Reduction of CFU-GM and circulating hematopoietic progenitors in a subgroup of children with chronic neutropenia associated with severe infections and delayed recovery.

Myelopoiesis was evaluated in 66 pediatric patients with chronic neutropenia who were positive for anti-neutrophil antibodies (median age at diagnosis: 11 months, median neutrophil count at diagnosis: 419/µl). Other causes of neutropenia were excluded. Bone marrow morphology, clonogenic tests and/or the peripheral blood CD 34+ cell count, and apoptotic rate were evaluated in 61 patients with neutropenia lasting > 12 months or severe infections. The peripheral blood CD 34+ cell count and apoptotic rate were evaluated in five patients with shorter neutropenia. The median follow-up time was 29 months (range 7-180 months). Forty-seven patients (71.2%) had a spontaneous recovery after 7-180 months (median 29 months). The group of patients younger than 24 months at diagnosis (n = 50) had a higher probability of recovery (40/50 vs. 7/16 χ2 p<0.01) with a shorter period of neutropenia (median 26 versus 47 months, Kaplan-Meier analysis p = 0.001). The colony-forming units-granulocyte-macrophage (CFU-GM) were significantly decreased in 26/35 patients (74%) evaluated for clonogenic tests. All patients with normal CFU-GM recovered (9/9 patients); whereas, neutropenia persisted in 12/26 patients with reduced CFU-GM (46%, Pearson χ2 p = 0.02). In 36/55 (65%) patients evaluated by flow cytometry we observed reduced circulating CD34+ cells compared with controls of the same age. An increase in the circulating CD34+ cell apoptotic rate was observed in 28/55 patients (51%). Infections requiring hospitalization were observed in 9/18 (50%; Pearson χ2, p = 0.03) patients with both decreased circulating CD34+ cells and increased CD34+ apoptotic rates. In the group aged < 24 months, we observed a significant correlation between the persistence of neutropenia and decreased circulating CD34+ cells (Pearson χ2 p = 0.008). In conclusion, reduced CFU-GM and circulating hematopoietic progenitors were observed in a subgroup of children with chronic neutropenia who were positive for anti-neutrophil antibodies and had a higher incidence of severe infections and delayed spontaneous remission.

Paroxysmal nocturnal hemoglobinuria clones in children with acquired aplastic anemia: a multicentre study.

A multicentre study evaluating the presence of glycosil phosphatidyl-inositol (GPI)-negative populations was performed in 85 children with acquired aplastic anemia (AA). A GPI-negative population was observed in 41% of patients at diagnosis, 48% during immune-suppressive therapy (IST), and 45% in patients off-therapy. No association was found between the presence of a GPI-negative population at diagnosis and the response to IST. In addition, the response rate to IST did not differ between the patients who were GPI-positive at diagnosis and later developed GPI-negative populations and the 11 patients who remained GPI-positive. Two patients with a GPI-negative population >10%, and laboratory signs of hemolysis without hemoglobinuria were considered affected by paroxysmal nocturnal hemoglobinuria (PNH) secondary to AA; no thrombotic event was reported. Excluding the 2 patients with a GPI-negative population greater than 10%, we did not observe a significant correlation between LDH levels and GPI-negative population size. In this study monitoring for laboratory signs of hemolysis was sufficient to diagnose PNH in AA patients. The presence of minor GPI-negative populations at diagnosis in our series did not influence the therapeutic response. As occasionally the appearance of a GPI-negative population was observed at cyclosporine (CSA) tapering or AA relapse, a possible role of GPI-negative population monitoring during IST modulation may need further investigation.

Functional evaluation of circulating hematopoietic progenitors in Noonan syndrome.

Noonan syndrome (NS) is an autosomal dominant disorder, characterized by short stature, multiple dysmorphisms and congenital heart defects. A myeloproliferative disorder (NS/MPD), resembling juvenile myelomonocytic leukemia (JMML), is occasionally diagnosed in infants with NS. In the present study, we performed a functional evaluation of the circulating hematopoietic progenitors in a series of NS, NS/MPD and JMML patients. The different functional patterns were compared with the aim to identify a possible NS subgroup worthy of stringent hematological follow-up for an increased risk of MPD development. We studied 27 NS and 5 JMML patients fulfilling EWOG-MDS criteria. The more frequent molecular defects observed in NS were mutations in the PTPN11 and SOS genes. The absolute count of monocytes, circulating CD34+ hematopoietic progenitors, their apoptotic rate and the number of circulating CFU-GMs cultured in the presence of decreasing concentrations or in the absence of granulocyte-macrophage colony-stimulating factor (GM-CSF) were evaluated. All JMML patients showed monocytosis>1,000/µl. Ten out of the 27 NS patients showed monocytosis>1,000/µl, which included the 3 NS/MPD patients. In JMML patients, circulating CD34+ cells were significantly increased (median, 109.8/µl; range, 44-232) with a low rate of apoptosis (median, 2.1%; range, 0.4-12.1%), and circulating CFU-GMs were hyper-responsive to GM-CSF. NS/MPD patients showed the same flow cytometric pattern as the JMML patients (median, CD34+ cells/µl, 205.7; range, 58-1374; median apoptotic rate, 1.4%; range, 0.2-2.4%) and their circulating CFU-GMs were hyper-responsive to GM-CSF. These functional alterations appeared 10 months before the typical clinical manifestations in 1 NS/MPD patient. In NS, the CD34+ absolute cell count and circulating CFU-GMs showed a normal pattern (median CD34+ cells/µl, 4.9; range, 1.3-17.5), whereas the CD34+ cell apoptotic rate was significantly decreased in comparison with the controls (median, 8.6%; range, 0-27.7% vs. median, 17.6%; range, 2.8-49.6%), suggesting an increased CD34+ cell survival. The functional evaluation of circulating hematopoietic progenitors showed specific patterns in NS and NS/MPD. These tests are a reliable integrative tool that, together with clinical data and other hematological parameters, could help detect NS patients with a high risk for a myeloproliferative evolution.

In vitro anti-neuroblastoma activity of saquinavir and its association with imatinib.

Neuroblastoma (NB) has a poor prognosis when in advanced stages, highlighting the need for new therapeutic options. The human immunodeficiency virus (HIV) protease inhibitor saquinavir is active in vitro against chronic myeloid leukaemia cells, in synergy with the tyrosine kinase inhibitor imatinib. Here, we evaluated the effects of saquinavir, alone or in association with imatinib, on cell proliferation (count of viable cells after trypan blue exclusion), apoptosis (Annexin V binding) and invasion (through a transwell membrane coated with Matrigel) in SJ-N-KP, IMR5, AF-8, SK-N-SH and SK-N-BE NB lines, all expressing c-kit and PDGF-R (determined by flow cytometry). Saquinavir showed a dose-dependent anti-proliferative and anti-invasive activity on NB lines, increased by the association with imatinib when the two drugs were utilized at clinically attainable concentrations. The same low saquinavir concentrations inhibited in NB cells the nuclear activation of NF-κB (Western immuno-blotting for nuclear NF-κB p50 and p65). Saquinavir at high concentrations also exerted a pro-apoptotic activity on NB lines, significantly increased by the association with imatinib. In conclusion, saquinavir and imatinib are both drugs utilized for long-term therapies, with good oral bioavailability and a well-known toxicity profile. The anti-NB activity of saquinavir and of its association with imatinib suggests a potential usefulness in the treatment of NB, particularly for remission maintenance.

In vitro antiproliferative and antimigratory activity of dasatinib in neuroblastoma and Ewing sarcoma cell lines.

Neuroblastoma (NB) and Ewing sarcoma (ES) are neuroectodermal tumors typical of pediatric age that, despite aggressive treatment, still present a poor prognosis when in advanced stages. Studies indicate that c-KIT and platelet-derived growth factor receptor (PDGFR) play a substantial role in the proliferation and survival of NB and ES cells. Dasatinib, an oral multi-targeted inhibitor of several kinases including BCR-ABL and SRC-family kinases, is also active against c-KIT and PDGFR. Here, we evaluated the effect of dasatinib on the NB cell lines SJ-N-KP, SK-N-BE, AF8 and IMR5, and on the ES lines PDE02, TC106 and 6647. Proliferation and viability assays showed that dasatinib exerts an antiproliferative activity with a peak effect occurring at 24 h. After a 24-h exposure to dasatinib at 100 nM, proliferation was inhibited by 29.4+/-5.7% in SJ-N-KP, 41.3+/-11.7% in IMR5, 35.3+/-7.6% in PDE02 and 14+/-10.6% in 6647. Dasatinib did not induce apoptosis in NB and ES cell lines. A possible antimigratory activity of dasatinib was evaluated by scratch test. Dasatinib at 100 nM inhibited the migration of NB and ES cell lines by a mean of 30.2 and 25.3%, respectively. This activity suggests a possible role of dasatinib in inhibiting metastasis and appears of particular interest, given the association between metastatic disease and poor prognosis in these tumors. In conclusion, the cytostatic and antimigratory activity of dasatinib in NB and ES cell lines and the lack of pro-apoptotic activity suggests a possible use for this compound in the treatment of these tumors as a combination with other cytotoxic therapy.

Inhibition of heat shock proteins (HSP) expression by quercetin and differential doxorubicin sensitization in neuroblastoma and Ewing's sarcoma cell lines.

Neuroblastoma (NB) and Ewing's sarcoma (ES) represent the most common extracranial solid tumors of childhood. Heat shock proteins (HSP) are elevated in cancer cells and their over-expression was correlated to drug-resistance. In this work we identified the HSP by a sensitive proteomic analysis of NB and ES cell lines, then, we studied the HSP response to doxorubicin. Some identified HSP were constitutively more expressed in NB than in ES cells. Doxorubicin-stimulated HSP response only in NB cells. Quercetin was found to inhibit HSP expression depleting heat shock factor 1 (HSF1) cellular stores. Quercetin caused a higher anti-proliferative effect in NB (IC(50): 6.9 +/- 5.8 mumol/L) than in ES cells (IC(50): 85.5 +/- 53.1 mumol/L). Moreover, quercetin caused a very pronounced doxorubicin sensitizing effect in NB cells (241 fold IC(50) decrease) and a moderate effect in ES cells. HSP involvement in NB cells sensitization was confirmed by the silencing of HSF1. Quercetin treatment and HSF1 silencing increased the pro-apoptotic effect of doxorubicin. In conclusion, the higher HSP levels, observed in NB cells, did not confer increased resistance to doxorubicin; on the contrary, HSP inhibition by quercetin or gene silencing caused higher sensitization to doxorubicin. These results may have a potential application in the treatment of NB.

The effects of saquinavir on imatinib-resistant chronic myelogenous leukemia cell lines.

We evaluated the effect of the human immunodeficiency virus (HIV) protease inhibitor saquinavir on the imatinib-sensitive and imatinib-resistant chronic myelogenous leukemia cell lines. Saquinavir, which is also a proteasome blocker, showed dose- and time-related anti-proliferative activity, particularly on the imatinib-resistant lines and a pro-apoptotic effect. Association with imatinib caused a significant increase of activity.

Multilineage engraftment of refrozen cord blood hematopoietic progenitors in NOD/SCID mice.

Seven cord blood (CB) units were tested for their capacity to repopulate irradiated NOD/SCID mice after one or two successive cryopreservation procedures. In primary transplants with frozen or refrozen CB cells we observed equivalent human colonies and percentages of human CD45+ cells, with multilineage engraftment. In secondary transplants flow cytometry and polymerase chain reaction for the a satellite region of chromosome 17 showed equivalent levels of human engraftment. Since CB units have, to date, mainly been stored in individual bags, our results suggest new options for optimizing the timing of infusions of expanded and non-expanded progenitors in transplants.

The broad spectrum of autoimmune lymphoproliferative disease: molecular bases, clinical features and long-term follow-up in 31 patients.

Autoimmune lymphoproliferative disorders, including autoimmune lymphoproliferative syndrome (ALPS) and Dianzani autoimmune lymphoproliferative disease (DALD), are inherited defects of the Fas apoptotic pathway characterized by lymphoid accumulation and autoimmune manifestations. We report the molecular, clinical, immunologic features and the long-term progress of 31 patients. Four carried Fas gene mutations and one also displayed a caspase 10 polymorphism that probably contributed to the phenotype. Seven patients developed antibody deficiency and their clinical pictures overlapped those of subjects with common variable immunodeficiency (CVID). We postulate the existence of a disorder that involves the Fas pathway and displays the characteristics of both autoimmune lymphoproliferative disease and CVID.

Flow cytometric evaluation of circulating CD34+ cell counts and apoptotic rate in children with acquired aplastic anemia and myelodysplasia.

OBJECTIVE: Identification of a rapid and noninvasive test for the follow-up of aplastic anemia (AA) patients during immunosuppressive therapy (IST) to evaluate its functional effect on hematopoietic progenitors (HPC) and for early detection of progression to myelodysplasia or relapse. MATERIALS AND METHODS: Absolute count and apoptotic rate (AR) of peripheral blood (PB) CD34+ cells were evaluated by three-color flow cytometry for CD45, CD34, and annexin V in cord blood (CB), normal children, and adults, as well as in pediatric patients with AA at diagnosis and during IST, Fanconi anemia (FA), chronic immune cytopenia, and refractory anemia with excess blasts (RAEB). RESULTS: In normal subjects, the AR of PB CD34+ cells showed a progressive increase (p < 0.05), while their counts decreased (p < 0.05) from birth to adulthood. In very severe AA (vSAA) and severe AA (SAA) at diagnosis, the AR was 91.6% +/- 2.8%, higher than controls (p < 0.05), and PB CD34+ cell count was 2.6 +/- 2.4/microL. In FA patients, the PB CD34+ AR was again significantly increased (54.2% +/- 13.7%) with an absolute count of 3.7 +/- 1.2/microL. Conversely, in RAEB the AR was 11.7% +/- 3.5% and the absolute count 85.1 +/- 48.2/microL (p < 0.05). Chronic immune cytopenias did not significantly differ from controls. CONCLUSIONS: Flow cytometry evaluation of PB CD34+ AR and counts is a noninvasive and feasible first-step method for the differentiation of AA and myelodysplasia (MDS), and it might be useful for monitoring AA during IST to secure the early detection of relapse or transformation to MDS.

Recovery of cord blood hematopoietic progenitors after successive freezing and thawing procedures.

BACKGROUND AND OBJECTIVES: Cord blood (CB) is a valuable source of stem cells. Most CB units are still cryopreserved in single bags in the world's CB banks. Thawing a single CB unit, dividing it into two parts, expanding the smaller one and refreezing the other would optimize ex vivo expansion of CB progenitors prior to transplantation: expanded and unexpanded cells could be infused together to accelerate early engraftment. DESIGN AND METHODS: The feasibility of refreezing CB samples was investigated by evaluating the effect of 3 successive cryopreservation procedures in 9 CB units. The number and viability of WBC, BFU-E, CFU-GM, CFU-MIX, LTC-IC, and the absolute CD34+ cell count were assessed at time 0 and after each thawing. The percentage of CD34 cells expressing CD38, L-selectin, VLA-4, VLA-5, H-CAM, LFA-1 and CXCR4 was also evaluated. RESULTS: After three freezing and thawing procedures, WBC counts decreased, while lymphocytes were unchanged. Viability was 90% of basal values after the first thawing and did not change. BFU-E decreased significantly only after the third thawing. CFU-GM and CFU-MIX did not change significantly, nor did LTC-IC, CD34+ cell counts and CAM and CXCR4 expression on CD34+/ CD38-- cells. INTERPRETATION AND CONCLUSIONS: These data show that two successive freeze-thaw procedures do not significantly affect the clonogenic potential and CAM expression of cord blood progenitors. This information could be exploited to devise new options in ex vivo expansion procedures and quality controls prior to transplantation.