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The treatment of pediatric patients with refractory or relapsed anaplastic large cell lymphoma (ALCL) is still a major challenge. In addition to conventional chemotherapy and stem cell transplantation, new therapeutic options such as anti-CD30 drugs and anaplastic lymphoma kinase (ALK) inhibitors have been recently introduced in this setting. Among ALK inhibitors, only the first-generation molecule crizotinib is approved for pediatric use, while second-generation molecules, such as brigatinib, are still under investigation. Here we report the case of a 13-year-old boy diagnosed with stage IV ALCL, refractory to first-line conventional chemotherapy and second-line therapy with the anti CD30 antibody–drug conjugate brentuximab-vedotin, who finally achieved remission after a combination of conventional high-dose chemotherapy and the second-generation ALK inhibitor brigatinib. The latter was chosen for its ability to penetrate through the blood–brain barrier, due to the persistent involvement of the patient’s cerebral nervous system. The remission was then consolidated with an allogeneic hematopoietic stem cell transplantation (HSCT) from an unrelated donor using myeloablative conditioning with total body irradiation. At 24 months after HSCT, the patient is in complete remission, alive and well. An updated review regarding the use of ALK inhibitors in ALCL patients is provided.

Objective Preparations with high-titer immunoglobulin-M (HT-IgM) have been used to treat neonatal and adult sepsis as adjuvant to antibiotics. Limited data are available of this use in pediatric oncohematological patients. We retrospectively assessed the characteristics and outcome of febrile episodes treated with broad-spectrum antibiotics and HT-IgM. Methods This study included febrile episodes diagnosed after chemotherapy or hematopoietic stem cell transplantation (HSCT) treated with antibiotics and HT-IgM. Study period was from January 2011 to March 2019. Results Seventy febrile episodes in 63 patients were eligible. In 40% of episodes (n = 28), blood cultures identified a causative organism: Gram-negative (n = 15), Gram-positive (n = 8), polybacterial (n = 4), fungi (n = 1). Twenty-six percent of Gram-negatives were extend spectrum β-lactamase (ESBL)-producers. In 44% of episodes, a deep-organ localization was present, mostly pulmonary. Severe or profound neutropenia, hypotension, and hypoxemia were present in 89, 26, and 21% of episodes, respectively; 20% of episodes required intensive care and 20% of episodes required the use of inotropes. Overall, 90-day mortality was 13% and infection-attributable mortality resulted 8.6%. More than half of the patients received HT-IgM within 24 hours from fever onset. HT-IgM-related allergic reactions occurred in three episodes. Risk factors for 90-day mortality were as follows: hypotension and hypoxemia at fever presentation, admission to intensive care unit (ICU), use of inotropes, presence of deep-organ infection, and escalation of antibiotic therapy within 5 days. Conclusion The combination of broad-spectrum antibiotics and HT-IgM was feasible, tolerated, and promising, being associated with a limited infectious mortality. Further prospective controlled studies are needed to assess the efficacy of this combination over a standard antibiotic approach.

Bloodstream infections (BSIs) after chemotherapy or hematopoietic stem cell transplantation (HSCT) are a leading cause of morbidity and mortality. Data on 154 BSIs that occurred in 111 onco-hematological patients (57 hematological malignancies, 28 solid tumors, and 26 non-malignant hematological diseases) were retrospectively collected and analyzed. Monomicrobial Gram-positive (GP), Gram-negative (GN), and fungal BSIs accounted for 50% (77/154), 38.3% (59/144), and 3.2% (5/154) of all episodes. Polymicrobial infections were 7.8% (12/154), while mixed bacterial–fungal infections were 0.6% (1/154). The most frequent GN isolates were Escherichia coli (46.9%), followed by Pseudomonas aeruginosa (21.9%), Klebsiella species (18.8%), and Enterobacter species (6.3%). Overall, 18.8% (12/64) of GN organisms were multidrug-resistant (seven Escherichia coli, three Klebsiella pneumoniae, and two Enterobacter cloacae), whereas GP resistance to glycopeptides was observed in 1% (1/97). Initial empirical antibiotic therapy was deemed inappropriate in 12.3% of BSIs (19/154). The 30-day mortality was 7.1% (11/154), while the bacteremia-attributable mortality was 3.9% (6/154). In multivariate analysis, septic shock was significantly associated with 30-day mortality (p = 0.0001). Attentive analysis of epidemiology and continuous microbiological surveillance are essential for the appropriate treatment of bacterial infections in pediatric onco-hematological patients.

Objective: Systemic sclerosis is characterized by endothelial dysfunction, autoimmunity abnormalities, and fibrosis of the skin and internal organs. The pathogenetic mechanisms underlying systemic sclerosis vasculopathy are still not clarified. A complex cellular and extracellular network of interactions has been studied, but it is currently unclear what drives the activation of fibroblasts/myofibroblasts and the extracellular matrix deposition. Methods: Using RNA sequencing, the aim of the work was to identify potential functional pathways implied in systemic sclerosis pathogenesis and markers of endothelial dysfunction and fibrosis in systemic sclerosis patients. RNA-sequencing analysis was performed on RNA obtained from biopsies from three systemic sclerosis patients and three healthy controls enrolled in our University Hospital. RNA was used to generate sequencing libraries that were sequenced according to proper transcriptomic analyses. Subsequently, we performed gene set enrichment analysis of differentially expressed genes on the entire list of genes that compose the RNA-sequencing expression matrix. Results: Gene set enrichment analysis revealed that healthy controls were characterized by gene signatures related to stromal stem cells proliferation, cytokine–cytokine receptor interaction, macrophage-enriched metabolic network, whereas systemic sclerosis tissues were enriched in signatures associated with keratinization, cornification, retinoblastoma 1 and tumor suppressor 53 signaling. Conclusion: According to our data, RNA-sequencing and pathway analysis revealed that systemic sclerosis subjects display a discrete pattern of gene expression associated with keratinization, extracellular matrix generation, and negative regulation of angiogenesis and stromal stem cells proliferation. Further analysis on larger numbers of patients is needed; however, our findings provide an interesting framework for the development of biomarkers useful to explore potential future therapeutic approaches.

Long-term survival for acute lymphoblastic leukemia (ALL) in children improved over the last three decades up to 80–90% of affected patients. Consequently, the quality of life of survivors has become increasingly important. This study analyses the clinical features and outcome of 119 children with ALL, focusing on the quality of long-term survival in a subset of 22 patients over 18 years of age. Among this group, the 10-year event-free survival and overall survival were 83.1% (C.I. 74.0–89.2) and 88.4% (C.I. 80.9–93.1), respectively. Treatment related long-term medical complications were reported only in 2 patients (9.1%). Secondary school was completed successfully in 20 of 22 patients (89.9%). The remaining 2 patients were still attending at the time of the analysis. In conclusion, current treatment for ALL is well tolerated and does not compromise significantly the quality of life of survivors.

Background: Chronic graft versus host disease (cGVHD) occurs in 20-30% of paediatric patients receiving haemopoietic stem cell transplantation (HSCT). Neuromuscular disorders such as polymyositis are considered a rare and distinctive but non-diagnostic manifestation of cGVHD and, in absence of other characteristic signs and symptoms, biopsy is highly recommended to exclude other causes. Case report: We report a case of a 17-months-old child affected by hemophagocytic lymphohistiocytosis who underwent a matched unrelated donor haematopoietic stem cell transplantation (HSCT). She developed a severe cGVHD-related polymyositis that was successfully treated with high-dose steroid therapy, rituximab and sirolimus. Conclusions: This is the first case of cGVHD-related-polymyositis described in a pediatric patient which was successfully treated with rituximab.

Background Invasive mucormycosis is a very aggressive fungal disease among immunocompromised pediatric patients caused by saprophytic fungi that belong to the order of the Mucorales. Case Report We describe a case of of Lichtheimia corymbifera infection in a 15-year-old child with B-cell Non-Hodgkin Lymphoma (NHL) involving lung, kidney and thyroid that initially was diagnosed as probable aspergillosis delaying the effective therapy for mucormycosis. Conclusions This case showed that also intensive chemotherapy with rituximab may represent a risk factor for mucormycosis infection. Liposomal amphotericin B and surgery remain key tools for a successful treatment of this aggressive disease.

Splenic hematopoiesis is a major feature in the course of myelofibrosis (MF). In fact, the spleen of patients with MF contains malignant hematopoietic stem cells retaining a complete differentiation program, suggesting both a pivotal role of the spleen in maintaining the disease and a tight regulation of hematopoiesis by the splenic microenvironment, in particular by mesenchymal stromal cells (MSCs). Little is known about splenic MSCs (Sp-MSCs), both in normal and in pathological context. In this work, we have in vitro expanded and characterized Sp-MSCs from 25 patients with MF and 13 healthy subjects (HS). They shared similar phenotype, growth kinetics, and differentiation capacity. However, MF Sp-MSCs expressed significant lower levels of nestin, and favored megakaryocyte (Mk) differentiation in vitro at a larger extent than their normal counterpart. Moreover, they showed a significant upregulation of matrix metalloprotease 2 (MMP2) and fibronectin 1 (FN1) genes both at mRNA expression and at protein level, and, finally, developed genetic abnormalities which were never detected in HS-derived Sp-MSCs. Our data point toward the existence of a defective splenic niche in patients with MF that could be responsible of some pathological features of the disease, including the increased trafficking of CD34+ cells and the expansion of the megakaryocytic lineage.

A xenograft model of stem cell rejection was developed by co-transplantating human CD34+ and allogeneic CD3+ T cells into NOD-scid ɣ-chainnull mice. T cells caused graft failure when transplanted at any CD34/CD3 ratio between 1:50 and 1:.1. Kinetics experiments showed that 2 weeks after transplantation CD34+ cells engrafted the marrow and T cells expanded in the spleen. Then, at 4 weeks only memory T cells populated both sites and rejected CD34+ cells. Blockade of T cell costimulation was tested by injecting the mice with abatacept (CTLA4-IgG1) from day –1 to +27 (group A), from day –1 to +13 (group B), or from day +14 to +28 (group C). On day +56 groups B and C had rejected the graft, whereas in group A graft failure was completely prevented, although with lower stem cell engraftment than in controls (P = .03). Retransplantation of group A mice with same CD34+ cells obtained a complete reconstitution of human myeloid and B cell lineages and excluded latent alloreactivity. In this first xenograft model of stem cell rejection we showed that transplantation of HLA mismatched CD34+ cells may be facilitated by treatment with abatacept and late stem cell boost.

Background Neovascularisation supports the metastatic switch in many aggressive solid cancers. Tumour neovessels are mostly lined by endothelial cells sprouting from nearby capillaries, but they could also be contributed by circulating endothelial progenitor cells (EPCs). However, scant information is available about tumour-derived EPCs. Methods We carried out the first thorough, unbiased comparison of phenotype, function and genotype of normal versus tumour-derived endothelial colony forming cells (ECFCs), a truly endothelial EPC subtype. We used healthy donors–derived ECFCs (N-ECFCs) as control for breast cancer (BC)– and renal cell carcinoma (RCC)–derived ECFCs. Results We found that both BC- and RCC-ECFCs belong to the endothelial lineage. Normal and tumour-derived ECFCs did not differ in terms of proliferative and tubulogenic rates. However, RCC-ECFCs were more resistant to rapamycin-induced apoptosis, whereas BC-ECFCs were more sensitive as compared with N-ECFCs. Gene expression profiling revealed 382 differentially expressed genes (DEGs; 192 upregulated and 150 downregulated) and 71 DEGs (33 upregulated, 38 downregulated) when comparing, respectively, BC- and RCC-ECFCs with N-ECFCs. Nonetheless, BC- and RCC-derived ECFCs shared 35 DEGs, 10 of which were validated by qRT-PCR; such 35 DEGs are organised in a gene network centred on FOS. Conclusion These results provide the first clear-cut evidence that BC- and RCC-derived ECFCs exhibit an altered gene expression profile as compared with N-ECFCs; yet, they share a common gene signature that could highlight novel and more specific targets to suppress tumour vascularisation.

Background: Chronic loss of lung function was described in SCD patients (pts), even if not fully characterized in children. Aim: to explore lung function in children with SCD, through the assessment of resistance measurements and ventilation patterns. Methods: spirometry, FOT, IOS and N2MBW were performed in 15 stable pediatric pts with SCD, F 46.67%, Caucasian 13.33%, aged 12 ±3.8 years, mean HbS 66.36 ±17.44, ICS/LABA therapy in 20%, ICS therapy in 13.33%. Results: A mild restrictive pattern was found (FEV1 86.96 ±15.91 %pred, FVC 75.47 ±26.62%pred, MMEF75-25 86.76 ±21%pred). Lung Clearance Index (LCI) 2.5% was elevated (7.91 ±2.26, 120%pred), as well as normalized acinar slope index Sacin (0.12 ±0.14, 220%pred). IOS measured an increase in resistance (R) at 5 Hz (119.37 [101.68-137.79] %pred) while FOT showed an increase in R at 8 Hz (118.05 [101.87-140.29] %pred) and decrease in reactance(X) at 8 Hz. Expiratory R inversely correlated with MMEF75-25 (r -0.6, p 0.03). Pts Conclusions: IOS and FOT may help to depict and monitor early lung function changes in children with SCD. N2MBW did not correlate here with spirometry, FOT or IOS, thus it may be considered to add a novel and complementary insight in functional status of children with SCD, through the representation of ventilation inhomogeneity.

The polyglandular autoimmune syndrome type I is a rare hereditary autosomal recessive disease. We describe a child with the classic triad of the disease and her sister with pure red cell aplasia and cerebellar hypoplasia. The latter received two haematopoietic stem cell transplantations, complicated by an acute disseminated encephalomyelitis.

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a clonal, neoplastic disorder of the hematopoietic stem cells, in which inflammation and immune dysregulation play an important role. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), also known as visfatin, is a cytokine implicated in a number of inflammatory and neoplastic diseases. Here plasma levels of eNAMPT in patients with MPN-associated myelofibrosis and their effects on disease phenotype and outcomes were examined. The concordance of eNAMPT levels with the marker of general inflammation high-sensitivity C-reactive protein (hs-CRP) was also studied. A total of 333 MPN-associated myelofibrosis patients (187 males and 146 females) and 31 age- and gender-matched normal-weight healthy subjects were enrolled in the study main body. Levels of eNAMPT and hs-CRP were simultaneously assayed in 209 MPN-associated myelofibrosis patients. Twenty-four polycythemia vera or essential thrombocythemia patients were used as controls. eNAMPT was over expressed in MPN-associated myelofibrosis, and eNAMPT expression was correlated with higher white blood cell count, higher hemoglobin, and higher platelet count, suggesting that eNAMPT is an indispensable permissive agent for myeloproliferation of MPN-associated myelofibrosis. The lack of correlation between eNAMPT and hs-CRP revealed that eNAMPT in MPN-associated myelofibrosis does not behave as a canonical inflammatory cytokine. In addition, higher levels of eNAMPT predicted longer time to blast transformation, and protected against progression toward thrombocytopenia and large splenomegaly. In conclusion, in MPN-associated myelofibrosis high levels of eNAMPT mark the myeloproliferative potential and, at variance with a high number of cancers, are protective against disease progression. Am. J. Hematol. 91:709-713, 2016. © 2016 Wiley Periodicals, Inc.

JAK2 V617F allele burden 50% is associated with response to ruxolitinib in persons with MPN-associated myelofibrosis and splenomegaly requiring therapy

Patients with high-risk myeloproliferative neoplasms (MPNs), and in particular myelofibrosis (MF), can be cured only with allogeneic hematopoietic stem cell transplantation (HSCT). Because MPNs and JAK2V617F-mutated cells show genomic instability, stalled replication forks, and baseline DNA double-strand breaks, DNA repair inhibition with poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors represents a potential novel therapy. Because the alkylating agent busulfan is integral in conditioning regimens for HSCT and leads to stalled replication forks through DNA strand cross-linking, we hypothesized that PARP inhibition with veliparib in combination with busulfan may lead to synergistic cytotoxicity in MPN cells. We first treated 2 MPN cell lines harboring the JAK2V617F mutation (SET2 and HEL) with veliparib at increasing concentrations and measured cell proliferation. SET2 and HEL cells were relatively sensitive to veliparib (IC50 of 11.3 μM and 74.2 μM, respectively). We next treated cells with increasing doses of busulfan in combination with 4 μM veliparib and found that the busulfan IC50 decreased from 27 μM to 4 μM in SET2 cells and from 45.1 μM to 28.1 μM in HEL cells. The mean combination index was .55 for SET2 cells and .40 for HEL cells. Combination treatment of SET2 cells caused G2M arrest in 53% of cells, compared with 30% with veliparib alone and 35% with busulfan alone. G2M arrest was associated with activation of the ATR-Chk1 pathway, as shown by an immunofluorescence assay for phosphorylated Chk1 (p-Chk1). We then tested in vivo the effect of combined low doses of busulfan and veliparib in a JAK2V617F MPN-AML xenotransplant model. Vehicle- and veliparib-treated mice had similar median survival of 39 and 40 days, respectively. Combination treatment increased median survival from 47 days (busulfan alone) to 50 days (P = .02). Finally, we tested the combined effect of busulfan and veliparib on CD34+ cells obtained from the bone marrow or peripheral blood of 5 patients with JAK2V617F-mutated and 2 patients with CALR-mutated MF. MF cells treated with the combination of veliparib and busulfan showed reduced colony formation compared with busulfan alone (87% versus 68%; P = .001). In contrast, treatment of normal CD34+ cells with veliparib did not affect colony growth. Here we show that in vivo confirmation that treatment with the PARP-1 inhibitor veliparib and busulfan results in synergistic cytotoxicity in MPN cells. Our data provide the rationale for testing novel pretransplantation conditioning regimens with combinations of PARP-1 inhibition and reduced doses of alkylators, such as busulfan and melphalan, for high-risk MPNs or MPN-derived acute myelogenous leukemia.

We describe three cases of sinusoidal obstruction syndrome/venoocclusive disease (SOS) in pediatric patients with acute lymphoblastic leukemia (ALL). All three episodes occurred during or just after the induction or reinduction phase of treatment based on prednisone/dexamethasone, vincristine, daunorubicin, and pegylated-l-asparaginase. SOS episodes were categorized as mild/moderate and resolved in 7, 10, and 16 days using supportive measures or defibrotide therapy. In all three episodes, the clinical diagnosis of SOS was associated with a significant increase in plasminogen-activator inhibitor-1 (PAI-1) that reduced with patient clinical improvement. PAI-1 warrants study as a diagnostic marker for SOS in ALL.

A xenograft model of stem cell rejection was developed by co-transplantating human CD34

Background: Juvenile myelomonocytic leukaemia (JMML) and chronic myelomonocytic leukaemia (CMML) are myelodysplastic myeloproliferative (MDS/MPN) neoplasms with unfavourable prognosis and without effective chemotherapy treatment. Trabectedin is a DNA minor groove binder acting as a modulator of transcription and interfering with DNA repair mechanisms; it causes selective depletion of cells of the myelomonocytic lineage. We hypothesised that trabectedin might have an antitumour effect on MDS/MPN. Methods: Malignant CD14+ monocytes and CD34+ haematopoietic progenitor cells were isolated from peripheral blood/bone marrow mononuclear cells. The inhibition of CFU-GM colonies and the apoptotic effect on CD14+ and CD34+ induced by trabectedin were evaluated. Trabectedin's effects were also investigated in vitro on THP-1, and in vitro and in vivo on MV-4-11 cell lines. Results: On CMML/JMML cells, obtained from 20 patients with CMML and 13 patients with JMML, trabectedin - at concentration pharmacologically reasonable, 1-5 nM - strongly induced apoptosis and inhibition of growth of haematopoietic progenitors (CFU-GM). In these leukaemic cells, trabectedin downregulated the expression of genes belonging to the Rho GTPases pathway (RAS superfamily) having a critical role in cell growth and cytoskeletal dynamics. Its selective activity on myelomonocytic malignant cells was confirmed also on in vitro THP-1 cell line and on in vitro and in vivo MV-4-11 cell line models. Conclusions: Trabectedin could be good candidate for clinical studies in JMML/CMML patients.

Endothelial progenitor cells (EPCs) have recently been employed in cell-based therapy (CBT) to promote regeneration of ischemic organs, such as heart and limbs. Furthermore, EPCs may sustain tumour vascularisation and provide an additional target for anticancer therapies. CBT is limited by the paucity of cells harvested from peripheral blood and suffers from several pitfalls, including the low rate of engrafted EPCs, whereas classic antiangiogenic treatments manifest a number of side effects and may induce resistance into the patients. CBT will benefit of a better understanding of the signal transduction pathway(s) which drive(s) EPC proliferation, trafficking, and incorporation into injured tissues. At the same time, this information might outline alternative molecular targets to impair tumor neovascularisation and improve the therapeutic outcome of antiangiogenic strategies. An increase in intracellular Ca 2+ concentration is the key signal in the regulation of cellular replication, migration, and differentiation. In particular, Ca 2+ signalling may regulate cellcycle progression, due to the Ca 2+ -sensitivity of a number of cycline-dependent kinases, and gene expression, owing to the Ca 2+ -dependence of several transcription factors. Recent work has outlined the role of the so-called store-operated Ca 2+ entry in driving EPC proliferation and migration. Unravelling the mechanisms guiding EPC engraftment into neovessels might supply the biological bases required to improve CBT and anticancer treatments. For example, genetic manipulation of the Ca 2+ signalling machinery could provide a novel approach to increase the extent of limb regeneration or preventing tumour vascularisation by EPCs.

Endothelial colony-forming cells (ECFCs) are the only endothelial progenitor cells (EPCs) that are capable of acquiring a mature endothelial phenotype. ECFCs are mainly mobilized from bone marrow to promote vascularization and represent a promising tool for cell-based therapy of severe ischemic diseases. Vascular endothelial growth factor (VEGF) stimulates the proliferation of peripheral blood-derived ECFCs (PB-ECFCs) through oscillations in intracellular Ca(2+) concentration ([Ca(2+)]i). VEGF-induced Ca(2+) spikes are driven by the interplay between inositol-1,4,5-trisphosphate (InsP3)-dependent Ca(2+) release and store-operated Ca(2+) entry (SOCE). The therapeutic potential of umbilical cord blood-derived ECFCs (UCB-ECFCs) has also been shown in recent studies. However, VEGF-induced proliferation of UCB-ECFCs is faster compared with their peripheral counterpart. Unlike PB-ECFCs, UCB-ECFCs express canonical transient receptor potential channel 3 (TRPC3) that mediates diacylglycerol-dependent Ca(2+) entry. The present study aimed at investigating whether the higher proliferative potential of UCB-ECFCs was associated to any difference in the molecular underpinnings of their Ca(2+) response to VEGF. We found that VEGF induces oscillations in [Ca(2+)]i that are patterned by the interaction between InsP3-dependent Ca(2+) release and SOCE. Unlike PB-ECFCs, VEGF-evoked Ca(2+) oscillations do not arise in the absence of extracellular Ca(2+) entry and after pharmacological (with Pyr3 and flufenamic acid) and genetic (by employing selective small interference RNA) suppression of TRPC3. VEGF-induced UCB-ECFC proliferation is abrogated on inhibition of the intracellular Ca(2+) spikes. Therefore, the Ca(2+) response to VEGF in UCB-ECFCs is shaped by a different Ca(2+) machinery as compared with PB-ECFCs, and TRPC3 stands out as a promising target in EPC-based treatment of ischemic pathologies.

To the editor: Although primary myelofibrosis (PMF) is generally regarded as arising from a mutated stem or progenitor hematopoietic cell, immune dysregulation is common. For example, there are increased plasma levels of inflammatory cytokines and clinical and laboratory manifestations of

Myeloproliferative neoplasm (MPN)-associated myelofibrosis is a clonal, neoplastic disorder of the hematopoietic stem cells, in which inflammation and immune dysregulation play an important role. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT), also known as visfatin, is a cytokine implicated in a number of inflammatory and neoplastic diseases. Here plasma levels of eNAMPT in patients with MPN-associated myelofibrosis and their effects on disease phenotype and outcomes were examined. The concordance of eNAMPT levels with the marker of general inflammation high-sensitivity C-reactive protein (hs-CRP) was also studied. A total of 333 MPN-associated myelofibrosis patients (187 males and 146 females) and 31 age- and gender-matched normal-weight healthy subjects were enrolled in the study main body. Levels of eNAMPT and hs-CRP were simultaneously assayed in 209 MPN-associated myelofibrosis patients. Twenty-four polycythemia vera or essential thrombocythemia patients were used as controls. eNAMPT was over expressed in MPN-associated myelofibrosis, and eNAMPT expression was correlated with higher white blood cell count, higher hemoglobin, and higher platelet count, suggesting that eNAMPT is an indispensable permissive agent for myeloproliferation of MPN-associated myelofibrosis. The lack of correlation between eNAMPT and hs-CRP revealed that eNAMPT in MPN-associated myelofibrosis does not behave as a canonical inflammatory cytokine. In addition, higher levels of eNAMPT predicted longer time to blast transformation, and protected against progression toward thrombocytopenia and large splenomegaly. In conclusion, in MPN-associated myelofibrosis high levels of eNAMPT mark the myeloproliferative potential and, at variance with a high number of cancers, are protective against disease progression. Am. J. Hematol. 91:709-713, 2016. © 2016 Wiley Periodicals, Inc.

DNA instability, including increased DNA double strand breaks, has recently been demonstrated in myeloproliferative neoplasms (MPN). Because PARP1 has a central role in DNA repair and maintaining genomic integrity, we tested whether DNA repair inhibition with the PARP inhibitor ABT-888 (Abbvie, Chicago, IL) could affect the growth of myeloid neoplasms in-vitro and in-vivo, and/or enhance the cytotoxic effect of a standard alkylating agent commonly used in preparative regimens for stem cell transplants. Since the JAK2V617Fmutation is common in chronic MPNs or acute myeloid leukemia (AML) secondary to MPNs, we initially utilized JAK2 mutated AML cell lines (SET2 and HEL) in-vitro and in-vivo. We then tested the effect of PARP inhibition on CD34+ cells obtained from patients with primary myelofibrosis. JAK2 mutated SET2 and HEL cells were treated with ABT-888 in liquid cultures. Both cell lines were relatively sensitive with IC50 of 11.3μM and 74.2μM respectively. When the cells were treated with a combination of increasing doses of busulfan and 8μM ABT-888, significant synergy was observed, with busulfan IC50 decreasing from 27μM to 4μM in SET2 cells and from 45.1μM to 28.1μM in HEL cells. Treatment of SET2 cells with 8μM ABT-888, or with 8μM ABT888 and 10μM busulfan, was also accompanied by marked increase in γH2AX foci compared to control at 24 hours. We subsequently showed that ABT-888, busulfan and combination treatments resulted in increasing numbers of cells in G2/M arrest (30% vs. 35% vs 53% respectively, p=0.002). Western blot analysis of cells in G/2M arrest after combination treatment demonstrated a strongly increased phosphorylation of checkpoint kinase 1 (Chk1). In an immunofluorescence assay on treated cells we then showed that activated Chk1 translocated to the nucleus, suggesting that the Chk1-ATR pathway may be responsible for cell cycle arrest. To demonstrate the in-vivo effect of PARP inhibition, we transplanted 5x106 SET2 cells into a NOD/SCID/ gamma null mice to create a xenograft model. Mice developed AML with splenomegaly and bone marrow engraftment resulting in a median survival of 36 days. In mice that were treated with daily intraperitoneal injections of low dose ABT-888 (1.5mg/kg), starting 14 days after leukemic cell injection, survival increased to a median of 40 days (p=0.002). We subsequently tested the effect of PARP inhibition on primary myelofibrosis CD34+ cells obtained from the bone marrow or peripheral blood of 3 patients with JAK2V617Fmutation and 2 with CALR mutation. Control experiments were performed with normal CD34+ progenitors. In a standard clonogenic assay in methylcellulose, cells were plated with or without 4μM ABT-888, 5μM busulfan or a combination of both. Compared to untreated cells, ABT-888, busulfan and the combination of the two drugs reduced colony formation by 39%, 70% and 89%, respectively (p=0.01). Both CALR and JAK2 mutated cells were sensitive to ABT-888. On the contrary, treatment of normal CD34+ cells with ABT-888 did not affect colony growth. Here we describe the potential for PARP inhibition to exploit the genomic instability of MPNs. Potential clinical applications include the addition of PARP inhibition to busulfan in pretransplant conditioning or novel drug combinations including PARP inhibitors. Disclosures No relevant conflicts of interest to declare.

Background: Kaposiform Hemangioendothelioma (KHE) is a rare vascular tumour of the infancy and of the first decade of life. It is locally aggressive and potentially life threatening when associated to consumptive coagulopathy, known as Kasabach-Merritt syndrome (KMS). No consensus or guideline for the therapy has been reached because of the lack of prospective trials and the different standard care suggestions are based on retrospective case series. Case report: We report the case of a 9-month-old male with KHE and KMS in which the initial response, obtained with prednisone and vincristine, was subsequently consolidated and strengthened by long-term treatment with sirolimus, an mTOR inhibitor. A summary of the published data is presented as well. Conclusions: The inhibition of mTOR pathway represents the most important therapeutic innovation introduced in the last few years for KHE. Our case shows the effectiveness and good tolerance of long-term therapy with sirolimus. Keywords: Kaposiform Hemangioendothelioma, Kasabach-Merrit syndrome, sirolimus, prednisone, vincristine

The new form of bronchopulmonary dysplasia (BPD) is characterized by lung immaturity with disrupted alveolar and capillary development after extremely premature birth, but the mechanism of impaired lung vascular formation is still not completely understood.We tested the hypothesis that reduced numbers of circulating endothelial progenitor cells at birth are associated with the development of BPD.We studied ninety-eight preterm infants with gestational age of less than 32 weeks or a birth weight less than 1,500 g. Endothelial colony-forming cells (ECFCs) were assessed by clonogenic analysis in infants for whom cord blood was available. The proportion of circulating endothelial and hematopoietic cells was measured by flow cytometry at birth, at 48 hours, and at 7 days of life.ECFCs in cord blood were lower in infants who later developed BPD (median [range]: 0.00 [0.00-0.48] vs. 2.00 [0.00-21.87]; P = 0.002). ECFCs decreased with decreasing gestational age (r = 0.41; P = 0.02), but even at extremely low gestational ages, infants with higher numbers of ECFCs were protected from BPD. The endothelial and hematopoietic cell subsets studied by flow cytometry were comparable in infants with and without BPD and rapidly decreased after birth.ECFCs are low at extremely low gestational ages and increase during gestation; extremely preterm infants who display lower numbers at birth have an increased risk of developing BPD. Our findings suggest that decreased ECFCs following extremely preterm birth may be associated with the risk for developing lung vascular immaturity characteristic of new BPD.

Mature endothelial cells are known to sense microbial products through toll-like receptors (TLRs), a family of membrane proteins which serve as pathogen recognition and signaling elements; however, there are limited data in the literature about the expression and function of TLRs in human circulating endothelial colony forming cells (ECFCs), which are considered the most likely endothelial precursors. We expanded and differentiated in vitro umbilical cord blood (UCB) and adult peripheral blood (PB) ECFCs and studied the expression of TLR1 to TLR10 mRNA by qPCR analysis, and we further characterized TLR function in ECFCs through functional assays including in vitro ECFC growth and differentiation, assessment of cytokine production, and measurement of intracellular Ca(2+) signals. Both UCB- and PB-ECFCs had detectable mRNA levels of all the TLRs from 1 to 10; TLR4, a sensor of Gram-negative bacterial lipopolysaccharide (LPS), had a higher level compared to other TLRs. Exposure to LPS induced cytokine production, although with less efficiency compared to PB-mononuclear cells. However, no effect of LPS was seen on ECFC growth and differentiation, and no increase in intracellular Ca(2+) concentrations, which is essential for ECFC proliferation, was observed after exposure to increasing amounts of LPS. Our data show that all TLRs from 1 to 10 are constitutively expressed in ECFCs, and suggest that TLR4 is functional in ECFCs, but its activation through its ligand LPS does not affect ECFC growth and differentiation.

Endothelial progenitor cells could be implicated in the aberrant neoangiogenesis that occurs in bone marrow and spleen in patients with primary myelofibrosis (PMF). However, antivascular endothelial growth factor (VEGF) monotherapy had only a modest and transient effect in these individuals. Recently it was found that VEGF-induced proangiogenic intracellular Ca 2+ oscillations could be impaired in endothelial progenitor cells of subjects with malignancies. Therefore, we employed Ca 2+ imaging, wavelet analysis, and functional assays to assess whether and how VEGF-induced Ca 2+ oscillations are altered in PMF-derived endothelial progenitor cells. We focused on endothelial colony-forming cells (ECFCs), which are the only endothelial progenitor cell subtype capable of forming neovessels both in vivo and in vitro. VEGF triggers repetitive Ca 2+ spikes in both normal ECFCs (N-ECFCs) and ECFCs obtained from PMF patients (PMF-ECFCs). However, the spiking response to VEGF is significantly weaker in PMF-ECFCs. VEGF-elicited Ca 2+ oscillations are patterned by the interaction between inositol-1,4,5-trisphosphate-dependent Ca 2+ mobilization and store-operated Ca 2+ entry. However, in most PMF-ECFCs, Ca 2+ oscillations are triggered by a store-independent Ca 2+ entry pathway. We found that diacylglycerol gates transient receptor potential canonical 1 channel to trigger VEGF-dependent Ca 2+ spikes by recruiting the phospholipase C/inositol-1,4,5-trisphosphate signaling pathway, reflected as a decrease in endoplasmic reticulum Ca 2+ content. Finally, we found that, apart from being less robust and dysregulated as compared with N-ECFCs, VEGF-induced Ca 2+ oscillations modestly stimulate PMF-ECFC growth and in vitro angiogenesis. These results may explain the modest effect of anti-VEGF therapies in PMF.

Endothelial progenitor cells (EPCs) have recently been shown to promote the angiogenic switch in solid neoplasms, thereby promoting tumour growth and metastatisation. The genetic suppression of EPC mobilization from bone marrow prevents tumour development and colonization of remote organs. Therefore, it has been assumed that anti-angiogenic treatments, which target vascular endothelial growth factor (VEGF) signalling in both normal endothelial cells and EPCs, could interfere with EPC activation in cancer patients. Our recent data, however, show that VEGF fails to stimulate tumour endothelial colony-forming cells (ECFCs), i.e. the only EPC subtype truly belonging to the endothelial lineage. The present article will survey current evidence about EPC involvement in the angiogenic switch: we will focus on the controversy about EPC definition and on the debate around their actual incorporation into tumour neovessels. We will then discuss how ECFC insensitivity to VEGF stimulation in cancer patients could underpin their well-known resistance to anti-VEGF therapies.

Background The number of patients with sickle cell disease (SCD) has increased in Italy in the past decade due to immigration. In spite of the established efficacy of hydroxyurea (HU) in childhood, population-based data regarding its prescription and effectiveness come mainly from studies performed in adults or outside Europe. Population and methods The Hydroxyurea in SCD: A Large Nation-wide Cohort Study from Italy was a retrospective cohort study of adult and pediatric patients with SCD attending 32 centers. Pediatric data are analyzed separately. Results Out of 504 children followed in 11 centers, 206 (40%) were on HU (194 SS/Sβ°, 12 SC/Ss+); 74% came from Sub-Saharian Africa and 18% from Europe. HU therapy indications for SS/Sβ° patients were as follows: 57% painful vaso-occlusive crisis, acute chest syndrome or both, 24% anemia, 8% anemia, and other reasons (the majority had Hb ≤ 8–8.5 g/dl, revealing scarce acceptance of low Hb values by pediatric hematologist). Mean starting dose was 15.5 mg/kg, and dose at full regimen was 17.1 mg/kg. Mean age at HU therapy was 7.68 years, although it was lower for SS/Sβ° patients. Only 10% started HU before 3 years. In 92%, 500 mg capsule was used; in 6%, the galenic was used; and in 2%, 100 mg tablet was used. Significant reduction of clinical events and inpatients admissions, with improvement in hematological parameters, was observed for SS/Sβ° patients and a trend toward improvement for SC/Ss+ patients was also observed. Conclusions HU effectiveness is demonstrated in a national cohort of children with SCD living in Italy, even at a lower dose than recommended, revealing good adherence to a treatment program by a socially vulnerable group of patients such as immigrants.

BackgroundAn increase in the frequency of circulating endothelial colony forming cells (ECFCs), the only subset of endothelial progenitor cells (EPCs) truly belonging to the endothelial phenotype, occurs in patients affected by primary myelofibrosis (PMF). Herein, they might contribute to the enhanced neovascularisation of fibrotic bone marrow and spleen. Store-operated Ca2+ entry (SOCE) activated by the depletion of the inositol-1,4,5-trisphosphate (InsP3)-sensitive Ca2+ store drives proliferation in ECFCs isolated from both healthy donors (N-ECFCs) and subjects suffering from renal cellular carcinoma (RCC-ECFCs). SOCE is up-regulated in RCC-ECFCs due to the over-expression of its underlying molecular components, namely Stim1, Orai1, and TRPC1.Methodology/principal findingsWe utilized Ca2+ imaging, real-time polymerase chain reaction, western blot analysis and functional assays to evaluate molecular structure and the functional role of SOCE in ECFCs derived from PMF patients (PMF-ECFCs). SOCE, induced by either pharmacological (i.e. cyclopiazonic acid or CPA) or physiological (i.e. ATP) stimulation, was significantly higher in PMF-ECFCs. ATP-induced SOCE was inhibited upon blockade of the phospholipase C/InsP3 signalling pathway with U73111 and 2-APB. The higher amplitude of SOCE was associated to the over-expression of the transcripts encoding for Stim2, Orai2-3, and TRPC1. Conversely, immunoblotting revealed that Stim2 levels remained constant as compared to N-ECFCs, while Stim1, Orai1, Orai3, TRPC1 and TRPC4 proteins were over-expressed in PMF-ECFCs. ATP-induced SOCE was inhibited by BTP-2 and low micromolar La3+ and Gd3+, while CPA-elicited SOCE was insensitive to Gd3+. Finally, BTP-2 and La3+ weakly blocked PMF-ECFC proliferation, while Gd3+ was ineffective.ConclusionsTwo distinct signalling pathways mediate SOCE in PMF-ECFCs; one is activated by passive store depletion and is Gd3+-resistant, while the other one is regulated by the InsP3-sensitive Ca2+ pool and is inhibited by Gd3+. Unlike N- and RCC-ECFCs, the InsP3-dependent SOCE does not drive PMF-ECFC proliferation.

Functional and genetic aberrations of in vitro -cultured marrow-derived mesenchymal stromal cells of patients with classical Philadelphia-negative myeloproliferative neoplasms