Isolation and characterization of endosteal niche cell populations that regulate hematopoietic stem cells.

The endosteal niche is critical for the maintenance of hematopoietic stem cells (HSCs). However, it consists of a heterogeneous population in terms of differentiation stage and function. In this study, we characterized endosteal cell populations and examined their ability to maintain HSCs.

Knockdown of N-cadherin suppresses the long-term engraftment of hematopoietic stem cells.

During postnatal life, the bone marrow (BM) supports both self-renewal and differentiation of hematopoietic stem cells (HSCs) in specialized microenvironments termed stem cell niches. Cell-cell and cell-extracellular matrix interactions between HSCs and their niches are critical for the maintenance of HSC properties. Here, we analyzed the function of N-cadherin in the regulation of the proliferation and long-term repopulation activity of hematopoietic stem/progenitor cells (HSPCs) by the transduction of N-cadherin shRNA.

Functional differences between two Tie2 ligands, angiopoietin-1 and -2, in regulation of adult bone marrow hematopoietic stem cells.

Objective: Angiopoietin-1 (Ang-1) plays a critical role in the maintenance of hematopoietic stem cells (HSCs) in the bone marrow (BM) through its binding to the Tie2 receptor. Ang-2, another Tie2 ligand, is known to be an antagonist of Tie2/Ang-1 signaling in angiogenesis; however, its function in regulation of HSCs remains unclear. Here, we investigated the functional differences between Ang-1 and Ang-2 in the maintenance of HSCs.

Niche regulation of hematopoietic stem cells in the endosteum.

During postnatal life, the bone marrow (BM) supports both the self-renewal and differentiation of hematopoietic stem cells (HSCs) in specialized niches. The interaction of HSCs with their niches also regulates the quiescence of HSCs. HSC quiescence is critical to ensure lifelong hematopoiesis and to protect the HSC pool from myelotoxic insult and premature exhaustion under conditions of hematopoietic stress.

Reconstitution activity of hypoxic cultured human cord blood CD34-positive cells in NOG mice.

Hematopoietic stem cells (HSCs) reside in hypoxic areas of the bone marrow. However, the role of hypoxia in the maintenance of HSCs has not been fully characterized. We performed xenotransplantation of human cord blood cells cultured in hypoxic or normoxic conditions into adult NOD/SCID/IL-2Rgamma(null) (NOG) mice.

Thrombopoietin/MPL signaling regulates hematopoietic stem cell quiescence and interaction with the osteoblastic niche.

Maintenance of hematopoietic stem cells (HSCs) depends on interaction with their niche. Here we show that the long-term (LT)-HSCs expressing the thrombopoietin (THPO) receptor, MPL, are a quiescent population in adult bone marrow (BM) and are closely associated with THPO-producing osteoblastic cells. THPO/MPL signaling upregulated beta1-integrin and cyclin-dependent kinase inhibitors in HSCs.

Fbxw7 acts as a critical fail-safe against premature loss of hematopoietic stem cells and development of T-ALL.

Common molecular machineries between hematopoietic stem cell (HSC) maintenance and leukemia prevention have been highlighted. The tumor suppressor Fbxw7 (F-box and WD-40 domain protein 7), a subunit of an SCF-type ubiquitin ligase complex, induces the degradation of positive regulators of the cell cycle. We demonstrate that inactivation of Fbxw7 in hematopoietic cells causes premature depletion of HSCs due to active cell cycling and p53-dependent apoptosis.

Preservation of hematopoietic stem and progenitor cells from umbilical cord blood stored in a surface derivatized with polymer nanosegments.

Tissue culture flasks were prepared with immobilized amphiphilic nanosegments of Pluronic F68 and F127, polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO triblock copolymers, on their surfaces. These so-called "Pluronic-immobilized flasks" were used for the preservation of hematopoietic stem and progenitor cells from umbilical cord blood. The expression ratio of surface markers (CD34) on hematopoietic stem and progenitor cells stored in Pluronic-immobilized flasks was significantly higher than that in polystyrene tissue culture flasks or commercially available bioinert flasks (i.

Function of oxidative stress in the regulation of hematopoietic stem cell-niche interaction.

During postnatal life, the bone marrow (BM) supports both self-renewal and differentiation of hematopoietic stem cells (HSCs) in specialized niches, such as osteoblastic niche and vascular niche. A cell adhesion molecule, N-cadherin expressed in the HSCs and osteoblasts, suggesting that homophylic binding of N-cadherin induce the adhesion of HSCs to the niche cells. Here we demonstrate that an anti-cancer drug, 5-fuluorouracil induces reactive oxygen species (ROS) in HSCs, which suppressed N-cadherin expression.

Separation of hematopoietic stem cells from human peripheral blood through modified polyurethane foaming membranes.

Cell separation from peripheral blood was investigated using polyurethane (PU) foam membranes having 5.2 mum pore size and coated with Pluronic F127 or hyaluronic acid. The permeation ratio of hematopoietic stem cells (CD34(+) cells) and lymphocytes through the membranes was lower than for red blood cells and platelets.

Separation of CD34+ cells from human peripheral blood through polyurethane foaming membranes.

Cell separation from peripheral blood was investigated using polyurethane (PU) foaming membranes and PU membranes (pore size, 5 or 12 mum) at different blood permeation speeds. Permeation ratio of hematopoietic stem cells (CD34(+) cells) through the PU membranes was the lowest among the blood cells at any blood permeation speed. This is thought to be because CD34(+) cells are more adhesive than red blood cells (RBCs), platelets, T cells, and B cells.

Bioinert surface of pluronic-immobilized flask for preservation of hematopoietic stem cells.

The bioinert materials on which cells do not proliferate, differentiate, nor de-differentiate should be useful for the culture and preservation of stem cells. The Pluronic F127, a triblock copolymer of ethylene oxide, and propylene oxide was activated using carbonyldiimidazole (CDI), and CDI-activated Pluronic was subsequently immobilized on the surface of a lysine-coated polystyrene tissue culture flask. The morphology of fibroblasts (L929 cells) on the Pluronic-immobilized flask was spherical, and did not show spreading behavior.

Synthesis and performance of amphiphilic copolymers for blood cell separation.

Three types of amphiphilic copolymers using n-butylmethacrylate (BMA) as a hydrophobic monomer, and each of N,N'-dimethylacrylamide (DMA), N-acryloylmorpholine (AMO), and N-vinylpyrrolidone (VP) as hydrophilic comonomers were synthesized for coating filters used to remove leukocytes. The influence of the amphiphilic property of the resulting filters, which were composed of nonwoven fabrics coated with the above copolymers, on leukocyte removal and platelet permeation through the filters from whole blood was investigated. The platelet permeation ratio through hydrophobic noncoated filters was only 0.

Cell separation between mesenchymal progenitor cells through porous polymeric membranes.

This study investigates the separation of two types of marrow stromal cells, KUSA-A1 osteoblasts and H-1/A preadipocytes, by filtration through various porous polymeric membranes. It was found that KUSA-A1 permeates better than H-1/A cells through 12-microm polyurethane foaming membranes. This appears to be due to the relatively smaller cell size of KUSA-A1 cells.