Potential role of Notch signalling in CD34+ chronic myeloid leukaemia cells: cross-talk between Notch and BCR-ABL.

Notch signalling is critical for haemopoietic stem cell (HSC) self-renewal and survival. The role of Notch signalling has been reported recently in chronic myeloid leukaemia (CML) - a stem cell disease characterized by BCR-ABL tyrosine kinase activation. Therefore, we studied the relationship between BCR-ABL and Notch signalling and assessed the expression patterns of Notch and its downstream target Hes1 in CD34+ stem and progenitor cells from chronic-phase CML patients and bone marrow (BM) from normal subjects (NBM).

Cell-surface Notch1 expression identifies a primitive phenotype within CD34+ CD38- haematopoietic cells.

Objective: Notch signalling has been implicated in haematopoietic stem cell self-renewal. Although several studies have tested the effect of activating or inhibiting the Notch signalling pathway in stem cells, no study has yet determined the functional differences associated with expressing Notch1. The aims of this study were to characterise the expression of human cell-surface Notch1 in cord blood (CB) CD34(+) cells and to study the function of Notch in CD34(+) cells in vitro.

CD154-CD40 interactions in the control of murine B cell hematopoiesis.

Interactions between CD40 and CD154 play a very important role in control of immune responses, including the delivery of T cell help to B cells and other APCs. Thus far, there has been no role postulated for CD40-CD154 interactions in hematopoiesis. We show here that CD40 is expressed on murine pro-B cells and that its ligation enhances pro-B cell proliferation in vitro and in vivo.

Notch protection against apoptosis in T-ALL cells mediated by GIMAP5.

Recent studies have highlighted the role of Notch signalling in the development of T cell acute lymphoblasic leukaemia (T-ALL). Over-expression of Notch3 and gain of function mutations in the Notch1 gene have been reported. The aims of this study were to determine the effect of Notch signalling on apoptosis in human T-ALL cell lines and to identify targets of Notch signalling that may mediate this effect.

Identification of novel Notch target genes in T cell leukaemia.

Background: Dysregulated Notch signalling is believed to play an important role in the development and maintenance of T cell leukaemia. At a cellular level, Notch signalling promotes proliferation and inhibits apoptosis of T cell acute lymphoblastic leukaemia (T-ALL) cells. In this study we aimed to identify novel transcriptional targets of Notch signalling in the T-ALL cell line, Jurkat.

Recreating the hematon: microfabrication of artificial haematopoietic stem cell microniches in vitro using dielectrophoresis.

The hematon is a three-dimensional aggregate of cells which is able to produce all blood types. To be able to do this, it must be able to create within the cell aggregate a microenvironment which enables haematopoietic stem cell maintenance, renewal and differentiation. A first step was taken towards the creation of artificial hematopoietic stem cell microniches in vitro by the creation with dielectrophoresis of hemispherical cell aggregates of a height of 50-100 mum with a defined internal architecture similar to that of a putative hematon.

Notch induces cell cycle arrest and apoptosis in human erythroleukaemic TF-1 cells.

Objective: Notch signalling is known to promote hematopoietic stem cell self-renewal and to influence the lineage commitment decisions of progenitor cells. The purpose of this study was to investigate the mechanism of Notch-induced apoptosis in the erythroleukaemic cell line TF-1, and in primary cord blood CD34+ cells.

Methods: Retroviral constructs containing constitutively active forms of Notch as well as components of the Notch signalling pathway were used to transduce cells and their effect on cell cycle kinetics and apoptosis assayed by immunostaining for the S-phase marker Ki67 and Annexin V.

Tissue engineering with electric fields: immobilization of mammalian cells in multilayer aggregates using dielectrophoresis.

Positive dielectrophoresis can be used to create aggregates of animal cells with 3D architectures. It is shown that the cells, when pulled together into an aggregate by positive dielectrophoresis in a low-conductivity iso-osmotic solution, adhere to each other. The adherence of the cells to each other is non-specific and increases in time, and after 10-15 min becomes strong enough to immobilize the cells in the aggregate, enabling the ac electric field to be released, and the iso-osmotic buffer to be replaced by growth or other media.

Notch signaling induces apoptosis in primary human CD34+ hematopoietic progenitor cells.

Notch signaling regulates diverse cell fate decisions during development and is reported to promote murine hematopoietic stem cell (HSC) self-renewal. The purpose of this study was to define the functional consequences of activating the Notch signaling pathway on self-renewal in human HSCs. Subsets of human umbilical cord blood CD34(+) cells were retrovirally transduced with the constitutively active human Notch 1 intracellular domain (N1ICD).

Anti-CD28 has a potent adjuvant effect on the antibody response to soluble antigens mediated through CTLA-4 by-pass.

With the surge in potential new vaccines produced as recombinant proteins or synthetic peptides has come a pressing need to identify safe, potent immunological adjuvants to enhance immunogenicity of these antigens. CD28 is an important costimulatory molecule for T cells, and it has been shown that cell surface expression of its ligands, CD80 and CD86, can enhance cellular immune responses against tumor cells, however, these tumor cells do not normally express the ligands. Many new vaccines will be based upon soluble recombinant antigens, and in vaccination with these antigens CD80 and CD86 would normally be expressed on activated antigen-presenting cells and additional stimulation through CD28 would not be predicted to enhance responses further.