High prognostic impact of flow cytometric minimal residual disease detection in acute myeloid leukemia: data from the HOVON/SAKK AML 42A study.

Purpose: Half the patients with acute myeloid leukemia (AML) who achieve complete remission (CR), ultimately relapse. Residual treatment-surviving leukemia is considered responsible for the outgrowth of AML. In many retrospective studies, detection of minimal residual disease (MRD) has been shown to enable identification of these poor-outcome patients by showing its independent prognostic impact.

Implementation of flow cytometry in the diagnostic work-up of myelodysplastic syndromes in a multicenter approach: report from the Dutch Working Party on Flow Cytometry in MDS.

Flow cytometry (FC) is recognized as an important tool in the diagnosis of myelodysplastic syndromes (MDS) especially when standard criteria fail. A working group within the Dutch Society of Cytometry aimed to implement FC in the diagnostic work-up of MDS. Hereto, guidelines for data acquisition, analysis and interpretation were formulated.

Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes.

The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes.

Identification of distinct prognostic subgroups in low- and intermediate-1-risk myelodysplastic syndromes by flow cytometry.

The World Health Organization (WHO) classification contributes to refined classification and prognostication of myelodysplastic syndromes (MDSs). Flow cytometry might add significantly to diagnostic and prognostic criteria. Our analysis of bone marrow samples from 50 patients with MDS showed aberrant expression of differentiation antigens in the myelomonocytic lineage.

Subendothelial heparan sulfate proteoglycans become major L-selectin and monocyte chemoattractant protein-1 ligands upon renal ischemia/reperfusion.

Leukocyte infiltration into inflamed tissues is considered to involve sequential steps of rolling over the endothelium, adhesion, and transmigration. In this model, the leukocyte adhesion molecule L-selectin and its ligands expressed on inflamed endothelial cells are involved in leukocyte rolling. We show that upon experimental and human renal ischemia/reperfusion, associated with severe endothelial damage, microvascular basement membrane (BM) heparan sulfate proteoglycans (HSPGs) are modified to bind L-selectin and monocyte chemoattractant protein-1.

Reduced supportive capacity of bone marrow stroma upon chemotherapy is mediated via changes in glycosaminoglycan profile.

High dose chemotherapy and radiation have been found to impair the hematopoiesis-supportive capacity of bone marrow stroma. We now provide evidence for an important role of chemotherapy-induced alterations in stromal glycosaminoglycans (GAGs) in reduction of the supportive properties of stromal fibroblasts. Exposure to cytarabine resulted in a pronounced increase in hyaluronan, both in the cell/matrix (p<0.

Synaptotagmin 3 deficiency in T cells impairs recycling of the chemokine receptor CXCR4 and thereby inhibits CXCL12 chemokine-induced migration.

Synaptotagmins regulate vesicle trafficking and fusion of vesicles with membranes - processes that have been implicated in cell migration. We therefore hypothesized that synaptotagmins play a role in T-cell migration. Amongst synaptotagmins 1-11, we found synaptotagmin 3 (SYT3) to be the only one that is expressed in T cells.

Identification of L-selectin binding heparan sulfates attached to collagen type XVIII.

L-selectin is a C-type lectin expressed on leukocytes that is involved in both lymphocyte homing to the lymph node and leukocyte extravasation during inflammation. Known L-selectin ligands include sulfated Lewis-type carbohydrates, glycolipids, and proteoglycans. Previously, we have shown that in situ detection of different types of L-selectin ligands is highly dependent on the tissue fixation protocol used.

Bone marrow stromal proteoglycans regulate megakaryocytic differentiation of human progenitor cells.

Adherence of hematopoietic progenitor cells (HPCs) to stroma is an important regulatory step in megakaryocytic differentiation. However, the mechanisms through which megakaryocytic progenitors are inhibited by stroma are poorly understood. We examined the role of sulfated glycoconjugates, such as proteoglycans (PGs), on human bone marrow stroma (hBMS).

Integrin alpha4beta1 involvement in stromal cell-derived factor-1alpha-promoted myeloma cell transendothelial migration and adhesion: role of cAMP and the actin cytoskeleton in adhesion.

The chemokine stromal cell-derived factor-1alpha (SDF-1alpha) is expressed by bone marrow (BM) stromal cells and plays key roles in cell homing to and retention into the bone marrow. In multiple myeloma, blood-borne malignant plasma cells home to the BM and accumulate in contact with stromal cells, implicating myeloma cell migration across endothelium. Myeloma cells express the SDF-1alpha receptor CXCR4, as well as the integrin alpha4beta1, which mediates their attachment to BM stroma.

In vitro model for hematopoietic progenitor cell homing reveals endothelial heparan sulfate proteoglycans as direct adhesive ligands.

Proteoglycans (PGs) play a dominant role within the bone marrow (BM), but their role in homing of transplanted hematopoietic progenitor cells (HPC) is unknown. In this study, the role of heparan sulfate (HS) PGs on BM endothelium as adhesive structures was investigated. HPC (primary CD34+ cells and cell line KG-1a) were able to bind fractionated heparin, which could be competed by highly sulfated heparin/HS-glycosaminoglycans (GAGs).

Early apoptosis largely accounts for functional impairment of CD34+ cells in frozen-thawed stem cell grafts.

Quality assessment of stem cell grafts is usually performed by flow cytometric CD34(+) enumeration or assessment of clonogenic output of fresh material. Previously, we identified the occurrence of early apoptosis, not detectable with the permeability marker 7-amino actinomycin D (7-AAD), in purified frozen-thawed CD34(+) cells, using the vital stain Syto16. Syto(high)/7-AAD(-) cells were defined as viable, Syto16(low)/7-AAD(-) cells as early apoptotic and Syto16(low)/7-AAD(+) as dead.

Proteoglycans guide SDF-1-induced migration of hematopoietic progenitor cells.

Stromal cell-derived factor-1 (SDF-1) is a chemoattractant involved in hematopoietic progenitor cell (HPC) trafficking to the bone marrow. We studied the role of bone marrow endothelial proteoglycans (PGs) in SDF-1-mediated migration of HPC using a transwell assay. A subclone of progenitor cell line KG-1 (KG-1v) was used, displaying CXCR4-dependent transmigration.

Granulocyte colony-stimulating factor mobilized whole blood containing over 0.3 x 106/kg CD34+ cells is a sufficient graft in autologous transplantation for relapsed non-Hodgkin's lymphoma.

The feasibility of unprocessed, granulocyte colony-stimulating factor (G-CSF)-mobilized whole blood (WB) as an alternative stem cell source for autologous stem cell transplantation was studied. Forty-seven relapsed non-Hodgkin's lymphoma (NHL) patients entered the study. After two or three ifosfamide, methotrexate and etoposide (IMVP) courses, 1 l of G-CSF-mobilized WB was collected and stored refrigerated for 72 h.

Homing and clonogenic outgrowth of CD34(+) peripheral blood stem cells: a role for L-selectin?

Objective: After transplantation of hematopoietic stem cells, adhesion molecules play a major role in the multistep process of engraftment in which L-selectin is suggested to be of relevance. A positive correlation previously was found between the number of reinfused L-selectin(+) stem cells and platelet recovery. In the present study, we determined the role of L-selectin in different engraftment steps, i.