-β in bone marrow of ET patients was significantly higher than that in nornal controls; PDGF-BB could activate JAK2/STAT3 and PI3K/AKT pathway of megakaryocytes, while the imatinib could block the effect of PDGF-BB on megakaryocyte.

CONCLUSIONThe elevated PDGF-BB and PDGFR-β may be involved in ET, and the physiopathologic mechanism is that the elevated PDGF-BB activates PDGFR with subsequent activation of the JAK2/STAT3 and PI3K/AKT pathways, stimulating megakaryopoiesis. Imatinib may have a therapeutical effect on ET via blocking of PDGFR.

Bone Marrow ; metabolism ; Case-Control Studies ; Humans ; Megakaryocytes ; metabolism ; Phosphatidylinositol 3-Kinases ; Proto-Oncogene Proteins c-sis ; metabolism ; Receptor, Platelet-Derived Growth Factor beta ; metabolism ; Signal Transduction ; Thrombocythemia, Essential ; metabolism ; Thrombopoiesis

Immune thrombocytopenia (ITP) is a common acquired autoimmune hematological disorders. Platelet autoantibodies lead to the decrease of platelet production and (or) increase of its destruction. The latest researches showed that the abnormal tryptophan metabolism mediated by indoleamine-2, 3-dioxygenase(IDO) is related with the pathogenesis of ITP. The patients with ITP show less expression of IDO, reduction of Treg cells and increase of autoreactive T cells and autoantibodies. CTLA-4-Ig can improve the expression of IDO in the patients with ITP, which also can inhibit the proliferation and activation of self-reactive T cells. Thus, clarifying the abnormal tryptophan metabolism mediated by IDO may provide a new idea for improving the understand of the pathogenesis and treatment of ITP. This review focuses on reasearch progress of the tryptophan metabolism mediated by IDO and ITP.
Autoantibodies ; Blood Platelets ; Humans ; Indoleamine-Pyrrole 2,3,-Dioxygenase ; Thrombocytopenia ; Thrombopoiesis ; Tryptophan

Imatinib mesylate has been commonly used in the treatment of patients with chronic myeloid leukemia (CML). However, a significant number of CML patients treated with imatinib developed thrombocytopenia. Platelet-derived growth factor (PDGF)/platelet-derived growth factor receptor (PDGFR) plays a significant role in the regulation of thrombopoiesis. It is suggested that imatinib may block the PDGF/PDGFR and PI3-K/Akt pathway, then inducing the apoptosis of megakaryocytes and developing thrombocytopenia in these patients. In this review, the potential molecular mechanism of imatinib-induced thrombocytopenia in the treatment of CML patients is discussed, including imatinib and thrombocytopenia, PDGF/PDGFR and thrombopoiesis, potential mechanism of imatinib-induced thrombocytopenia in treatment of patients with CML and so on.
Antineoplastic Agents ; adverse effects ; therapeutic use ; Benzamides ; Caspase 3 ; metabolism ; Humans ; Imatinib Mesylate ; Leukemia, Myelogenous, Chronic, BCR-ABL Positive ; drug therapy ; genetics ; metabolism ; Piperazines ; adverse effects ; therapeutic use ; Platelet-Derived Growth Factor ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyrimidines ; adverse effects ; therapeutic use ; Signal Transduction ; Thrombocytopenia ; chemically induced ; Thrombopoiesis

Platelet-derived growth factor (PDGF), a potent chemotactic and mitogenic factor, is involved in the regulation of hematopoiesis and platelet production. Our studies demonstrate the presence of functional PDGF receptors (PDGFR) on human megakaryocytes/platelets and CD34(+) cells, and their ability to mediate a mitogenic response. PDGF promotes the ex vivo expansion of human hematopoietic stem (CD34(+)) and progenitor (CD41(+)) cells. More significantly, PDGF enhances the engraftment of human CD45(+) cells and their myeloid subsets (CD33(+), CD14(+) cells) in NOD/SCID mice. PDGF also stimulates in vitro megakaryocytopoiesis via PDGFR and/or the indirect effect on bone marrow microenvironment to produce TPO and other cytokines. It also shows a direct stimulatory effect of PDGF on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors may be involved in the signal transduction of PDGF on the regulation of megakaryocytopoiesis. PDGF also enhances platelet recovery in mouse model with radiation-induced thrombocytopenia. This radioprotective effect is likely to be mediated via PDGFR with subsequent activation of the PI3K/Akt pathway. It provides a possible explanation that blockage of PDGFR may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia.
Animals ; Hematopoietic Stem Cells ; cytology ; Humans ; Megakaryocytes ; cytology ; Mice ; Platelet-Derived Growth Factor ; metabolism ; Receptors, Platelet-Derived Growth Factor ; metabolism ; Thrombopoiesis

OBJECTIVETo investigate the effect of Angelica polysaccharide (APS), platelet-derived growth factor (PDGF) and thrombopoietin (TPO) on the proliferation and apoptosis of human megakaryocytic cell line M-07e.

METHODSCell count and the viability testing of M-07e cells (trypan blue exclusion assay) were performed at 24 hours, 48 hours and 72 hours after treatment with APS, PDGF or TPO. Three apoptosis related flow cytometric assays including Annexin V, Caspase-3 and JC-1 were performed to determine apoptotic rate of each group at 72 hours after the treatment.

RESULTSAfter the incubation, the number of M-07e cells in the APS, PDGF and TPO group increased and the viabilities of the three groups were significantly higher than the control group (P < 0.05). The dead cells in the APS, PDGF and TPO group were (19.41 +/- 7.59)%, (21.38 +/- 7.25)% and (18.77 +/- 8.00)%, respectively by flow cytometry using Annexin V method, which were significantly lower compared to the control group (34.33 +/- 5.46)%. The expression of the activated caspase-3 in the group of APS, PDGF and TPO were (12.27 +/- 5.18)%, (12.39 +/- 6.26)% and (13.75 +/- 8.25)%, the APS and PDGF group decreased significantly compared to the control group (18.92 +/- 6.09)%. The ratio of total cell deaths in the APS, PDGF and TPO group were (23.64 +/- 6.69)%, (28.00 +/- 10.05)% and (27.99 +/- 8.99)%, the ratio in APS group decreased significantly compared to the control group (39.48 +/- 11.86)% by JC-1 method. Differences between APS and PDGF groups and between APS and TPO groups were not statistically significant.

CONCLUSIONAPS, PDGF and TPO have similar effect in stimulating proliferation and inhibiting serum-free-culture induced apoptosis of M-07e cells.

Angelica ; chemistry ; Apoptosis ; drug effects ; Benzimidazoles ; pharmacology ; Carbocyanines ; pharmacology ; Caspase 3 ; metabolism ; Cell Proliferation ; drug effects ; Flow Cytometry ; Fluorescent Dyes ; pharmacology ; Humans ; Megakaryocytes ; drug effects ; physiology ; Organic Chemicals ; pharmacology ; Platelet-Derived Growth Factor ; pharmacology ; Thrombopoiesis ; Thrombopoietin ; pharmacology

This study was purposed to investigate the correlation between the dose infused megakaryocytic precursors (CD34+, CD34+CD61+) and recovery time of platelet count following an allogeneic PBSCT and/or BMT through quantitative detection of CD34+ and its subpopulation in peripheral blood and BM mobilized by G-CSF. 24 patients with various hematologic malignancies received PBSCT/BMT from their HLA matched or unrelated donors and haploidentical siblings in April-December 2007. 20 evaluated patients were divided into 2 groups according to different transplant schemes. HLA matched group received PBSCT regime and haploidentical group received PBSCT combined with BMT. CD34+CD61+ subpopulations in sample from patients receiving PBSCT/BMT were measured by flow cytometry immediately or storage over night. The results showed that the median number of infused CD34+, CD34+CD61+ and CD34-CD61+ cells in haploidentical group were 6.24x10(6)/kg (1.53-20.48), 66.19x10(4)/kg (8.16-493.83), and 34.38x10(6)/kg (14.71-109.16) respectively, in HLA matched group those were 4.88x10(6)/kg (1.00-8.24), 14.16x10(4)/kg (11.63-96.87), and 13.50x10(6)/kg (1.74-35.61), respectively. Median days of ANCs>0.5x10(9)/L and platelets>20x10(9)/L were 18.5 (11.0-29.0) days and 16.5 (9.0-35.0) days in haploidentical group respectively; in HLA matched group those were 14.5 (9.0-24.0) and 10.5 (6.0-37.0) respectively. A significance difference of median days for ANC engraftment presented between two groups (p=0.048). There was no significant difference of time for platelet engraftment between 2 groups. For patients with CD34+ cell dose>2x10(6)/kg there was significant difference of time of platelet engraftment between HLA matched and haploidentical groups (p=0.006). The number of CD34+CD61+ cells infused in 12 haploidentical patients or in 8 HLA matched patients were much better correlated with the time of platelet recovery up to 20x10(9)/L than that of number of CD34+ cells infused in total 20 patients (r=-0.768 and p=0.004 for haploidentical CD34+CD61+ cells, r=-0.747 and p=0.033 for HLA matched CD34+ CD61+ cells, r=-0.449 and p=0.047 for CD34+ cells). There was an inverse correlation between the number of infused CD34+ CD61+ cells and time of platelet engraftment. Therefore, as the number of CD34+ CD61+ cells increased, duration of platelet engraftment (time to reach platelet count of 20x10(9)/L) shortened significantly. It is concluded that the determining the number of megakaryocytic precursor by flow cytometry may predict the platelet reconstitutive capacity of the allogeneic hematopoietic stem cell transplantation, which is in haploidentical PBSCT and in BMT.
Antigens, CD34 ; immunology ; Bone Marrow Transplantation ; Female ; Flow Cytometry ; Graft Survival ; Haploidy ; Hematopoietic Stem Cell Transplantation ; Humans ; Male ; Megakaryocytes ; cytology ; immunology ; Platelet Count ; Thrombopoiesis ; Transplantation, Homologous

BACKGROUND: It has been known that the increase of reticulated platelets indicates the increase of thrombopoiesis in platelet consumptive diseases or the impending platelet recovery in patients with thrombocytopenic conditions. A new rapid automated method to assess reticulated platelets, the immature platelet fraction (IPF), was recently introduced. We evaluated the usefulness of the IPF for the prediction of platelet recovery in patients after hematopoietic stem cell transplantation (HSCT) and cytotoxic chemotherapy. METHODS: Thirty one healthy volunteers and 59 patients formed 3 groups: the allogenic HSCT group (n=23, an ABO major-mismatch 6 of 23), the autologous HSCT group (n=8) and the cytotoxic chemotherapy group (n=28). The platelet count, % of IPF and the % of reticulocytes were checked every day by using a Sysmex XE-2100. RESULTS: The IPF in the healthy volunteers was a mean of 2.2+/-1.6% (range: 0.3~6.7%), and the maximum level of the IPF in the patient group was 6.1+/-1.7% (range: 3.3~13.5%). The ideal cut-off value of the IPF increase to discriminate the platelet recovery group was 5.1%. When this cut-off value is used, the positive predictive value is 90.9% in the HSCT groups and 87.5% for the total patients. The 4 patients who showed an IPF higher than 5.1% without platelet recovery were in platelet consumptive conditions. It took 8.0+/-8.3 days to show platelet recovery after elevation of the IPF over 5.1% and an ABO major mismatch HSCT doesnt affect platelet recovery. CONCLUSION: The IPF is thought to be a useful parameter for the prediction of platelet recovery after HSCT and cytotoxic chemotherapy, but the problem of the patient' conditions affects the accuracy of the IPF, and the variable intervals between the increase of the IPF and platelet recovery is thought to be improved.
Blood Platelets* ; Drug Therapy ; Healthy Volunteers ; Hematopoietic Stem Cell Transplantation ; Humans ; Platelet Count ; Platelet Transfusion* ; Reticulocytes ; Thrombopoiesis

5-hydroxtryptamine (5-HT, serotonin) has been recognized not only as a neurotransmitter and vasoactive agent, but also as a growth factor. 5-HT mainly binds to 5-HT(2) receptors or 5-HT(1) receptors on cell surface to stimulate cell proliferation through Ras or MAPK pathway in many cell types. It has been reported that 5-HT stimulates megakaryocytopoiesis via 5-HT receptors. The possible mechanism of 5-HT on the proliferation and differentiation of megakaryocytes (MK) has been discussed in this review article. In early stage of megakaryocytopoiesis, 5-HT may bind to 5-HT(2B) receptor on megakaryocytes, and promotes their proliferation and differentiation. In the late stage, 5-HT may involve in the platelet release procedure by inducing nitric oxide (NO) synthesis via 5-HT(2A) receptors. 5-HT can also antagonize the apoptotic effect induced by thrombospondin-1 (TSP-1) which is a platelet alpha granule protein and has synergic effect with platelet-derived growth factor (PDGF) to enhance megakaryocytes proliferation. Therefore, 5-HT is likely to be an important substance in the feedback regulation of thrombopoiesis. In this review the 5-HT and its receptors, 5-HT as cell growth factor, pathway of 5-HT stimulating cell proliferation and influance of 5-HT on MK-progenitor cells were summarized.
Humans ; Megakaryocytes ; physiology ; Receptors, Serotonin ; metabolism ; Receptors, Serotonin, 5-HT2 ; metabolism ; Serotonin ; metabolism ; pharmacology ; Thrombopoiesis ; physiology ; Thrombopoietin ; physiology