Stimulation of megakaryocytopoiesis and thrombopoiesis by the c-Mpl ligand

Sauvage, Frédéric J. de; Hass, Philip E.; Spencer, Susan D.; Malloy, B; Gurney, Austin; Spencer, Steven A.; Darbonne, Walter C.; Henzel, William J.; Wong, Suzy C.; Kuang, Wun-Jing; Oles, Karl J.; Hultgren, Bruce; Solberg, Lawrence A.; Goeddel, David V.; Eaton, Dan

doi:10.1038/369533a0

Cited by 1,293 publications

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“…14,16 However, the CFU-MK assay has yielded variable results, in part, because best growth is obtained with a combination of growth stimulators, colony size can be quite small, and colony identification can present problems to the inexperienced observer. 25 In the present study, we used TPO and SCF as growth factors for CFU-MK; these produce more and larger colonies than previous methods, [18][19][20][21] and these CFU-MK characteristics were inversely correlated with the time to platelet recovery (r = Ϫ0.55). Although colony assays are reliable with TPO, the method is laborious and requires 2 weeks to obtain results, making it generally unsuitable for use as a routine method in a clinical laboratory.…”

Section: Discussionmentioning

confidence: 89%

“…13,14,16,17 Thrombopoietin (TPO), the ligand for the c-mpl receptor, has been shown to stimulate the growth of megakaryocyte colonies in vitro. [18][19][20] The number and size of CFU-MK induced by TPO was greater than that induced by any other combination of growth factors, suggesting that TPO may be useful for assaying CFU-MK. 21 Based on these observations, we analyzed the expression of different platelet glycoproteins on CD34 + cells by flow cytometry and the number of TPO-induced CFU-MK in PBSC grafts.…”

Section: Discussionmentioning

confidence: 97%

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CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation

Feng

Shimazaki

Inaba

et al. 1998

Bone Marrow Transplant

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Summary:Reliable markers for megakaryocytic reconstitution after peripheral blood stem cell transplantation (PBSCT) have not been established. To determine a convenient and reliable predictor, we measured the number of megakaryocyte progenitor cells in PBSC grafts by clonogenic and flow cytometric assays. Seventeen patients with hematological and solid malignancies were included in this study. For the clonogenic assay, we used thrombopoietin (TPO) as a growth factor to evaluate the maximum number of megakaryocyte progenitor cells. Using a flow cytometric assay, we examined the expression of platelet glycoproteins on CD34 + cells to count the number of megakaryocyte progenitor cells. We used buffer containing EDTA to prevent platelet adhesion to CD34 + cells and selected CD34 + cells by immunomagnetic beads. The best correlation was observed between the number of CD34 + /CD41a + cells and the time to platelet recovery (P = 0.0205), rather than the total number of CD34 + cells. In addition, a close correlation was observed between the number of CD34 + /CD41a + cells and colony-forming unit megakaryocyte (CFU-MK) (P = 0.0018). These observations suggest that the number of CD34 + /CD41a + cells is the best predictor for platelet reconstitution after PBSCT. Keywords: PBSCT; platelet recovery; CD34; CFU-MK; thrombopoietinAutologous peripheral blood stem cell transplantation (PBSCT) has been increasingly used following high-dose chemotherapy with or without total body irradiation (TBI) for patients with hematologic or nonhematologic malignancies. 1,2 Chemotherapy and/or hematopoietic growth factors have been used to mobilize stem and progenitor cells into blood for transplantation. [3][4][5][6] However, the minimum number of stem cells for engraftment has not been fully elucidated, and the factors which predict the tempo of hematopoietic recovery are also undefined. Several reports have shown a correlation between the number of colony-forming unit granulocyte-macrophage (CFU-GM) and CD34 + cells Correspondence: Dr C Shimazaki, Second Department of Medicine, Kyoto Prefectural University of Medicine, 465 Kawaramachi-Hirokoji, Kamigyoku, Kyoto, 602, Japan Received 22 November 1997; accepted 27 January 1998 and the time to granulocyte recovery. 7-9 As for platelet recovery, few studies have been reported; some have shown that the number of CFU-GM and CD34 + cells correlate with platelet recovery, 7-14 but others have not shown a significant correlation. 15,16 Recently, specific markers for megakaryocyte progenitors such as colony-forming unit megakaryocyte (CFU-MK) and CD34 + /CD41 + or CD34 + /CD61 + cells have predicted platelet engraftment in PBSCT. 13,14,16,17 Thrombopoietin (TPO), the ligand for the c-mpl receptor, has been shown to stimulate the growth of megakaryocyte colonies in vitro. [18][19][20] The number and size of CFU-MK induced by TPO was greater than that induced by any other combination of growth factors, suggesting that TPO may be useful for assaying CFU-MK. 21 Based on these observations, we analyzed th...

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Section: Discussionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 97%

CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation

Feng

Shimazaki

Inaba

et al. 1998

Bone Marrow Transplant

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“…Recently, several groups [2][3][4][5] cloned the ligand for the c-Mpl proto-oncogene [6] which is a member of the cytokine receptor superfamily. These studies and others have demonstrated that c-Mpl ligand plays a critical role in megakaryocytopoiesis and thrombopoiesis both in vitro and in vivo [2][3][4][5][7][8][9][10]. Therefore, c-Mpl ligand has been termed thrombopoietin (TPO) [3,7,8] or megakaryocyte growth and development factor (MGDF) [4].…”

Section: Introductionmentioning

confidence: 99%

Thrombopoietin, c‐Mpl ligand, induces tyrosine phosphorylation of Tyk2, JAK2, and STAT3, and enhances agonists‐induced aggregation in platelets in vitro

1995

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We investigated in vitro effects of recombinant human thrombopoietin (TPO), or c-Mpl ligand, on human platelets. TPO induced rapid dose-dependent tyrosine phosphorylation of several proteins. We identified Janus tyrosine kinases, Tyk2 and JAK2, and a member of STAT (signal transducers and activators of transcription) family, STAT3, as the tyrosine-phosphorylated proteins in response to TPO. TPO by itself did not cause platelet aggregation and shape change, but augmented ADP-indnced aggregation in a dose-dependent manner. Acetyisalicylic acid inhibited the secondary aggregation enhanced by TPO, but not the TPO-induced potentiation of the primary aggregation. TPO modulates platelet activation possibly through protein-tyrosine phosphorylation.

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“…[1][2][3] The recently defined ligand for the Mpl receptor, thrombopoietin (TPO), has been found to be the principal regulatory cytokine of megakaryocytopoiesis and thrombopoiesis. [4][5][6][7][8] It appears that TPO is able not only to induce differentiation of megakaryocytic precursors, but also to expand early megakaryocytic progenitors. 9,10 TPO also directly affects more primitive hematopoietic cells, not yet committed towards the megakaryocytic lineage.…”

Section: Introductionmentioning

confidence: 99%

True

1999

Leukemia

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The recently defined ligand for the Mpl receptor, thrombopoietin (TPO), has been found to be the principal regulatory cytokine of megakaryocytopoiesis. Furthermore, it has been hypothesized that direct interaction between stroma or stromaderived extracellular matrix (ECM) and human progenitor cells (HPC) may modulate megakaryocytopoiesis. For that purpose, we studied megakaryocytic development of HPC, obtained from patients with hematological malignancies in complete remission or solid tumors without bone marrow involvement, under the influence of megakaryocyte growth and development factor (MGDF, a pegylated, truncated molecule related to the endogenous Mpl ligand). The megakaryocytic development of HPC cultured in contact with a stromal layer (contact cultures) was compared with cultures in which HPC were grown separated from a stromal layer by a microporous membrane (noncontact cultures). A significantly lower number of megakaryocytes (CD41-and CD61-positive cells) was obtained from contact cultures compared to non-contact cultures. Furthermore, the expression of CD42b was higher in non-contact cultures, as compared to contact cultures, indicating an increase in megakaryocyte maturation in non-contact cultures. In contrast, no difference in clonogenic capacity was observed (CFU-GM, BFU-E, CFU-Mk). The possibility that direct contact between HPC and stroma induces the production of a soluble inhibitory cytokine as an explanation for the diminished megakaryocytic development in contact cultures, was excluded by performing transwell experiments in which HPC were cultured in direct contact and in a transwell simultaneously. The percentage of megakaryocytes raised from HPC present in the transwell did not decrease, irrespective of the presence of HPC simultaneous below the transwell in direct contact with stroma. It is concluded that both megakaryocytic development out of HPC and megakaryocytic differentiation is reduced in contact cultures, as compared to non-contact cultures. This is due to modulation by adhesive interactions with stroma, stromaderived ECM or cytokines bound to the membrane of stromal cells, rather than resulting from the production of diffusible cytokines by stromal cells.

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Stimulation of megakaryocytopoiesis and thrombopoiesis by the c-Mpl ligand

Cited by 1,293 publications

References 40 publications

CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation

CD34+/CD41a+ cells best predict platelet recovery after autologous peripheral blood stem cell transplantation

Thrombopoietin, c‐Mpl ligand, induces tyrosine phosphorylation of Tyk2, JAK2, and STAT3, and enhances agonists‐induced aggregation in platelets in vitro

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