Does Outcome/Survival of Patients With Myelodysplastic Syndromes Should Be Predicted by Reduced Levels of ADAMTS-13? Results From a Pilot Study.

INTRODUCTION: Von Willebrand factor (vWF) cleaving protease ADAMTS-13 has a key role for maintaining normal size of vWF. A deficiency or dysfunction of vWF cleaving protease is associated with ultra large vWF multimers and thrombotic microangiopathy. Patients with cancers have reduced levels of vWF cleaving protease. In this pilot study, we have evaluated whether or not deficiencies of ADAMTS-13 were present in myelodysplastic syndromes (MDS). Moreover, we assessed if a reduction in basal levels of ADAMTS-13 may play a role in the prognosis of MDS. PATIENTS AND METHODS: We measured and compared the levels of vWF cleaving protease ADAMTS-13 in 100 patients with MDS and 35 healthy controls. Patients were divided into 2 groups according to the International Prognostic Scoring System: group I consisting of 44 patients with low-risk MDS and group II of 56 patients with high-risk MDS. Patients with high-risk and low-risk MDS presented significantly lower levels of ADAMTS-13 than controls (P < .001 and P = .0177, respectively). High-risk patients had significantly lower levels of ADAMTS-13 when compared with the low-risk group (P < .001). RESULTS: We found that reduced levels of ADAMTS-13 have a relationship with overall survival (P < .001). Statistical analysis showed that ADAMTS-13 correlates with cytogenetics (P < .001) and a tendency of slight correlation with platelet count and basal levels of ADAMTS-13 (R, 0.35; P value, 0.001). Moreover, we found that levels of ADAMTS-13 have correlation with response to treatment (P < .001). CONCLUSIONS: ADAMTS-13 in MDS might represent a surrogate marker of prognosis, response to therapy, or disease progression. Further studies are needed.

Management of anemia in low-risk myelodysplastic syndromes treated with erythropoiesis-stimulating agents newer and older agents.

The myelodysplastic syndromes (MDSs) are clonal hematopoietic stem cell disorders. The International Prognostic Score System (IPSS) groups MDS in lower-risk (IPSS low and intermediate-1) and higher-risk disease (IPSS intermediate-2 and high). AML transformation is the main concern in higher-risk MDS, while anemia and transfusion dependency represent the major issues for low-risk MDS patients. Improving erythropoiesis, and eliminating fatigue and symptoms, is the main therapeutic goal for low-risk MDS patients. Around 50% of MDS patients present with anemia with an Hb level < 100 g/L. Severe anemia increases the negative effects of comorbidities, such as heart and lung failure. Erythropoiesis-stimulating agents (ESAs), with or without granulocyte colony-stimulating factor, induce erythroid response rates in 40-50% of lower-risk anemic MDS patients. The median response duration of 24 months. Apoptosis of erythroid cells is inhibited by ESAs leading to erythrocyte production. Our paper considers the state of the art of treatment of anemia in low-risk MDS patients and the treatment options in MDS resistant or refractory to ESAs.

The impact of anaemia, transfusion dependency, comorbidities and polypharmacy in elderly patients with low-risk myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are heterogeneous clonal disorders ranging from indolent conditions with a near-normal life expectancy to forms approaching acute myeloid leukaemia. Comorbid conditions have rarely been systematically studied among patients with MDS. Older age per se has a negative impact on survival of MDS patients, in particular of those with lower risk. However, age indirectly affects also the survival of higher-risk patients by limiting their eligibility to intensive treatments. In addition, ageing is associated with an increasingly high risk of developing comorbidity, and a high prevalence of comorbid diseases has indeed been reported in MDS patients. The impact of multi-morbidities/comorbidities and polypharmacy in patients with low-risk MDS patients is a poorly explored topic. We focused on medications, multi-morbidities and comorbidities of 155 low-risk MDS patients followed in the haematological outpatients clinics or in medical/oncology wards of our University Hospital. One or more comorbidities were present at diagnosis in 24 younger patients with MDS syndromes (31%), whereas 56 older patients with MDS (75%) presented 1 or more comorbidities (P < 0.001).The most frequent comorbidity was cardiac comorbidity 18% in younger patients and 25% in older patients. With no statistical significance between older and younger patients, congestive heart failure was the most frequent observed disease. Our study has shown a statistical correlation between transfusion dependency and polypathology (P = 0.0014). These data were also confirmed in a subanalysis of the younger group of patients. Our study has shown that comorbidity is very common among patients with MDS, potentially affecting the clinical course and outcome of MDS patients.

High prevalence of heparin induced thrombocytopenia with thrombosis among patients with essential thrombocytemia carrying V617F mutation.

Arterial and venous complications are major causes of morbidity and mortality in myeloproliferative neoplasms (MPNs). MPNs patients, frequently receive heparin. Heparin-induced thrombocytopenia (HIT) is a rare but potentially life-threatening complication resulting in a severe acquired thrombophilic condition. We carried out a retrospective analysis to evaluate occurrence of new thrombotic events during heparin therapy in essential thrombocythemia (ET) patients. We studied 108 ET patients on heparin for treatment of previous thrombotic events or in thromboprophilaxis. Fifty-eight of them carried JAK 2 V617F mutation while 50 patients were without V617F mutation. Ten patients, among those with JAK 2 V617F mutation after a median of 10 days from heparin treatment presented a platelet drop, new thrombotic events and in 10/10 cases heparin-related antibodies were found. In the other group, two patients (4%) presented a platelet drop, thrombotic manifestations and heparin related antibodies. Our data show that HIT is more frequent, during heparin treatment, in patients with ET carrying V617F mutation, as compared with patients without mutations (P = 0.029). ET with V617F mutation seems to be associated with higher risk of thrombotic complications during heparin treatment. Monitoring platelet counts very closely during the course of heparin is essential especially in ET patients in which platelet drop may be hidden by constitutional thrombocytosis.

First-line treatment with bendamustine and rituximab, in patients with intermediate-/high-risk splenic marginal zone lymphomas.

Splenic marginal zone lymphomas (SMZLs) are rare indolent B cell neoplasms that affect the spleen, bone marrow, and blood. Although they have an indolent course in the majority of patients, who have a median survival of 8-10 years, ∼ 30% may experience a worse outcome. The prognostic criteria of progression are lymph node and extra-nodal involvement, high lymphocyte counts, anaemia, and thrombocytopenia. The treatment of SMZLs include a "wait and watch strategy", splenectomy, and alkylating agents ± rituximab. We here describe data relating to 70 patients with intermediate-/high-risk SMZLs, who received rituximab/bendamustine as first-line treatment for a median of 60 days (range 1-75) after diagnosis. Sixty patients (86%) achieved a complete response (CR), and seven (10%) a partial response (PR). Three patients (4.3%) experienced disease progression (PD). The median duration of remission was 18 months. Side effects were generally mild. Our findings suggest that rituximab/bendamustine is a feasible treatment option in patients with intermediate-/high-risk SMZLs.

Dose-Reduced Versus Standard Conditioning Followed by Allogeneic Stem-Cell Transplantation for Patients With Myelodysplastic Syndrome: A Prospective Randomized Phase III Study of the EBMT (RICMAC Trial).

Purpose To compare a reduced-intensity conditioning regimen (RIC) with a myeloablative conditioning regimen (MAC) before allogeneic transplantation in patients with myelodysplastic syndrome (MDS) within a randomized trial. Patients and Methods Within the European Society of Blood and Marrow Transplantation, we conducted a prospective, multicenter, open-label, randomized phase III trial that compared a busulfan-based RIC with MAC in patients with MDS or secondary acute myeloid leukemia. A total of 129 patients were enrolled from 18 centers. Patients were randomly assigned in a 1:1 ratio and were stratified according to donor, age, and blast count. Results Engraftment was comparable between both groups. The CI of acute graft-versus-host disease II to IV was 32.3% after RIC and 37.5% after MAC ( P = .35). The CI of chronic graft-versus-host disease was 61.6% after RIC and 64.7% after MAC ( P = .76). The CI of nonrelapse mortality after 1 year was 17% (95% CI, 8% to 26%) after RIC and 25% (95% CI, 15% to 36%) after MAC ( P = .29). The CI of relapse at 2 years was 17% (95% CI, 8% to 26%) after RIC and 15% (95% CI, 6% to 24%) after MAC ( P = .6), which resulted in a 2-year relapse-free survival and overall survival of 62% (95% CI, 50% to 74%) and 76% (95% CI, 66% to 87%), respectively, after RIC, and 58% (95% CI, 46% to 71%) and 63% (95% CI, 51% to 75%), respectively, after MAC ( P = .58 and P = .08, respectively). Conclusion This prospective, randomized trial of the European Society of Blood and Marrow Transplantation provides evidence that RIC resulted in at least a 2-year relapse-free survival and overall survival similar to MAC in patients with MDS or secondary acute myeloid leukemia.

Bendamustine and Rituximab, as First Line Treatment, in Intermediate, High Risk Splenic Marginal Zone Lymphomas of Elderly Patients.

BACKGROUND: Splenic marginal zone lymphoma (SMZL) is a chronic B-cell lymphoproliferative disorder, comprising less than 2% of non-Hodgkin's lymphomas, and affecting mainly middle-aged and elderly patients with a median survival of >10 years. The typical clinical features of SMZL include splenomegaly. Treatment should be patient-tailored and can range from a 'watchful waiting' approach for asymptomatic patients without cytopenias to surgery, localized radiation therapy or immuno/chemotherapies. Recently, the combination of rituximab and Bendamustine (R-Benda) has been defined as highly active in patients with follicular lymphomas, but little is known about the efficacy of R-Benda in SMZL. AIM OF THE STUDY: The purpose of this retrospective study was to report our experience on the efficacy of R-Benda as first line treatment in 23 consecutive elderly SMZL patients. RESULTS: All patients had a complete resolution of splenomegaly along with restoration of their blood counts. Nineteen patients (83%) achieved a complete response (CR) to therapy; three patients (13%) achieved a partial response (PR).Ten patients (43%) obtained molecular remission. Toxicities were mild and mainly haematological and result in dose reductions for fourteen patients. CONCLUSIONS: Our data suggest a high activity and good tolerance of R-Benda, despite dose reduction due to potential toxicity.

Laboratory and clinical risk assessment to treat myelodysplatic syndromes.

Myelodisplastic syndromes (MDS) are heterogeneous myeloid disorders characterized by peripheral cytopenias and increased risk of transformation into acute myelogenous leukemia (AML). MDS are generally suspected in the presence of cytopenia on routine analysis and the evaluation of bone marrow cells morphology and cellularity leads to correct diagnosis of MDS. The incidence of MDS is approximately five cases per 100,000 people per year in the general population, but it increases up to 50 cases per 100,000 people per year after 60 years of age. Typically MDS affect the elderly, with a median age at diagnosis of 65-70 years. Here the current therapeutic approaches for MDS are evaluated by searching the PubMed database. Establishing the prognosis in MDS patients is a key element of therapy. In fact an accurate estimate of prognosis drives decisions about the choice and timing of the therapeutic options. Therapy is selected based on prognostic risk assessment, cytogenetic pattern, transfusion needs and biological characteristics of the disease, comorbidities and clinical condition of the patients. In lower-risk patients the goals of therapy are different from those in higher-risk patients. In lower-risk patients, the aim of therapy is to reduce transfusion needs and transformation to higher risk disease or AML, improving the quality of life and survival. In higher-risk patients, the main goal of therapy is to prolong survival and to reduce the risk of AML transformation. Current therapies include growth factor support, lenalidomide, immunomodulatory and hypomethylating agents, intensive chemotherapy, and allogenic stem cell transplantation. The challenge when dealing with MDS patients is to select the optimal treatment by balancing efficacy and toxicity.

Biosimilar epoetin in elderly patients with low-risk myelodysplastic syndromes improves anemia, quality of life, and brain function.

The myelodysplastic syndromes (MDS) are a group of clonal hematopoietic disorders characterized by bone marrow failure and a risk of progression to acute myeloid leukemia (AML). Anemia affects the course of disease, quality of life (QOL), and cognitive function of MDS patients. Erythroid-stimulating agents (ESAs) are effective; however, not all patients respond to ESAs. To evaluate the effectiveness of a biosimilar epoetin α (Binocrit) for the treatment of anemia in low-/intermediate-1 risk MDS patients and to evaluate the impact of ESAs on QOL and on cognitive function, 24 consecutive patients aged over 65 years were treated with Binocrit at 40,000 IU once a week for 12 weeks and were followed for at least 3 months. Responsive patients continued with 40,000 IU once a week for a further 12 weeks. Changes in QOL were assessed by the Functional Assessment of Cancer Therapy-Anemia (FACT-An), while cognitive assessment was carried out by mini-mental state examination (MMSE). All patients completed 12 weeks of therapy. Sixteen patients (66.67 %) achieved an erythroid response (ER), 15 patients (62.5 %) became transfusion independent and remained free from transfusion requirement for at least 3 months, while two patients had reduction in transfusion requirement of at least four RBC transfusions/8 weeks compared with the pretreatment transfusion requirement. Seven patients were nonresponders (29.1 %), of whom four patients were low risk and three intermediate-I risk. Seven transfusion-independent patients were low risk, and eight were intermediate-1 risk. Median hemoglobin (Hb) values were significantly higher after treatment in responders (p < 0.001). ER was maintained after 24 weeks. Statistically significant positive correlations between improvement in Hb and variations in patients' mini-mental (Spearman's Rho = 0.54, p < 0.01) and FACT-An scores (Spearman's Rho = 0.59, p < 0.003) were demonstrated. This preliminary study shows that Binocrit is promising for the treatment of anemia of MDS patients. ER positively correlates with improvements in patients' cognitive status and positive changes in QOL.

Single-agent Smac-mimetic compounds induce apoptosis in B chronic lymphocytic leukaemia (B-CLL).

Defective apoptosis is a hallmark of the progression of B chronic lymphocytic leukaemia (B-CLL). Smac-mimetics have been shown to induce apoptosis in several tumours. We describe the in vitro pro-apoptotic activity and regulation of the molecular pathway induced by new Smac-mimetics in B-CLL. The cytotoxic effect was significantly higher in B-CLL samples than in healthy controls. No significant synergistic effect was observed in combined treatment. In conclusion one of our compounds (Smac66), used as monotherapy and not in combination, is highly active against B-CLL cells thus suggesting a promising therapeutic potential as a new class of antileukemic drugs in haematology.

Metabolic syndrome in patients with hematological diseases.

The term metabolic syndrome (MS) defines a clustering of cardiovascular risk factors, formerly known as syndrome X. There is some debate about the diagnostic criteria; but the most widely accepted framework is that defined by the National Cholesterol Education Program Adult Treatment Panel III, which requires the simultaneous occurrence of at least three of abdominal obesity, arterial hypertension, hyperglycemia, hypertrigliceridemia and low high-density lipoprotein cholesterol (HDL-C). The prevalence of MS increases with age and varies depending on genetic factors. An abnormally high prevalence has been observed in patients with heterogeneous conditions, such as solid organ transplant recipients, AIDS patients and long-term cancer survivors. As some of the pathogenetic factors possibly involved include cyclosporine A, corticosteroids and cancer chemoradiotherapy, it is possible that MS may also be a complication in hematological patients. Some of the characteristics of MS have been reported with a certain frequency in thalassemia patients, and are mainly attributed to iron overload. Impaired hemostasis is a feature of MS rather than a factor predisposing to its development. In oncohematology, an abnormally high prevalence of MS features has been observed in survivors of pediatric acute lymphoblastic leukemia. In addition to corticosteroid- and cancer therapy-related hypogonadism, hypothyroidism and defective growth hormone incretion are other factors related to the development of MS. Moreover, the highest frequency of MS is observed in hematopoietic stem cell transplantation (HSCT) recipients. Pediatric patients and allogeneic HSCT recipients have been the subject of foremost investigations; but adult patients and autologous HSCT recipients have also been studied more recently. A wide range of factors may contribute to the development of MS in HSCT recipients. Unfortunately, the real entity of the problem is far from clear because of the retrospective design of the studies, the limited size of their populations and their heterogeneous selection criteria, thus making it difficult to determine whether MS is a transient and possibly reversible phenomenon or a true late effect of the procedure.

Neuroprotective effects of human mesenchymal stem cells on neural cultures exposed to 6-hydroxydopamine: implications for reparative therapy in Parkinson's disease.

Stem cell (SC) transplantation represents a promising tool to treat neurodegenerative disorders, such as Parkinson's disease (PD), but positive therapeutic outcomes require elucidation of the biological mechanisms involved. Therefore, we investigated human Mesenchymal SCs (hMSCs) ability to protect murine differentiated Neural SCs (mdNSCs) against the cytotoxic effects of 6-hydroxydopamine (6-OHDA) in a co-culture model mimicking the in vivo neurovascular niche. The internalization of 6-OHDA mainly relies on its uptake by the dopamine active transporter (DAT), but its toxicity could also involve other pathways. We demonstrated that mdNSCs consistently expressed DAT along the differentiative process. Exposure to 6-OHDA did not affect hMSCs, but induced DAT-independent apoptosis in mdNSCs with generation of reactive oxygen species and caspases 3/7 activation. The potential neuroprotective action of hMSCs on mdNSCs exposed to 6-OHDA was tested in different co-culture conditions, in which hMSCs were added to mdNSCs prior to, simultaneously, or after 6-OHDA treatment. In the presence of the neurotoxin, the majority of mdNSCs acquired an apoptotic phenotype, while co-cultures with hMSCs significantly increased their survival (up to 70%) in all conditions. Multiplex human angiogenic array analysis on the conditioned media demonstrated that cytokine release by hMSCs was finely modulated. Moreover, sole growth factor addition yielded a similar neuroprotective effect on mdNSCs. In conclusion, our findings demonstrate that hMSCs protect mdNSCs against 6-OHDA neurotoxicity, and rescue cells from ongoing neurodegeneration likely through the release of multiple cytokines. Our findings provide novel insights for the development of therapeutic strategies designed to counteract the neurodegenerative processes of PD.

Immunomodulatory effects of unselected haematopoietic stem cells autotransplantation in refractory Crohn's disease.

BACKGROUND: Autologous haematopoietic stem cells transplantation (HSCT) has been shown to be effective in refractory Crohn's disease. AIM: We analysed the effects of HSCT on the immune response of patients treated for moderate-severe Crohn's disease, refractory or intolerant to multiple drugs. METHODS: Unselected peripheral blood stem cells were collected after mobilisation with cyclophosphamide (CTX) and G-CSF. The conditioning regimen included CTX and rabbit antithymocyte globulin. Blood samples for immunological analyses were collected at baseline, after mobilisation, and 3, 6 and 12 months after transplantation. Immunological analyses evaluated: (1) CD4(+)/CD25(high+)/FoxP3(+) regulatory T cells (T-regs); (2) Toll-like receptor 2-(TLR2) and TRL4-expressing monocytes (CD14(+) cells); (3) IL-12, IL-10, TNF-alpha-production by mitogen-stimulated CD14(+) cells and IFN-gamma production by CD4(+) T cells. Immunological results were compared with healthy donors and associated with clinical and endoscopic response during 12 months of follow-up. RESULTS: Overall, T-regs increased, whilst TLR4-expressing cells, as well as TNF-alpha and IL-10, all higher than healthy donors at baseline, significantly decreased after transplantation. Full responders at T(3) had higher T-regs and lower IFN-gamma and IL12. T-regs decreased and IL12 and TLR2 increased in the only relapsed patient. CONCLUSIONS: HSCT can induce and maintain clinical and endoscopic remission in refractory Crohn's disease, which is associated with immunomodulation.

Health-related quality of life in chronic myeloid leukemia patients receiving long-term therapy with imatinib compared with the general population.

The main objective of this study was to investigate whether patients with chronic myeloid leukemia (CML) in treatment with long-term therapy imatinib have a different health-related quality-of-life (HRQOL) profile compared with the general population. In total, 448 CML patients were enrolled, and the SF-36 Health Survey was used to compare generic HRQOL profiles. Symptoms were also assessed. HRQOL comparisons were adjusted for key possible confounders. The median age of patients was 57 years and the median time of imatinib treatment was 5 years (range 3-9 years). The largest HRQOL differences were found in younger patients. In particular, patients aged between 18 and 39 years had marked impairments in role limitations because of physical and emotional problems, respectively: -22.6 (P < .001), -22.3 (P < .001). Patients with CML age 60 or older had a HRQOL profile very similar to that reported by the general population. Women had a worse profile than men when each were compared with their peers in the general population. Fatigue was the most frequently reported symptom. The HRQOL of CML patients is comparable with that of population norms in many areas, however, younger and female patients seem to report the major limitations.

Myocardial blood flow and infarct size after CD133+ cell injection in large myocardial infarction with good recanalization and poor reperfusion: results from a randomized controlled trial.

OBJECTIVE: Large acute ST-elevation myocardial infarction (STEMI) sometimes leaves extensive ischemic damage despite timely and successful primary angioplasty. This clinical picture of good recanalization with incomplete reperfusion represents a good model to assess the reparative potential of locally administered cell therapy. Thus, we conducted a randomized controlled trial aimed at evaluating the effect of intracoronary administration of CD133 stem cells on myocardial blood flow and function in this setting. METHODS: Fifteen patients with large anterior STEMI, myocardial blush grade 0-1 and more than 50% ST-elevation recovery after optimal coronary recanalization (TIMI 3 flow) with stenting were randomly assigned to receive CD133 cells from either bone marrow (group A) or peripheral blood (group B), or to stay on drug therapy alone (group C). The cells were intracoronary injected within 10-14 days of STEMI. Infarct-related myocardial blood flow (MBF) was evaluated by NH positron emission tomography 2-5 days before cell administration and after 1 year. RESULTS: MBF increased in the infarct area from 0.419 (0.390-0.623) to 0.544 (0.371-0.729) ml/min per g in group A, decreased from 0.547 (0.505-0.683) to 0.295 (0.237-0.472) ml/min per g in group B and only slightly changed from 0.554 (0.413-0.662) to 0.491 (0.453-0.717) ml/min per g in group C (A vs. C: P = 0.023; B vs. C: P = 0.066). Left ventricular volume tended to increase more in groups B and C than in group A, ejection fraction and wall motion score index remained stable in the three groups. CONCLUSION: These findings support the hypothesis that intracoronary administration of bone marrow-derived, but not peripheral blood-derived CD133 cells 10-14 days after STEMI may improve long-term perfusion.

Dioxin exposure of human CD34+ hemopoietic cells induces gene expression modulation that recapitulates its in vivo clinical and biological effects.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) has a large number of biological effects, including skin, cardiovascular, neurologic diseases, diabetes, infertility, cancers and immunotoxicity. We analysed the in vitro TCDD effects on human CD34+ cells and tested the gene expression modulation by means of microarray analyses before and after TCDD exposure. We identified 257 differentially modulated probe sets, identifying 221 well characterized genes. A large part of these resulted associated to cell adhesion and/or angiogenesis and to transcription regulation. Synaptic transmission and visual perception functions, with the particular involvement of the GABAergic pathway were also significantly modulated. Numerous transcripts involved in cell cycle or cell proliferation, immune response, signal transduction, ion channel activity or calcium ion binding, tissue development and differentiation, female or male fertility or in several metabolic pathways were also affected after dioxin exposure. The transcriptional profile induced by TCDD treatment on human CD34+ cells strikingly reproduces the clinical and biological effects observed in individuals exposed to dioxin and in biological experimental systems. Our data support a role of dioxin in the neoplastic transformation of hemopoietic stem cells and in immune modulation processes after in vivo exposure, as indicated by the epidemiologic data in dioxin accidentally exposed populations, providing a molecular basis for it. In addition, TCDD alters genes associated to glucidic and lipidic metabolisms, to GABAergic transmission or involved in male and female fertility, thus providing a possible explanation of the diabetogenic, dyslipidemic, neurologic and fertility effects induced by TCDD in vivo exposure.

Increased expression of vascular endothelial growth factor receptor 1 correlates with VEGF and microvessel density in Philadelphia chromosome-negative myeloproliferative neoplasms.

AIMS: The authors investigated vascular endothelial growth factor receptor 1 (VEGFR-1) protein expression in a series of Philadelphia chromosome-negative myeloproliferative neoplasms (Ph- MPNs) and its correlations with microvessel density (MVD) and vascular endothelial growth factor (VEGF). METHODS: 83 bone marrow biopsies of Ph- MPNs patients, including 27 essential thrombocythaemia (ET), 21 polycythaemia vera (PV) and 35 primary myelofibrosis (PMF), and 10 normal controls (NCs) were investigated by immunohistochemistry. RESULTS: Patients with PV and PMF showed an increased MVD (PV: 20.1±10.6; PMF: 25.8±6.5) compared with those with ET or NCs (ET: 10.4±4.6; NCs: 7±3.4). VEGFR-1 expression was increased in Ph- MPNs, particularly in PV and PMF (NCs: 0.07±0.03; ET: 0.15±0.09; PV: 0.31±0.2; PMF: 0.31±0.04). VEGF expression parallelled VEGFR-1 and resulted increased in Ph- MPNs (NCs: 0.08±0.04; ET: 0.13±0.06; PV: 0.29±0.2; PMF: 0.31±0.15) and higher in post-polycythaemic myelofibrosis and in the fibrotic stage of PMF than in the non-fibrotic phases of both diseases. VEGFR-1 protein expression correlated with MVD and VEGF expression in Ph- MPNs. VEGFR-1 and VEGF were expressed by the same bone marrow populations: megakaryocytes, macrophages and immature myeloid precursors showed a moderate to strong immunostaining intensity in both Ph- MPNs and NCs. The erythroid precursors were not immunoreactive. CONCLUSIONS: VEGFR-1 and VEGF were increased and co-localised in megakaryocytes, macrophages and myeloid precursors of Ph- MPNs. This finding supports the hypothesis of a VEGF/VEGFR-1 autocrine loop in the neoplastic cells of Ph- MPNs.