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Twenty-eight children with beta-thalassaemia major aged between 11 and 48 months were given intensive transfusions. Serum iron, transferrin saturation, serum ferritin, non-transferrin iron, and subcutaneous desferrioxamine-induced urinary iron excretion were measured. The results showed that even children with a limited number of transfusions had severe iron overload as indicated, in particular, by the raised serum ferritin levels and the high excretion rates after subcutaneous infusion of desferrioxamine. The desferrioxamine test was useful, even in very young children, in assessing response to chelation therapy thus enabling such treatment to be started early to prevent harm from iron overload. [ABSTRACT FROM AUTHOR]

The relationship between blood requirement and the mean level of maintained haemoglobin was examined in 392 patients with homozygous beta-thalassaemia. Pre- and post-transfusional haemoglobin levels and the amounts of blood transfused were measured during a 1-year period. No significant differences were noted in the blood requirements of patients (splenectomised or not) irrespective of the haemoglobin level. It may be supposed that if the mean haemoglobin level is high the haematopoietic activity is inhibited, and hence the bone marrow mass and total blood volume are reduced. High haemoglobin levels may thus be obtained with no increase in blood intake. [ABSTRACT FROM AUTHOR]

We investigated the expression of different cell adhesion molecules on cord blood (CB) and bone marrow (BM) CD34+/CD38+ and CD34+/CD38- cells. CD11a and CD62L were more expressed in CB than in BM CD34+/CD38- subset, suggesting a possible advantage in homing and engraftment. A short exposure to various cytokines increased CD62L expression only in the more differentiated CB and BM CD34+/CD38+ cells.

Self-renewal, proliferation, differentiation, homing, and mobilization of hematopoietic progenitor cells (HPCs) are regulated by a complex mechanism that involves the bone marrow (BM) microenvironment. Cell adhesion molecules (CAMs) expressed on HPCs and on endothelial and stromal cells play a pivotal role in this process. In this study, we have used three-color cytofluorometric analysis to compare CAM expression in the subsets of cord blood (CB) and BM HPCs and examined the effect of a short exposure to various cytokines on L-selectin expression. The study was carried out on unseparated samples to avoid any possible bias from positive CD34 selection. CAMs were highly expressed in both CB and BM CD34+CD38+ cells. In this population, L-selectin, H-CAM, and LFA-1 were significantly more expressed in BM than in CB. With regard to the more immature progenitors, the subsets of CD34+/CD38-/L-selectin+ and CD34+/CD38-/LFA1+ cells were significantly larger in CB than in BM. Since the expression of such CAMs has been related to the repopulating capacity of HPCs, our results suggest a possible advantage in homing and engraftment of more undifferentiated CB as opposed to BM HPCs. A 4/24-h exposure to various cytokines significantly increased the percentage of CB CD34+/CD38+/L-selectin+ cells, while HPCs were differentiated since the percentage of CD34+/CD38-/L-selectin+ cells was reduced. These data show that a short exposure to cytokines increases L-selectin expression in the more differentiated CB HPCs. This could improve their homing in a transplant setting.

Characterization of proteins that control the passage through the G1 phase of the cell cycle is of particular interest because virtually all stimuli regulating cell proliferation or differentiation act primarily during this phase. We have analyzed the G1 phase proteic machinery, including cyclin D types, cyclin-dependent kinases (CDKs) and CDK inhibitors, of cell populations obtained at different stages of hematopoietic cell lineage. In particular, five cellular phenotypes, namely CD34+ cells (which contain stem cells), BFU-E, CFU-E, CFU-GM and peripheral lymphocytes were studied as representatives of distinct differentiation pathways. The results obtained indicated that all the cellular preparations express cyclin D2 and D3, while cyclin D1, which is the major cyclin D occurring in mesenchimal tissues, is not expressed. Moreover, CDK6 (but not CDK4) was detectable in all the populations investigated. Among the CDK inhibitors studied, p18INK4C and p19INK4D signals were clearly evidentiable in the various cell types. Interestingly, high levels of p15INK4B, a putative tumor suppressor protein, were detectable especially in granulocyte-monocyte precursors. Our results indicate that a specific hematopoietic G1 phase machinery occurs, which is conserved during the various steps of the different maturation processes.

Previous studies have reported erythrocyte macrocytosis in adults and children with Down syndrome (DS), the significance of which remains unclear. We compared hematological parameters of 50 DS children aged 2 to 15 years, divided into three age groups, with those of 68 aged-matched healthy children. Patients with DS had a significantly increased mean corpuscular volume (MCV) and hemoglobin in all groups when compared with the controls. Erythrocyte creatine content, hexokinase (Hk) activity, erythrocyte and serum folates, vitamin B12, haptoglobin, serum iron, and ferritin were tested. All of these parameters were not significantly different from those of the control group. We conclude that macrocytosis may not be an expression of reduced red cell survival but rather of an altered folate remethylation pathway, secondary to enhanced cystathionine beta-synthase (CBS) activity, the gene for which is present on chromosome 21.

The improvement in survival and quality of life of iron-overloaded patients achieved by regular subcutaneous chelation has been extensively documented over the years. A review of the long-term results allows one to establish the following points: (1) with regular subcutaneous chelation, a negative iron balance can be obtained in most patients, except very young ones; (2) severe deferoxamine (DFO) toxicity may be prevented by skipping high doses and by carefully monitoring and modulating chelation, especially in patients with a low iron overload; (3) the maintenance of compliance with DFO over 0.6 and of ferritin levels below 2,000 prevents iron overloaded complications, at least for the first 20 years of life; (4) long-term chelation can reverse functional complications such as liver fibrosis, arrhythmia and echocardiographic abnormalities, but not complications due to extensive tissue alterations, such as frank diabetes, hypothyroidism and myocardiosclerosis; (5) intensive intravenous protocols can be successfully applied in heavily overloaded patients and represent the only possibility to reverse their dangerous iron burden in a relatively short period of time; (6) survival and quality of life in well-chelated patients are approaching a normal pattern, and (7) clinical outcome and prognosis are better evaluated by parameters that consider iron overload and chelation trends.

Long-term blood transfusions lead to the accumulation of iron that in the absence of chelation therapy causes complications such as liver cirrhosis, growth failure, hypogonadism, hypothyroidism, hypoparathyroidism, diabetes and myocardiopathy. The last still represents the most frequent cause of death in haemosiderotic transfusion-dependent patients. At the moment the only chelator widely used is desferrioxamine (DFX). The drug works best when administered as a continuous infusion, mainly by the subcutaneous route. To patients with severe iron overload, impending organ failure, or poor compliance to chelation, DFX can be administered intravenously, through an externalized central catheter or, preferably, a subcutaneous port. Several studies have shown the effectiveness of DFX in reducing the iron burden, thus preventing the complications, once considered inevitable, of iron overload, and even in reverting some, but not all, of the iron-induced dysfunctions. Practical and psychological support are necessary to ensure satisfactory compliance with a therapy that is cumbersome and difficult. Toxic effects of DFX such as growth failure, hearing impairment and bone abnormalities seem to occur mainly in patients who have received high doses of DFX despite a low iron burden. Visual loss and renal and pulmonary toxicities, on the contrary, seem to be more directly related to high DFX peak doses administered irrespective of the patient's amount of iron overload. After bone marrow transplantation, phlebotomy or erythrocytoapheresis might be necessary to reduce further the iron accumulated during years of transfusions.

The iron chelator desferrioxamine (DFO) has been shown to inhibit the proliferation of hemopoietic progenitors and several tumor cell lines. We have compared the in viro hemopoietic inhibitory effect of desferrioxamine (DFO) and hydroxypyridones (HPOs) on hemopoietic progenitors and two human neuroectodermal (NE) tumor cell lines, NB 100 and SKNMC. Both DFO and HPOs showed a direct dose-related inhibitory effect on BFU-E and CFU-GM obtained from purified human non-T MNAC (T-lymphocyte-depleted nonadherent mononuclear cells) and CD34+ cells. DFO and HPOs displayed both an inhibitory and a cytotoxic effect on NE cell lines. We calculated the ratio between NE cell and hemopoietic cell growth inhibition for a range of concentrations of chelators. DFO showed the most satisfactory ratio. This suggests that DFO is still the most preferable chelating agent for the treatment of neuroblastoma, since it combines the highest antineuroblastoma effect with the lowest hematopoietic toxicity.

A high number of stem cells migrate in fetal blood and, at birth, the number of progenitors in cord blood equals or exceeds that of adult bone marrow. Recently hemopoiesis has been successfully reconstituted with the infusion of cord blood cells. It is important to clearly define the quantity and quality of cord blood totipotent and multilineage progenitors to evaluate the possibility of their utilization in transplants. Our first aim was to study the growth characteristics of cord blood progenitors. We have evaluated the number of cycling cells with the thymidine suicide technique and the production, by phytohemagglutinin (PHA) stimulated cord blood mononuclear cells, of some cytokines involved in the proliferation of progenitor cells, such as granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin 6 (IL-6) and leukemia inhibitory factor (LIF). We have also studied by flow cytometry the CD34+CD33-, CD34+CD33+ cell subsets and the presence of the c-kit receptor in order to quantitate the number of earlier progenitors. Our second aim was to elucidate whether the cord blood totipotent stem cell population or the committed progenitors could be expanded in vitro. Our results showed that in cord blood the number of early progenitors, as evaluated by the number of mixed lineage colony forming units (CFU-Mix), by the CD34+CD33- subsets and the expression of the c-kit, is higher than in bone marrow. We have also demonstrated the possibility in vitro of increasing the number of progenitors by more than 30-fold by utilizing stem cell factor (SCF) in association with other cytokines.(ABSTRACT TRUNCATED AT 250 WORDS)