Indeterminate cell histiocytosis in association with later occurrence of acute myeloblastic leukaemia.

Indeterminate cell histiocytosis (ICH) is a proliferation of indeterminate CD1a+, CD68+, S100+ and CD207- dermal dendritic cells. We describe a 39-year-old man who developed diffuse ICH and, 6 years later, acute myeloblastic leukaemia (AML). He was treated with cyclophosphamide, etoposide and vinblastine until 2003. In August 2004, he presented dyspnoea, hyperpyrexia and infiltration of the lung parenchyma, compatible with an AML invasion, and died after a course of induction chemotherapy. Cytomorphology and immunophenotype analyses suggested an ICH clonal evolution. The leukaemogenic role of etoposide is discussed. ICH has previously been reported in association with B-cell malignancy, but only one case has shown systemic progression.

Sensitivity of human multiple myelomas and myeloid leukemias to the proteasome inhibitor I.

The proteasome inhibitor PSI is potently cytotoxic in vitro against human chronic myeloid leukemia (CML) and acute myeloid leukemias (AML). Here, we have tested proteasome inhibitor I (PSI) in a panel of 11 human multiple myeloma (MM) cell lines and found that it has antiproliferative activity, with an IC50 between 4.5 and 557 nM at 48 h. PSI potentiated the toxicity of a number of chemotherapeutic agents in myeloid leukemia but not in MM cell lines, while in combination with therapeutic proteasome inhibitor PS-341 (Bortezomib) it had a synergistic effect. PSI suppressed the growth of AML cell lines more effectively than PS-341. CFU-GM colony assays revealed that CD34+ bone marrow progenitors from CML and AML patients were more sensitive to PSI than those from normal subjects (IC50: 5, 15 and 50 nM for AML, CML and normal, respectively). Moreover, the growth of normal primitive progenitors (LTC-IC) was unaffected by 15 nM PSI (P=0.576). PSI-induced cell death required RNA transcription and protein synthesis, but not DNA replication, was accompanied by the upregulation of Bcl-2 and modest reduction of Bax and Bcl-XL proteins, and involved the activation of caspases 2, 3, 7 and 8. These findings lend additional support to preclinical investigations with PSI.

Neuro-glial differentiation of human bone marrow stem cells in vitro.

Bone marrow (BM) is a rich source of stem cells and may represent a valid alternative to neural or embryonic cells in replacing autologous damaged tissues for neurodegenerative diseases. The purpose of the present study is to identify human adult BM progenitor cells capable of neuro-glial differentiation and to develop effective protocols of trans-differentiation to surmount the hematopoietic commitment in vitro. Heterogeneous cell populations such as whole BM, low-density mononuclear and mesenchymal stem (MSCs), and several immunomagnetically separated cell populations were investigated. Among them, MSCs and CD90+ cells were demonstrated to express neuro-glial transcripts before any treatment. Several culture conditions with the addition of stem cell or astroblast conditioned media, different concentrations of serum, growth factors, and supplements, used alone or in combinations, were demonstrated to alter the cellular morphology in some cell subpopulations. In particular, MSCs and CD90+ cells acquired astrocytic and neuron-like morphologies in specific culture conditions. They expressed several neuro-glial specific markers by RT-PCR and glial fibrillary acid protein by immunocytochemistry after co-culture with astroblasts, both in the absence or presence of cell contact. In addition, floating neurosphere-like clones have been observed when CD90+ cells were grown in neural specific media. In conclusion, among the large variety of human adult BM cell populations analyzed, we demonstrated the in vitro neuro-glial potential of both the MSC and CD90+ subset of cells. Moreover, unidentified soluble factors provided by the conditioned media and cellular contacts in co-culture systems were effective in inducing the neuro-glial phenotype, further supporting the adult BM neural differentiative capability.

Transdermal fentanyl in HSCT patients: an open trial using transdermal fentanyl for the treatment of oral mucositis pain.

Fentanyl is a synthetic opioid that can be delivered through a transdermal therapeutic system (TTS). The aim of this study was to assess the efficacy of fentanyl TTS in treating oral mucositis pain in 75 adult hematopoietic stem cell transplant (HSCT) patients. The analysis was based on 62 patients who developed mucositis. Pain control was assessed by the patients using a visual analogue scale (VAS) from day 0 to day +33 after HSCT. Fentanyl TTS was administered at the patient's request. In all, 20 patients did not require fentanyl (group A). The first 22 patients asking for the patch received fentanyl 25 microg/h (group B) and the subsequent 20 patients received 50 microg/h (group C). There were no significant differences in pain relief between groups B and C. The expected effect of a decrease in mean pain score (mean of the VAS scores of all of the patients in the same group each day) following the application of fentanyl TTS was not noted. We can conclude that fentanyl TTS at the doses used in this study may not adequately relieve oral mucositis pain.

Esophageal involvement as an uncommon modality of relapse of Hodgkin lymphoma.

We present a case of systemic Hodgkin's lymphoma, relapsed with esophageal involvement after 3 years of complete remission. The importance of an accurate diagnostic work-up is emphasized. Esophagectomy and chemotherapy followed by bone marrow transplantation allowed a complete response and the long-term survival of the patient.

Treatment of advanced mycosis fungoides by allogeneic stem-cell transplantation with a nonmyeloablative regimen.

SUMMARY: Given the poor prognosis of patients with advanced cutaneous T-cell lymphoma and the high transplant-related mortality associated with conventional allogeneic bone marrow transplantation, we performed nonmyeloablative transplantation of allogeneic stem cells (ASCT) from HLA-identical siblings in three patients with this disease. All patients achieved full donor engraftment, clearance of clonal T cells leading to durable complete remissions but experienced high incidence of infections, which proved fatal in one case. These results suggest that nonmyeloablative ASCT is a novel and potentially curative therapy for patients with advanced T-cell lymphomas who have a histocompatible sibling.

Modulated generation of neuronal cells from bone marrow by expansion and mobilization of circulating stem cells with in vivo cytokine treatment.

The aim of the present study is to determine whether the expansion and mobilization of circulating bone marrow (BM) stem cells by in vivo treatment with granulocyte-colony stimulating factor (G-CSF) and stem cell factor (SCF) increase the amount of BM-derived neuronal cells in mouse brain. The presence of BM-derived cells in the brain was traced by transplanting into lethally irradiated adults and newborns adult BM from transgenic mice that ubiquitously expressed enhanced green fluorescent protein (GFP). GFP+ and Y-chromosome+ donor-derived cells were present in several brain areas of all treated mice (cortical and subcortical areas, cerebellum, olfactory bulb). The presence of GFP+ cells expressing nuclear neural specific antigen (NeuN), neurofilament, and beta-III tubulin in cortical forebrain and olfactory bulb (OB) was higher in G-CSF-SCF treated groups (P < 0.05, analysis of variance, Fisher post hoc). We observed that overall the amount of double positive cells was higher in animals treated at birth than in adults and in OB than in forebrain areas (P < 0.05). Temporal cortical areas of cytokine-treated adult animals revealed a mean threefold increase in the number of GFP+ cells expressing the nuclear neural specific antigen (211 +/- 86 GFP+NeuN+/mm(3) in G-CSF + SCF treated mice and 66 +/- 33 GFP+NeuN+/mm(3) in control animals). GFP+ cells coexpressing neuronal markers contain only one nucleus and have a DNA index (a measure of DNA ploidy) identical to that of surrounding neurons, thus excluding donor cell fusion with endogenous cells as a relevant phenomenon under these experimental conditions. Our results indicate that G-CSF and SCF administration modulates the availability of GFP+ cells in the brain and enhances their capacity to acquire neuronal characteristics. Cytokine stimulation of autologous stem cells might be seen as a new strategy for neuronal repair in neurodegenerative diseases.

A subpopulation of murine bone marrow cells fully differentiates along the myogenic pathway and participates in muscle repair in the mdx dystrophic mouse.

Bone marrow (BM) transplantation in mice suggests the existence of pluripotent cells able to differentiate into skeletal muscle tissue, although sustained myofiber reconstitution has not yet been achieved. We investigated the myogenic potential of mouse BM cells and evaluated whether a BM fraction enriched for cells expressing skeletal muscle markers would ameliorate muscle repair, when compared to whole BM, into the dystrophic mdx mouse. We demonstrate that cells expressing striated-muscle-specific proteins are already present in the BM independently from experimentally forced myogenic conversion. We observed the presence of both markers of early myogenic program such as Pax3, Myf5, MyoD, desmin, and late myogenesis such as myosin heavy chain and alpha-sarcomeric actin. These myogenic cells are more represented in the early nonadherent BM fraction, which generates clones able to fully differentiate into myotubes. Transplantation in mdx mice by intravenous injection of whole BM and a tenfold BM myogenic enriched fraction resulted in BM reconstitution and limited dystrophin restoration. Taken together, these data show that a fraction of BM cells have a definite potential for differentiation along the skeletal muscle pathway and can be recruited by muscle repair mechanisms. They also indicate that factors limiting the degree of muscle recruitment and the host stem cell competition should be assessed in order to evaluate the usefulness of BM-derived myogenic cells into the context of cell-mediated gene therapy of inherited muscle diseases.

Ultrastructural features of CD34+ hematopoietic progenitor cells from bone marrow, peripheral blood and umbilical cord blood.

Hematopoietic progenitor cells from different sources have been widely characterized, but their ultrastructural morphology has never been described in detail. In this study, imunomagnetically separated CD34+ cells from normal bone marrow (BM), mobilized peripheral blood (PBSC) and human umbilical cord blood (CB) were studied by transmission electron microscopy (TEM) using a cytochemical method which reveals endogenous myelo-peroxidase (MPO) activity. This technique is particularly suited for detecting early signs of the myeloid commitment. The CD34+ cells from PBSC were morphologically very homogeneous and 94.7+/-4.5% of these cells were MPO-: these ultrastructural features are generally considered typical of immature cells. The CD34+ BM cells were instead more heterogeneous, with 24.6+/-7.4% showing intense MPO activity. The ultrastructural characteristics of CB cells fell between those observed in PBSC and BM, but there was a high percentage of morphologically immature cells with no evidence of MPO activity (about 83%). The number of apoptotic cells within samples from different sources was also examined both by TEM and flow cytometry. The percentage of apoptotic cells was 0.7% in PBSC, 2.3% in BM, 2.9% in CB from vaginal delivery and 11.6% in CB from cesarean section. These observations confirm the relative phenotypic immaturity of CB in comparison with BM cells; they also suggest that CB collected after cesarean section may be associated with reduced stem cells viability.

Differentiation and expansion of endothelial cells from human bone marrow CD133(+) cells.

We report a method of purifying, characterizing and expanding endothelial cells (ECs) derived from CD133(+) bone marrow cells, a subset of CD34(+) haematopoietic progenitors. Isolated using immunomagnetic sorting (mean purity 90 +/- 5%), the CD133(+) bone marrow cells were grown on fibronectin-coated flasks in M199 medium supplemented with fetal bovine serum (FBS), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and insulin growth factor (IGF-1). The CD133(+) fraction contained 95 +/- 4% CD34(+) cells, 3 +/- 2% cells expressing VEGF receptor (VEGFR-2/KDR), but did not express von Willebrand factor (VWF), VE-cadherin, P1H12 or TE-7. After 3 weeks of culture, the cells formed a monolayer with a typical EC morphology and expanded 11 +/- 5 times. The cells were further purified using Ulex europaeus agglutinin-1 (UEA-1)-fluorescein isothiocyanate (FITC) and anti-FITC microbeads, and expanded with VEGF for a further 3 weeks. All of the cells were CD45(-) and CD14(-), and expressed several endothelial markers (UEA-1, VWF, P1H12, CD105, E-selectin, VCAM-1 and VE-cadherin) and typical Weibel-Palade bodies. They had a high proliferative potential (up to a 2400-fold increase in cell number after 3 weeks of culture) and the capacity to modulate cell surface antigens upon stimulation with inflammatory cytokines. Purified ECs were also co-cultivated with CD34(+) cells, in parallel with a purified fibroblastic cell monolayer. CD34(+) cells (10 x 10(5)) gave rise to 17,951 +/- 2422 CFU-GM colonies when grown on endothelial cells, and to 12,928 +/- 4415 CFU-GM colonies on fibroblast monolayers. The ECs also supported erythroid blast-forming unit (BFU-E) colonies better. These results suggest that bone marrow CD133(+) progenitor cells can give rise to highly purified ECs, which have a high proliferative capacity, can be activated by inflammatory cytokines and are superior to fibroblasts in supporting haematopoiesis. Our data support the hypothesis that endothelial cell progenitors are present in adult bone marrow and may contribute to neo-angiogenesis.

Efficient retrovirus-mediated transduction of primitive human peripheral blood progenitor cells in stroma-free suspension culture.

Retroviral transduction of hematopoietic cells has resulted in unsatisfactory gene marking in clinical studies. Since cytokine-stimulated stem cells have engrafted poorly in animal models, we investigated phenotypic changes during culture of peripheral blood progenitor cells (PBPC). Human CD34(+) HLA-DR(low) cells, immunomagnetically separated from PBPC collections, were found to extrude rhodamine-123, which is characteristic for primitive hematopoietic cells. Cells were grown in suspension cultures supplemented with cytokines. While interleukin-3-containing factor combinations promoted cell proliferation they caused loss of rhodamine-123 extrusion and reduced the frequencies of cobblestone area-forming cells (CAFC). Several other cytokines failed to stimulate cell divisions, which are required for retroviral transduction. A combination including Flt-3 ligand (FL), interleukin-6 and stem cell factor (SCF) preserved an immature phenotype for 5 to 6 days and stimulated cell divisions, which was improved upon addition of leukemia inhibitory factor and interleukin-11. Furthermore, the CAFC frequency among cells treated with these cytokines was increased as compared with widely used cocktails containing interleukin-3, interleukin-6 and SCF. Rhodamine-123 appeared to be a particularly sensitive indicator for differentiation of PBPC. For analysis of gene transfer, amphotropic retroviruses conferring an MDR1 cDNA were added repeatedly for 6 days to cytokine-treated PBPC stroma-free cultures. Proviral cDNA was detected by polymerase chain reaction in 68% of cobblestone areas derived from CD34(+)HLA-DR(low) cells that had been exposed to Flt-3 ligand, interleukin-6 and SCF. In summary, conditions were identified that facilitate efficient transduction of early PBPC with amphotropic retroviruses while preserving a primitive phenotype for extended periods.

Unrelated donor marrow transplantation: an update of the experience of the Italian Bone Marrow Group (GITMO).

BACKGROUND AND OBJECTIVES: Unrelated donor bone marrow transplant (UD-BMT) has become an attractive alternative source of hematopoietic cells for patients lacking a matched sibling. The aim of this paper was to report on results of the 696 UD BMTs performed in 31 Italian institutions during the first 10 years of activity of the Italian Bone Marrow Donor Registry (IBMDR). EVIDENCE AND INFORMATION SOURCES: In 1989 the Italian Bone Marrow Transplant Group (GITMO) established the IBMDR to facilitate donor search and marrow procurement for patients lacking an HLA identical sibling. By end of December 1999, 260,000 HLA-A, B typed volunteer donors had been cumulatively registered and 2,620 searches had been activated for Italian patients. At least one HLA-A, B, DRB1 matched donor was found for 54% of the patients and 696 UD BMTs were performed. In 50% of cases the donor was found in the IBMDR and in 50% in 15 other Registries. The average time from search activation to transplant was 6 months for disease other than CML. For CML it was 14 months. Actuarial 12-month transplant-related mortality (TRM) was 68% in patients grafted between 1979 and 1992 and 44% for patients grafted after 1993. Twenty-eight per cent of patients developed grade III or IV acute GvHD and 24% developed extensive chronic GvHD. The rate of disease free survival at three years was 57% for patients with 1st chronic phase CML, 37% for patients with 1st or 2nd CR ALL, 31% for AML or MDS patients 18 years of age and 54% for patients with inborn errors. PERSPECTIVES: We conclude that the IBMDR has benefited a substantial number of patients lacking a matched sibling and has facilitated the recruitment of UDs into the international donor pool. The long time required for the search is the major obstacle to the success of this programme. This suggests that early transplant and a decrease in TRM could further improve these encouraging results.

The apoptogenic response of human myeloid leukaemia cell lines and of normal and malignant haematopoietic progenitor cells to the proteasome inhibitor PSI.

Degradation of several intracellular proteins involved in cell cycle control and tumour growth is regulated by the ubiquitin-dependent multicatalytic protease complex (proteasome). We report that proteasome inhibitor Z-Ile-Glu(OtBu)-Ala-Leucinal (PSI) was cytotoxic on most human myeloid leukaemia cell lines at IC50 doses ranging from 5 to 25 nmol/l. Additionally, PSI pre-treatment enhanced cytotoxicity by taxol and cisplatinum. PSI was more active on leukaemic than on normal CD34(+) bone marrow progenitors because the 50% growth inhibition of colony-forming unit granulocyte macrophage (CFU-GM) from cases of chronic myelogenous leukaemia (CML) and normal subjects was achieved by 15 nmol/l and 50 nmol/l PSI respectively. PSI killed cells by apoptosis as revealed by ultrastructural changes, nuclear DNA fragmentation, cleavage of poly (ADP-ribose) polymerase (PARP) and of beta-catenin, and was antagonized by ectopic expression of Bcl-2 but not by inactivating mutations of p53. This event was associated with a slight accumulation of Bcl-2, a decrease of Bax but no changes in Bcl-X(L) protein expression at any time point. In Ph(+) cell lines BCR-ABL protein was only down-regulated after 48 h of treatment with 10 nmol/l PSI. Altogether, these results indicate that PSI, alone or in association with other cytotoxic agents, has anti-tumour activity against myeloid malignancies and is more effective on leukaemic than on normal haematopoietic progenitor cells.

Bone marrow-disseminated tumor cells in patients with carcinoma of the esophagus or cardia.

BACKGROUND: The long-term prognosis after surgical therapy for esophageal carcinoma depends on tumor stage and completeness of resection. Similarly to other epithelial tumors, the presence of micro deposits of neoplastic cells in the bone marrow may indicate residual disease and the potential for recurrence. This study assesses the prevalence of bone marrow-disseminated tumor cells in patients undergoing surgical resection for esophageal carcinoma. In addition, we investigated the agreement between immunohistochemical and molecular techniques for the detection of micrometastases in a subgroup of patients. METHODS: Between January 1998 and November 1999, forty-eight patients with adenocarcinoma of the esophagogastric junction (n = 29) or squamous cell carcinoma of the thoracic esophagus (n = 19) and no evidence of overt metastatic disease entered the study. An immunohistochemical assay (capable of detecting 1 carcinoma cell in 7 x 10(5) bone marrow cells) was used to test bone marrow obtained by flushing a resected rib or by needle aspiration either of the iliac crest or of a rib. A polymerase chain reaction (PCR) molecular technique was also used to identify bone marrow and peripheral blood epithelial cells. RESULTS: Cytokeratin-positive cells were found in 79.1% of the bone marrow samples obtained from the rib, and in only 8% of the needle aspirates either from the iliac crest or from a contiguous rib: This difference is probably explained by the improved removal of metastatic cells with the flushing of the rib. Comparable results were obtained at a qualitative level by the PCR technique on bone marrow. In addition, PCR-positive results were found in 3 of 18 peripheral blood samples. There was no association with tumor type, neoadjuvant therapy, or lymph node status. Patients with a pT3 or pT4 tumor showed, at a borderline statistical level, a higher proportion of cytokeratin-positive cells in the flushed rib. CONCLUSIONS: Bone marrow-disseminated tumor cells are present in the resected rib of a high proportion of patients undergoing esophagectomy for carcinoma, and immunohistochemistry seems to be the method of choice for their quantitative assessment. However, the prognostic and therapeutic implications of this finding need further investigation.

Hereditary hemochromatosis in a patient with congenital dyserythropoietic anemia.

Herein is described the case of a young woman presenting with iron overload and macrocytosis. The initial diagnosis was hereditary hemochromatosis. Severe anemia developed after a few phlebotomies, and she was also found to have congenital dyserythropoietic anemia that, though not completely typical, resembled type II. Only genetic testing allowed the definition of the coexistence of the 2 diseases, both responsible for the iron overload. This report points out the need to consider congenital dyserythropoietic anemia in patients with hemochromatosis and unexplained macrocytosis and, conversely, to check for the presence of hereditary hemochromatosis in patients with congenital dyserythropoietic anemia and severe iron overload. To the authors' knowledge, this is the first report of homozygosity for the C282Y mutation of the HFE gene in a patient affected by congenital dyserythropoietic anemia.

Histological alterations in bone marrow in patients with late engraftment after autologous bone marrow transplantation.

Bone marrow histology after bone marrow transplantation has rarely been studied. Here, we reviewed the pre- and post-transplant bone marrow biopsies (BMB) of 40 acute myelogenous leukemia (AML) patients autografted in our center, 28 with normal and 12 with delayed peripheral recovery. The two groups were comparable in terms of previous therapy, disease phase and the number of infused cells, and received the same conditioning regimen. In the former group, reduced bone marrow cellularity and mild reticulin abnormalities were usual histological findings; in the latter, five patients had the same pattern, but the other seven had an almost undetectable hematopoietic parenchyma and severe reticulin derangement. One of these seven patients died of reactivated hepatitis B virus infection; the others eventually achieved peripheral recovery, with none of them experiencing a relapse. Autografted AML patients are excellent subjects for histological investigations. They account for the majority of delayed engraftments, the contribution of extramedullary components to the timing of engraftment is minimal, and leukemia relapse cannot be ruled out. These results suggest that BMB is a useful investigation in the work-up of late engraftment. A high degree of reticulin derangement with an almost undetectable hematopoietic parenchyma appear to be the morphological hallmarks of late engraftment.

Functional differences between dendritic cells derived from CD34+ bone marrow and peripheral blood stem cells.

BACKGROUND AND OBJECTIVE: It has been previously demonstrated that dendritic cells (DCs) are characterized by an immature stage with high antigen internalization capacity, followed by a mature stage with predominantly immunostimulatory ability. The shift from the immature to the mature state can be induced in vitro by the addition of tumor necrosis factor-a (TNFa). The aim of our study was to investigate the maturation steps of DCs obtained from CD34(+) cells from peripheral blood stem cells (PBSC) and bone marrow (BM). DESIGN AND METHODS: DCs were generated in vitro from PBSC and BM CD34(+) selected cells. The endocytic activity of the cells was measured by means of dextran-FITC uptake and alloreactivity evaluated with mixed leukocyte reactions. Immunophenotypic analysis was performed by flow cytometry. RESULTS: We observed that DCs from PBSC, in contrast to the BM derived DCs, were never able to take up soluble antigens. Mixed leukocyte reactions (MLR) performed both on PBSC and BM CD34(+) derived DCs showed an allo-stimulatory activity comparable to normal controls at day 10, but significantly higher at day 14 after the addition of TNFa. Immunophenotypic analysis showed typical dendritic markers in all the samples and, after treatment with TNFa, enhanced expression of co-stimulatory molecules. INTERPRETATION AND CONCLUSIONS: Our data seem to indicate that, in our culture conditions, BM-derived DCs could be efficiently used for pulsing with specific peptides, while PBSC-derived DCs, being functionally mature, should be more suitable for gene therapy.

Unrelated donor marrow transplantation: an update of the experience of the Italian Bone Marrow Transplant Group (GITMO).

Unrelated donor bone marrow transplant (UD-BMT) has become an attractive alternative source of hematopoietic cells for patients lacking a matched sibling. The aim of this paper was to report on results of the 696 UD BMTs performed in 31 Italian institutions during the first 10 years of activity of the Italian Bone Marrow Donor Registry (IBMDR). In 1989 the Italian Bone Marrow Transplant Group (GITMO) established the IBMDR to facilitate donor search and marrow procurement for patients lacking an HLA identical sibling. By end of December 1999, 260,000 HLA-A, B typed volunteer donors had been cumulatively registered and 2,620 searches had been activated for Italian patients. At least one HLA-A, B, DRB1 matched donor was found for 54% of the patients and 696 UD BMTs were performed. In 50% of cases the donor was found in the IBMDR and in 50% in 15 other Registries. The average time from search activation to transplant was 6 months for disease other than CML. For CML it was 14 months. Actuarial 12-month transplant-related mortality (TRM) was 68% in patients grafted between 1979 and 1992 and 44% for patients grafted after 1993. Twenty-eight per cent of patients developed grade III or IV acute GvHD and 24% developed extensive chronic GvHD. The rate of disease free survival at three years was 57% for patients with 1st chronic phase CML, 37% for patients with 1st or 2nd CR ALL, 31% for AML or MDS patients < or = 18 years of age and 54% for patients with inborn errors. We conclude that the IBMDR has benefited a substantial number of patients lacking a matched sibling and has facilitated the recruitment of UDs into the international donor pool. The long time required for the search is the major obstacle to the success of this programme. This suggests that early transplant and a decrease in TRM could further improve these encouraging results.

Angiogenesis in myelodysplastic syndromes.

It is now well established that solid tumour growth depends on angiogenesis. However, less is known about the generation of new vessels in haematological malignancies and, in particular, in preleukaemic-myelodysplastic syndromes (MDS). In this study, bone marrow microvessel density (MVD) was assessed by immunohistochemistry and compared in trephine biopsies from 14 controls, five infectious disease (ID), 82 MDS, 15 acute myeloid leukaemia (AML) and 14 myeloproliferative disorder (MPD) patients. Statistical analysis (P < 0.001) demonstrated that MDS MVD was higher than in controls and ID (21 +/- 9 vs 6 +/- 2 and 10 +/- 8 respectively) but lower than AML (30 +/- 12) and MPD (40 +/- 12). Among MDS-FAB subtypes, MVD was significantly higher in RAEB-t, CMML and fibrosis subsets compared to RA, RARS and RAEB subsets (P= 0.008). To further investigate angiogenesis machinery, the expression of vascular endothelial growth factor (VEGF) was evaluated by means of immunohistochemistry in control, MDS, AML and MPD biopsies. Even though VEGF mRNA expression was reported in the past in AML cell cultures and cell lines, in our samples VEGF expression was found to be particularly strong in most of the megakaryocytes but significantly less prominent in other cell populations including blasts. Since our findings suggest a correlation between angiogenesis and progression to leukaemia, additional work is now warranted to determine what regulates the generation of new vessels in MDS and leukaemia.