Angiogenesis in chronic myeloproliferative diseases detected by CD34 expression

Revisiting Circulating Extracellular Matrix Fragments as Disease Markers in Myelofibrosis and Related Neoplasms

Philadelphia chromosome-negative chronic myeloproliferative neoplasms (MPNs) arise due to acquired somatic driver mutations in stem cells and develop over 10-30 years from the earliest cancer stages (essential thrombocythemia, polycythemia vera) towards the advanced myelofibrosis stage with bone marrow failure. The JAK2V617F mutation is the most prevalent driver mutation. Chronic inflammation is considered to be a major pathogenetic player, both as a trigger of MPN development and as a driver of disease progression. Chronic inflammation in MPNs is characterized by persistent connective tissue remodeling, which leads to organ dysfunction and ultimately, organ failure, due to excessive accumulation of extracellular matrix (ECM). Considering that MPNs are acquired clonal stem cell diseases developing in an inflammatory microenvironment in which the hematopoietic cell populations are progressively replaced by stromal proliferation-"a wound that never heals"-we herein aim to provide a comprehensive review of previous promising research in the field of circulating ECM fragments in the diagnosis, treatment and monitoring of MPNs. We address the rationales and highlight new perspectives for the use of circulating ECM protein fragments as biologically plausible, noninvasive disease markers in the management of MPNs.

Systematic dissection of coordinated stromal remodeling identifies Sox10+ glial cells as a therapeutic target in myelofibrosis

Remodeling of the tissue niche is often evident in diseases, yet, the stromal alterations and their contribution to pathogenesis are poorly characterized. Bone marrow fibrosis is a maladaptive feature of primary myelofibrosis (PMF). We performed lineage tracing and found that most collagen-expressing myofibroblasts were derived from leptin-receptor-positive (LepR+) mesenchymal cells, whereas a minority were from Gli1-lineage cells. Deletion of Gli1 did not impact PMF. Unbiased single-cell RNA sequencing (scRNA-seq) confirmed that virtually all myofibroblasts originated from LepR-lineage cells, with reduced expression of hematopoietic niche factors and increased expression of fibrogenic factors. Concurrently, endothelial cells upregulated arteriolar-signature genes. Pericytes and Sox10+ glial cells expanded drastically with heightened cell-cell signaling, suggesting important functional roles in PMF. Chemical or genetic ablation of bone marrow glial cells ameliorated fibrosis and improved other pathology in PMF. Thus, PMF involves complex remodeling of the bone marrow microenvironment, and glial cells represent a promising therapeutic target.

Expression of CD markers in JAK2V617F positive myeloproliferative neoplasms: Prognostic significance

Myeloproliferative neoplasms (MPNs) are clonal stem cell disorders characterized by the presence of JAK2^V617F mutation. Thrombohemorrhagic as well as autoimmune or inflammatory phenomena are common clinical outcomes of these disorders. Recent studies have shown that abnormality in frequency and function of blood cells manifested by an alteration in CD markers' expression patterns play a key role in these complications. So, there may be a relationship between CD markers' expressions and prognosis of JAK2^V617F positive MPNs. Therefore, in this review, we have focused on these abnormalities from the perspective of changing expressions of CD markers and assessment of the relationship between these changes with prognosis of JAK2^V617F positive MPNs. It can be stated that the abnormal expression of a large number of CD markers can be used as a prognostic biomarker for clinical outcomes including thrombohememorrhagic events, as well as autoimmune and leukemic transformation in JAK2^V617F positive MPNs. Considering the possible role of CD markers' expressions in JAK2^V617F MPNs prognosis, further studies are needed to confirm the relationship between the expression of CD markers with prognosis to be able to find an appropriate therapeutic approach via targeting CD markers.

Increased Dkk-1 plasma levels may discriminate disease subtypes in myeloproliferative neoplasms

Alterations in the bone marrow niche induced by abnormal production of cytokines and other soluble factors have been associated with disease progression in classical BCR-ABL1 negative myeloproliferative neoplasms (MPN). Variations in circulating proteins might reflect local disease processes and plasma proteome profiling could serve to identify possible diagnostic and prognostic biomarkers. We employed a human cytokine array to screen for 105 distinct analytes in pooled plasma samples obtained from untreated young MPN patients (<35 years) with different clinical phenotypes and driver mutations, as well as from healthy individuals. Among molecules that exhibited significantly increased levels in MPN patients versus controls, the top of the list was represented by Dickkopf-related protein 1 (Dkk-1), which also showed the highest potential for discrimination between MPN subtypes. In the next step, a quantitative ELISA was used to measure plasma Dkk-1 levels in 30 young-onset MPN-10 essential thrombocythemia (ET), 10 polycythemia vera (PV), 10 pre-fibrotic primary myelofibrosis (pre-PMF)-and 10 controls. The results suggested that plasma Dkk-1 levels could differentiate ET from pre-PMF, in JAK2 V617F-positive as well as in CALR-positive patients, and also ET from PV in JAK2 V617F-positive patients.

Bone marrow microvessel density and plasma angiogenic factors in myeloproliferative neoplasms: clinicopathological and molecular correlations

Increased angiogenesis in BCR-ABL1 negative myeloproliferative neoplasms (MPNs) has been recognized, but its connection with clinical and molecular markers needs to be defined. The aims of study were to (1) assess bone marrow (BM) angiogenesis measured by microvessel density (MVD) using CD34 and CD105 antibodies; (2) analyze correlation of MVD with plasma angiogenic factors including vascular endothelial growth factor, basic fibroblast growth factor, and interleukin-8; (3) examine the association of MVD with clinicopathological and molecular markers. We examined 90 de novo MPN patients (30 polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET)) and 10 age-matched controls. MVD was analyzed by immunohistochemistry "hot spot" method, angiogenic factors by immunoassay and JAK2V617F, and CALR mutations by DNA sequencing and allelic PCR. MVD was significantly increased in MPNs compared to controls (PMF > PV > ET). Correlation between MVD and plasma angiogenic factors was found in MPNs. MVD was significantly increased in patients with JAK2V617F mutation and correlated with JAK2 mutant allele burden (CD34-MVD: ρ = 0.491, p < 0.001; CD105-MVD: ρ = 0.276, p = 0.02) but not with CALR mutation. MVD correlated with leukocyte count, serum lactate dehydrogenase, hepatomegaly, and splenomegaly. BM fibrosis was significantly associated with CD34-MVD, CD105-MVD, interleukin-8, and JAK2 mutant allele burden. JAK2 homozygote status had positive predictive value (100%) for BM fibrosis. Patients with prefibrotic PMF had significantly higher MVD than patients with ET, and we could recommend MVD to be additional histopathological marker to distinguish these two entities. This study also highlights the strong correlation of MVD with plasma angiogenic factors, JAK2 mutant allele burden, and BM fibrosis in MPNs.

Nuclear factor-erythroid 2, nerve growth factor receptor, and CD34-microvessel density are differentially expressed in primary myelofibrosis, polycythemia vera, and essential thrombocythemia

Because of the presence of various overlapping findings, the discrimination of polycythemia vera (PV) from prefibrotic/fibrotic primary myelofibrosis (PF/F-PMF) and essential thrombocythemia (ET) may be challenging, particularly in suboptimal bone marrow biopsy specimens. In this study, we assessed whether differences in the expression of nuclear factor-erythroid 2 (NF-E2), nerve growth factor receptor (NGFR; CD271), CD34, CD68, p53, CD3, CD20, and CD138 by immunohistochemistry could be useful in separating among them. Higher frequencies of nuclear positive erythroblasts with NF-E2 were observed in ET and PV cases (50% ± 13.3% and 41.5% ± 9.4%, respectively) when compared with both PF-PMF (21% ± 11.7%) and F-PMF (28.5% ± 10.8%). We found that with a cutoff level of at least 30% nuclear staining for NF-E2 in erythroblasts, we could reliably exclude the possibility of PMF. Conversely, NGFR+ stromal cells per high-power field (HPF) was significantly increased in F-PMF (53.5 ± 19.1/HPF) and PF-PMF (13.5 ± 3.8/HPF) compared with ET (4.4 ± 2.2/HPF) and PV (6.6 ± 3.3/HPF). Similarly, differences in CD34-microvessel density was remarkable in F-PMF and PF-PMF cases in comparison with PV and ET (49.9 ± 12.1/HPF, 29.3 ± 12.4/HPF, 13.7 ± 4.6/HPF, and 11.9 ± 5.1/HPF, respectively). Thus, the assessment of NF-E2 and NGFR expression and the evaluation of CD34-microvessel density may provide additional support in reaching a correct diagnosis in these cases of myeloproliferative neoplasms.

Increased angiogenesis in primary myelofibrosis: latent transforming growth factor-β as a possible angiogenic factor

Objective

The aim of this work was to demonstrate a possible relationship between anti-latency-associated peptide human latent transforming growth factor beta 1 (latent TGF-β1) expression in megakaryocytes and microvascular density in bone marrow biopsies from patients with essential thrombocythemia and primary myelofibrosis.

Methods

Microvascular density was evaluated by immunohistochemical analysis and the expression of latent TGF-β1 in samples (100 megakaryocytes per bone marrow sample) from 18 essential thrombocythemia and 38 primary myelofibrosis (19 prefibrotic and 19 fibrotic) patients. Six bone marrow donor biopsies were used as controls. Fibrosis in the bone marrow biopsies was evaluated according to the European Consensus.

Results

The average fibrosis grade differed between essential thrombocythemia and primary myelofibrosis groups when compared to the control group. Latent TGF-β1 expression differed significantly between the fibrotic primary myelofibrosis (PMF) group and the control group (p-value < 0.01). A high degree of neo-angiogenesis (demonstrated by analysis of CD34 expression) was detected in patients with myelofibrosis. There were correlations between latent TGF-β1 expression and microvascular density (r = 0.45; p-value < 0.0009) and between degree of microvascular density and fibrosis grade (r = 0.80; p-value < 0.0001). Remarkable differences for neo-angiogenesis were not observed between patients with essential thrombocythemia and controls.

Conclusion

Angiogenesis participates in the pathogenesis of primary myelofibrosis, in both the prefibrotic and fibrotic stages, while latent TGF-β is differentially expressed only in the prefibrotic stage.

Assessment of fibrosis and vascularization of bone marrow stroma of chronic myeloid Leukemia patients treated with imatinib mesylate and their relationship with the cytogenetic response

Chronic Myeloid Leukemia (CML) is a myeloproliferative disease characterized by the presence of the Philadelphia chromosome (translocation between chromosomes 9 and 22), resulting in the formation of the hybrid BCR-ABL protein. Currently, the treatment of CML patients is performed with imatinib mesylate (IM), which promotes the elimination of leukemic cells by inhibiting the kinase activity of BCR-ABL. This study evaluated the effectiveness of IM by monitoring 22 CML patients in a chronic phase treated at the CEPON/SC with IM for a minimum follow-up period of two years. Cytogenetic Response (CR) and bone marrow biopsies (BMB) were evaluated before and after IM treatment. BMB were evaluated by detection of reticulin degree and vascularization. The results were correlated to the CR. Mean time to achieve CR was 9 months and was attained by 77.27% of the patients. The results from the initial BMB analysis showed that 59.09% presented reticulin of between 2+ and 4+ whereas after treatment, only 27.17% presented this degree. With regard to vascularization of the initial sample, 90.91% were graded between II and IV, whereas after treatment, 40.91% had this degree. The results suggest a positive correlation of degree of reticulin and vascularization with CR.

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.

Anti-angiogenesis effect of essential oil from Curcuma zedoaria in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Curcuma zedoaria (Berg.) Rosc., a traditional Chinese herb, was used widely but absolutely prohibited for the pregnant in clinic. Based on that there is abundant angiogenesis in endometrium and placenta during gestation period, we hypothesized that some components from it could inhibit angiogenesis and then damaged the supply of oxygen and nutrition to the embryo, which finally led to gestation failure.

AIM OF THE STUDY

This study was set to demonstrate whether essential oil, major components of Curcuma zedoaria had anti-angiogenic effect.

MATERIALS AND METHODS

Essential oil of Curcuma zedoaria (EO-CZ) was abstracted by steam distillation extraction. Cell proliferation assay and two angiogenic models, rat aortic ring assay and chick embryo chorioallantoic membrane assay were presented. Furthermore, melanoma growth and experimental lung metastasis assay in mice were performed to evaluate its anti-angiogenesis effect in vivo. Immunohistochemical analysis and enzyme-linked immunosorbent assay (ELISA) were used to respectively detect the expression of CD34 and matrix metalloproteinases (MMPs).

RESULTS

EO-CZ exhibited anti-proliferative effect on B16BL6 and SMMC-7721 cells, the IC(50), respectively was 41.8 μg/ml and 30.7 μg/ml, and on HUVEC (Human Umbilical Vein Endothelial Cells) cells with IC(50) of far more than 120 μg/ml. Both 20 μg/ml and 40 μg/ml EO-CZ indicated significant suppression on sprouting vessels of aortic ring and formation of microvessels in chick embryo chorioallantoic membrane in vitro. Moreover, solid melanoma grown in left oxter of mice was obviously inhibited after oral intake of 100 and 200 mg/kg of EO-CZ a day for 28 days, and CD34 expression indicating angiogenesis in melanoma reduced significantly compared with control; melanoma metastatic nodules in lung were detected to be inhibited, as well as MMP-2 and MMP-9 expression in serum.

CONCLUSIONS

Essential oil, a fat-soluble fraction of Curcuma zedoaria, presented anti-angiogenic activity in vitro and in vivo, resulting in suppressing melanoma growth and lung metastasis. And this was associated with down-regulating MMPs.

Beta-elemene inhibits melanoma growth and metastasis via suppressing vascular endothelial growth factor-mediated angiogenesis

PURPOSE

It was to assess antiangiogenic effect of β-elemene in vitro and in vivo, and it was involved in inhibiting melanoma growth and metastasis, as well as to elucidate its intrinsic mechanism.

METHODS

Inhibitive effect of β-elemene on B16F10 cells was performed by cell proliferation assay. Angiogenesis assays in vitro including rat aortic ring and chick embryo chorioallantoic membrane were used, as well as melanoma growth and metastasis assay in C57BL/6 mice. Vascular endothelial growth factor (VEGF) expression in vitro and in vivo was measured respectively by western blot analysis and enzyme-linked immunosorbent assay (ELISA). Immunohistochemistry analysis of CD34 and VEGF expression in primary melanoma was also presented.

RESULTS

β-Elemene inhibited B16BF10 cell proliferation starting from 200 μM, but VEGF from 20 μM. Both 20 and 50 μM β-elemene in vitro inhibited VEGF-induced sprouting vessel of rat aortic ring and microvessel formation of chick embryo chorioallantoic membrane. In vivo, tumor size of primary melanoma in mice intraperitoneally treated with β-elemene was significantly smaller than that of the control; CD34 expression of primary melanoma was also suppressed; and the metastatic melanoma colonies and content of melanin in lung were detected obviously decreased in mice of β-elemene-treated groups. Furthermore, results of VEGF expressing in primary melanoma, serum and lung of mice also disclosed that VEGF was inhibited in vivo.

CONCLUSIONS

β-Elemene inhibited melanoma growth and metastasis through suppressing VEGF-mediated angiogenesis. It is a natural potential antiangiogenic agent.

Angiogenesis and Anti-angiogenic Therapy in Myelofibrosis with Myeloid Metaplasia

Myelofibrosis with myeloid metaplasia (MMM) is a clonal stem cell disorder that is characterized by florid bone marrow stromal reaction including collagen fibrosis, osteosclerosis, and angiogenesis. Almost all patients with MMM display increased bone marrow microvessel density (MVD) and the extent is among the highest in hematological malignancies. This particular information has encouraged the therapeutic use of anti-angiogenic drugs in MMM. In the current review, we summarize the general concepts regarding angiogenesis, assessment of angiogenesis in hematological malignancies and then the current literature on angiogenesis and anti-angiogenic therapy in MMM.

Angiogenesis and vascular endothelial growth factor-/receptor expression in myeloproliferative neoplasms: correlation with clinical parameters and JAK2-V617F mutational status

Data on angiogenesis in the bone marrow of BCR-ABL1-negative myeloproliferative neoplasm (MPN) patients suggest an increase of the microvessel density (MVD) and vascular endothelial growth factor (VEGF) expression, but relations to the JAK2-V617F status remain controversial. We performed immunohistochemical studies of MVD and VEGF-expression in 100 MPN, including 24 essential thrombocythemia- (ET), 46 polycythemia vera- (PV), 26 primary myelofibrosis- (PMF), four myelodysplastic (MDS)/MPN- and 20 control reactive bone marrow cases, and correlated these findings with biological and clinical key data and the JAK2-V617F status. We found significantly increased MVD, particularly that assessed by CD105, and VEGF expression in MPN compared to controls (PMF > PV > MDS/MPN > ET). We observed stronger association between CD105-MVD and VEGF expression, fibrosis, and JAK2-V617F mutant allele burden, compared to CD34-MVD. MVD was strongly increased in MPN with high JAK2-V617F mutant allele burden. Our study highlights the importance of newly formed CD105+ vessels in the bone marrow of MPN patients, and indicates that assessment of CD105-MVD better reflects angiogenic activity in MPN. In addition, it provides evidence that despite the fact that angiogenesis is generally independent of the JAK2-V617F status in MPN, new vessel formation might be linked to Jak2 effects in some cases with high JAK2-V617F mutant allele burden.

Choice of endothelial marker is crucial for assessment of bone marrow microvessel density in chronic lymphocytic leukemia

Angiogenesis is a potential prognostic factor in chronic lymphocytic leukemia (CLL). Elevated circulating levels of angiogenic factors in CLL have been repeatedly reported. Nevertheless, the issue of bone marrow neovascularization in CLL remains controversial, partly due to limited number of published studies, different methods of assessing microvessel density (MVD) and small patient cohorts. Moreover, there are very scarce data regarding the relationship of marrow angiogenesis to prognostic markers in CLL. Our objectives were: 1. To assess bone marrow MVD in CLL using two different monoclonal antibodies and a reproducible method of MVD quantification; 2. To examine the possible association of marrow MVD and clinical course, pattern of marrow infiltration, Rai stage, cytogenetic abnormalities detected by fluorescence in situ hybridization (FISH), and mutation status of immunoglobulin heavy chain variable region (IgVH). MVD was higher using CD34 vs vWF antibody (p<0.0001). However, no MVD differences were detected between CLL subgroups subdivided according to the above-mentioned prognostic factors. In conclusion, MVD assessment using anti-CD34 resulted in higher MVD counts than when using anti-vWF antibody. No association of MVD with any prognostic factors was observed, possibly due to the limited patient cohort. As the need for bone marrow trephine biopsies in CLL is significantly decreasing, a standardized method of neovascularization assessment is required to enable possible multicentre studies in order to conduct larger investigations and thereby shed more light on the real clinical significance of bone marrow angiogenesis in CLL.

Serum levels, and bone marrow immunohistochemical expression of, vascular endothelial growth factor in patients with chronic myeloproliferative diseases

Current data suggest that angiogenesis plays a significant role in the pathogenesis and progression of chronic myeloproliferative diseases (cMPDs). In the present study, we evaluated serum levels of vascular endothelial growth factor (VEGF) in 83 patients with cMPDs [myelofibrosis with myeloid metaplasia (MMM, n = 25), essential thrombocythaemia (ET, n = 40), polycythaemia vera (PV, n = 8) and chronic myeloid leukemia (CML, n = 10)] and in 27 healthy individuals. Serum VEGF levels were significantly increased in patients with cMPDs compared to healthy individuals (all p values were < or = 0.05) and were significantly correlated with bone marrow microvessel density (MVD) (p = 0.0013). In addition, the immunohistochemical expression of VEGF protein in bone marrow biopsy specimens were analyzed in 61 patients with cMPDs, (ET, n = 36 and MMM, n = 25) and in 27 healthy individuals. The cellular distribution of VEGF expression was similar in bone marrow specimens of patients and healthy individuals. VEGF protein was detected mainly in erythroid cells, whereas myeloid cells and megakaryocytes exhibited a variable expression of the protein. The percentage of bone marrow VEGF positive cells was positively correlated with serum levels of VEGF (p = 0.001). The results of the present study suggest that, VEGF is a major angiogenetic factor in patients with cMPDs and contributes to the pathogenesis of these diseases.

Bone marrow microvessel density in chronic myeloproliferative disorders: a study of 115 patients with clinicopathological and molecular correlations

Philadelphia-negative chronic myeloproliferative disorders (CMD) include polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). Angiogenesis is critical in the pathogenesis of PMF. We studied angiogenesis in 115 patients with CMD (23 PV, 24 ET, 46 PMF, 12 post-PV and 10 post-ET myelofibrosis) by assessment of microvessel density (MVD) in bone marrow (BM). Kruskall-Wallis analysis of variance showed that patients with PMF had significantly higher values of MVD than those with PV (P < 0.001), ET (P < 0.001) and controls (P < 0.001). Mann-Whitney U-test demonstrated that patients with PMF at the prefibrotic stage had significantly higher MVD values than those with ET (P = 0.02). Patients with post-PV myelofibrosis showed significantly higher MVD values than those with PV (P < 0.001), as did patients with post-ET myelofibrosis compared with ET (P < 0.001). In patients with CMD, the multivariate generalized linear regression model showed that the JAK2 (V617F) mutational burden (P = 0.01), serum lactate dehydrogenase level (P = 0.003), and anaemia (P < 0.001) independently correlated with MVD. In summary, this study indicates that assessment of BM angiogenesis, as measured by MVD, may be a useful additional tool in the histopathological definition of CMD.

Increased angiogenesis in chronic idiopathic myelofibrosis: vascular endothelial growth factor as a prominent angiogenic factor

Increased angiogenesis has been suggested to be implicated in the pathogenesis of chronic idiopathic myelofibrosis (CIMF). We hypothesized that vascular endothelial growth factor (VEGF) drives CIMF-associated angiogenesis, and thus, we aimed to determine its expression and biologic impact in newly diagnosed patients. All patients with CIMF diagnosed between 1990 and 2001, for whom adequate bone marrow specimens and clinical data were available, were deemed eligible. Each case was reclassified according to World Health Organization criteria. Microvessel density (MVD), as assessed by CD34 staining, and VEGF expression were examined by standard immunohistochemistry on paraffin-embedded trephine bone marrow biopsy specimens. The cytogenetic phenotype was determined by fluorescence in situ hybridization. Appropriate summary statistics were used for comparisons between groups; survival was calculated using Kaplan-Meier estimates. Parameters found to be of prognostic significance in univariate analysis were verified in a multivariate Cox regression model. Fifty-five patients with CIMF were investigated. With a median of 43 vascular lumina per 0.747 mm(2), patients with CIMF displayed significantly greater MVD than did age-matched controls (n = 10; median MVD, 19; P < .001) with equal distribution between the various fibrosis stages. Moreover, VEGF expression was significantly increased in CIMF (median, 12 cells/0.747 mm(2) versus 1.4 cells/0.747 mm(2); P = .01) and correlated with MVD (P = .001). However, neither MVD nor VEGF expression correlated with cytogenetics or clinical outcome. We conclude that in CIMF, increased MVD is detectable even in early (pre-)fibrotic stages. Moreover, we found significantly elevated VEGF expression correlating with MVD, thus suggesting VEGF to play a prominent angiogenic role and representing a novel potential therapeutic target in CIMF.

Characterization of Ph-negative abnormal clones emerging during imatinib therapy

BACKGROUND

Imatinib is a tyrosine kinase-specific inhibitor widely used for the treatment of chronic myeloid leukemia (CML). Studies reported the occurrence of additional cytogenetic abnormalities in the Philadelphia chromosome (Ph)-negative cell population emerging after treatment-induced suppression of the Ph-positive clone. These abnormalities were described in a relatively high proportion of patients treated with imatinib compared with the anecdotal reports of similar cases in patients treated with other drugs. However, the origin of these abnormalities as well as their biological and clinical significance are unknown.

METHODS

The study involved 13 cases of patients diagnosed with CML carrying cytogenetic abnormalities in their Ph-negative cell population after imatinib treatment. The presence of the markers within the CD34+ stem cell compartment and the cell culture growth were analyzed and patients were followed over time.

RESULTS

CD34+ cells express the cytogenetic markers present in Ph- cells, suggesting a possible involvement of the stem cell population. Cultured cells showed normal growth in all but 1 patient. No growth advantage was demonstrated for the Ph-negative or the Ph-positive clone after cell culture.

CONCLUSIONS

After follow-up of up to 49 months, none of the patients had evolved to myelodysplasia or acute leukemia. Hypothesis regarding the biological and clinical significance of these abnormalities are formulated.

Statins in the treatment of polycythaemia vera and allied disorders: An antithrombotic and cytoreductive potential?

Thrombohaemorrhagic complications are major clinical problems in the classical chronic Ph-negative myeloproliferative disorders (CMPDs), polycytaemia vera (PV), essential thrombocythaemia (ET) and idiopathic myelofibrosis (IMF), contributing significantly to morbidity and mortality. Pathophysiologically these disorders are characterized by clonal myeloproliferation, myeloaccumulation and a propensity to develop myelofibrosis and neoangiogenesis in both the bone marrow and spleen. Based upon in vitro and in vivo studies of the effects of statins (antithrombotic, antiproliferative, proapoptotic and antiangiogenic), this review focuses on the translation of these effects into potential clinical benefits of statin therapy in patients with CMPDs.

Serum interleukin (IL)-1, IL-2, sIL-2Ra, IL-6 and thrombopoietin levels in patients with chronic myeloproliferative diseases

A number of growth factors are involved in clonal haematopoietic expansion and their clinical significance in patients with chronic myeloproliferative diseases requires further evaluation. Using enzyme-linked immunosorbent assays, we analysed serum levels of interleukin (IL)-1a, IL-1b, IL-2, IL-6, the soluble IL-2 receptor alpha (sIL-2Ra), and thrombopoietin (TPO), in 25 individuals with myelofibrosis with myeloid metaplasia (MMM), 40 with essential thrombocythaemia (ET), eight with polycythaemia vera (PV), 10 patients with chronic myeloid leukaemia (CML) and 27 normal controls. These were correlated with clinicopathological characteristics including overall survival, and histopathological bone marrow features, including angiogenesis. The serum derived from patients with MMM, ET, PV and CML contained significantly higher IL-2 and sIL-2Ra than healthy subjects, while IL-6 levels were higher only in MMM and CML than controls. IL-2, sIL-2Ra and IL-6 levels were raised during the transformation phase of CML, during progression of MMM to AML, and ET and PV to myelofibrosis (P < 0.001). There was a positive correlation between IL-2, sIL-2Ra, IL-6 and angiogenesis in bone marrow samples. Cytokines may be useful markers for predicting clinical evolution, reflecting increased angiogenesis. This requires further evaluation to guide diagnostic and therapeutic options.

Clinical correlation of bone marrow microvessel density in essential thrombocythemia

The aim of this study was to investigate the prognostic relevance of angiogenesis expressed as bone marrow microvessel density (MVD) in 40 patients with essential thrombocythemia (ET). Bone marrow MVD was visualized in paraffin tissue sections using immunohistochemical staining for CD34 protein. Increased MVD of bone marrow specimens was not significantly correlated with clinical (sex, age, microvascular disturbances, liver and spleen size, complications, treatment or no before biopsy), laboratory (peripheral blood count), bone marrow histopathological parameters (cellularity, megakaryocyte clumping and reticulin fibrosis) and overall survival. These preliminary findings suggest that angiogenesis has no prognostic value in patients with ET.

Expression of the proliferation-associated nuclear protein MIB-1 and its relationship with microvascular density in bone marrow biopsies of patients with myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a group of disorders characterized by dysplastic hemopoiesis and an increased risk of leukemic transformation. The process of angiogenesis has been implicated in the pathogenesis and evolution of MDS. In this study the proliferative activity and extent of angiogenesis was examined in bone marrow samples from 54 patients with MDS in relation to clinicopathologic features. Cellular proliferation and microvascular density (MVD) were examined immunohistochemically, using the monoclonal antibody MIB-1 (Ki-67) and an anti-CD34 monoclonal antibody respectively. Serum concentrations of interleukin-6 (IL-6) were measured by ELISA. The results showed that the MIB-1 Labeling Index (MIB-1 LI), MVD and IL-6 increased significantly with advancing severity of disease. Among the MDS-FAB subtypes, MIB-1 LI, MVD and IL-6 were significantly higher in RAEB-t, RAEB and CMML in comparison to RA and RARS (p < 0.0001 in all cases). Similarly, MIB-1 and MVD were increased in patients with score 3 in comparison to scores 0 and 1 in the IPSS system (p < 0.05). All parameters studied were significantly higher in patients versus controls. We conclude that cellular proliferative activity and angiogenesis are associated with disease progression in MDS patients.