Thrombopoietin (TPO) can activate hematopoietic cell proliferation by its receptor c-MPL mediated downstream pathways and induce the generation of megakaryocyte. In recent years, domestic and foreign researches have confirmed that TPO/ c-MPL pathway also plays an important role in the self-renewal and quiescence of leukemia stem cell, and its expression in acute myeloid leukemia (AML) also indicates the chemotherapy resistance and poor prognosis. In this article, the research progress of the roles of TPO/c-MPL pathway in chemotherapy resistance, prognosis of AML patients, and the application of TPO/ c-MPL receptor agonists in AML were summarized briefly.
Humans ; Leukemia, Myeloid, Acute ; Neoplasm Proteins ; Proto-Oncogene Proteins/metabolism* ; Receptors, Cytokine ; Receptors, Thrombopoietin ; Signal Transduction ; Thrombopoietin

Thrombopoietin (TPO) is a major cytokine for megakaryocytopoiesis and thrombopoiesis, and also plays an important role in the regulation of early hematopoiesis. TPO activates a number of signal pathways to exert its biological function by binding to its receptor (c-mpl). Once these signal pathways (including Jak/STAT, PI3K/Akt, Ras/MAPK) are activated, the expression of the downstream signal molecules can be changed, which then induces biological effects. Recent researches have suggested the novel functions of TPO in many systems. The receptor of TPO (c-mpl) has been shown not only present in hematological cells, but also in many other cells and organs, such as neurons, heart muscle cells, vessel endothelial cells and so on. TPO exerts a protective effect on these cells through the interaction with c-mpl. This review discusses the molecular mechanism of TPO signal and the effect of TPO on multi-nonhematopoietic cells.
Animals ; Humans ; Myocytes, Cardiac ; Neurons ; Signal Transduction ; genetics ; Thrombopoietin ; genetics ; metabolism

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

OBJECTIVE: To investigate the effect and relative mechanism of Recombinant Human Thrombopoietin (rhTPO) on long-term hematopoietic recovery in mice with acute radiation sickness. METHODS: Mice were intramuscularly injected with rhTPO (100 μg/kg) 2 hours after total body irradiation with ⁶⁰Co γ-rays (6.5 Gy). Moreover, six months after irradiation, peripheral blood, hematopoietic stem cells (HSC) ratio, competitive transplantation survival rate and chimerization rate, senescence rate of c-kit⁺ HSC, and p16 and p38 mRNA expression of c-kit⁺ HSC were detected. RESULTS: Six months after 6.5 Gy γ-ray irradiation, there were no differences in peripheral blood white blood cells, red blood cells, platelets, neutrophils and bone marrow nucleated cells in normal group, irradiated group and rhTPO group (P>0.05). The proportion of hematopoietic stem cells and multipotent progenitor cells in mice of irradiated group was significantly decreased after irradiation (P<0.05), but there was no significant changes in rhTPO group (P>0.05). The counts of CFU-MK and BFU-E in irradiated group were significantly lower than that in normal group, and rhTPO group was higher than that of the irradiated group(P<0.05). The 70 day survival rate of recipient mice in normal group and rhTPO group was 100%, and all mice died in irradiation group. The senescence positive rates of c-kit⁺ HSC in normal group, irradiation group and rhTPO group were 6.11%, 9.54% and 6.01%, respectively (P<0.01). Compared with the normal group, the p16 and p38 mRNA expression of c-kit⁺ HSC in the irradiated mice were significantly increased (P<0.01), and it was markedly decreased after rhTPO administration (P<0.01). CONCLUSION The hematopoietic function of mice is still decreased 6 months after 6.5 Gy γ-ray irradiation, suggesting that there may be long-term damage. High-dose administration of rhTPO in the treatment of acute radiation sickness can reduce the senescence of HSC through p38-p16 pathway and improve the long-term damage of hematopoietic function in mice with acute radiation sickness.
Humans ; Mice ; Animals ; Thrombopoietin/metabolism* ; Hematopoietic Stem Cells ; Blood Platelets ; Recombinant Proteins/therapeutic use* ; Radiation Injuries ; RNA, Messenger/metabolism*

The objective of this study was to investigate the expressions of TPO receptor (c-mpl) proteins on CD34 positive bone marrow cells (CD34+ BMCs), platelets and the expression of c-mpl mRNA in bone marrow cells of the patients with polycythemia vera (PV). The expressions of c-mpl proteins on CD34+ bone marrow hematopoietic cells of 13 PV patients and 15 normal controls were assessed by bicolor flow cytometry and the expressions of c-mpl proteins on platelets of 15 PV patients and 15 normal controls were assessed by monocolor flow cytometry, and the expressions of c-mpl mRNA in bone marrow hematopoietic cells (BMHCs) were assessed by RT-PCR. The results showed that no difference was found between the expression of c-mpl proteins on CD34+ BMHCs of PV patients (0.99% +/- 0.14%) and that of normal controls (0.92% +/- 0.12%) (p > 0.05). There was no difference too between the expression of c-mpl protein on platelets in PV patients (20.33% +/- 4.84%) and that in normal controls (23.50% +/- 3.64%) (p > 0.05). No difference between the expression of c-mpl mRNA in BMHCs of PV patients and that in normal controls was seen. In conclusion, the expressions of c-mpl proteins on CD34+ BMHCs, platelets and c-mpl mRNA in BMHCs of PV patients were not obviously abnormal.
Antigens, CD34 ; analysis ; Blood Platelets ; metabolism ; Bone Marrow Cells ; metabolism ; pathology ; Hematopoietic Stem Cells ; metabolism ; pathology ; Humans ; Polycythemia Vera ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Receptors, Thrombopoietin ; metabolism

This study was aimed to investigate the expression of c-MPL in acute myeloid leukemia (AML) and the correlation of the c-MPL expression with CD34 and CD38, so as to define the expression of c-MPL in leukemic stem cells. The expression levels of CD34, CD38 and c-MPL were detected by flow cytometry in bone marrow cells from 29 newly diagnosed AML patients. The relationship of c-MPL positive cell ratio with clinical parameters and correlation of c-MPL with CD34 and CD38 expression in AML patients were analyzed. The results showed that expression level of c-MPL in AML patients was significantly higher than that of normal controls (P < 0.05), and the expression level of c-MPL did not correlate with age, sex, white blood cell count, AML1-ETO fusion gene and remission after chemotherapy, but the expression of c-MPL in M2 and M5 patients was higher than that of normal control (P < 0.05). Expression of c-MPL in CD34 positive AML patients was obviously higher than that in CD34 negative AML patients (P < 0.01). c-MPL was significantly higher expressed in CD34(+) cells than that in CD34(-) cells (P < 0.001), while c-MPL expression was not significantly different between CD34(+)CD38(-) and CD34(+)CD38(-) cell groups. Positive correlation between c-MPL and CD34 expression was observed (r = 0.380, P = 0.042). It is concluded that expression of c-MPL is higher in AML patients, and positively correlates with the expression level of CD34. The c-MPL expresses in leukemic stem cells.
Adolescent ; Adult ; Aged ; Case-Control Studies ; Child ; Female ; Humans ; Leukemia, Myeloid, Acute ; metabolism ; pathology ; Male ; Middle Aged ; Neoplastic Stem Cells ; metabolism ; Receptors, Thrombopoietin ; metabolism ; Young Adult

OBJECTIVEIn order to investigate whether or not thrombopoietin (TPO) could promote the fibrogenesis of bone marrow stromal cells in absence of megakaryocytes (MKs).

METHODSImproved dexter culture system with various TPO concentrations was used for ex vivo culture of bone marrow stromal cells. Relative proliferation index, the expressions of fibronectin, laminin and type IV collagen, and the systhesis of type III procollagen were detected at different time points during culture process.

RESULTSTPO stimulated the proliferation of bone marrow stromal cells. Relative proliferation index of the stromal cells increased with the TPO concentration increasing, and was not related to the exposure time. The expressions of fibronectin, laminin, and type IV collagen appeared stronger in the TPO groups than those in the control group. But the expressions of these molecules were not dependent upon the culture time. TPO could accelerate the synthesis of type III procollagen in bone marrow stromal cells, and this acceleration was unrelated to the TPO concentration.

CONCLUSIONThese findings suggested that TPO could stimulate the stromal cells with a consequence of increased syntheses and secretions of the extracellular matrix and collagen in absence of MKs. In other words, TPO could promote the fibrogenesis of bone marrow stromal cells without the existence of MKs.

Cells, Cultured ; Collagen Type III ; metabolism ; Collagen Type IV ; metabolism ; Extracellular Matrix ; metabolism ; Fibronectins ; metabolism ; Fibrosis ; pathology ; Humans ; Laminin ; metabolism ; Megakaryocytes ; cytology ; Mesenchymal Stromal Cells ; cytology ; metabolism ; pathology ; Thrombopoietin ; pharmacology

This study was aimed to assess the effect of Astragalus Polysaccharide (ASPS) on in-vitro hematopoiesis. CFU-GM assays were used to determine the effect of ASPS and thrombopoietin (TPO) on granulocytic-monocyte progenitor cells. The CFU assays were also used to investigate the effect of ASPS on the proliferation of HL-60 cells.HL-60 cells were cultured with serum-free RPMI 1640 medium and treated with or without of different concentrations of ASPS. After 72 h incubation, the number of cells were counted.In addition, the caspase-3 and JC-1 expression was determined by flow cytometry with Annexin V/PI double staining. The results showed that ASPS (100, 200 µg/ml) and TPO (100 ng/ml) significantly promoted CFU-GM formation in vitro. Various concentrations of ASPS and TPO also promoted the colony formation of HL-60 cells, the largest effect of ASPS was observed at a concentration of 100 µg/ml. There were no synergistic effects between TPO and ASPS on cellular proliferation. The results also showed that ASPS significantly protected HL-60 cells from apoptosis in condition of serum-free medium culture, suppressed caspase 3 activation, and reduced the cell apoptosis. It is concluded that ASPS can significantly promote the formation of bone marrow CFU-GM and the proliferation of HL-60 cells, the optimal concentration of ASPS is at 100 µg/ml. In the absence of serum inducing apoptosis, ASPS also significantly reduced the apoptosis of HL-60 cells via suppressing the activation of caspase-3.
Apoptosis ; drug effects ; Astragalus Plant ; Caspase 3 ; metabolism ; Cell Proliferation ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; HL-60 Cells ; Hematopoiesis ; drug effects ; Humans ; Polysaccharides ; pharmacology ; Thrombopoietin ; pharmacology

OBJECTIVETo study the expressions of erythropoietin receptor (EPOR) and thrombopoietin receptor (TPOR) on CD34+ CD59- and CD34+ CD59+ bone marrow (BM) cells from patients with paroxysmal nocturnal hemoglobinuria (PNH).

METHODS(1) The expressions of EPOR and TPOR on CD34+ CD59- and CD34+ CD59- BM cells from 26 PNH patients and 16 normal controls were examined by flow cytometry (FCM). (2) The mRNA expression of the EPOR and the TPOR in BM mononuclear cells (BMMNC) from 25 PNH patients and 13 normal controls were examined by RT-PCR.

RESULTS(1) The percentage of EPOR positive cells in PNH CD34+ CD59+ BMMNC [(30.67 +/- 18.30)%] was significantly higher than that in PNH CD34+ CD59- BMMNC [(8.05 +/- 3.51)%] (P < 0.01) and than that in control CD34+ CD59+ BMMNC [(8.24 +/- 6.51)%] (P < 0.01), but there was no obvious difference between the CD34+ CD59-BMMNC in PNH and CD34+ CD59+ BMMNC in control. (2) The percentage of TPOR positive cells in PNH CD34+ CD59+ BMMNC [(28.15 +/- 17.75)%] was significantly higher than that in PNH CD34+ CD59-BMMNC [(15.65 +/- 14.45)%] (P < 0.05) and than that in control CD34+ CD59+ BMMNC [(10.77 +/- .39)%] (P < 0.01), but there was no obvious difference between the CD34+ CD59- BMMNC in PNH and CD34+ CD59+ BMMNC in control. (3) There was no statistic difference in EPOR mRNA and TPOR mRNA expressions in BMMNCs between PNH patients group [(0.41 +/- 0.37) and (0.32 +/- 0.19), respectively] and control group [(0.47 +/- 0.33) and (0.40 +/- 0.29), respectively].

CONCLUSIONThe expression of EPOR and TPOR of PNH patients on BM CD34+ CD59+ cells are significantly higher than those on BM CD34+ CD59- cells. The difference may be due to abnormal transcription of both receptor coding genes.

Adult ; Bone Marrow Cells ; metabolism ; CD59 Antigens ; metabolism ; Case-Control Studies ; Cells, Cultured ; Female ; Flow Cytometry ; Hemoglobinuria, Paroxysmal ; metabolism ; Humans ; Male ; Middle Aged ; Receptors, Erythropoietin ; metabolism ; Receptors, Thrombopoietin ; metabolism ; Young Adult

The aim of this study was to investigate the role of mesenchymal stem cells in the hematopoietic reconstitution of patients who had received haploidentical allogeneic hematopoietic stem cell transplantation (hi-allo-HSCT). 15 patients who underwent treatment with both MSCs and HSCs, were selected as study group, while 20 patients receiving only HSCT were taken as control. Bone marrow samples were obtained from iliac crest aspirates at several times after HSCT for the isolation, purification and expansion of MSCs. The confluent ratio and time were measured and compared with those of the control. The peripheral blood samples were obtained from patients, then absolute neutrophil and platelet counts were assayed. From day 4 before transplantation to day 28 after transplantation, serum was obtained every four days from patients of the two groups, and then 3 cytokines as SDF-1alpha, TPO and IL-11 were detected by ELISA. The results indicated that as compared with the control group, the ratio of primary confluent layer formation of MSCs in study group was obviously higher (27.3%) (p < 0.01), and the confluence time in culture was significantly less (p < 0.05). In the study group, the concentration of SDF-1alpha amounted to peak value (2975.19 +/- 681.56 pg/ml) on the 8th day after HSCT, which was obviously higher than that before HSCT (2403.70 +/- 522.39 pg/ml, p < 0.05), whereas in the control, the concentration of highest point of SDF-1alpha reached to peak valve (2280.60 +/- 701.25 pg/ml) on the 16th day after HSCT, which was less than that before HSCT (2701.46 +/- 483.21 pg/ml, p < 0.05). The concentration of TPO and IL-11 was higher in study group compared with the control from day 16 to 28 after HSCT (p < 0.05). It is concluded that the transfusion of MSCs combined with hi-all-HSCT may improve the injured state of the hematopoietic microenvironment in bone marrow of patients during allo-HSCT.
Adolescent ; Adult ; Bone Marrow ; metabolism ; pathology ; Chemokine CXCL12 ; metabolism ; Child ; Hematopoietic Stem Cell Transplantation ; methods ; Hematopoietic System ; Humans ; Interleukin-11 ; metabolism ; Mesenchymal Stem Cell Transplantation ; methods ; Middle Aged ; Thrombopoietin ; metabolism ; Young Adult