scholarly journals PDGF/PDGFR May be Involved in the Physiopathologic Mechanism of Essential Thrombocythemia

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 5208-5208
Author(s):  
Li Xia Zhou ◽  
Jieyu Ye ◽  
En Yu Liang ◽  
Chunfu Li ◽  
Beng H Chong ◽  
...  

Abstract Our previous studies have demonstrated that PDGF (Platelet-derived growth factor) has a potential effect in the regulation of hematopoiesis and megakaryopoiesis (Yang et al, Thromb Haemastasis, 1997; Ye et al, Haematologica, 2010). Essential Thrombocythemia (ET) is characterized by persistently elevated platelet counts in the context of a normal red cell mass. However, the physiopathologic mechanism of ET is still under investigation. Here, we tested the bone marrow plasma levels of PDGF-BB in essential thrombocythemia patients (n=16) and normal control (n=8), and found an increased PDGF-BB levels in ET patients (2070.92±123.98 pg/ml), compared with normal control (1381.85±128.37pg/ml) (P=0.002). Furthermore, we have demonstrated the presence of functional PDGF receptors (PDGFR) in human megakaryocytes, and their ability to mediate a mitogenic response by bone marrow colony-forming unit-megakaryocyte (CFU-MK) formation assay (n=6). PDGF-BB stimulated in vitro megakaryopoiesis via PDGFR. It also showed a direct stimulatory effect of PDGF-BB on c-Fos expressions in megakaryocytic cells, CHRF. We speculate that these transcription factors might be involved in the signal transduction of PDGF on the regulation of megakaryopoiesis. PDGF also enhanced platelet recovery in mice model with radiation-induced thrombocytopenia. Studies showed that PDGF, like thrombopoietin (TPO), significantly promoted platelet recovery and the formation of bone marrow CFU-MK in this irradiated-mouse. An increased number of hematopoietic stem/progenitor cells and a reduction of apoptosis were found in the bone marrow histology sections. We also demonstrated that PDGF activated the p- Akt, p-Jak2 and p-Stat3 expression, while addition of imatinib mesylate reduced p-Akt, p-Jak2 and p-Stat3 expression in CHRF cells. Our findings suggested that the PDGF-initiated megakaryopoiesis is likely to be mediated via PDGF receptors with subsequent activation of the Akt and Jak2/ Stat3 pathways. These studies provide a possible explanation that PDGF/PDGFR may be involved in the physiopathologic mechanism of essential thrombocythemia. Disclosures Yang: National Natural Science Foundation of China(81270580): Research Funding.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3348-3348
Author(s):  
Mo Yang ◽  
Fanyi Meng ◽  
Jie yu Ye ◽  
Yue Xu ◽  
Bin Xiao ◽  
...  

Abstract Abstract 3348 Platelet-derived growth factor (PDGF), a platelet alpha-granule molecule, imply their potential effect in the regulation of megakaryocytopoiesis and thrombopoiesis, which also intimates the existence of an autocrine and/or paracrine loop constructed by megakaryocytes/platelets and their granular constituents. Our previous studies demonstrated the presence of functional PDGF receptors (PDGFR) on human megakaryocytes and platelets (Yang et al, Thromb Haemastasis, 1997) and CD34+ cells, and their ability to mediate a mitogenic response. PDGF promoted the ex vivo expansion of human hematopoietic stem (CD34+) and progenitor (CD41+ CD61+) cells. More significantly, PDGF enhanced the engraftment of human CD45+ cells and their myeloid subsets (CD33+, CD14+ cells) in NOD/SCID mice. PDGF stimulated in vitro megakaryocytopoiesis via PDGFR and/or the indirect effect on bone marrow microenvironment to produce TPO and other cytokines. It also showed a direct stimulatory effect of PDGF on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors might be involved in the signal transduction of PDGF on the regulation of megakaryocytopoiesis. PDGF also enhanced platelet recovery in mice model with radiation-induced thrombocytopenia. Studies showed that PDGF, like thrombopoietin (TPO), significantly promoted platelet recovery and the formation of bone marrow colony-forming unit-megakaryocyte (CFU-MK) in this irradiated-mouse. An increased number of hematopoietic stem/progenitor cells and a reduction of apoptosis were found in the bone marrow histology sections. In the M-07e apoptotic model, PDGF had a similar anti-apoptotic effect as TPO on megakaryocytes. We also demonstrated that PDGF activated the PI3k/Akt signaling pathway, while addition of imatinib mesylate reduced p-Akt expression. Our findings suggested that the PDGF-initiated radioprotective effect is likely to be mediated via PDGF receptors with subsequent activation of the PI3k/Akt pathway. The study provides a possible explanation that blockage of PDGFR may reduce thrombopoiesis and play a role in imatinib mesylate-induced thrombocytopenia in the treatment of CML. Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4217-4217
Author(s):  
Mo Yang ◽  
Liang Li ◽  
Yi Luo ◽  
Weiqing Su ◽  
Huimin Kong ◽  
...  

Abstract Background: Essential Thrombocythemia (ET) is characterized by persistently elevated platelet counts in the context of a normal red cell mass. However, the molecular mechanism of ET is still under investigation. Our previous studies demonstrated the presence of functional PDGF receptors (PDGFR) on megakaryocytes and their ability to mediate hematopoiesis and megakaryopoiesis (Ye et al, Haematologica, 2010). The role of PDGF-BB on megakaryocytic progenitors (CD41+, CD34+ cells) and its mechanisms on ET will be further studied in this project. Methods: ELISA, CFU assay, immunofluorescence microscope, flow cytometry and NOD/SCID mice were used in this study. Results: Bone marrow plasma levels of PDGF-BB in ET patients (n=18) and normal control (n=10) were tested and found an increased PDGF-BB levels in ET patients (2071.2±124.8 pg/ml), compared with normal control (1382.5±128.3pg/ml) (P=0.002). In vitro experiment, PDGF-BB promoted the ex vivo expansion of human hematopoietic stem (CD34 +) and progenitor (CD41 + CD61 +) cells. More significantly, PDGF enhanced the engraftment of human CD45 + cells and their myeloid subsets (CD33 +, CD14 + cells) in NOD/SCID mice. PDGF-BB stimulated megakaryopoiesis via PDGFR and its signalling. It also showed a direct stimulatory effect of PDGF-BB on c-Fos, GATA-1 and NF-E2 expressions in megakaryocytes. We speculate that these transcription factors might be involved in the signal transduction of PDGF-BB on the regulation of megakaryopoiesis. PDGF-BB also enhanced platelet recovery in mice model with radiation-induced thrombocytopenia. Studies showed that PDGF, like TPO, significantly promoted platelet recovery and the formation of CFU-MK in this irradiated-mouse. An increased number of hematopoietic stem/progenitor cells and a reduction of apoptosis were found in the bone marrow histology sections. In the CHRF apoptotic model, PDGF-BB had a similar anti-apoptotic effect as TPO on megakaryocytes. We also demonstrated that PDGF-BB activated the p -Akt , p-Jak2 and p-Stat3 expression, while addition of imatinib mesylate reduced p-Akt, p-Jak2 and p-Stat3 expression in CHRF cells. Conclusion: Our findings suggested that PDGF-BB is likely to be mediated via PDGF receptors with subsequent activation of the Akt and Jak2/ Stat3 pathways in megakaryopoiesis. These studies provide a possible explanation that PDGF-BB and its signaling may be involved in the molecular mechanism of essential thrombocythemia. Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 962-962
Author(s):  
Xiao Chai ◽  
Deguan Li ◽  
Mingfeng Zhao ◽  
Wenyi Lu ◽  
Juan Mu ◽  
...  

Abstract A substantial portion of patients with inherited blood disorders such as beta thalassemia, or bone marrow failure syndromes such as aplastic anemia(AA), myelodysplastic syndromes(MDS) require frequent transfusions of red blood cells. Frequent blood transfusions may lead to the excess of plasma non-transferrin -bound iron(NTBI) and iron overload occurs, which will significantly injure bone marrow (BM) function as well as induce organ dysfunctions such as liver cirrhosis, diabetes and cardiac diseases. However, the exact mechanism behind this effect remains elusive and ideal treatment needs to be explored. In our preliminary studies, we have demonstrated free iron catalyzes oxidative damage to hematopoietic cells/ mesenchymal stem cells in vitro and suppresses hematopoiesis in iron overload patients (Zhao et al.,blood, 2010 abstract; Lu et al.,blood,2012 abstract; Lu et al., Eur J Haematol, 2013). Here we observed the hematopoiesis inhibitory effects of iron overload on the basis of estabalished iron overload mice model and preliminarily disscussed the mechanism. In this study, we first established an iron overload mice model by administering different doses(12.5mg/ml,25mg/ml,50mg/ml) iron dextran by intraperitoneal injection every three days for four weeks. To confirm the efficacy of the mice model, the BM, hepatic and splenic iron deposits were observed by morphological study and the labile iron pool level (LIP) of bone marrow mononuclear cells(BMMNCs) was detected using the calcein-AM fluorescent dye. It was found that iron deposits in BM cells of iron overload mice, liver and spleen were markedly increased and the BMMNCs LIP level was much higher than that of normal control mice. The above results showed that the iron-overloaded mice model has been established successfully. Next we observed whether iron overload (25mg/ml) could affect the hematopoiesis of BM. The colony-forming cell assay was performed by culturing BMMNCs in MethoCult M3434 methylcellulose medium to evaluate hematopoietic progenitor cells(HPCs) proliferation function. The competitive repopulation assay and single-cell colony cultures of sorted hematopoietic stem cells (HSCs,CD34-Lin- sca1+c-kit+cells,LSK+)were used to validate HSCs function. The counts of BMMNCs have no significant difference. However, It was found that hematopoietic colony-forming unit (CFU-E, BFU-E, CFU-GM and CFU-mix) was much lower than that of normal control(P<0.05)(Fig.1). Notely, the number of LSK+ cells (*103/femur) was decreased significantly in iron overload mouse (26.43±3.28) compared with normal control(40.12±5.21) and the single-cell colony formation(/60wells) was reduced significantly in iron overload mouse(28.54±3.33) compared with normal control(47.93±4.82) (P<0.05). The long-term and multilineage engraftment capability of the iron-overloaded HSCs was weaken after transplantation. We then explored the possible mechanism of this inhibitory effects. Our previous studies have shown that iron overload could elevated reactive oxygen species (ROS) levels of mesenchymal stem cells and HSCs in vitro. Similarly, the intracellular ROS levels were analyzed by a flow cytometer. It was found that ROS level in iron overload BM was increased by 3.32 folds in erythroid cells, 1.51 folds in granulocytes and 4.80 folds in LSK+ cells,respectively. And also, the expression of p53, p38MAPK and p16Ink4a mRNA remained significantly elevated, which indicated that ROS related signal pathway was involved in the deficient hematopoiesis of iron overload BM. In addition, we also observed the effects of iron overload on the mice with deficient hematopoiesis exposed to 4Gy total body irradiation(TBI), which was more similar to clinical pathological conditions such as AA or MDS. It was found that BM damage caused by iron overload was aggravated in pathological conditions (primary findings were not shown). In conclusion, our study confirmed that iron overload injures the hematopoiesis of BM by enhancing oxidative stress in mice, which would be helpful to further study on the mechanism and would provide an experimental basis to find new therapeutic targets for the treatment of iron overload in patients with hematopoietic dysfunction.Figure 1Results of hematopoietic colony forming unit of different groups(*P<0.05)Figure 1. Results of hematopoietic colony forming unit of different groups(*P<0.05) Disclosures: No relevant conflicts of interest to declare.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2320-2320
Author(s):  
Silvia Giannini ◽  
Antonija Jurak Begonja ◽  
Max Adelmann ◽  
Karin M. Hoffmeister

Abstract Platelet recovery following myelosuppressive/myeloablative chemotherapy is crucial to avoid bleeding complications of cancer treatment. Platelets are produced by bone marrow megakaryocytes (MKs), which develop and mature from hematopoietic stem cells (HSC). Mature MKs interact with sinusoidal bone marrow endothelial cells to form transendothelial pseudopods called proplatelets from which platelets are released into the bloodstream. Platelet survival is dependent on correct glycan expression. We here investigate the role of Type-2-Lactosaminoglycans (Type-2-LacNAc) in platelet production. beta1,4Galactosyltransferase 1 (beta4GalT1) is a major enzyme involved in Type-2-LacNAc synthesis which adds Galactose (Gal) to terminal N-Acetylglucosamine (GlcNAc) to form beta1,4Gal-GlcNAc (Type-2-LacNAc).beta4GalT1 deficient mice die in uthero between E15.5 and E16.5. A small percentage of beta4GalT1-/- mice survive until adulthood and they have severe macrothrombocytopenia but normal platelet clearance. Lethally irradiated wild type mice transplanted with beta4GalT1 deficient fetal liver cells failed to produce circulating beta4GalT1 deficient platelets, in marked contrast to beta4GalT1 deficient white blood cells, despite beta4GalT1 deficient MKs have been detected in the bone marrow of transplanted mice. beta4GalT1 deficient fetal liver MKs poorly produce proplatelets in vitro, following their normal maturation and differentiation, as judged by number, morphology, ploidy and expression of main surface glycoproteins. Our data strongly support the notion that glycosylation mediated by beta4GalT1 is crucial for platelet production in vitro and in vivo and demonstrate for the first time a role for post-translational glycan modification in platelet production. Disclosures: No relevant conflicts of interest to declare.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marie-Theresa Weickert ◽  
Judith S. Hecker ◽  
Michèle C. Buck ◽  
Christina Schreck ◽  
Jennifer Rivière ◽  
...  

AbstractMyelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are clonal hematopoietic stem cell disorders with a poor prognosis, especially for elderly patients. Increasing evidence suggests that alterations in the non-hematopoietic microenvironment (bone marrow niche) can contribute to or initiate malignant transformation and promote disease progression. One of the key components of the bone marrow (BM) niche are BM stromal cells (BMSC) that give rise to osteoblasts and adipocytes. It has been shown that the balance between these two cell types plays an important role in the regulation of hematopoiesis. However, data on the number of BMSC and the regulation of their differentiation balance in the context of hematopoietic malignancies is scarce. We established a stringent flow cytometric protocol for the prospective isolation of a CD73+ CD105+ CD271+ BMSC subpopulation from uncultivated cryopreserved BM of MDS and AML patients as well as age-matched healthy donors. BMSC from MDS and AML patients showed a strongly reduced frequency of CFU-F (colony forming unit-fibroblast). Moreover, we found an altered phenotype and reduced replating efficiency upon passaging of BMSC from MDS and AML samples. Expression analysis of genes involved in adipo- and osteogenic differentiation as well as Wnt- and Notch-signalling pathways showed significantly reduced levels of DLK1, an early adipogenic cell fate inhibitor in MDS and AML BMSC. Matching this observation, functional analysis showed significantly increased in vitro adipogenic differentiation potential in BMSC from MDS and AML patients. Overall, our data show BMSC with a reduced CFU-F capacity, and an altered molecular and functional profile from MDS and AML patients in culture, indicating an increased adipogenic lineage potential that is likely to provide a disease-promoting microenvironment.


Blood ◽  
1997 ◽  
Vol 89 (11) ◽  
pp. 3919-3924 ◽  
Author(s):  
Jean C.Y. Wang ◽  
Monica Doedens ◽  
John E. Dick

Abstract We have previously reported the development of in vivo functional assays for primitive human hematopoietic cells based on their ability to repopulate the bone marrow (BM) of severe combined immunodeficient (SCID) and nonobese diabetic/SCID (NOD/SCID) mice following intravenous transplantation. Accumulated data from gene marking and cell purification experiments indicate that the engrafting cells (defined as SCID-repopulating cells or SRC) are biologically distinct from and more primitive than most cells that can be assayed in vitro. Here we demonstrate through limiting dilution analysis that the NOD/SCID xenotransplant model provides a quantitative assay for SRC. Using this assay, the frequency of SRC in cord blood (CB) was found to be 1 in 9.3 × 105 cells. This was significantly higher than the frequency of 1 SRC in 3.0 × 106 adult BM cells or 1 in 6.0 × 106 mobilized peripheral blood (PB) cells from normal donors. Mice transplanted with limiting numbers of SRC were engrafted with both lymphoid and multilineage myeloid human cells. This functional assay is currently the only available method for quantitative analysis of human hematopoietic cells with repopulating capacity. Both CB and mobilized PB are increasingly being used as alternative sources of hematopoietic stem cells in allogeneic transplantation. Thus, the findings reported here will have important clinical as well as biologic implications.


Author(s):  
Omika Katoch ◽  
Mrinalini Tiwari ◽  
Namita Kalra ◽  
Paban K. Agrawala

AbstractDiallyl sulphide (DAS), the pungent component of garlic, is known to have several medicinal properties and has recently been shown to have radiomitigative properties. The present study was performed to better understand its mode of action in rendering radiomitigation. Evaluation of the colonogenic ability of hematopoietic progenitor cells (HPCs) on methocult media, proliferation and differentiation of hematopoietic stem cells (HSCs), and transplantation of stem cells were performed. The supporting tissue of HSCs was also evaluated by examining the histology of bone marrow and in vitro colony-forming unit–fibroblast (CFU-F) count. Alterations in the levels of IL-5, IL-6 and COX-2 were studied as a function of radiation or DAS treatment. It was observed that an increase in proliferation and differentiation of hematopoietic stem and progenitor cells occurred by postirradiation DAS administration. It also resulted in increased circulating and bone marrow homing of transplanted stem cells. Enhancement in bone marrow cellularity, CFU-F count, and cytokine IL-5 level were also evident. All those actions of DAS that could possibly add to its radiomitigative potential and can be attributed to its HDAC inhibitory properties, as was observed by the reversal radiation induced increase in histone acetylation.


Blood ◽  
2007 ◽  
Vol 110 (7) ◽  
pp. 2276-2285 ◽  
Author(s):  
Maria De La Luz Sierra ◽  
Paola Gasperini ◽  
Peter J. McCormick ◽  
Jinfang Zhu ◽  
Giovanna Tosato

The mechanisms underlying granulocyte-colony stimulating factor (G-CSF)–induced mobilization of granulocytic lineage cells from the bone marrow to the peripheral blood remain elusive. We provide evidence that the transcriptional repressor growth factor independence-1 (Gfi-1) is involved in G-CSF–induced mobilization of granulocytic lineage cells from the bone marrow to the peripheral blood. We show that in vitro and in vivo G-CSF promotes expression of Gfi-1 and down-regulates expression of CXCR4, a chemokine receptor essential for the retention of hematopoietic stem cells and granulocytic cells in the bone marrow. Gfi-1 binds to DNA sequences upstream of the CXCR4 gene and represses CXCR4 expression in myeloid lineage cells. As a consequence, myeloid cell responses to the CXCR4 unique ligand SDF-1 are reduced. Thus, Gfi-1 not only regulates hematopoietic stem cell function and myeloid cell development but also probably promotes the release of granulocytic lineage cells from the bone marrow to the peripheral blood by reducing CXCR4 expression and function.


Pathogens ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 372 ◽  
Author(s):  
Jaishree Garhyan ◽  
Surender Mohan ◽  
Vinoth Rajendran ◽  
Rakesh Bhatnagar

One-third of the world’s population is estimated to be latently infected with Mycobacterium tuberculosis (Mtb). Recently, we found that dormant Mtb hides in bone marrow mesenchymal stem cells (BM-MSCs) post-chemotherapy in mice model and in clinical subjects. It is known that residual Mtb post-chemotherapy may be responsible for increased relapse rates. However, strategies for Mtb clearance post-chemotherapy are lacking. In this study, we engineered and formulated novel bone-homing PEGylated liposome nanoparticles (BTL-NPs) which actively targeted the bone microenvironment leading to Mtb clearance. Targeting of BM-resident Mtb was carried out through bone-homing liposomes tagged with alendronate (Ald). BTL characterization using TEM and DLS showed that the size of bone-homing isoniazid (INH) and rifampicin (RIF) BTLs were 100 ± 16.3 nm and 84 ± 18.4 nm, respectively, with the encapsulation efficiency of 69.5% ± 4.2% and 70.6% ± 4.7%. Further characterization of BTLs, displayed by sustained in vitro release patterns, increased in vivo tissue uptake and enhanced internalization of BTLs in RAW cells and CD271+BM-MSCs. The efficacy of isoniazid (INH)- and rifampicin (RIF)-loaded BTLs were shown using a mice model where the relapse rate of the tuberculosis was decreased significantly in targeted versus non-targeted groups. Our findings suggest that BTLs may play an important role in developing a clinical strategy for the clearance of dormant Mtb post-chemotherapy in BM cells.


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