ALBERT

Description: Abstract 5049 Introduction: New blood vessel formation (angiogenesis) is a multistep process that involves extracellular matrix remodeling, endothelial cell migration and proliferation, capillary differentiation and anastomosis formation. Angiogenesis has a key role in tumor growth and spread. Vascular endothelial growth factor (VEGF) is a positive regulatory cytokine and has a key, rate-limiting dose in promoting tumor angiogenesis. Abnormal VEGF expression has been described in acute leukemias as well as lymphomas. The available data in chronic myeloproliferative neoplasms (MPN) suggests that microvascular density (MVD) and VEGF expression are involved in angiogenesis process. Aim: The aim of this study was to evaluate MVD, VEGF expression and its correlation with clinical parameters. Material and Methods: The study was performed according to the regulation of the Ethics comitee. We included 41 patients with newly diagnosed MPN and 6 controls [28 PV, 23 PMF, 6 secondary eryhtrocytosis] from 2006 through 2009. G-band karyotype, FISH analysis (chromosomes 5, 7, 8 and 20) and JAK2V617F mutation were done according to standard techniques. Two experienced pathologists assessed morphology on hematoxylin-eosin stained slides, bone marrow fibrosis on Gomori silver slides and fibrosis was determined according to Thiele criteria (Thiele et al 2005). Bone marrow MVD was visualized in paraffin tissue sections using CD34 immunohistochemical staining and classified using a score system 0–4. Immunoexpression of VEGF was done in bone marrow core biopsies. A VEGF score was based on VEGF-positive megakaryocytes vs VEGF-immunohistochemistry staining. Statistical analysis was done using Chi-square test. Results: Most of PV patients had a low MVD (grade 0+1) (73%), whereas the majority of PMF patients had high MVD (grade 2+4) (76 %). MVD score was higher in PMF than PV (median grade 3 vs 1, respectively p=0.8). There were no differences in MVD score (both PV and PMF) according to JAK2V617F mutation status (respectively p=0.79 and p=0.8). Interestingly, PV and PMF patients with high MVD presented high platelet count (315 vs 694 × 109/L in PV, 664 vs 985 ×109/L in PMF); and a high incidence of thrombosis (18.1 vs 50% in PV p=0.9; and 0 vs 26.3% in PMF). VEGF score was higher in PV than PMF (median score 3 vs 2 p=0.22). Thus, PV and PMF patients with low MVD presented a higher rate of abnormal karyotype than high MVD patients (18% vs 0 in PV; 33 vs 10,5% in PMF p=0.0002). We combined data and analyzed together PV and PMF patients who presented low MVD and high MVD. High MVD patients (n=23) were older than low MVD group (68 vs 59 p=0.77), had low hemoglobin value (12.5 vs 18.5g/dL p=0.10), presented high platelet count (738 vs 351 × 109/L) and had a high incidence of thrombosis (30.4 vs 15.3% p=0.98) but there was no difference in VEGF score (median score 3 p=0.39). There was a correlation of high MVD and advanced fibrosis in (r=0.54 Pearson test). Low and high MVD patients had similar JAK2V617F rate mutation (61.5 vs 60.8%, p=0.4) and low MVD patients presented a slightly higher incidence of abnormal cytogenetic findings (31 vs 6.6%). There was no correlation with MVD and VEGF score (r=0.34), age (r=0.17), platelet count (r=0.27). There were no differences in VEGF score according to JAK2V617F mutation status. There was a correlation between VEGF score (grade 2+3) and the occurrence of massive splenomegaly in PV patients (r=0.52 Pearson test). PV patients who presented advanced fibrosis had a high platelet compared to mild fibrosis (567 vs 1031× × 109/L). There were no changes in platetet count regarding to fibrosis degree in PMF. Discussion and Conclusions: According to our results we found increase of platetet count and thrombosis in patients with high MVD. VEGF score did not relate to MVD findings neither thrombosis. The occurrence of high MVD correlated with high platelet count and thrombosis, suggest that MVD mechanisms may determine clonal changes and influence platelet differentiation and survival. Probably other biological interactions such as abnormal signaling network in bone marrow may play a role in determining MVD changes in MPN. This question remains to be further validated and investigated in other studies. Our current data show that stromal abnormalities were correlated with thrombosis and raise the question of the evolutive changes in the hematopoietic stem cell leading to abnormal changes in bone marrow during the course of the disease. Disclosures: No relevant conflicts of interest to declare.

Description: Background: Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are involved in tumor neoangiogenesis which plays an important role in hematological neoplasias progression and prognosis. Myelofibrosis (MF) and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPNs) resulting from acquired hematopoietic stem cell mutations. Most patients share the JAK2V617F mutation and may exhibit substantial overlap. The molecular mechanisms involved in MPNs pathogenesis are not completely elucidated. In this context, evaluation of genes and proteins related with angiogenesis could be useful to better understand MPN pathobiology. Aims: To investigate the mRNA and protein expressions of MMPs and TIMPs and their relationship with plasma markers of angiogenesis (VEGFA and FGF2) and JAK2V617F mutation status in MF and ET patients. Methods: Forty-three MPNs patients (MF=29 and ET=14) and 36 control subjects were studied. The controls were matched with patients according to age and gender. MPN diagnosis was defined according to the 2008 WHO criteria. The MMP2, MMP9, TIMP1 and TIMP2 mRNA expression from peripheral leukocytes and serum proteins levels were measured by real time PCR and Luminex technology. VEGFA and FGF2 concentration were measured in plasma from MPN patients and controls. JAK2V617F mutation status and allele burden and MPL W515K/L analysis were performed in total leukocytes DNA by real time PCR, using Taqman MGB probes. Results: Higher MMP2, MMP9 and TIMP1 mRNA expression were observed in MF patients compared to controls (P

Description: Background: Myelofibrosis (MF) and essential thrombocythemia (ET) are clonal hematopoietic stem cell malignancies classified as myeloproliferative neoplasms (MPNs). FGF2 and TGF-β were associated with pathophysiology and progression of these diseases. Although FGF2 and TGF-β roles in angiogenesis and fibrosis are known, their mRNA expression in leukocytes of MPNs patients was not yet evaluated. Furthermore, the detailed mechanism of TGF-β signaling in the pathophysiology of these diseases remains unclear. In regular signaling process, Smads are a group of proteins critical for transmitting signals from TGF-β superfamily of the cell surface to the nucleus. Thus, Smads signaling plays an important role in the regulation of hematopoiesis and it could modulate TGF-β action in MPNs. Aims: The aim of this study was to investigate if there are differences in mRNA expression of FGF2, TGFB1 and SMADS 1 to 7 in MPNs patients and healthy controls and if it is related to JAK2 mutation status and allele burden. Methods: Fifteen primary myelofibrosis (PMF), 15 myelofibrosis post essential thrombocytemia (MPET), and 22 essential trombocythemia (ET) patients diagnosed according to the World Health Organization criteria (2008) were selected from the Hematology Department of the Federal University of de Sao Paulo and from the Hematology Division of the Catholic University of Sao Paulo. Other group with healthy subjects was also included. The control group was matched by age and gender with MPNs patients: 30 for PMF, 17 for MPET, and 34 for ET. Expressions of FGF2, TGFB1 and SMADs 1 to 7 mRNA were evaluated in total leukocytes by Real Time PCR, using Taqman assays. JAK2V617F mutation status and allele burden and MPL W515K/L analysis were performed in total leukocytes DNA by Real Time PCR, using Taqman MGB probes. Results: No difference was found between frequencies of JAK2V617F mutated subjects (P=0.520) and in allele burden percentage (P=0.415) in MPNs groups. Allele burden was also not associated with mRNA levels of studied genes in each group of MPNs, and none of the patients presented MPL W515K/L mutations. MF and ET patients had higher TGFB1 and FGF2 mRNA levels than its controls (P