Abnormal localization of immature precursors (ALIP) in the bone marrow of myelodysplastic syndromes: current state of knowledge and future directions

Impairment of FOXM1 expression in mesenchymal cells from patients with myeloid neoplasms, de novo and therapy-related, may compromise their ability to support hematopoiesis

Bone marrow mesenchymal stem cells (BM-MSCs) exhibit multiple abnormalities in myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML), including reduced proliferative and clonogenic capacity, altered morphology, impaired immunoregulatory properties and capacity to support hematopoiesis. Here, we investigated expression of the FOXM1 gene, a transcription factor driving G2/M gene expression, in BM-MSCs isolated from patients with MDS and AML, de novo and therapy-related, compared to BM-MSCs isolated from healthy donors (HD). We observed a statistically significant downregulation of FOXM1 expression in BM-MSCs isolated from MDS and AML patients, as compared to controls. In parallel, expression of FOXM1 mitotic targets (CCNB1, CDC20, PLK1 and NDC80) was suppressed in patients' BM-MSCs, as compared to HD. No differences in the expression of FOXM1 and its mitotic targets were observed in BM-mononuclear cells from the different sources. From a functional standpoint, silencing of FOXM1 mRNA in healthy MSC induced a significant decrease in the expression of its targets. In this line, healthy MSC silenced for FOXM1 showed an impaired ability to support hematopoiesis in vitro. These findings suggest that deregulation of FOXM1 may be involved in the senescent phenotype observed in MSC derived from myeloid neoplasms.

Nature or Nurture? Role of the Bone Marrow Microenvironment in the Genesis and Maintenance of Myelodysplastic Syndromes

Myelodysplastic syndrome (MDS) are clonal haematopoietic stem cell (HSC) disorders driven by a complex combination(s) of changes within the genome that result in heterogeneity in both clinical phenotype and disease outcomes. MDS is among the most common of the haematological cancers and its incidence markedly increases with age. Currently available treatments have limited success, with <5% of patients undergoing allogeneic HSC transplantation, a procedure that offers the only possible cure. Critical contributions of the bone marrow microenvironment to the MDS have recently been investigated. Although the better understanding of the underlying biology, particularly genetics of haematopoietic stem cells, has led to better disease and risk classification; however, the role that the bone marrow microenvironment plays in the development of MDS remains largely unclear. This review provides a comprehensive overview of the latest developments in understanding the aetiology of MDS, particularly focussing on understanding how HSCs and the surrounding immune/non-immune bone marrow niche interacts together.

The Dynamic Interface Between the Bone Marrow Vascular Niche and Hematopoietic Stem Cells in Myeloid Malignancy

Hematopoietic stem cells interact with bone marrow niches, including highly specialized blood vessels. Recent studies have revealed the phenotypic and functional heterogeneity of bone marrow endothelial cells. This has facilitated the analysis of the vascular microenvironment in steady state and malignant hematopoiesis. In this review, we provide an overview of the bone marrow microenvironment, focusing on refined analyses of the marrow vascular compartment performed in mouse studies. We also discuss the emerging role of the vascular niche in “inflamm-aging” and clonal hematopoiesis, and how the endothelial microenvironment influences, supports and interacts with hematopoietic cells in acute myeloid leukemia and myelodysplastic syndromes, as exemplar states of malignant myelopoiesis. Finally, we provide an overview of strategies for modulating these bidirectional interactions to therapeutic effect in myeloid malignancies.

The orphan nuclear receptor EAR-2 (NR2F6) inhibits hematopoietic cell differentiation and induces myeloid dysplasia in vivo

Background

In patients with myelodysplastic syndrome (MDS), bone marrow cells have an increased predisposition to apoptosis, yet MDS cells outcompete normal bone marrow (BM)-- suggesting that factors regulating growth potential may be important in MDS. We previously identified v-Erb A related-2 (EAR-2, NR2F6) as a gene involved in control of growth ability.

Methods

Bone marrow obtained from C57BL/6 mice was transfected with a retrovirus containing EAR-2-IRES-GFP. Ex vivo transduced cells were flow sorted. In some experiments cells were cultured in vitro, in other experiments cells were injected into lethally irradiated recipients, along with non-transduced bone marrow cells. Short-hairpin RNA silencing EAR-2 was also introduced into bone marrow cells cultured ex vivo.

Results

Here, we show that EAR-2 inhibits maturation of normal BM in vitro and in vivo and that EAR-2 transplant chimeras demonstrate key features of MDS. Competitive repopulation of lethally irradiated murine hosts with EAR-2-transduced BM cells resulted in increased engraftment and increased colony formation in serial replating experiments. Recipients of EAR-2-transduced grafts had hypercellular BM, erythroid dysplasia, abnormal localization of immature precursors and increased blasts; secondary transplantation resulted in acute leukemia. Animals were cytopenic, having reduced numbers of erythrocytes, monocytes and granulocytes. Suspension culture confirmed that EAR-2 inhibits granulocytic and monocytic differentiation, while knockdown induced granulocytic differentiation. We observed a reduction in the number of BFU-E and CFU-GM colonies and the size of erythroid and myeloid colonies. Serial replating of transduced hematopoietic colonies revealed extended replating potential in EAR-2-overexpressing BM, while knockdown reduced re-plating ability. EAR-2 functions by recruitment of histone deacetylases, and inhibition of differentiation in 32D cells is dependent on the DNA binding domain.

Conclusions

This data suggest that NR2F6 inhibits maturation of normal BM in vitro and in vivo and that the NR2F6 transplant chimera system demonstrates key features of MDS, and could provide a mouse model for MDS.

Prognostic evaluation of ALIP and CD34 immunostaining in IPSS-R subgroups of myelodysplastic syndromes

In order to evaluate the prognostic value of abnormal localisation of immature precursors (ALIP) and CD34 immunostaining in myelodysplastic syndromes (MDS), bone marrow histopathological features in 187 MDS patients were retrospectively analysed and the prognostic significance of ALIP and CD34 immunostaining on overall survival (OS) and progression to leukaemia-free survival (PFS) in total patients and different Revised-International Prognostic Scoring System (IPSS-R) subgroups were evaluated. In univariate analysis, age ≥60, ALIP, ≥5% CD34+ cells, CD34+ clusters and IPSS-R subgroups were associated with shorter OS (p = 0.027, p < 0.0001, p < 0.0001, p < 0.0001, p < 0.0001, respectively) and PFS (p = 0.029, p = 0.006, p = 0.001, p < 0.0001, p < 0.0001, respectively). Haemoglobin level had a significant impact on OS (p < 0.0001) but not on PFS (p = 0.054). In multivariate analysis, ALIP, haemoglobin level, ≥5% CD34+ cells, CD34+ clusters and IPSS-R subgroups had independent influence on OS (p = 0.012, p < 0.0001, p = 0.010, p < 0.0001, p < 0.0001, respectively), while only CD34+ clusters and IPSS-R subgroups had independent influence on PFS (p < 0.0001, p = 0.016, respectively). In different IPSS-R subgroups, ALIP could maintain its prognostic impact in lower IPSS-R risk subgroups, while ≥5% CD34+ cells and CD34+ clusters had significant prognostic value in both lower and intermediate-higher IPSS-R risk subgroups. Therefore, CD34+ clusters showed more important prognostic impact on survival and progression to leukaemia.

Revisiting the case for genetically engineered mouse models in human myelodysplastic syndrome research

Much-needed attention has been given of late to diseases specifically associated with an expanding elderly population. Myelodysplastic syndrome (MDS), a hematopoietic stem cell-based blood disease, is one of these. The lack of clear understanding of the molecular mechanisms underlying the pathogenesis of this disease has hampered the development of efficacious therapies, especially in the presence of comorbidities. Mouse models could potentially provide new insights into this disease, although primary human MDS cells grow poorly in xenografted mice. This makes genetically engineered murine models a more attractive proposition, although this approach is not without complications. In particular, it is unclear if or how myelodysplasia (abnormal blood cell morphology), a key MDS feature in humans, presents in murine cells. Here, we evaluate the histopathologic features of wild-type mice and 23 mouse models with verified myelodysplasia. We find that certain features indicative of myelodysplasia in humans, such as Howell-Jolly bodies and low neutrophilic granularity, are commonplace in healthy mice, whereas other features are similarly abnormal in humans and mice. Quantitative hematopoietic parameters, such as blood cell counts, are required to distinguish between MDS and related diseases. We provide data that mouse models of MDS can be genetically engineered and faithfully recapitulate human disease.

Bone Marrow Examination for Unexplained Cytopenias Reveals Nonspecific Findings in Patients With Collagen Vascular Disease

Context.—Collagen vascular diseases are frequently included in the differential diagnosis for unexplained cytopenias and often prompt a bone marrow biopsy in this patient population to exclude malignancy. Few large-scale studies have characterized the bone marrow morphology in patients with collagen vascular disease, and most are limited to systemic lupus erythematosus or rheumatoid arthritis.

Objective.—To identify morphologic and immunohistochemical abnormalities specific to each of a wide range of collagen vascular disease cases.

Design.—We examined 102 cases of collagen vascular disease and 38 controls and evaluated the complete blood count, peripheral blood morphology, bone marrow morphology, as well as immunohistochemical staining, for numerous cell lineages.

Results.—Bone marrow findings, including abnormalities such as lymphoid aggregates, lipogranulomas, or abnormal localization of immature precursors, were not significantly different as compared to the control group.

Conclusions.—Bone marrow examination in patients with collagen vascular disease with cytopenias seldom provides new information. Caution should be exercised in interpreting morphologic findings suggestive of myelodysplasia since these are of a reactive nature in up to 27% of patients with collagen vascular disease. In a cost-effective diagnostic strategy, successful utilization may favor postponing a bone marrow biopsy while a more standardized autoimmune diagnostic panel is being performed.

Diagnosis of myelodysplastic syndromes in cytopenic patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

Diagnosis of Myelodysplastic Syndromes in Cytopenic Patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

The myelodysplastic syndromes: diagnosis and treatment

The myelodysplastic syndromes (MDSs) are common, acquired, clinically challenging hematologic conditions that are characterized by bone marrow failure and a risk of progression to acute leukemia. These disorders can arise de novo, especially in elderly patients or, less often, as a consequence of prior chemotherapy or radiotherapy for an unrelated disease. The MDS classification systems were revised recently and updated. These refined classification and prognostic schemes help stratify patients by their risk of leukemia progression and death; this knowledge can help clinicians select appropriate therapy. Although many treatments for MDS have been proposed and evaluated, at present, only hematopoietic stem cell transplantation offers any real hope for cure, and no available therapy beyond general supportive care offers benefit to more than a minority of patients. However, recent clinical trials enrolling patients with MDS have reported encouraging results with use of newer drugs, including lenalidomide, decitabine, and darbepoetin alfa. Other exciting treatment regimens are being tested. Here, we present a contemporary, practical clinical approach to the diagnosis and risk-stratified treatment of MDS. We review when to suspect MDS, detail how to evaluate patients who may have a form of the condition, explain key features of treatments that are currently available in the United States, and summarize a general, common-sense therapeutic approach to patients with MDS.

Clinical, haematological and histomorphological profile of adult myelodysplastic syndrome. Study of 96 cases in a single institute

Myelodysplastic syndromes (MDS) are clonal haematopoietic stem cell disorders characterised by ineffective and dyspoietic haematopoiesis. The natural history of these disorders is variable and ranges from a chronic to a rapid course towards leukaemic progression. Certain shortcomings have been encountered in the French-American-British (FAB) classification over the years, and therefore there is a need for an alternative method of classification. In 1999, the WHO published a revised classification of MDS. In the present study, we have analysed the clinical, haematological and histomorphological features in 96 cases of primary MDS seen in the department of haematology at the All India Institute of Medical Sciences (AIIMS) over a 6-yr period (1996-2001). Both FAB and WHO classifications have been incorporated and the Bournemouth scoring system applied in each case at presentation. The Bournemouth scoring system, in the absence of a cytogenetic study, offers a good prognostication and long-term survival estimate.

Bone marrow biopsy: interpretive guidelines for the surgical pathologist

Ideally, the bone marrow core biopsy should be reviewed with knowledge of the clinical history, complete blood count, and findings in the peripheral blood and bone marrow aspirate smears. However, for a variety of reasons, the pathologist may receive the core biopsy and aspirate clot section without all of this information. Although this approach is not optimal, a great deal of valuable information can be generated from these specimens. Over the past 20 years, there has been considerable progress in the fields of flow cytometric analysis, immunohistochemistry, and molecular diagnostic studies that can be performed on smears or extracted DNA from paraffin embedded tissue. These modalities have augmented and refined diagnostic criteria formerly ascertained by light microscopy, cytochemistry, and cytogenetics. This is particularly true of some myeloid and lymphoreticular neoplasms where a collaborative and multidisciplinary approach to the diagnosis has become necessary. Despite this growing complexity and dependence on newer methodologies, the traditional role of histopathology in evaluating the bone marrow biopsy remains as important as it has been in the past. In this review, we focus on contemporary practices and expectations for interpreting bone marrow biopsies and clot sections.

The myelodysplastic syndromes: morphology, risk assessment, and clinical management (2002)

The Myelodysplastic Syndromes (MDS) represent a group of potentially acute myeloid leukemic disorders. There exists a delicate balance between increased apoptosis and proliferation of the leukemic hematopoietic stem cell that permits many patients to survive for years. When the balance shifts towards proliferation AML develops with a poor outcome for most but not all patients. I will review the latest proposals from the W.H.O. in classification, including pediatric MDS, prognostic factors and response criteria. Then I will present a strategy for the management of low risk patients with supportive care or low intensity treatment (cytokines, Immune modulation, anti-VEGF agents) and finally chemotherapy and intensive therapy with auto and allo BMT.

Dual colour FISH in paraffin wax embedded bone trephines for identification of numerical and structural chromosomal abnormalities in acute myeloid leukaemia and myelodysplasia

AIMS/BACKGROUND

The advent of new treatments for haematological malignancies has led to the need for a correlation between cytogenetic and morphological abnormalities. This study aimed to achieve this by the application of interphase cytogenetics to marrow trephine sections, a technique not previously reported for formalin fixed, paraffin wax embedded trephine biopsies.

METHODS

Dual colour fluorescence in situ hybridisation (FISH) was used to detect numerical and structural abnormalities in routinely processed paraffin wax embedded trephine biopsies. Three cases with t(8;21) and three with t(15;17) were analysed, together with a case of trisomy 8. Chromosome specific probes were hybridised with sections and disclosed by fluorescein isothiocyanate and rhodamine/Texas red labelled antidigoxigenin and antibiotin amplification; translocations were identified by colocalisation of probes using a double wavelength bypass filter.

RESULTS

A translocation signal was present in 12% and 11.5% of the cells counted in the t(8;21) and t(15;17) cases, respectively, but in none of the normal controls (p < 0.001). In the case of trisomy 8, 9% of the cells counted contained three hybridisation signals for chromosome 8, whereas no cell contained more than two in the normal control (p < 0.001).

CONCLUSIONS

This technique is useful for archived routinely processed material, enabling it to be used as a research tool but also, and perhaps more importantly, in clinical practice.

Pathogenetic Aspects of Myelodysplastic Syndromes

The myelodysplastic syndromes (MDS) are acquired clonal disorders of the bone marrow. They were clearly defined in morphological terms by the French-American-British (FAB) group in 1982, as five conditions each with their own diagnostic criteria, but with the shared characteristics of ineffective blood cell production in one or more cell line, morphological dysplasia and a variable propensity to evolve into acute myeloid leukaemia (AML). In clinical practice patients typically present in old age with macrocytic anaemia, cytopenias, monocytosis and accumulation of marrow blast cells leading in time to fatal bone marrow failure or AML. To date treatment is unable to alter the natural history of MDS except in those few individuals who are able to undergo allogeneic progenitor cell transplantation.

CD34 immunohistochemistry of bone marrow biopsies: prognostic significance in primary myelodysplastic syndromes

Bone marrow (BM) biopsies from 58 patients with primary myelodysplastic syndrome (MDS) were studied using QBEND10, a monoclonal antibody that recognizes the human progenitor CD34 antigen in routine aldehyde-fixed paraffin-embedded samples. FAB subtypes were RA (5 patients), RARS (9 patients), RAEB (20 patients), RAEBt (11 patients), CMML (3 patients). In addition, 10 MDS patients whose BM biopsies revealed heavy reticulum fibrosis were included. Neither the percentage of CD34+ cells nor the number of CD34+ aggregates (defined as clusters of 3 or more cells) correlated with the presence and morphology of abnormal localizations of immature precursors (ALIP). When all patients were considered, median survival was 69 months in those with less, and 25 months in patients with more than 1% CD34+ cells (P < 0.05). Median survival was 15 months in patients with CD34+ aggregates and 41 months in those without aggregates (P = 0.0017). When RAEB patients were considered median survival was 41 months in those with less than 1%, and 29 months in those with more than 1% CD34+ cells; the 4-year survival chance was 45% in the former and 18.3% in the latter group. Therefore, CD34 positivity of more than 1% identifies a subset of RAEB patients with shorter life expectancy. In addition, leukemic transformation was observed in 11 of 35 patients (31%) with no CD34 aggregates, but in 14 of 23 patients (60%) with aggregates (P < 0.05). CD34 immunostaining, which can be easily performed on routinely prepared BM biopsies, was found to be a powerful prognostic tool for predicting survival and outcome in MDS.

Prognostic relevance of histological findings on bone marrow biopsy in myelodysplastic syndromes

Bone marrow biopsy (BMB) has aroused growing interest as a possible aid in the diagnostic and prognostic evaluation of myelodysplastic syndromes (MDS). Previous reports have pointed out that MDS patients with blastic aggregates or severe bone marrow (BM) fibrosis are characterized by a worse clinical outcome. BMBs of 106 MDS patients were retrospectively reviewed, and relationships among the different histological parameters as well as clinicopathological correlations were looked for. Three patterns of BM blastic infiltration ("diffuse," "cluster," and "large") were recognized. Overt leukemic transformation and overall survival were selected as prognostic end points. BM infiltration was "diffuse" in 18, "cluster" in 48, and "large" in 40 cases. RAEB-t patients accounted for about half of the "large" cases, and none had a "diffuse" pattern (p < 0.01). Nineteen patients showed extensive BM fibrosis; most of them were characterized by "cluster" blastic infiltration and megakaryocyte hyperplasia. Leukemic transformation occurred in 67% of "large" cases (p< 0.001) and in none of the "cluster" cases with severe BM fibrosis (p < 0.01); however, survival was equally poor in these two groups because of early leukemic transformation (large cases) and BM failure (cluster cases). The FAB classification did not significantly correlate with prognosis. Patients with "cluster" BM infiltration and severe fibrosis can be regarded as a true separate MDS subset characterized by unique clinicopathological and prognostic features. Because of the subacute clinical behavior of most cases, and the poor performance status of many elderly patients, there is still controversy as to the best therapeutic approach in MDS. Histological analysis allowed two groups of MDS patients to be identified, both characterized by poor life expectancy, who could benefit from early aggressive chemotherapy.

Bone marrow histology. 3: Value of bone marrow core biopsy in acute leukaemia, myelodysplastic syndromes, and chronic myeloid leukaemia

Images